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1
Skrzypek, Ruth, and Richard Callaghan. "The “pushmi-pullyu” of resistance to chloroquine in malaria." Essays in Biochemistry 61, no. 1 (February 28, 2017): 167–75. http://dx.doi.org/10.1042/ebc20160060.
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Malarial infection continues to impart devastating health problems in the developing world. Treatment of malaria has involved chemotherapy since 168 BC, with the most prevalent and successful forms using plant alkaloids. Perhaps the greatest treatment success against malaria was by chloroquine, a synthetic derivative of the quinines found in the Cinchona tree bark. Chloroquine is able to kill parasites by interfering with haem metabolism in the parasite’s digestive vacuole. The widespread use of chloroquine predictably resulted in the development of drug-resistant malaria and the most highly implicated resistance mediators are the transporter proteins P-glycoprotein (P-gp) homologue 1 (P-gh1) and Plasmodium falciparum chloroquine-resistance transporter (PfCRT), which reside on the parasite’s digestive vacuole. The presence of PfCRT and P-gh1 on the vacuole membrane is analogous to the two-headed fictional creature known as the “Pushmi-Pullyu”. P-gh1 (Pushmi) increases influx of chloroquine into the vacuole, while PfCRT (Pullmi) causes efflux of chloroquine from the vacuole. This review describes how drug-resistant malarial parasites co-ordinate chloroquine distribution through adaptive mutations to promote their survival in the presence of this cytotoxic drug.
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Yusuf, Yenni. "ANTI-MALARIAL DRUG RESISTANCE." Majalah Kedokteran Andalas 37, no. 1 (May 3, 2015): 64. http://dx.doi.org/10.22338/mka.v37.i1.p64-69.2014.
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AbstrakTujuan studi ini adalah untuk menjelaskan mekanisme resistensi parasit malaria danusaha-usaha yang dapat dilakukan untuk menghadapi munculnya strain parasit yangresisten terhadap artemisinin. Metode yang digunakan adalah studi kepustakaan. ResistensiP.falciparum terhadap obat-obat anti malaria disebabkan oleh perubahan spontan yangterjadi pada beberapa gen seperti P.falciparum multi drug resistance1 (Pfmdr1), P.falciparumchloroquine transporter (Pfcrt), P.falciparum dihydropteroate synthase (Pfdhps), P.falciparumdihydrofolate reductase (Pfdhfr), and P.falciparum multidrug resistance-associated proteins(Pfmrp). Penyebaran resistensi tersebut dipengaruhi oleh tingkat transmisi di sebuah wilayah.WHO telah menjalankan usaha untuk menanggulangi penyebaran resistensi tersebut misalnyadengan merekomendasikan penghentian monoterapi artemisinin, dan pemberian anti malariasetelah konfirmasi laboratorium. Selain itu, perlu adanya penggunaan obat kombinasi, produksirejimen dosis tetap, dan pengembangan obat anti malaria baru. Kesimpulan dari hasil studiini ialah munculnya malaria resisten terhadap artemisinin akan menghambat usaha eradikasimalaria karena itu diperlukan usaha-usaha untuk menanggulanginya.AbstractThe objective of this study was to describe the development of anti-malarial drug resistanceof the parasites and the efforts taken to contain the emergence of artemisinin resistant malaria.This was a literature study. The development of resistance to anti-malarial drugs are due tospontaneous changes in certain genes such as of P.falciparum multi drug resistance1 (Pfmdr1),P.falciparum chloroquine resistance transporter (Pfcrt), P.falciparum dihydropteroate synthase(Pfdhps), P.falciparum dihydrofolate reductase (Pfdhfr), and P.falciparum multidrug resistanceassociatedproteins (Pfmrp). The spread of the resistance depends on the transmission ratewithin each area. WHO has established a global plan to contain the spread of this resistance,such as recommendation to withdraw artemisinin-based monotherapies and administrationof treatment after laboratory confirmation. In addition, administration of anti-malarial drugcombination, production of fixed dose regimen and development of new drugs are necessary.The Conclusion is emergence of artemisinin resistant malaria will threaten malaria eradicationthus some efforts are necessarily needed to contain it.Afiliasi penulis: Bagian Parasitologi Fakultas Kedokteran Universitas Hasanudin
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Mixson-Hayden, Tonya, Vidhan Jain, Andrea M. McCollum, Amanda Poe, Avinash C. Nagpal, Aditya P. Dash, Jonathan K. Stiles, Venkatachalam Udhayakumar, and Neeru Singh. "Evidence of Selective Sweeps in Genes Conferring Resistance to Chloroquine and Pyrimethamine in Plasmodium falciparum Isolates in India." Antimicrobial Agents and Chemotherapy 54, no. 3 (December 28, 2009): 997–1006. http://dx.doi.org/10.1128/aac.00846-09.
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ABSTRACT Treatment of Plasmodium falciparum is complicated by the emergence and spread of parasite resistance to many of the first-line drugs used to treat malaria. Antimalarial drug resistance has been associated with specific point mutations in several genes, suggesting that these single nucleotide polymorphisms can be useful in tracking the emergence of drug resistance. In India, P. falciparum infection can manifest itself as asymptomatic, mild, or severe malaria, with or without cerebral involvement. We tested whether chloroquine- and antifolate drug-resistant genotypes would be more commonly associated with cases of cerebral malaria than with cases of mild malaria in the province of Jabalpur, India, by genotyping the dhps, dhfr, pfmdr-1, and pfcrt genes using pyrosequencing, direct sequencing, and real-time PCR. Further, we used microsatellites surrounding the genes to determine the origins and spread of the drug-resistant genotypes in this area. Resistance to chloroquine was essentially fixed, with 95% of the isolates harboring the pfcrt K76T mutation. Resistant genotypes of dhfr, dhps, and pfmdr-1 were found in 94%, 17%, and 77% of the isolates, respectively. Drug-resistant genotypes were equally likely to be associated with cerebral malaria as with mild malaria. We found evidence of a selective sweep in pfcrt and, to a lesser degree, in dhfr, indicating high levels of resistance to chloroquine and evolving resistance to pyrimethamine. Microsatellites surrounding pfcrt indicate that the resistant genotypes (SVMNT) were most similar to those found in Papua New Guinea.
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Shujatullah, Fatima, Haris M. Khan, Abida Khatoon, Parvez A. Khan, and Mohammad Ashfaq. "In Vitro Chloroquine Resistance in Plasmodium falciparum Isolates from Tertiary Care Hospital." Malaria Research and Treatment 2012 (September 24, 2012): 1–4. http://dx.doi.org/10.1155/2012/538481.
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Chloroquine (CQ) has been the mainstay of treatment of malaria for decades. This cost-effective and safe drug has become ineffective for treatment of falciparum malaria in many parts of the world due to development of resistance by the parasite. In addition CQ is not gametocytocidal for P. falciparum and thus cannot block transmission. The extent of problem of chloroquine resistance in P. falciparum is increasing every year. The study was done in period of 2 years. A total of 5653 specimens were examined for malarial infection by employing different diagnostic modalities. Four hundred and thirty-five were found to be positive for P. falciparum by using different diagnostic techniques. All positive specimens were cultured on RPMI 1640 medium; only 108 were found to be culture positive. Sensitivity of isolates to chloroquine was done using Mark III WHO sensitivity plates. The prevalence of malaria infection was found 9.54% in 2010. There were schizont formation at 8 pmol/liter or more of chloroquine concentration in 26 isolates. The emergence of chloroquine (CQ) resistance pattern in Aligarh isolates increases. Antimalarial agents should be used with caution; monotherapies should be avoided.
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Wicht, Kathryn J., Sachel Mok, and David A. Fidock. "Molecular Mechanisms of Drug Resistance in Plasmodium falciparum Malaria." Annual Review of Microbiology 74, no. 1 (September 8, 2020): 431–54. http://dx.doi.org/10.1146/annurev-micro-020518-115546.
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Understanding and controlling the spread of antimalarial resistance, particularly to artemisinin and its partner drugs, is a top priority. Plasmodium falciparum parasites resistant to chloroquine, amodiaquine, or piperaquine harbor mutations in the P. falciparum chloroquine resistance transporter (PfCRT), a transporter resident on the digestive vacuole membrane that in its variant forms can transport these weak-base 4-aminoquinoline drugs out of this acidic organelle, thus preventing these drugs from binding heme and inhibiting its detoxification. The structure of PfCRT, solved by cryogenic electron microscopy, shows mutations surrounding an electronegative central drug-binding cavity where they presumably interact with drugs and natural substrates to control transport. P. falciparum susceptibility to heme-binding antimalarials is also modulated by overexpression or mutations in the digestive vacuole membrane–bound ABC transporter PfMDR1 ( P. falciparum multidrug resistance 1 transporter). Artemisinin resistance is primarily mediated by mutations in P. falciparum Kelch13 protein (K13), a protein involved in multiple intracellular processes including endocytosis of hemoglobin, which is required for parasite growth and artemisinin activation. Combating drug-resistant malaria urgently requires the development of new antimalarial drugs with novel modes of action.
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Summers, Kelly L. "A Structural Chemistry Perspective on the Antimalarial Properties of Thiosemicarbazone Metal Complexes." Mini-Reviews in Medicinal Chemistry 19, no. 7 (March 28, 2019): 569–90. http://dx.doi.org/10.2174/1389557518666181015152657.
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Malaria is a potentially life-threatening disease, affecting approx. 214 million people worldwide. Malaria is caused by a protozoan, Plasmodium falciparum, which is transmitted through the Anopheles mosquito. Malaria treatment is becoming more challenging due to rising resistance against the antimalarial drug, chloroquine. Novel compounds that target aspects of parasite development are being explored in attempts to overcome this wide-spread problem. Anti-malarial drugs target specific aspects of parasite growth and development within the human host. One of the most effective targets is the inhibition of hematin formation, either through inhibition of cysteine proteases or through iron chelation. Metal-thiosemicarbazone (TSC) complexes have been tested for antimalarial efficacy against drug-sensitive and drug-resistant strains of P. falciparum. An array of TSC complexes with numerous transition metals, including ruthenium, palladium, and gold has displayed antiplasmodial activity. Au(I)- and Pd(II)-TSC complexes displayed the greatest potency; 4-amino-7-chloroquine moieties were also found to improve antiplasmodial activity of TSCs. Although promising metal-TSC drug candidates have been tested against laboratory strains of P. falciparum, problems arise when attempting to compare between studies. Future work should strive to completely characterize synthesized metal-TSC structures and assess antiplasmodial potency against several drug-sensitive and drugresistant strains. Future studies need to precisely determine IC50 values for antimalarial drugs, chloroquine and ferroquine, to establish accurate standard values. This will make future comparisons across studies more feasible and potentially help reveal structure-function relationships. Investigations that attempt to link drug structures or properties to antiplasmodial mechanism(s) of action will aid in the design of antimalarial drugs that may combat rising drug resistance.
