Journal articles: 'Quinine alkaloids'

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Griffin, Carol E., Jonathan M. Hoke, Upeka Samarakoon, Junhui Duan, Jianbing Mu, Michael T. Ferdig, David C. Warhurst, and Roland A. Cooper. "Mutation in the Plasmodium falciparum CRT Protein Determines the Stereospecific Activity of Antimalarial Cinchona Alkaloids." Antimicrobial Agents and Chemotherapy 56, no. 10 (August 6, 2012): 5356–64. http://dx.doi.org/10.1128/aac.05667-11.

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ABSTRACTTheCinchonaalkaloids are quinoline aminoalcohols that occur as diastereomer pairs, typified by (−)-quinine and (+)-quinidine. The potency of (+)-isomers is greater than the (−)-isomersin vitroandin vivoagainstPlasmodium falciparummalaria parasites. They may act by the inhibition of heme crystallization within the parasite digestive vacuole in a manner similar to chloroquine. Earlier studies showed that a K76I mutation in the digestive vacuole-associated protein, PfCRT (P. falciparumchloroquine resistance transporter), reversed the normal potency order of quinine and quinidine towardP. falciparum. To further explore PfCRT-alkaloid interactions in the malaria parasite, we measured thein vitrosusceptibility of eight clonal lines ofP. falciparumderived from the 106/1 strain, each containing a uniquepfcrtallele, to fourCinchonastereoisomer pairs: quinine and quinidine; cinchonidine and cinchonine; hydroquinine and hydroquinidine; 9-epiquinine and 9-epiquinidine. Stereospecific potency of theCinchonaalkaloids was associated with changes in charge and hydrophobicity of mutable PfCRT amino acids. In isogenic chloroquine-resistant lines, the IC50ratio of (−)/(+) CA pairs correlated with side chain hydrophobicity of the position 76 residue. Second-site PfCRT mutations negated the K76I stereospecific effects: charge-change mutations C72R or Q352K/R restored potency patterns similar to the parent K76 line, while V369F increased susceptibility to the alkaloids and nullified stereospecific differences between alkaloid pairs. Interactions between key residues of the PfCRT channel/transporter with (−) and (+) alkaloids are stereospecifically determined, suggesting that PfCRT binding plays an important role in the antimalarial activity of quinine and otherCinchonaalkaloids.

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Horie, Masao, Mitsuo Oishi, Fusako Ishikawa, Tetsuya Shindo, Akiko Yasui, Shuzo Ogino, and Koichi Ito. "Liquid Chromatographic Analysis of Cinchona Alkaloids in Beverages." Journal of AOAC INTERNATIONAL 89, no. 4 (July 1, 2006): 1042–47. http://dx.doi.org/10.1093/jaoac/89.4.1042.

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Abstract A method for the determination of Cinchona extract (whose main components are the alkaloids cinchonine, cinchonidine, quinidine, and quinine) in beverages by liquid chromatography was developed. A beverage with an alcohol content of more than 10% was loaded onto an OASIS HLB solid-phase extraction cartridge, after it was adjusted to pH 10 with 28% ammonium hydroxide. Other beverages were centrifuged at 4000 rpm for 5 min, and the supernatant was loaded onto the cartridge. The cartridge was washed with water followed by 15% methanol, and the Cinchona alkaloids were eluted with methanol. The Cinchona alkaloids in the eluate were chromatographed on an L-column ODS (4.6 mm id × 150 mm) with methanol and 20 mmol/L potassium dihydrogen phosphate (3 + 7) as the mobile phase. Cinchona alkaloids were monitored with an ultraviolet (UV) detector at 230 nm, and with a fluorescence detector at 405 nm for cinchonine and cinchonidine and 450 nm for quinidine and quinine (excitation at 235 nm). The calibration curves for Cinchona alkaloids with the UV detector showed good linearity in the range of 2400 μg/mL. The detection limit of each Cinchona alkaloid, taken to be the concentration at which the absorption spectrum could be identified, was 2 μg/mL. The recovery of Cinchona alkaloids added at a level of 100 μg/g to various kinds of beverages was 87.6-96.5%, and the coefficients of variation were less than 3.3%. A number of beverage samples, some labeled to contain bitter substances, were analyzed by the proposed method. Quinine was detected in 2 samples of carbonated beverage.

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Eyal, Sara. "The Fever Tree: from Malaria to Neurological Diseases." Toxins 10, no. 12 (November 23, 2018): 491. http://dx.doi.org/10.3390/toxins10120491.

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This article describes the discovery and use of the South American cinchona bark and its main therapeutic (and toxic) alkaloids, quinine and quinidine. Since the introduction of cinchona to Europe in the 17th century, it played a role in treating emperors and peasants and was central to colonialism and wars. Over those 400 years, the medical use of cinchona alkaloids has evolved from bark extracts to chemical synthesis and controlled clinical trials. At the present time, the use of quinine and quinidine has declined, to a large extent due to their toxicity. However, quinine is still being prescribed in resource-limited settings, in severe malaria, and in pregnant women, and quinidine made a limited comeback in the treatment of several cardiac and neurological syndromes. In addition, the article presents more recent studies which improved our understanding of cinchona alkaloids’ pharmacology. The knowledge gained through these studies will hopefully lead to a wider use of these drugs in precision medicine and to design of new generation, safer quinine and quinidine derivatives.

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Dubey, Anubhav, and Yatendra Singh. "Medicinal Properties of Cinchona Alkaloids - A Brief Review." Asian Journal of Research in Pharmaceutical Sciences 11, no. 3 (August 14, 2021): 224–28. http://dx.doi.org/10.52711/2231-5659.2021.00036.

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Cinchona which belongs to family Rubiaceae, got its importance from the centuries because of its anti- malarial activity. Alkaloids present in this herb, Quinine, Chichonine, Quinidine and Cinchonidine are the main, but percentage may vary in species to species. Since the early 17th century, these alkaloid are frequently used in Indian ayurvedic, sidha and traditional folk medicine to treating fever and Still now in modern medicine cinchona alkaloids are used for the treatment of malaria as well as for other diseases and became the well-known drug after the treatment of malaria caused by Plasmodium Sp. Literature study revealed that along with the antimalarial activity the cinchona alkaloids has other potentiality like anti-obesity, anti-cancer, anti-oxidant, anti-inflammatory, anti-microbial activity. These article reviews the biological activities of cinchona alkaloids along with its toxic effect.

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Montagnac, A., M. Litaudon, and M. País. "Quinine- and quinicine-derived alkaloids from Guettarda noumeana." Phytochemistry 46, no. 5 (November 1997): 973–75. http://dx.doi.org/10.1016/s0031-9422(97)00358-0.

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Malchow, R. P., H. Qian, and H. Ripps. "A novel action of quinine and quinidine on the membrane conductance of neurons from the vertebrate retina." Journal of General Physiology 104, no. 6 (December 1, 1994): 1039–55. http://dx.doi.org/10.1085/jgp.104.6.1039.

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The cinchona alkaloids quinine and quinidine have been shown to block a broad range of voltage-gated membrane conductances in a variety of excitable tissues. Using the whole-cell version of the patch clamp technique, we examined the effects of these compounds on voltage-dependent currents from horizontal cells dissociated enzymatically from the all-rod retina of the skate. We report here a novel and unexpected action of quinine and quinidine on isolated horizontal cells. In addition to blocking several of the voltage-activated currents of these cells, the introduction of the alkaloids evoked a large outward current when the cells were held at depolarized potentials. Using tail current analysis, the reversal potential of the outward current was close to O mV, and the current was markedly suppressed by extracellularly applied cobalt, acetate, and halothane. Depolarization in the presence of quinine also permitted entry into the cells of extracellularly applied Lucifer yellow (MW = 443 D), whereas a 3-kD fluorescein-dextran complex was excluded. These findings suggest that the large, apparently nonselective conductance induced by quinine and quinidine results from the opening of hemi-gap junctional channels.

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Ratnadewi, Diah. "Strictosidine Synthase Coding Gene Expression towards Quinine Biosynthesis and Accumulation: Inconsistency in Cultured Cells and Fresh Tissues of Cinchona ledgeriana." International Journal of Agriculture and Biology 26, no. 01 (July 1, 2021): 131–38. http://dx.doi.org/10.17957/ijab/15.1817.