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Abdulla Mohammed, Walaa Salah, Kyakonye Yasin, N. S. Mahgoub, and Muzamil Mahdi Abdel Hamid. "Cross sectional study to determine chloroquine resistance among Plasmodium falciparum clinical isolates from Khartoum, Sudan." F1000Research 7 (February 20, 2018): 208. http://dx.doi.org/10.12688/f1000research.13273.1.
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Background: Malaria continues to present a global health threat; the World Health Organization (WHO) reported 214 million cases of malaria by the year 2015 with a death rate of 438000. Sudan is endemic to malaria with over 95% of malaria cases due to Plasmodium falciparum. Chloroquine is a well-established drug in the treatment of P. falciparum malaria although its use has declined since its introduction as the drug of choice in treatment of malaria in Sudan. The mechanism of resistance has been attributed to mutations in P. falciparum Chloroquine resistance transporter gene coding for a key food vacuole proteins. In current study we aimed at verifying the genetic cause of resistance to Chloroquine in field isolates of P. falciparum. Methods: Twenty P. falciparum cases were diagnosed from East Nile hospital in Khartoum and recruited in the investigation. Nested PCR was conducted to isolate mutation region in the PfCRT gene and the amplicons were sequenced using Sanger sequencing technique (Macrogen, Soule Korea). Results: 16/20 (80%) of the field isolates contained base pair mutation of codon 76 in the pfcrt gene thus being resistant to chloroquine treatment and only 4/20 (20%) did not contain such mutation. Conclusions: High treatment failures associated with Chloroquine treatment is evident of the high prevalence of mutant strains of P. falciparum field isolates thus suggesting the reduced relevance of Chloroquine as a treatment choice in the management of P. falciparum malaria.
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Maraka, Moureen, Hoseah M. Akala, Asito S. Amolo, Dennis Juma, Duke Omariba, Agnes Cheruiyot, Benjamin Opot, et al. "A seven-year surveillance of epidemiology of malaria reveals travel and gender are the key drivers of dispersion of drug resistant genotypes in Kenya." PeerJ 8 (March 12, 2020): e8082. http://dx.doi.org/10.7717/peerj.8082.
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Malaria drug resistance is a global public health concern. Though parasite mutations have been associated with resistance, other factors could influence the resistance. A robust surveillance system is required to monitor and help contain the resistance. This study established the role of travel and gender in dispersion of chloroquine resistant genotypes in malaria epidemic zones in Kenya. A total of 1,776 individuals presenting with uncomplicated malaria at hospitals selected from four malaria transmission zones in Kenya between 2008 and 2014 were enrolled in a prospective surveillance study assessing the epidemiology of malaria drug resistance patterns. Demographic and clinical information per individual was obtained using a structured questionnaire. Further, 2 mL of blood was collected for malaria diagnosis, parasitemia quantification and molecular analysis. DNA extracted from dried blood spots collected from each of the individuals was genotyped for polymorphisms in Plasmodium falciparum chloroquine transporter gene (Pfcrt 76), Plasmodium falciparum multidrug resistant gene 1 (Pfmdr1 86 and Pfmdr1 184) regions that are putative drug resistance genes using both conventional polymerase chain reaction (PCR) and real-time PCR. The molecular and demographic data was analyzed using Stata version 13 (College Station, TX: StataCorp LP) while mapping of cases at the selected geographic zones was done in QGIS version 2.18. Chloroquine resistant (CQR) genotypes across gender revealed an association with chloroquine resistance by both univariate model (p = 0.027) and by multivariate model (p = 0.025), female as reference group in both models. Prior treatment with antimalarial drugs within the last 6 weeks before enrollment was associated with carriage of CQR genotype by multivariate model (p = 0.034). Further, a significant relationship was observed between travel and CQR carriage both by univariate model (p = 0.001) and multivariate model (p = 0.002). These findings suggest that gender and travel are significantly associated with chloroquine resistance. From a gender perspective, males are more likely to harbor resistant strains than females hence involved in strain dispersion. On the other hand, travel underscores the role of transport network in introducing spread of resistant genotypes, bringing in to focus the need to monitor gene flow and establish strategies to minimize the introduction of resistance strains by controlling malaria among frequent transporters.
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Bushman, Mary, Lindsay Morton, Nancy Duah, Neils Quashie, Benjamin Abuaku, Kwadwo A. Koram, Pedro Rafael Dimbu, et al. "Within-host competition and drug resistance in the human malaria parasite Plasmodium falciparum." Proceedings of the Royal Society B: Biological Sciences 283, no. 1826 (March 16, 2016): 20153038. http://dx.doi.org/10.1098/rspb.2015.3038.
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Infections with the malaria parasite Plasmodium falciparum typically comprise multiple strains, especially in high-transmission areas where infectious mosquito bites occur frequently. However, little is known about the dynamics of mixed-strain infections, particularly whether strains sharing a host compete or grow independently. Competition between drug-sensitive and drug-resistant strains, if it occurs, could be a crucial determinant of the spread of resistance. We analysed 1341 P. falciparum infections in children from Angola, Ghana and Tanzania and found compelling evidence for competition in mixed-strain infections: overall parasite density did not increase with additional strains, and densities of individual chloroquine-sensitive (CQS) and chloroquine-resistant (CQR) strains were reduced in the presence of competitors. We also found that CQR strains exhibited low densities compared with CQS strains (in the absence of chloroquine), which may underlie observed declines of chloroquine resistance in many countries following retirement of chloroquine as a first-line therapy. Our observations support a key role for within-host competition in the evolution of drug-resistant malaria. Malaria control and resistance-management efforts in high-transmission regions may be significantly aided or hindered by the effects of competition in mixed-strain infections. Consideration of within-host dynamics may spur development of novel strategies to minimize resistance while maximizing the benefits of control measures.
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Neto, Zoraima, Marta Machado, Ana Lindeza, Virgílio do Rosário, Marcos L. Gazarini, and Dinora Lopes. "Treatment ofPlasmodium chabaudiParasites with Curcumin in Combination with Antimalarial Drugs: Drug Interactions and Implications on the Ubiquitin/Proteasome System." Journal of Parasitology Research 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/429736.
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Antimalarial drug resistance remains a major obstacle in malaria control. Evidence from Southeast Asia shows that resistance to artemisinin combination therapy (ACT) is inevitable. Ethnopharmacological studies have confirmed the efficacy of curcumin againstPlasmodiumspp. Drug interaction assays between curcumin/piperine/chloroquine and curcumin/piperine/artemisinin combinations and the potential of drug treatment to interfere with the ubiquitin proteasome system (UPS) were analyzed.In vivoefficacy of curcumin was studied in BALB/c mice infected withPlasmodium chabaudiclones resistant to chloroquine and artemisinin, and drug interactions were analyzed by isobolograms. Subtherapeutic doses of curcumin, chloroquine, and artemisinin were administered to mice, and mRNA was collected following treatment for RT-PCR analysis of genes encoding deubiquitylating enzymes (DUBs). Curcumin was found be nontoxic in BALB/c mice. The combination of curcumin/chloroquine/piperine reduced parasitemia to 37% seven days after treatment versus the control group’s 65%, and an additive interaction was revealed. Curcumin/piperine/artemisinin combination did not show a favorable drug interaction in this murine model of malaria. Treatment of mice with subtherapeutic doses of the drugs resulted in a transient increase in genes encoding DUBs indicating UPS interference. If curcumin is to join the arsenal of available antimalarial drugs, future studies exploring suitable drug partners would be of interest.
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Sá, Juliana M., Jason L. Chong, and Thomas E. Wellems. "Malaria drug resistance: new observations and developments." Essays in Biochemistry 51 (October 24, 2011): 137–60. http://dx.doi.org/10.1042/bse0510137.
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Drug-resistant micro-organisms became widespread in the 20th Century, often with devastating consequences, in response to widespread use of natural and synthetic drugs against infectious diseases. Antimalarial resistance provides one of the earliest examples, following the introduction of new medicines that filled important needs for prophylaxis and treatment around the globe. In the present chapter, we offer a brief synopsis of major antimalarial developments from two natural remedies, the qinghaosu and cinchona bark infusions, and of synthetic drugs inspired by the active components of these remedies. We review some contributions that early efficacy studies of antimalarial treatment brought to clinical pharmacology, including convincing documentation of atebrine-resistant malaria in the 1940s, prior to the launching of what soon became first-choice antimalarials, chloroquine and amodiaquine. Finally, we discuss some new observations on the molecular genetics of drug resistance, including delayed parasite clearances that have been increasingly observed in response to artemisinin derivatives in regions of South-East Asia.
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Sharma, Vijay. "Therapeutic Drugs for Targeting Chloroquine Resistance in Malaria." Mini-Reviews in Medicinal Chemistry 5, no. 4 (April 1, 2005): 337–51. http://dx.doi.org/10.2174/1389557053544029.
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Ibraheem, Zaid O., Roslaini Abd Majid, Hasidah Mohd Sidek, Sabariah Md Noor, Mun Fei Yam, Mohammad Faruq Abd Rachman Isnadi, and Rusliza Basir. "In Vitro Antiplasmodium and Chloroquine Resistance Reversal Effects of Andrographolide." Evidence-Based Complementary and Alternative Medicine 2019 (December 13, 2019): 1–16. http://dx.doi.org/10.1155/2019/7967980.
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The emergence of drug-resistant strains of Plasmodium falciparum is the worst catastrophe that has ever confronted the dedicated efforts to eradicate malaria. This urged for searching other alternatives or sensitizers that reverse chloroquine resistance. In this experiment, the potential of andrographolide to inhibit plasmodial growth and reverse CQ resistance was tested in vitro using the SYBRE green-1-based drug sensitivity assay and isobologram technique, respectively. Its safety level toward mammalian cells was screened as well against Vero cells and RBCs using MTT-based drug sensitivity and RBC hemolysis assays, respectively. Its effect against hemozoin formation was screened using β-hematin formation and heme fractionation assays. Its molecular characters were determined using the conventional tests for the antioxidant effect measurement and the in silico molecular characterization using the online free chemi-informatic Molinspiration software. Results showed that andrographolide has a moderate antiplasmodium effect that does not entitle it to be a substituent for chloroquine. Furthermore, andrographolide ameliorated the sensitivity of the parasite to chloroquine. Besides, it showed an indirect inhibitory effect against hemozoin formation within the parasite and augmented the chloroquine-induced inhibition of hemozoin formation. The study suggests that its chloroquine resistance reversal effect may be due to inhibition of chloroquine accumulation or due to its impact on the biological activity of the parasite. Overall, this in vitro study is a clue for the reliability of andrographolide to be added with chloroquine for reversal of chloroquine resistance and tolerance, but further in vivo studies are recommended to confirm this notion. In spite of its prominent and safe in vitro and in vivo growth inhibitory effect and its in vitro chloroquine resistance reversing effect, it is inapplicable to implement it in malaria chemotherapy to substitute chloroquine or to reverse its resistance.