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Strictosidine synthase, encoded by the gene STR, facilitates the regeneration of strictosidine, a critical intermediate for the synthesis of many plant alkaloids. The gene has, however, never been studied in Cinchona spp. The plants produce quinine alkaloid used for malaria medication, SARS-CoV-2 treatment and other industrial purposes. Cultured cells can produce the alkaloid but only at a much lower yield than the natural tree. This study describes STR expression and quinine content in various plant materials. Bioinformatic analyses were conducted on nine species of Rubiaceae to obtain reference sequences to design conservative primers for Cinchona ledgeriana STR (ClSTR). ClSTR expression was analyzed using qRT-PCR and quinine content was determined using HPLC. A complete coding sequence (CDS) of ClSTR was deposited in NCBI GenBank under the accession number MK422544.1. ClSTR was expressed in cultured cells, young and mature leaves, and stem bark. The elicited cells have higher expression than the control and they performed since the fourth week. However, the quinine content was greater in older cells. The gene expression in young leaves was superior, but quinine was most abundant in the stem bark. Every cell of C. ledgeriana, in culture or in the plant, expressed ClSTR and was capable of synthesizing the alkaloid quinine. The alkaloid from the leaves of the plant might be translocated and accumulated in the bark. No efflux of alkaloids from the confined cultured cells might contribute in triggering feedback inhibition in the biosynthetic pathway. This study revealed a critical obstacle in cell culture as a means of secondary metabolites production that needs further development of metabolic engineering. © 2021 Friends Science Publishers

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Brittain, Harry G. "Vibrational Spectroscopic Study of the Cocrystal Products Formed by Cinchona Alkaloids with 5-Nitrobarbituric Acid." Journal of Spectroscopy 2015 (2015): 1–13. http://dx.doi.org/10.1155/2015/340460.

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X-ray powder diffraction, differential scanning calorimetry, infrared absorption spectroscopy, and Raman spectroscopy have been used to study the phenomenon of cocrystal formation in the molecular complexes formed by 5-nitrobarbituric acid with four cinchona alkaloids. The cocrystal products were found to contain varying degrees of hydration, ranging from no hydration in the nitrobarbiturate-quinidine cocrystal up to a 4.5-hydrate species in the nitrobarbiturate-cinchonine cocrystal. For the nitrobarbiturate cocrystals with cinchonine, cinchonidine, and quinidine, the predominant interaction was with the quinoline ring system of the alkaloid. However, for quinine, the predominant interaction was with the quinuclidine group of the alkaloid. These properties serve to demonstrate the utility of 5-nitrobarbituric acid as a preferred reagent for chemical microscopy, since the differing range of hydrate and structural types would serve to easily differentiate the cinchona alkaloids from each other, even when different compounds contained the same absolute configurations at their dissymmetric centers.

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Sanders, Natalie G., David J. Meyers, and David J. Sullivan. "Antimalarial Efficacy of Hydroxyethylapoquinine (SN-119) and Its Derivatives." Antimicrobial Agents and Chemotherapy 58, no. 2 (November 18, 2013): 820–27. http://dx.doi.org/10.1128/aac.01704-13.

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ABSTRACTQuinine and other cinchona-derived alkaloids, although recently supplanted by the artemisinins (ARTs), continue to be important for treatment of severe malaria. Quinine and quinidine have narrow therapeutic indices, and a safer quinine analog is desirable, particularly with the continued threat of antimalarial drug resistance. Hydroxyethylapoquinine (HEAQ), used at 8 g a day for dosing in humans in the 1930s and halving mortality from bacterial pneumonias, was shown to cure bird malaria in the 1940s and was also reported as treatment for human malaria cases. Here we describe synthesis of HEAQ and its novel stereoisomer hydroxyethylapoquinidine (HEAQD) along with two intermediates, hydroxyethylquinine (HEQ) and hydroxyethylquinidine (HEQD), and demonstrate comparable but elevated antimalarial 50% inhibitory concentrations (IC50) of 100 to 200 nM againstPlasmodium falciparumquinine-sensitive strain 3D7 (IC50, 56 nM). Only HEAQD demonstrated activity against quinine-tolerantP. falciparumstrains Dd2 and INDO with IC50s of 300 to 700 nM. HEQD had activity only against Dd2 with an IC50of 313 nM. In the lethal mouse malaria modelPlasmodium bergheiANKA, only HEQD had activity at 20 mg/kg of body weight comparable to that of the parent quinine or quinidine drugs measured by parasite inhibition and 30-day survival. In addition, HEQ, HEQD, and HEAQ (IC50≥ 90 μM) have little to no human ether-à-go-go-related gene (hERG) channel inhibition expressed in CHO cells compared to HEAQD, quinine, and quinidine (hERG IC50s of 27, 42, and 4 μM, respectively). HEQD more closely resembled quininein vitroandin vivoforPlasmodiuminhibition and demonstrated little hERG channel inhibition, suggesting that further optimization and preclinical studies are warranted for this molecule.

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Pratiwi, Dian Rahma, Yohana Caecilia Sulistyaningsih, and Diah Ratnadewi. "Localization of Alkaloid and Other Secondary Metabolites in Cinchona ledgeriana Moens: Anatomical and Histochemical Studies on Fresh Tissues and Cultured Cells." HAYATI Journal of Biosciences 27, no. 1 (January 1, 2020): 1. http://dx.doi.org/10.4308/hjb.27.1.1.

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Cinchona ledgeriana produces several secondary metabolites. The main quinoline alkaloid, quinine that is widely used as an antimalarial drug, is most commonly extracted from the bark of Cinchona, and its leaves contain several other metabolites. Many studies have revealed that cell culture of Cinchona also produces quinine. Nevertheless, the sites of secondary metabolites accumulation are still elusive. This study is aimed at describing specific anatomical structures where alkaloids and some other secondary metabolites are accumulated as well as their localization in leaves and barks of C. ledgeriana, compared to those found in cultured cells. Fresh leaves and barks, and cells of C. ledgeriana were used for anatomical observation and histochemical tests. It was found that these plant parts have specialized structures, idioblast cells with elliptical- and spherical-shapes, scattered in leaf hypodermis, stem cortex, and secondary phloem. Unspecialized structures such as epidermis and palisade mesophyll tissues were also found accumulating some metabolites. Histochemical tests showed that bark and leaves contained alkaloids, terpenoids, phenolic, and lipophilic compounds. Cultured cells presented positive results for alkaloids and terpenoids.

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Wink, Michael. "Potential of DNA Intercalating Alkaloids and Other Plant Secondary Metabolites against SARS-CoV-2 Causing COVID-19." Diversity 12, no. 5 (April 30, 2020): 175. http://dx.doi.org/10.3390/d12050175.

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Many plants produce secondary metabolites (PSMs) with antiviral activities. Among the antiviral PSMs, lipophilic terpenoids in essential oils can disturb the lipid envelope of viruses. Phenols and polyphenols (flavonoids, rosmarinic acid and tannins) attack viral proteins present in the viral membrane or inside the virus particle. Both phenolics and essential oils are active against free viral particles but not—or to a lesser degree—after a virus has entered a host cell. Another group of PSMs is directed against DNA or RNA. These are DNA intercalators such as sanguinarine, berberine, emetine and other isoquinoline alkaloids, ß-carboline, and quinoline alkaloids such as quinine, cinchonine, dictamine and skimmianine. The DNA intercalators stabilize double-stranded nucleic acids and inhibit the replication, transcription, and translation of genetic material. These alkaloids can inhibit viral development and viral replication in cells, as shown for SARS-CoV-1 and other viruses. Since chloroquine (which is also a DNA intercalator and a chemical derivative of the alkaloid quinine) is apparently clinically helpful against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, it is assumed that intercalating alkaloids, or the medicinal plants producing them, may be interesting candidates for the development of new antiviral drugs for the treatment of coronavirus disease 2019 (COVID-19).

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Tichá, Iveta Chena, Simona Hybelbauerová, and Jindřich Jindřich. "New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions." Beilstein Journal of Organic Chemistry 15 (April 1, 2019): 830–39. http://dx.doi.org/10.3762/bjoc.15.80.