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Ohrt, Colin, George D. Willingmyre, Patricia Lee, Charles Knirsch, and Wilbur Milhous. "Assessment of Azithromycin in Combination with Other Antimalarial Drugs against Plasmodium falciparum In Vitro." Antimicrobial Agents and Chemotherapy 46, no. 8 (August 2002): 2518–24. http://dx.doi.org/10.1128/aac.46.8.2518-2524.2002.
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ABSTRACT Initial field malaria prophylaxis trials with azithromycin revealed insufficient efficacy against falciparum malaria to develop azithromycin as a single agent. The objective of this in vitro study was to determine the best drug combination(s) to evaluate for future malaria treatment and prophylaxis field trials. In vitro, azithromycin was tested in combination with chloroquine against 10 representative Plasmodium falciparum isolates. Azithromycin was also assessed in combination with eight additional antimalarial agents against two or three multidrug-resistant P. falciparum isolates. Parasite susceptibility testing was carried out with a modification of the semiautomated microdilution technique. The incubation period was extended from the usual 48 h to 68 h. Fifty percent inhibitory concentrations (IC50s) were calculated for each drug alone and for drugs in fixed combinations of their respective IC50s (1:1, 3:1, 1:3, 4:1, 1:4, and 5:1). These data were used to calculate fractional inhibitory concentrations and isobolograms. Chloroquine-azithromycin studies revealed a range of activity from additive to synergistic interactions for the eight chloroquine-resistant isolates tested, while an additive response was seen for the two chloroquine-sensitive isolates. Quinine, tafenoquine, and primaquine were additive to synergistic with azithromycin, while dihydroartemisinin was additive with a trend toward antagonism. The remaining interactions appeared to be additive. These results suggest that a chloroquine-azithromycin combination should be evaluated for malaria prophylaxis and that a quinine-azithromycin combination should be evaluated for malaria treatment in areas of drug resistance.
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Peters, W. "The problem of drug resistance in malaria." Parasitology 90, no. 4 (April 1985): 705–15. http://dx.doi.org/10.1017/s003118200005232x.
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The resistance in human malaria is mainly of practical importance in relation to Plasmodium falciparum. Strains resistant not only to chloroquine but also to dihydrofolate reductase inhibitors, and even to potentiating combinations of these with sulphonamides or sulphones, are appearing in an ever increasing geographical area which now includes tropical Africa and India. Few new drugs are available or foreseen for the near future, mefloquine and artemisinine being the leading contenders. It is vital that all measures possible should be taken to protect such new compounds, their deployment in the form of judiciously selected combinations with other antimalarials being an essential procedure that should be followed. Drugs in new chemical classes and with different modes of action are still urgently needed. Reliance should not be placed on drugs alone to control malaria on a community basis.
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Niyibizi, Jean Baptiste, Peter G. Kirira, Francis T. Kimani, Fiona Oyatsi, and Joseph K. Ng’ang’a. "Chemical Synthesis, Efficacy, and Safety of Antimalarial Hybrid Drug Comprising of Sarcosine and Aniline Pharmacophores as Scaffolds." Journal of Tropical Medicine 2020 (April 9, 2020): 1–12. http://dx.doi.org/10.1155/2020/1643015.
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Malaria is a disease caused by protozoans transmitted to humans by infected female Anopheles mosquitoes. According to the WHO report of 2015, there were 214 million cases of malaria with 438,000 deaths worldwide. Ninety percent of world’s malaria cases occur in Africa, where the disease is recognized as a serious impediment to economic and social development. Despite advancement in malaria research, the disease continues to be a global problem, especially in developing countries. Currently, there is no effective vaccine for malaria control. In addition, although there are effective drugs for treatment of malaria, this could be lost to the drug resistance in different Plasmodium species. The most lethal form is caused by P. falciparum which has developed resistance to many chemotherapeutic agents and possibly to the current drugs of choice. Reducing the impact of malaria is a key to achieving the sustainable development goals which are geared toward combating the disease. Covalent bitherapy is a rational and logical way of drug design which entails joining a couple of molecules with individual intrinsic action into a unique agent, hence packaging dual activity into one hybrid. This suggests the need to develop new antimalarial drugs that are effective against malaria parasites based on the new mode of action, molecular targets, and chemical structures. In silico studies have shown that sarcosine is able to bind to unique plasmodia proteins (P. falciparum ATCase), whereas aniline can be a ligand to target protein (enoyl acyl carrier protein reductase), hence suppressing the progression of the disease. The main objective of this study was to synthesize and determine the efficacy and safety of antiplasmodial hybrid drug comprising the sarcosine and aniline derivative for management of plasmodial infections. The hybrid drug was synthesized by adding thionyl chloride to sarcosine to form acyl chloride which was then added to aniline to form sarcosine-aniline hybrid molecule. The IC50 of sarcosine-aniline hybrid was 44.80 ± 4.70 ng/ml compared with that of aniline derivative which was 22.86 ± 1.26 ng/ml. The IC50 of control drugs was 2.63 ± 0.38 ng/ml and 5.69 ± 0.39 ng/ml for artesunate and chloroquine, respectively. There was a significant difference between IC50 of sarcosine-aniline hybrid and aniline derivative (p<0.05). There was also a significant difference between sarcosine-aniline hybrid and standard drugs used to treat malaria including artesunate and chloroquine (p<0.05). The ED50 of sarcosine-aniline hybrid drug was 6.49 mg/kg compared with that of aniline derivative which was 3.61 mg/kg. The ED50 of control drugs was 3.56 mg/kg, 2.94 mg/kg, and 1.78 mg/kg for artesunate-aniline hybrid, artesunate, and chloroquine, respectively. There was a significant difference (p<0.05) between ED50 of sarcosine-aniline hybrid and both controls such as aniline derivative, artesunate, artesunate-aniline hybrid, and chloroquine. Cytotoxicity results revealed that sarcosine-aniline hybrid was safe to vero cells with a CC50 of 50.18 ± 3.53 μg/ml. Sarcosine-aniline hybrid was significantly less toxic compared with artesunate, chloroquine, and doxorubicin. Sarcosine-aniline hybrid was efficacious and safe to mice. Therefore, covalent bitherapy should be used in drug development for drug resistance mitigation.
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Talisuna, Ambrose O., Peter Bloland, and Umberto D’Alessandro. "History, Dynamics, and Public Health Importance of Malaria Parasite Resistance." Clinical Microbiology Reviews 17, no. 1 (January 2004): 235–54. http://dx.doi.org/10.1128/cmr.17.1.235-254.2004.
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SUMMARY Despite considerable efforts, malaria is still one of the most devastating infectious diseases in the tropics. The rapid spread of antimalarial drug resistance currently compounds this grim picture. In this paper, we review the history of antimalarial drug resistance and the methods for monitoring it and assess the current magnitude and burden of parasite resistance to two commonly used drugs: chloroquine and sulfadoxine-pyrimethamine. Furthermore, we review the factors involved in the emergence and spread of drug resistance and highlight its public health importance. Finally, we discuss ways of dealing with such a problem by using combination therapy and suggest some of the research themes needing urgent answers.
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Crandall, Ian, Jeffrey Charuk, and Kevin C. Kain. "Nonylphenolethoxylates as Malarial Chloroquine Resistance Reversal Agents." Antimicrobial Agents and Chemotherapy 44, no. 9 (September 1, 2000): 2431–34. http://dx.doi.org/10.1128/aac.44.9.2431-2434.2000.
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ABSTRACT Malaria-associated morbidity and mortality are increasing because of widespread resistance to one of the safest and least expensive antimalarials, chloroquine. The availability of an inexpensive agent that is capable of reversing chloroquine resistance would have a major impact on malaria treatment worldwide. The interaction of nonylphenolethoxylates (NPEs, commercially available synthetic surfactants) with drug-resistant Plasmodium falciparum was examined to determine if NPEs inhibited the growth of the parasites and if NPEs could sensitize resistant parasites to chloroquine. NPEs inhibited the development of the parasite when present in the low- to mid-micromolar range (5 to 90 μM), indicating that they possess antimalarial activity. Further, the presence of <10 μM concentrations of NPEs caused the 50% inhibitory concentrations for chloroquine-resistant lines to drop to levels (≤12 nM) observed for sensitive lines and generally considered to be achievable with treatment courses of chloroquine. Long-chain (>30 ethoxylate units) NPEs were found to be most active in P. falciparum, which contrasts with previously observed maximal activity of short-chain (∼9 ethoxylate units) NPEs in multidrug-resistant mammalian cell lines. NPEs may be attractive chloroquine resistance reversal agents since they are inexpensive and may be selectively directed againstP. falciparum without inhibiting mammalian tissue P glycoproteins. Antimalarial preparations that include these agents may prolong the effective life span of chloroquine and other antimalarials.
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Amin, Md Nurul, Mahmuda Yasmin, Marufa Zerin Akhtar, and Chowdhury Rafiqul Ahsan. "Molecular Pattern of Anti-malarial Drug Resistance of Plasmodium falciparum in Bangladeshi Troops Working in Endemic Areas of Bangladesh and Africa." Bangladesh Journal of Microbiology 37, no. 1 (June 30, 2020): 1–6. http://dx.doi.org/10.3329/bjm.v37i1.51202.