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The preparation of new organocatalysts for asymmetric syntheses has become a key stage of enantioselective catalysis. In particular, the development of new cyclodextrin (CD)-based organocatalysts allowed to perform enantioselective reactions in water and to recycle catalysts. However, only a limited number of organocatalytic moieties and functional groups have been attached to CD scaffolds so far. Cinchona alkaloids are commonly used to catalyze a wide range of enantioselective reactions. Thus, in this study, we report the preparation of new α- and β-CD derivatives monosubstituted with cinchona alkaloids (cinchonine, cinchonidine, quinine and quinidine) on the primary rim through a CuAAC click reaction. Subsequently, permethylated analogs of these cinchona alkaloid–CD derivatives also were synthesized and the catalytic activity of all derivatives was evaluated in several enantioselective reactions, specifically in the asymmetric allylic amination (AAA), which showed a promising enantiomeric excess of up to 75% ee. Furthermore, a new disubstituted α-CD catalyst was prepared as a pure AD regioisomer and also tested in the AAA. Our results indicate that (i) the cinchona alkaloid moiety can be successfully attached to CD scaffolds through a CuAAC reaction, (ii) the permethylated cinchona alkaloid–CD catalysts showed better results than the non-methylated CDs analogues in the AAA reaction, (iii) promising enantiomeric excesses are achieved, and (iv) the disubstituted CD derivatives performed similarly to monosubstituted CDs. Therefore, these new CD derivatives with cinchona alkaloids effectively catalyze asymmetric allylic aminations and have the potential to be successfully applied in other enantioselective reactions.

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Woodland, John G., Roger Hunter, Peter J. Smith, and Timothy J. Egan. "Shining new light on ancient drugs: preparation and subcellular localisation of novel fluorescent analogues of Cinchona alkaloids in intraerythrocytic Plasmodium falciparum." Organic & Biomolecular Chemistry 15, no. 3 (2017): 589–97. http://dx.doi.org/10.1039/c6ob02110g.

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Utami, Maulidiyah, Diah Ratnadewi, Dyah Iswantini, and Trivadila Trivadila. "Aktivitas NADP(H) Oksidoreduktase pada Kultur Sel Kina (Cinchona ledgeriana Moens) Terelisitasi." Jurnal Ilmu Pertanian Indonesia 25, no. 4 (October 27, 2020): 540–46. http://dx.doi.org/10.18343/jipi.25.4.540.

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Cinchona ledgeriana Moens is an industrial plant producing secondary metabolite quinoline alkaloids. To maintain and moreover, to increase the quinoline production especially quinine, in vitro culture system through cell culture could be a potential alternative. If the use of elicitor in cell culture can increase the production of a secondary metabolite, the activity of the enzymes involved in the biosynthetic pathway of the secondary metabolite in question might be increasing. This study aimed to examine the activity of NADPH oxidoreductase in the elicitated cell culture of C. ledgeriana and to evaluate the correlation between the activity of this enzyme and the level of quinine production. The cell cultures of Cinchona were treated with abscisic acid (ABA) or paclobutrazol (PBZ), combined with sucrose, sorbitol, or mannitol in Wood Plant (WP) media, for 7 weeks on a shaker. The quinine concentration was determined using high-performance liquid chromatography (HPLC) and the enzyme activity was measured using fluorometry. The results showed that the highest enzyme activity was found in the P7M cells (PBZ 7 mg/L + mannitol 5.3 g/L + sucrose 20 g/L), followed by the A3S cells (ABA 3 mg/L + sorbitol 5.3 g/L + sucrose 20 g/L). These results correspond to their production level of the quinine alkaloids. The lowest enzyme activity was found in the cultures without elicitor. The increase of NADP(H) enzyme activity in the P7M and A3S treatments were 13.5 and 8.5%, respectively, compared to that in the control cells. Keywords: elicitation, fluorometry, NADP(H) oxidoreductase, quinoline alkaloid

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Handayani, Tien Wahyu, Yulistien Yusuf, and Joni Tandi. "Analisis Kualitatif dan Kuantitatif Metabolit Sekunder Ekstrak Biji Kelor (Moringa oleifera Lam.) dengan Metode Spektrofotometri UV-Vis." KOVALEN: Jurnal Riset Kimia 6, no. 3 (December 30, 2020): 230–38. http://dx.doi.org/10.22487/kovalen.2020.v6.i3.15324.