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Members of Bangladesh Armed Forces work in two different malaria endemic area, Chittagong Hill Tracts (CHT) in Bangladesh and Sub-Saharan countries in Africa. This under-recognized group remained unexplored for long in respect to drug resistant falciparum malaria they usually suffer from. In this study, a total of 252 ‘dried blood samples on filter paper’ were collected between November 2014 and February 2016, from Plasmodium falciparum positive Bangladeshi troops working in Chittagong Hill Tracts (CHT), Bangladesh and five Sub Saharan African Countries namely, Central African Republic (CAR), Democratic Republic of Congo (DRC), Liberia, Mali and Ivory Coast. After DNA extraction from all these samples (94 from Bangladesh and 138 from African countries), plasmodium species was confirmed by a nested PCR following standard protocol with minor modifications. Thereafter, a multiplex nested PCR followed by restriction fragment length polymorphism (RFLP) method was employed to investigate the presence of chloroquine resistance marker ‘K76T mutation’ in P. falciparum chloroquine resistance transporters (pfcrt) gene and lumifantrine and mefloquine resistance marker ‘N86Y mutation’ in P. falciparum multidrug resistance1 (pfmdr1) gene. The P. falciparum DNA was confirmed in 35 (37.23%) Bangladeshi and 45 (28.48%) African samples. The ‘pfcrt (K76T) mutation’ that confers resistance to chloroquine, was detected in 93.10% Bangladeshi and 29.27% African samples. The ‘pfmdr1 (N86Y) mutation’ that confers resistance to lumifantrine and mefloquine, was detected in 20.69% Bangladeshi and only 2.44% African samples. The higher prevalence of chloroquine resistance of P. falciparum in Bangladesh than in African countries revealed that possible withdrawal of chloroquine from endemic areas and also periodic molecular survey to monitor pf resistance to chloroquine, mefloquine, lumefantrine and artemisinin among these troops working in both endemic areas.
Bangladesh J Microbiol, Volume 37 Number 1 June 2020, pp 1-6
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Mockenhaupt, Frank P., Jürgen May, Yngve Bergqvist, Olusegun G. Ademowo, Peter E. Olumese, Adeyinka G. Falusi, Lars Großterlinden, Christian G. Meyer, and Ulrich Bienzle. "Concentrations of Chloroquine and Malaria Parasites in Blood in Nigerian Children." Antimicrobial Agents and Chemotherapy 44, no. 4 (April 1, 2000): 835–39. http://dx.doi.org/10.1128/aac.44.4.835-839.2000.
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ABSTRACT Consumption of chloroquine (CQ) and subtherapeutic drug levels in blood are considered to be widespread in areas where malaria is endemic. A cross-sectional study was performed with 405 Nigerian children to assess factors associated with the presence of CQ in blood and to examine correlations of drug levels with malaria parasite species and densities. Infections with Plasmodium species and parasite densities were determined by microscopy and PCR assays. Whole-blood CQ concentrations were measured by high-performance liquid chromatography. Plasmodium falciparum, P. malariae, and P. ovale were observed in 80, 16, and 9% of the children, respectively, and CQ was detected in 52% of the children. CQ concentrations were >17 and <100 nmol/liter in 25% of the children, 100 to 499 nmol/liter in 14% of the children, and ≥500 nmol/liter in 13% of the children. Young age, attendance at health posts, and absence of parasitemia were factors independently associated with CQ in blood. With increasing concentrations of CQ, the prevalence of P. falciparum infection and parasite densities decreased. However, at concentrations corresponding to those usually attained during regular prophylaxis (≥500 nmol/liter), 62% of children were still harboring P. falciparum parasites. In contrast, no infection with P. malariae and only one infection with P. ovale were observed in children with CQ concentrations of ≥100 nmol/liter. These data show the high prevalence of subcurative CQ concentrations in Nigerian children and confirm the considerable degree of CQ resistance in that country. Subtherapeutic drug levels are likely to further promote CQ resistance and may impair the development and maintenance of premunition in areas where malaria is endemic.
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Salomone, Salvatore, and Théophile Godfraind. "Drugs that reverse chloroquine resistance in malaria." Trends in Pharmacological Sciences 11, no. 11 (November 1990): 475–76. http://dx.doi.org/10.1016/0165-6147(90)90135-u.
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HOSHEN, M. B., W. D. STEIN, and H. GINSBURG. "Modelling the chloroquine chemotherapy of falciparum malaria: the value of spacing a split dose." Parasitology 116, no. 5 (May 1998): 407–16. http://dx.doi.org/10.1017/s0031182098002480.
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We have attempted to provide a rational basis for improving the protocols for chemotherapy of malaria. We model the regression of parasitaemia by Plasmodium falciparum, its subsequent elimination from the body, or recrudescence, for populations of cells treated with chloroquine. Our model assumes that the drug forms a complex with some receptor in the parasite and that parasites possessing this complex die at a defined rate. We take into account that chloroquine is eliminated exponentially from the body. We show how the parameters of the model can be derived from observations in the field. The model correctly predicts the effects of drug dose, degree of initial parasitaemia, rate of parasite multiplication and degree of drug resistance to chloroquine chemotherapy. The level of parasitaemia will reduce to a minimum at sufficiently high concentrations of chloroquine, but only if the parasitaemia is reduced to below that of 1 parasite per infected person will a cure of malaria be obtained. Otherwise, recrudescence will, sooner or later, occur. We show that, even for drug-resistant malaria, if 2 doses of chloroquine are given to a patient with an interval of some 10 days between them, parasites can be eliminated from the body without toxic levels of chloroquine being reached.
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Castro e Souza, Mateus Araújo, Naialy Fernandes Araújo Reis, Larissa de Souza Batista, Isabela da Costa César, Christian Fernandes, and Gerson Antônio Pianetti. "An Easy and Rapid Spectrophotometric Method for Determination of Chloroquine Diphosphate in Tablets." Current Pharmaceutical Analysis 16, no. 1 (December 20, 2019): 5–11. http://dx.doi.org/10.2174/1573412914666180730123426.
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Introduction: Malaria, an infectious disease caused by protozoa of the genus Plasmodium, is highly prevalent in the Brazilian Amazon. Chloroquine is the first-choice drug for the treatment of malaria caused by P. vivax and P. malariae. The humid and hot climate characteristic of the Brazilian endemic region favors drug degradation and modification of its biopharmaceutical properties, which may result in subtherapeutic dosage, formation of degradation products that can be toxic to humans and appearance of parasitic resistance. Thus, it is necessary to monitor the quality of chloroquine tablets. Materials and Methods: An analytical method was developed and validated to determine chloroquine content in tablets by ultraviolet spectrophotometry. The diluent consisted of 0.06 M monosodium phosphate buffer pH 6.8 and detection was performed at 343 nm. Results and Conclusion: The method proved to be linear in the range of 7.2 to 19.2 µg.mL-1, precise, accurate, selective, robust, and statistically equivalent to a liquid chromatographic method by the United States Pharmacopeia. The developed method was applied to determine chloroquine content in six batches of the drug. The evaluated batches were considered adequate for identification, assay, dissolution, disintegration and uniformity of dosage units, and were found to be inadequate in terms of friability.
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Kondrashin, A. V., E. V. Stepanova, L. F. Morozova, V. P. Sergiev, M. S. Maksimova, N. A. Turbabina, N. S. Malysheva, et al. "Artemether and imatinib combination therapy against malaria infection." Infekcionnye bolezni 19, no. 1 (2021): 139–43. http://dx.doi.org/10.20953/1729-9225-2021-1-139-143.
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Artemisinin-based combination therapy (ACT) is recommended by the World Health Organization (WHO) as the first and second line of treatment for uncomplicated malaria caused by P. falciparum, as well as for chloroquine-resistant P. vivax malaria. Despite the large number of antimalarial drugs, there is no any ideal drug, since each individual combination of drugs or monotherapy have their own limitations, ranging from their triple (activity) in relation to certain forms of the development of Plasmodium in the human body, side effects, toxicity and resistance. During the course of the study carried out, the most promising compound-candidate was selected – imatinib, which is currently used as targeted therapy for a number of oncological diseases. The objective of this work is to evaluate the efficacy of the combined use of imatinib and artemether in vivo studies on the human malarial model – the rodent malaria parasites Plasmodium berghei. Dut to the optimally selected treatment scheme, it was possible to reduce the dosage of imatinib twice – to 0,25 mg/kg, and that of artemether three times – to 33 mg/kg. The use of this scheme made it possible to considerably reduce the toxic effect of these drugs due to the potentiation of antimalarial effect. Key words: malaria, drug resistance, telomerase inhibitors, imatinib, chemotherapy of malaria
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Maiga, Hamma, Anastasia Grivoyannis, Issaka Sagara, Karim Traore, Oumar B. Traore, Youssouf Tolo, Aliou Traore, et al. "Selection of pfcrt K76 and pfmdr1 N86 Coding Alleles after Uncomplicated Malaria Treatment by Artemether-Lumefantrine in Mali." International Journal of Molecular Sciences 22, no. 11 (June 3, 2021): 6057. http://dx.doi.org/10.3390/ijms22116057.
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Background: Artemether-lumefantrine is a highly effective artemisinin-based combination therapy that was adopted in Mali as first-line treatment for uncomplicated Plasmodium falciparum malaria. This study was designed to measure the efficacy of artemether-lumefantrine and to assess the selection of the P. falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multi-drug resistance 1 (pfmdr1) genotypes that have been associated with drug resistance. Methods: A 28-day follow-up efficacy trial of artemether-lumefantrine was conducted in patients aged 6 months and older suffering from uncomplicated falciparum malaria in four different Malian areas during the 2009 malaria transmission season. The polymorphic genetic markers MSP2, MSP1, and Ca1 were used to distinguish between recrudescence and reinfection. Reinfection and recrudescence were then grouped as recurrent infections and analyzed together by PCR-restriction fragment length polymorphism (RFLP) to identify candidate markers for artemether-lumefantrine tolerance in the P. falciparum chloroquine resistance transporter (pfcrt) gene and the P. falciparum multi-drug resistance 1 (pfmdr1) gene. Results: Clinical outcomes in 326 patients (96.7%) were analyzed and the 28-day uncorrected adequate clinical and parasitological response (ACPR) rate was 73.9%. The total PCR-corrected 28-day ACPR was 97.2%. The pfcrt 76T and pfmdr1 86Y population prevalence decreased from 49.3% and 11.0% at baseline (n = 337) to 38.8% and 0% in patients with recurrent infection (n = 85); p = 0.001), respectively. Conclusion: Parasite populations exposed to artemether-lumefantrine in this study were selected toward chloroquine-sensitivity and showed a promising trend that may warrant future targeted reintroduction of chloroquine or/and amodiaquine.
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Nanyunja, Miriam, Juliet Nabyonga Orem, Frederick Kato, Mugagga Kaggwa, Charles Katureebe, and Joaquim Saweka. "Malaria Treatment Policy Change and Implementation: The Case of Uganda." Malaria Research and Treatment 2011 (September 19, 2011): 1–14. http://dx.doi.org/10.4061/2011/683167.
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Malaria due to P. falciparum is the number one cause of morbidity and mortality in Uganda where it is highly endemic in 95% of the country. The use of efficacious and effective antimalarial medicines is one of the key strategies for malaria control. Until 2000, Chloroquine (CQ) was the first-line drug for treatment of uncomplicated malaria in Uganda. Due to progressive resistance to CQ and to a combination of CQ with Sulfadoxine-Pyrimethamine, Uganda in 2004 adopted the use of ACTs as first-line drug for treating uncomplicated malaria. A review of the drug policy change process and postimplementation reports highlight the importance of managing the policy change process, generating evidence for policy decisions and availability of adequate and predictable funding for effective policy roll-out. These and other lessons learnt can be used to guide countries that are considering anti-malarial drug change in future.
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Spencer, Lilian M., Andreyna Peña-Quintero, Nieves Canudas, Inexis Bujosa, and Neudo Urdaneta. "Antimalarial effect of two photo-excitable compounds in a murine model with Plasmodium berghei (Haemosporida: Plasmodiidae)." Revista de Biología Tropical 66, no. 2 (May 24, 2018): 880. http://dx.doi.org/10.15517/rbt.v66i2.33420.
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Malaria represents a major health problem worldwide, affecting around 198 million people in 2016 according to WHO database. For decades, anti-malarial drug therapy has been used in the battle against this disease and its uncontrolled usage in endemic areas has developed the appearance of the drug resistance. Thus, it has emerged the necessity of finding new treatments that could be used as an alternative cure to malaria infection. The aim of this work was the evaluation of two photo-excitable compounds: Compound 1, which is (2E)-3-(4-dimethylamino-phenyl)-1-(4-imidazol-1-yl-phenyl)prop-2-en-1-one) and Compound 2, (1E,4E)-1-[4-(dimethylamino)phenyl]-5-(4-methoxyphenyl)-1,4-pentadiene-3-one) as possible anti-malaria drugs with Plasmodium berghei ANKA strain in BALB/c mice as murine model. Cytotoxicity effect was evaluated by a cell proliferation by colorimetry assay (MTS); and the drug incorporation into the parasite was assessed in vitro with Indirect Immunofluorescence Assay (IFA) to determine the localization of the drugs into the parasitized red blood cells (RBCs). Finally, the curative effect of compounds no-radiation (fundamental state) and ration drugs were evaluated by oral drug administration of this drugs in BALB/c mice and chloroquine was used as positive control. This curative effect was determined daily by the parasitemia percentage. The results showed that both compounds were cytotoxic in fundamental state. Furthermore, cytotoxic effect was increased after radiation into the Solar Simulator, and compound 2 was more cytotoxic than compound 1. Curative assays showed that both compounds in fundamental state were non effective as anti-malarial drug. However, in the curative assays in the mice treated with compound 2, when this was ration showed a survival rate of 33 % and a parasitemia percentage decrease in compare to compound 1. Although the compounds did not show a similar or better anti-malarial effect than Chloroquine, Compound 2 presented certain anti-malarial effect after solar radiation. Rev. Biol. Trop. 66(2): 880-891. Epub 2018 June 01.
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Boudhar, Aicha, Xiao Wei Ng, Chiew Yee Loh, Wan Ni Chia, Zhi Ming Tan, Francois Nosten, Brian W. Dymock, and Kevin S. W. Tan. "Overcoming Chloroquine Resistance in Malaria: Design, Synthesis, and Structure-Activity Relationships of Novel Hybrid Compounds." Antimicrobial Agents and Chemotherapy 60, no. 5 (March 7, 2016): 3076–89. http://dx.doi.org/10.1128/aac.02476-15.
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ABSTRACTResistance to antimalarial therapies, including artemisinin, has emerged as a significant challenge. Reversal of acquired resistance can be achieved using agents that resensitize resistant parasites to a previously efficacious therapy. Building on our initial work describing novel chemoreversal agents (CRAs) that resensitize resistant parasites to chloroquine (CQ), we herein report new hybrid single agents as an innovative strategy in the battle against resistant malaria. Synthetically linking a CRA scaffold to chloroquine produces hybrid compounds with restored potency toward a range of resistant malaria parasites. A preferred compound, compound 35, showed broad activity and good potency against seven strains resistant to chloroquine and artemisinin. Assessment of aqueous solubility, membrane permeability, andin vitrotoxicity in a hepatocyte line and a cardiomyocyte line indicates that compound 35 has a good therapeutic window and favorable drug-like properties. This study provides initial support for CQ-CRA hybrid compounds as a potential treatment for resistant malaria.
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Opsenica, Dejan Milos, and Bogdan Aleksandar Šolaja. "Artemisinins and synthetic peroxides as highly efficient antimalarials." Macedonian Journal of Chemistry and Chemical Engineering 31, no. 2 (December 20, 2012): 137. http://dx.doi.org/10.20450/mjcce.2012.50.
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Malaria is devastating disease and global public health problem, with nearly half world population exposed to risk. Illness is caused by five Plasmodium species, P. falciparum, P. ovale, P. vivax, P. malarie and P. knowlesi, from which P. falciparum is the most serious one causing cerebral malaria and is the major reason for malaria mortality. Vaccine against malaria is not expected in the near future and chemotherapy remains as most feasible alternative for treatment of the disease. The development of widespread drug-resistance to chloroquine (CQ), the most successful antimalarial drug up to date, has resulted in severe health issues for countries in malaria endemic regions. Organic peroxides, like artemisinins, 1,2,4-trioxanes, 1,2,4-trioxolanes, 1,2,4,5-tetraoxanes and their chimeras, are the best choice for malaria treatment nowadays. These therapeutics are fast acting, non-toxic, low costing and without reported data of parasite resistance. Stability of peroxide bonds enables synthetic comfort and resulting in diversity of synthesised structures. The most important classes of peroxide antimalarials with promising representatives are reviewed and possible mechanisms of action were presented in details.
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Kumar, Rakesh, Ritika Sharma, Inder Kumar, Pooja Upadhyay, Ankit Kumar Dhiman, Rohit Kumar, Rakesh Kumar, Rituraj Purohit, Dinkar Sahal, and Upendra Sharma. "Evaluation of Antiplasmodial Potential of C2 and C8 Modified Quinolines: in vitro and in silico Study." Medicinal Chemistry 15, no. 7 (October 14, 2019): 790–800. http://dx.doi.org/10.2174/1573406414666181015144413.
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Background: Malaria remains a common life-threatening infectious disease across the globe due to the development of resistance by Plasmodium parasite against most antimalarial drugs. The situation demands new and effective drug candidates against Plasmodium. Objectives: The objective of this study is to design, synthesize and test novel quinoline based molecules against the malaria parasite. Methods: C2 and C8 modified quinoline analogs obtained via C-H bond functionalization approach were synthesized and evaluated for inhibition of growth of P. falciparum grown in human red blood cells using SYBR Green microtiter plate based screening. Computational molecular docking studies were carried out with top fourteen molecules using Autodoc software. Results: The biological evaluation results revealed good activity of quinoline-8-acrylate 3f (IC50 14.2 µM), and the 2-quinoline-α-hydroxypropionates 4b (IC50 6.5 µM), 4j (IC50 5.5 µM) and 4g (IC50 9.5 µM), against chloroquine sensitive Pf3D7 strain. Top fourteen molecules were screened also against chloroquine resistant Pf INDO strain and the observed resistant indices were found to lie between 1 and 7.58. Computational molecular docking studies indicated a unique mode of binding of these quinolines to Falcipain-2 and heme moiety, indicating these to be the probable targets of their antiplasmodial action. Conclusion: An important finding of our work is the fact that unlike Chloroquine which shows a resistance Index of 15, the resistance indices for the most promising molecules studied by us were about one indicating equal potency against drug sensitive and resistant strains of the malaria parasite.
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Baird, J. Kevin. "Resistance to Therapies for Infection by Plasmodium vivax." Clinical Microbiology Reviews 22, no. 3 (July 2009): 508–34. http://dx.doi.org/10.1128/cmr.00008-09.
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SUMMARY The gravity of the threat posed by vivax malaria to public health has been poorly appreciated. The widely held misperception of Plasmodium vivax as being relatively infrequent, benign, and easily treated explains its nearly complete neglect across the range of biological and clinical research. Recent evidence suggests a far higher and more-severe disease burden imposed by increasingly drug-resistant parasites. The two frontline therapies against vivax malaria, chloroquine and primaquine, may be failing. Despite 60 years of nearly continuous use of these drugs, their respective mechanisms of activity, resistance, and toxicity remain unknown. Although standardized means of assessing therapeutic efficacy against blood and liver stages have not been developed, this review examines the provisional in vivo, ex vivo, and animal model systems for doing so. The rationale, design, and interpretation of clinical trials of therapies for vivax malaria are discussed in the context of the nuance and ambiguity imposed by the hypnozoite. Fielding new drug therapies against real-world vivax malaria may require a reworking of the strategic framework of drug development, namely, the conception, testing, and evaluation of sets of drugs designed for the cure of both blood and liver asexual stages as well as the sexual blood stages within a single therapeutic regimen.
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Co, Edgie-Mark A., Richard A. Dennull, Drew D. Reinbold, Norman C. Waters, and Jacob D. Johnson. "Assessment of Malaria In Vitro Drug Combination Screening and Mixed-Strain Infections Using the Malaria Sybr Green I-Based Fluorescence Assay." Antimicrobial Agents and Chemotherapy 53, no. 6 (April 6, 2009): 2557–63. http://dx.doi.org/10.1128/aac.01370-08.
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ABSTRACT Several drug development strategies, including optimization of new antimalarial drug combinations, have been used to counter malaria drug resistance. We evaluated the malaria Sybr green I-based fluorescence (MSF) assay for its use in in vitro drug combination sensitivity assays. Drug combinations of previously published synergistic (atovaquone and proguanil), indifferent (chloroquine and azithromycin), and antagonistic (chloroquine and atovaquone) antimalarial drug interactions were tested against Plasmodium falciparum strains D6 and W2 using the MSF assay. Fifty percent inhibitory concentrations (IC50s) were calculated for individual drugs and in fixed ratio combinations relative to their individual IC50s. Subsequent isobologram analysis and fractional inhibitory concentration determinations demonstrated the expected drug interaction pattern for each combination tested. Furthermore, we explored the ability of the MSF assay to examine mixed parasite population dynamics, which are commonly seen in malaria patient isolates. Specifically, the capacity of the MSF assay to discern between single and mixed parasite populations was determined. To simulate mixed infections in vitro, fixed ratios of D6 and W2 strains were cocultured with antimalarial drugs and IC50s were determined using the MSF assay. Dichotomous concentration curves indicated that the sensitive and resistant parasites composing the genetically heterogeneous population were detectable. Biphasic analysis was performed to obtain subpopulation IC50s for comparison to those obtained for the individual malaria strains alone. In conclusion, the MSF assay allows for reliable antimalarial drug combination screening and provides an important method to discern between homogenous and heterogeneous parasite populations.
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Yousif, M. A., and A. A. Adeel. "Antimalarials prescribing patterns in Gezira state: precepts and practices." Eastern Mediterranean Health Journal 6, no. 5-6 (December 15, 2000): 939–47. http://dx.doi.org/10.26719/2000.6.5-6.939.
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A longitudinal pharmacoepidemiological study on prescribing patterns of antimalarials was conducted in Gezira State, Sudan. Different core drug prescribing indicators were identified, measured and correlated. Chloroquine and quinine were the most frequently prescribed antimalaria drugs but in 44.7% of cases, the dosage was inappropriate and did not conform to standard regimens. Due to variable and unmonitored patterns of drug resistance, most medical practitioners in Sudan tend to follow their own protocols to treat severe cases of malaria rather than conforming to standard regimens. We attribute the emergence of a high rate of resistance to malaria chemotherapy to such practices. We recommend interventions to ensure rational prescribing, and call for the formulation of a national antimalarial drugs policy.
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Guiguemde, W. Armand, Nicholas H. Hunt, Jintao Guo, Annael Marciano, Richard K. Haynes, Julie Clark, R. Kiplin Guy, and Jacob Golenser. "Treatment of Murine Cerebral Malaria by Artemisone in Combination with Conventional Antimalarial Drugs: Antiplasmodial Effects and Immune Responses." Antimicrobial Agents and Chemotherapy 58, no. 8 (June 9, 2014): 4745–54. http://dx.doi.org/10.1128/aac.01553-13.
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ABSTRACTThe decreasing effectiveness of antimalarial therapy due to drug resistance necessitates constant efforts to develop new drugs. Artemisinin derivatives are the most recent drugs that have been introduced and are considered the first line of treatment, but there are already indications ofPlasmodium falciparumresistance to artemisinins. Consequently, drug combinations are recommended for prevention of the induction of resistance. The research here demonstrates the effects of novel combinations of the new artemisinin derivative, artemisone, a recently described 10-alkylamino artemisinin derivative with improved antimalarial activity and reduced neurotoxicity. We here investigate its ability to killP. falciparumin a high-throughputin vitroassay and to protect mice against lethal cerebral malaria caused byPlasmodium bergheiANKA when used alone or in combination with established antimalarial drugs. Artemisone effects againstP. falciparumin vitrowere synergistic with halofantrine and mefloquine, and additive with 25 other drugs, including chloroquine and doxycycline. The concentrations of artemisone combinations that were toxic against THP-1 cellsin vitrowere much higher than their effective antimalarial concentration. Artemisone, mefloquine, chloroquine, or piperaquine given individually mostly protected mice against cerebral malaria caused byP. bergheiANKA but did not prevent parasite recrudescence. Combinations of artemisone with any of the other three drugs did completely cure most mice of malaria. The combination of artemisone and chloroquine decreased the ratio of proinflammatory (gamma interferon, tumor necrosis factor) to anti-inflammatory (interleukin 10 [IL-10], IL-4) cytokines in the plasma ofP. berghei-infected mice. Thus, artemisone in combinations with other antimalarial drugs might have a dual action, both killing parasites and limiting the potentially deleterious host inflammatory response.
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Cowell, Annie N., and Elizabeth A. Winzeler. "The genomic architecture of antimalarial drug resistance." Briefings in Functional Genomics 18, no. 5 (May 23, 2019): 314–28. http://dx.doi.org/10.1093/bfgp/elz008.
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Abstract Plasmodium falciparum and Plasmodium vivax, the two protozoan parasite species that cause the majority of cases of human malaria, have developed resistance to nearly all known antimalarials. The ability of malaria parasites to develop resistance is primarily due to the high numbers of parasites in the infected person’s bloodstream during the asexual blood stage of infection in conjunction with the mutability of their genomes. Identifying the genetic mutations that mediate antimalarial resistance has deepened our understanding of how the parasites evade our treatments and reveals molecular markers that can be used to track the emergence of resistance in clinical samples. In this review, we examine known genetic mutations that lead to resistance to the major classes of antimalarial medications: the 4-aminoquinolines (chloroquine, amodiaquine and piperaquine), antifolate drugs, aryl amino-alcohols (quinine, lumefantrine and mefloquine), artemisinin compounds, antibiotics (clindamycin and doxycycline) and a napthoquinone (atovaquone). We discuss how the evolution of antimalarial resistance informs strategies to design the next generation of antimalarial therapies.
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Kirk, Kiaran, and Kevin J. Saliba. "Chloroquine resistance and the pH of the malaria parasite's digestive vacuole." Drug Resistance Updates 4, no. 6 (December 2001): 335–38. http://dx.doi.org/10.1054/drup.2002.0234.
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Tang, Yu-Qing, Qian Ye, He Huang, and Wei-Yi Zheng. "An Overview of Available Antimalarials: Discovery, Mode of Action and Drug Resistance." Current Molecular Medicine 20, no. 8 (December 29, 2020): 583–92. http://dx.doi.org/10.2174/1566524020666200207123253.
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: Malaria is one of the three most deadly infectious diseases in the world and seriously endangers human health and life. To reduce the public health burden of this disease, scientists have focused on the discovery and development of effective antimalarial drugs, from quinine and chloroquine to antifolates and artemisinin and its derivatives, which all play a profound role in the treatment of malaria. However, drugresistant strains of Plasmodium falciparum have emerged due to frequent use of antimalarials and have become increasingly resistant to existing antimalarial drugs, causing disastrous consequences in the world. In particular, artemisinin resistance is of greatest concern which was reported in 2008. Resistance to artenisinins has been a major obstacle for malaria control, and current efforts to curb artemisinin resistance have not been successful. Based on the current situation, it is urgent to develop more effective new antimalarials with distinct targets from conventional antimalarials in the world, which could facilitate to minimize the phenomenon of drug resistance. This review aims to summarize different kinds of antimalarial therapeutic efficacy, mechanisms of action and resistance, and proposes new solutions aiming towards further improvement of malaria elimination.
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Nzila, Alexis, Eddy Mberu, Pat Bray, Gilbert Kokwaro, Peter Winstanley, Kevin Marsh, and Steve Ward. "Chemosensitization of Plasmodium falciparum by Probenecid In Vitro." Antimicrobial Agents and Chemotherapy 47, no. 7 (July 2003): 2108–12. http://dx.doi.org/10.1128/aac.47.7.2108-2112.2003.
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ABSTRACT Resistance to drugs can result from changes in drug transport, and this resistance can sometimes be overcome by a second drug that modifies the transport mechanisms of the cell. This strategy has been exploited to partly reverse resistance to chloroquine in Plasmodium falciparum. Studies with human tumor cells have shown that probenecid can reverse resistance to the antifolate methotrexate, but the potential for reversal of antifolate resistance has not been studied in P. falciparum. In the present study we tested the ability of probenecid to reverse antifolate resistance in P. falciparum in vitro. Probenecid, at concentrations that had no effect on parasite viability alone (50 μM), was shown to increase the sensitivity of a highly resistant parasite isolate to the antifolates pyrimethamine, sulfadoxine, chlorcycloguanil, and dapsone by seven-, five-, three-, and threefold, respectively. The equivalent effects against an antifolate-sensitive isolate were activity enhancements of approximately 3-, 6-, 1.2-, and 19-fold, respectively. Probenecid decreased the level of uptake of radiolabeled folic acid, suggesting a transport-based mechanism linked to folate salvage. When probenecid was tested with chloroquine, it chemosensitized the resistant isolate to chloroquine (i.e., enhanced the activity of chloroquine). This enhancement of activity was associated with increased levels of chloroquine accumulation. In conclusion, we have shown that probenecid can chemosensitize malaria parasites to antifolate compounds via a mechanism linked to reduced folate uptake. Notably, this effect is observed in both folate-sensitive and -resistant parasites. In contrast to the activities of antifolate compounds, the effect of probenecid on chloroquine sensitivity was selective for chloroquine-resistant parasites (patent P407595GB [W. P. Thompson & Co., Liverpool, United Kingdom] has been filed to protect this intellectual property).
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Christensen, Søren Brøgger. "Natural Products That Changed Society." Biomedicines 9, no. 5 (April 26, 2021): 472. http://dx.doi.org/10.3390/biomedicines9050472.
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Until the end of the 19th century all drugs were natural products or minerals. During the 19th century chemists succeeded in isolating pure natural products such as quinine, morphine, codeine and other compounds with beneficial effects. Pure compounds enabled accurate dosing to achieve serum levels within the pharmacological window and reproducible clinical effects. During the 20th and the 21st century synthetic compounds became the major source of drugs. In spite of the impressive results achieved within the art of synthetic chemistry, natural products or modified natural products still constitute almost half of drugs used for treatment of cancer and diseases like malaria, onchocerciasis and lymphatic filariasis caused by parasites. A turning point in the fight against the devastating burden of malaria was obtained in the 17th century by the discovery that bark from trees belonging to the genus Cinchona could be used for treatment with varying success. However isolation and use of the active principle, quinine, in 1820, afforded a breakthrough in the treatment. In the 20th century the synthetic drug chloroquine severely reduced the burden of malaria. However, resistance made this drug obsolete. Subsequently artemisinin isolated from traditional Chinese medicine turned out to be an efficient antimalarial drug overcoming the problem of chloroquine resistance for a while. The use of synthetic analogues such as chloroquine or semisynthetic drugs such as artemether or artesunate further improved the possibilities for healing malaria. Onchocerciasis (river blindness) made life in large parts of Africa and South America miserable. The discovery of the healing effects of the macrocyclic lactone ivermectin enabled control and partly elimination of the disease by annual mass distribution of the drug. Also in the case of ivermectin improved semisynthetic derivatives have found their way into the clinic. Ivermectin also is an efficient drug for treatment of lymphatic filariasis. The serendipitous discovery of the ability of the spindle toxins to control the growth of fast proliferating cancer cells armed physicians with a new efficient tool for treatment of some cancer diseases. These possibilities have been elaborated through preparation of semisynthetic analogues. Today vincristine and vinblastine and semisynthetic analogues are powerful weapons against cancer diseases.
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BUCKLING, A., L. C. RANFORD-CARTWRIGHT, A. MILES, and A. F. READ. "Chloroquine increases Plasmodium falciparum gametocytogenesis in vitro." Parasitology 118, no. 4 (April 1999): 339–46. http://dx.doi.org/10.1017/s0031182099003960.
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Malaria parasites are capable of modulating the diversion of resources from asexual growth to the production of stages infective to mosquitoes (gametocytes). Increased rates of gametocytogenesis appear to be a general response to stress, both naturally encountered and novel. We have previously reported earlier and greater gametocytogenesis in response to subcurative antimalarial chemotherapy in the rodent malaria, Plasmodium chabaudi, in vivo. Using an immunofluorescent assay to detect parasites that had invaded red blood cell monolayers, we demonstrate a 5-fold increase in gametocytogenesis in the human malaria, P. falciparum, in vitro, in response to treatment with the antimalarial drug chloroquine. In all clones used, gametocytogenesis increased with increasing inhibition of asexual growth by chloroquine. Furthermore, there were clone differences in the relationship between stress and gametocyte production, implying the response was genetically variable. This was not, however, associated with chloroquine resistance. The epidemiological significance of these results is discussed.
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Abugri, James, Felix Ansah, Kwaku P. Asante, Comfort N. Opoku, Lucas A. Amenga-Etego, and Gordon A. Awandare. "Prevalence of chloroquine and antifolate drug resistance alleles in Plasmodium falciparum clinical isolates from three areas in Ghana." AAS Open Research 1 (December 3, 2018): 1. http://dx.doi.org/10.12688/aasopenres.12825.2.
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Background: The emergence and spread of resistance in Plasmodium falciparum to chloroquine (CQ) necessitated the change from CQ to artemisinin-based combination therapies (ACTs) as first-line drug for the management of uncomplicated malaria in Ghana in 2005. Sulphadoxine-pyrimethamine (SP) which was the second line antimalarial drug in Ghana, was now adopted for intermittent preventive treatment of malaria in pregnancy (IPTp). Methods: To examine the prevalence of molecular markers associated with CQ and antifolate drug resistance in Ghana, we employed restriction fragment length polymorphism polymerase chain reaction to genotype and compare single nucleotide polymorphisms (SNPs) in the P. falciparum chloroquine resistance transporter ( pfcrt, PF3D7_0709000), multidrug resistance ( pfmdr1, PF3D7_0523000), bifunctional dihydrofolate reductase-thymidylate synthase ( pfdhfr, PF3D7_0417200) and dihydropteroate synthase ( pfdhps, PF3D7_0810800) genes. Parasites were collected from children with malaria reporting to hospitals in three different epidemiological areas of Ghana (Accra, Kintampo and Navrongo) in 2012-2013 and 2016-2017. Results: The overall prevalence of the CQ resistance-associated pfcrt 76T allele was 8%, whereas pfmdr1 86Y and 184F alleles were present in 10.2% and 65.1% of infections, respectively. The majority of the isolates harboured the antifolate resistance-associated pfdhfr alleles 51I (83.4%), 59R (85.9 %) and 108N (90.5%). Pfdhps 437G and 540E were detected in 90.6% and 0.7% of infections, respectively. We observed no significant difference across the three study sites for all the polymorphisms except for pfdhps 437G, which was more common in Accra compared to Kintampo for the 2016-2017 isolates. Across both pfdhfr and pfdhps genes, a large proportion (61%) of the isolates harboured the quadruple mutant combination (I 51 R 59 N 108/ G 437). CQ resistance alleles decreased during the 12 years after CQ withdrawal, but an mediate SP resistance alleles increased. Conclusion: Surveillance of the prevalence of resistance alleles is necessary in monitoring the efficacy of antimalarial drugs.
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Pradines, Bruno, Adama Tall, Thierry Fusai, Andre Spiegel, Remi Hienne, Christophe Rogier, Jean Francois Trape, Jacques Le Bras, and Daniel Parzy. "In Vitro Activities of Benflumetol against 158 Senegalese Isolates of Plasmodium falciparum in Comparison with Those of Standard Antimalarial Drugs." Antimicrobial Agents and Chemotherapy 43, no. 2 (February 1, 1999): 418–20. http://dx.doi.org/10.1128/aac.43.2.418.
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ABSTRACT The 50% inhibitory concentration (IC50s) of benflumetol (range, 12.5 to 240 nM; mean, 55.1 nM) for 158 Senegalese isolates were evaluated. Ten isolates (6%) showed decreased susceptibility to benflumetol. Benflumetol was slightly more potent against chloroquine-resistant isolates (P < 0.025). No correlation or weak correlations in the responses to benflumetol and pyrimethamine, chloroquine, amodiaquine, artemether, quinine, and pyronaridine were observed, and these correlations are insufficient to suggest cross-resistance. Benflumetol may be an important alternative drug for the treatment of chloroquine-resistant malaria.
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Noisang, Chaturong, Wieland Meyer, Nongyao Sawangjaroen, John Ellis, and Rogan Lee. "Molecular Detection of Antimalarial Drug Resistance in Plasmodium vivax from Returned Travellers to NSW, Australia during 2008–2018." Pathogens 9, no. 2 (February 5, 2020): 101. http://dx.doi.org/10.3390/pathogens9020101.
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To monitor drug resistance in Plasmodium vivax, a multidrug resistance 1 (Pvmdr1) gene and a putative transporter protein (Pvcrt-o) gene were used as molecular markers for chloroquine resistance. The biomarkers, the dihydrofolate reductase (Pvdhfr) gene and the dihydropteroate synthetase (Pvdhps) gene, were also used for the detection of resistance to sulphadoxine-pyrimethamine (SP); this drug is often accidentally used to treat P. vivax infections. Clinical blood samples (n = 120) were collected from patients who had been to one of eight malaria-endemic countries and diagnosed with P. vivax infection. The chloroquine resistance marker, the Pvmdr1 gene, showed F976:L1076 mutations and L1076 mutation. A K10 insertion in the Pvcrt-o gene was also found among the samples successfully sequenced. A combination of L/I57:R58:M61:T117 mutations in the Pvdhfr gene and G383:G553 mutations in the Pvdhps gene were also observed. Mutations found in these genes indicate that drug resistance is present in these eight countries. Whether or not countries are using chloroquine to treat P. vivax, there appears to be an increase in mutation numbers in resistance gene markers. The detected changes in mutation rates of these genes do suggest that there is still a trend towards increasing P. vivax resistance to chloroquine. The presence of the mutations associated with SP resistance indicates that P. vivax has had exposure to SP and this may be a consequence of either misdiagnosis or coinfections with P. falciparum in the past.
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Chan, Li, Joshua Teo, Kevin Tan, Keitaro Sou, Wei Kwan, and Chi-Lik Lee. "Near Infrared Fluorophore-Tagged Chloroquine in Plasmodium falciparum Diagnostic Imaging." Molecules 23, no. 10 (October 14, 2018): 2635. http://dx.doi.org/10.3390/molecules23102635.
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Chloroquine was among the first of several effective drug treatments against malaria until the onset of chloroquine resistance. In light of diminished clinical efficacy of chloroquine as an antimalarial therapeutic, there is potential in efforts to adapt chloroquine for other clinical applications, such as in combination therapies and in diagnostics. In this context, we designed and synthesized a novel asymmetrical squaraine dye coupled with chloroquine (SQR1-CQ). In this study, SQR1-CQ was used to label live Plasmodium falciparum (P. falciparum) parasite cultures of varying sensitivities towards chloroquine. SQR1-CQ positively stained ring, mature trophozoite and schizont stages of both chloroquine–sensitive and chloroquine–resistant P. falciparum strains. In addition, SQR1-CQ exhibited significantly higher fluorescence, when compared to the commercial chloroquine-BODIPY (borondipyrromethene) conjugate CQ-BODIPY. We also achieved successful SQR1-CQ labelling of P. falciparum directly on thin blood smear preparations. Drug efficacy experiments measuring half-maximal inhibitory concentration (IC50) showed lower concentration of effective inhibition against resistant strain K1 by SQR1-CQ compared to conventional chloroquine. Taken together, the versatile and highly fluorescent labelling capability of SQR1-CQ and promising preliminary IC50 findings makes it a great candidate for further development as diagnostic tool with drug efficacy against chloroquine-resistant P. falciparum.
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Akanni, O. Ifeoluwa, J. O. Ehinmidu, and R. O. Bolaji. "Evaluation of antimalarial prescription pattern and susceptibility of Plasmodium falciparum isolates in Kaduna, Nigeria." International Journal of Biological and Chemical Sciences 13, no. 7 (February 13, 2020): 3398–410. http://dx.doi.org/10.4314/ijbcs.v13i7.34.
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Nigeria carries the highest burden of malaria in terms of morbidity and mortality. This is compounded by continuous resistance of Plasmodium falciparum to antimalarial drugs. This study was designed to evaluate the profile of malaria patients’ antimalarial drug prescription and in vitro susceptibility of P. falciparum isolates to commonly prescribed antimalarial drugs in Kaduna, Nigeria. Three years’ records of patients antimalarial drug prescriptions were collated (2013 to 2015) and the in vitro antimalarial agent susceptibility was determined for 28 clinical isolates using WHO Mark III microtest. Artemisinin-based combination therapy (ACT) was the most prescribed antimalarial for the period under review (92.3-93.7%). Among the ACTs, Artemether-lumefantrine was most prescribed. Of the 28 P. falciparum isolates evaluated, 3 (10.71%) were resistant to chloroquine with a median IC50 of 4.82μM (4.60-8.14μM), while five (17.86%) were resistant to mefloquine with a median IC50 of 25μM (10.3-41μM), 7(25.00%) to artemether with a median IC50 of 2.69μM (2.09-8.77μM), 9 (32.14%) to artesunate-mefloquine combination with a median IC50 of 9.0μM (7.98-35μM) and to artesunate, 11(39.29%) were resistant with a median IC50 of 2.4μM (1.56-5.65μM). This result shows a decline in resistance of P. falciparum to chloroquine compared to period prior to artemisinin-combination therapy as well as reduced susceptibility to artesunate and artemether. Further in vitro and in vivo monitoring will be required to inform antimalarial drug policy change.Keywords: Antimalarial, Artemisinin-combination therapy, resistance, susceptibility, microtest.
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Pickard, Amy L., Chansuda Wongsrichanalai, Anne Purfield, Deborah Kamwendo, Kathryn Emery, Christy Zalewski, Fumihiko Kawamoto, R. Scott Miller, and Steven R. Meshnick. "Resistance to Antimalarials in Southeast Asia and Genetic Polymorphisms in pfmdr1." Antimicrobial Agents and Chemotherapy 47, no. 8 (August 2003): 2418–23. http://dx.doi.org/10.1128/aac.47.8.2418-2423.2003.
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ABSTRACT Resistance to antimalarial drugs is a public health problem worldwide. Molecular markers for drug-resistant malaria, such as pfcrt and pfmdr1 polymorphisms, could serve as useful surveillance tools. To evaluate this possibility, sequence polymorphisms in pfcrt (position 76) and pfmdr1 (positions 86, 184, 1034, 1042, and 1246) and in vitro drug sensitivities were measured for 65 Plasmodium falciparum isolates from Thailand, Myanmar, Vietnam, and Bangladesh. The pfcrt Thr76 polymorphism was present in 97% of samples, consistent with observations that chloroquine resistance is well established in this region. Polymorphisms in pfmdr1 clustered into four specific patterns: the wild type (category I), a Tyr86 polymorphism only (category II), a Phe184 polymorphism only (category III), and Phe184 in combination with Cys1034 and/or Asp1042 (category IV). Isolates in categories I and III were more sensitive to chloroquine and more resistant to mefloquine, artesunate, and artemisinin than isolates in categories II and IV (P ≤ 0.01). Mefloquine resistance was significantly more common in category I and III isolates than in category II and IV isolates, with a prevalence ratio of 14.95 (95% confidence interval, 3.88 to 57.56). These categories identified mefloquine resistance with a sensitivity and a specificity of 94 and 91%, respectively. The pfmdr1 gene copy number was measured by real-time PCR as a ratio of the amount of pfmdr1 DNA to the amount of lactate dehydrogenase (ldh) DNA. Eight samples had pfmdr1 DNA/ldh DNA ratios ≥3. The isolates in all 8 samples fell into categories I and III and were significantly more resistant to mefloquine, quinine, artemisinin, and artesunate and more sensitive to chloroquine than the isolates in the 57 samples with <3 copies of the gene (P ≤ 0.001). Thus, measurement of pfmdr1 mutations and gene copy number may be useful for surveillance of mefloquine-resistant malaria in Southeast Asia.
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MEIERJOHANN, Svenja, Rolf D. WALTER, and Sylke MÜLLER. "Regulation of intracellular glutathione levels in erythrocytes infected with chloroquine-sensitive and chloroquine-resistant Plasmodium falciparum." Biochemical Journal 368, no. 3 (December 15, 2002): 761–68. http://dx.doi.org/10.1042/bj20020962.
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Malaria is one of the most devastating tropical diseases despite the availability of numerous drugs acting against the protozoan parasite Plasmodium in its human host. However, the development of drug resistance renders most of the existing drugs useless. In the malaria parasite the tripeptide glutathione is not only involved in maintaining an adequate intracellular redox environment and protecting the cell against oxidative stress, but it has also been shown that it degrades non-polymerized ferriprotoporphyrin IX (FP IX) and is thus implicated in the development of chloroquine resistance. Glutathione levels in Plasmodium-infected red blood cells are regulated by glutathione synthesis, glutathione reduction and glutathione efflux. Therefore the effects of drugs that interfere with these metabolic processes were studied to establish possible differences in the regulation of the glutathione metabolism of a chloroquine-sensitive and a chloroquine-resistant strain of Plasmodiumfalciparum. Growth inhibition of P. falciparum 3D7 by d,l-buthionine-(S,R)sulphoximine (BSO), an inhibitor of γ-glutamylcysteine synthetase (γ-GCS), and by Methylene Blue (MB), an inhibitor of gluta thione reductase (GR), was significantly more pronounced than inhibition of P.falciparum Dd2 growth by these drugs. These results correlate with the higher levels of total glutathione in P. falciparum Dd2. Short-term incubations of Percoll-enriched trophozoite-infected red blood cells in the presence of BSO, MB and N,N1-bis(2-chloroethyl)-N-nitrosourea and subsequent determinations of γ-GCS activities, GR activities and glutathione disulphide efflux revealed that maintenance of intracellular glutathione in P. falciparum Dd2 is mainly dependent on glutathione synthesis whereas in P. falciparum 3D7 it is regulated via GR. Generally, P. falciparum Dd2 appears to be able to sustain its intracellular glutathione more efficiently than P. falciparum 3D7. In agreement with these findings is the differential susceptibility to oxidative stress of both parasite strains elicited by the glucose/glucose oxidase system.
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Oboh, Mary Aigbiremo, Daouda Ndiaye, Hiasindh Ashmi Antony, Aida Sadikh Badiane, Upasana Shyamsunder Singh, Nazia Anwar Ali, Praveen Kumar Bharti, and Aparup Das. "Status of Artemisinin Resistance in Malaria Parasite Plasmodium falciparum from Molecular Analyses of the Kelch13 Gene in Southwestern Nigeria." BioMed Research International 2018 (October 3, 2018): 1–5. http://dx.doi.org/10.1155/2018/2305062.
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Evolution and spread of malaria parasite Plasmodium falciparum capable of evading antimalarials are the prime concern to malaria control. The currently effective drug, artemisinin (ART), is under threat due to detection of ART-resistant P. falciparum parasites in the Southeast Asian countries. It has been shown that amino acid (AA) mutations at the P. falciparum Kelch13 (Pfk13) gene provide resistance to ART. Nigeria, a part of the Sub-Saharan Africa, is highly endemic to malaria, contributing quite significantly to malaria, and resistance to chloroquine (CQ) and sulfadoxine-pyrimethamine (SP) combination drugs has already been reported. Since artemisinin combined therapy (ACT) is the first-line drug for treatment of uncomplicated malaria in Nigeria and five amino acid mutations have been validated in the Pfk13 gene alongside with candidate mutations for ART resistance, we performed molecular surveillance for mutations (following PCR and DNA sequence analyses) in this gene from two southwestern states of Nigeria. Statistical analyses of DNA sequences were also performed following different evolutionary models. None of the different validated and candidate AA mutations of Pfk13 gene conferring resistance to ART could be detected in P. falciparum sampled in the two southwestern states of Nigeria. In addition, DNA sequencing and sequence analyses indicated neither evolutionary selection pressure on the Pfk13 gene nor association of mutations in Pfk13 gene with mutations of other three genes conferring resistance to CQ and SP. Therefore, based on the monomorphism at the Pfk13 gene and nonassociation of mutations of this gene with mutations in three other drug-resistant genes in malaria parasite P. falciparum, it can be proposed that malaria public health is not under immediate threat in southwestern Nigeria concerning ART resistance.
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Ndung'u, Loise, Benard Langat, Esther Magiri, Joseph Ng'ang'a, Beatrice Irungu, Alexis Nzila, and Daniel Kiboi. "Amodiaquine resistance in Plasmodium berghei is associated with PbCRT His95Pro mutation, loss of chloroquine, artemisinin and primaquine sensitivity, and high transcript levels of key transporters." Wellcome Open Research 2 (June 6, 2018): 44. http://dx.doi.org/10.12688/wellcomeopenres.11768.2.
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Background: The human malaria parasite Plasmodium falciparum has evolved drug evasion mechanisms to all available antimalarials. The combination of amodiaquine-artesunate is among the drug of choice for treatment of uncomplicated malaria. In this combination, a short-acting, artesunate is partnered with long-acting, amodiaquine for which resistance may emerge rapidly especially in high transmission settings. Here, we used a rodent malaria parasite Plasmodium berghei ANKA as a surrogate of P. falciparum to investigate the mechanisms of amodiaquine resistance. Methods: We used the ramp up approach to select amodiaquine resistance. We then employed the 4-Day Suppressive Test to measure the resistance level and determine the cross-resistance profiles. Finally, we genotyped the resistant parasite by PCR amplification, sequencing and relative quantitation of mRNA transcript of targeted genes. Results: Submission of the parasite to amodiaquine pressure yielded resistant line within thirty-six passages. The effective doses that reduced 90% of parasitaemia (ED90) of the sensitive and resistant lines were 4.29mg/kg and 19.13mg/kg respectively. The selected parasite retained resistance after ten passage cycles in the absence of the drug and freezing at -80ºC for one month with ED90 of 20.34mg/kg and 18.22mg/kg. The parasite lost susceptibility to chloroquine by (6-fold), artemether (10-fold), primaquine (5-fold), piperaquine (2-fold) and lumefantrine (3-fold). Sequence analysis of Plasmodium berghei chloroquine-resistant transporter revealed His95Pro mutation. We found no variation in the nucleotide sequences of Plasmodium berghei multidrug resistance gene-1 (Pbmdr1), Plasmodium berghei deubiquitinating enzyme-1 or Plasmodium berghei Kelch13 domain. However, high mRNA transcripts of essential transporters; Pbmdr1, V-type/H+ pumping pyrophosphatase-2 and sodium hydrogen ion exchanger-1 and Ca2+/H+ antiporter accompanies amodiaquine resistance. Conclusions: The selection of amodiaquine resistance yielded stable “multidrug-resistant’’ parasites and thus may be used to study shared resistance mechanisms associated with other antimalarial drugs. Genome-wide analysis of the parasite may elucidate other functionally relevant genes controlling AQ resistance in P. berghei.
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Azlin, Emil, Ichwan HH Batubara, Wisman Dalimunte, Charles Siregar, Bidasari Lubis, Munar Lubis, and Syahril Pasaribu. "The effectiveness of chloroquine compared to Fansidar in treating falciparum malaria." Paediatrica Indonesiana 44, no. 1 (October 10, 2016): 17. http://dx.doi.org/10.14238/pi44.1.2004.17-20.
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Background The most difficult problem in eradicating malaria isthe resistance of P. falciparum to drugs. Mandailing Natal has thehighest malaria incidence in North Sumatera.Objective This study aimed to investigate the efficacy of chloro-quine and Fansidar in treating falciparum malaria.Methods A randomized double-blind study was done from April toMay 2001. Eighty-three patients with acute uncomplicated P.falciparum malaria infection were randomized into two groups.Group I (35 patients) received chloroquine and group II (48 pa-tients) received Fansidar. Blood examinations were performed onthe 1 st , 2 nd , 7 th , and 28 th days.Results The resistance of P. falciparum to drugs in the chloro-quine group were found in 10 patients with R II and 1 patients withR III, while in the Fansidar group, there were 14 patients with R II.Conclusion The efficacy of chloroquine and Fansidar in treatingfalciparum malaria was not significantly different