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This study aims to determine the content and total levels of secondary metabolites of ethanol extract of moringa seed (Moringa oleifera Lam.). Extraction of moringa seed using the maceration method to obtain a filtrate. The filtrate obtained was concentrated using a rotary evaporator to obtain a concentrated extract. The extract was tested qualitatively for alkaloids, flavonoids, saponins, and tannins using a suitable reagent with the test parameters. The quantitative test was using UV-Visible spectrophotometry. Alkaloids using test parameters equivalent total alkaloid quinine, flavonoids use parameter test equivalent of the total flavonoids quercetin, saponin using test parameters from Quillaja total saponins and tannins quantitative bark using test parameters total tannin tannic acid equivalent. The result showed that moringa seed positive for alkaloids characterized by orange deposition, flavonoids are characterized by the formation of the yellow color orange, saponin their stable foam, and tannins are marked in black. Quantitative test results alkaloids of 916,87 µg/g, flavonoids of 0.255%, saponin of 6.367%, and tannin of 3,724.5 µg/g. Keywords: Moringa oleifera Lam., secondary metabolites, spectrophotometry

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Cadar, Emin, Aneta Tomescu, Cristina Luiza Erimia, Alef Mustafa, and Rodica Sîrbu. "The Impact of Alkaloids Structures from NaturalCompounds on Public Health." European Journal of Social Sciences Education and Research 5, no. 1 (December 30, 2015): 34. http://dx.doi.org/10.26417/ejser.v5i1.p34-39.

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Alkaloids are organic heterocycle substances with nitrogen, of plant origin, with basic character, arising from the secondary metabolism of plants, which give characteristic reactions and exert an effect on animal bodies, most often of a toxic nature. Alkaloids have at least one atom of heterocycle nitrogen, in which case it is often tertiary, less frequently quaternary. The heterocycles can condense among themselves or with other cycles in such a way that alkaloid molecules may become poly- or macro-cycles. Alkaloids are classified on both the criterion of chemical structure, as well as based on their origin. Thus, the known alkaloids are divided into the following categories: derivatives of pyridine, derivatives of pyrolidine, derivatives of tryptophan, derivatives of quinolone and izoquinolone, derivatives of phenetylamine, indole derivatives, derivatives of purine, terpenes, and derivatives of betaine with quaternary nitrogen.This work presents the structures, location in natural compounds, as well as data pertaining to the extraction, identification, metering, and purification for various compounds, such as coniine, nicotine, atropine and cocaine, morphine and codeine, quinine, papaverine, strychnine, and caffeine.The effects these substances have on human health are highlighted.

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Uzor, Philip F. "Alkaloids from Plants with Antimalarial Activity: A Review of Recent Studies." Evidence-Based Complementary and Alternative Medicine 2020 (February 12, 2020): 1–17. http://dx.doi.org/10.1155/2020/8749083.

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Malaria is one of the major health problems in developing countries. The disease kills a large number of people every year and also affects financial status of many countries. Resistance of the plasmodium parasite, the causative agent, to the existing drugs, including chloroquine, mefloquine, and artemisinin based combination therapy (ACT), is a serious global issue in malaria treatment and control. This warrants an urgent quest for novel compounds, particularly from natural sources such as medicinal plants. Alkaloids have over the years been recognized as important phytoconstituents with interesting biological properties. In fact, the first successful antimalarial drug was quinine, an alkaloid, which was extracted from Cinchona tree. In the present review work, the alkaloids isolated and reported recently (2013 till 2019) to possess antimalarial activity are presented. Several classes of alkaloids, including terpenoidal, indole, bisindole, quinolone, and isoquinoline alkaloids, were identified with a promising antimalarial activity. It is hoped that the reports of the review work will spur further research into the structural modification and/or development of the interesting compounds as novel antimalarial drugs.

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Hasibuan, Yustiny Andaliza, Diah Ratnadewi, and Zainal Alim Mas’ud. "Alkaloids Production and Cell Growth of Cinchona ledgeriana Moens: Effects of Fungal Filtrate and Methyl Jasmonate Elicitors." Indonesian Journal of Science and Technology 6, no. 1 (January 19, 2021): 31–40. http://dx.doi.org/10.17509/ijost.v6i1.31479.

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Cinchona alkaloids are known as antimalaria and anti-arrhythmic. Due to the long waiting time to harvest, cell culture technology is a challenge. This study aimed to determine the effects of elicitors, filtrate of two strains of endophytic fungi and methyl jasmonate (MeJA), in cell suspension culture of Cinchona ledgeriana on quinine and quinidine production. The cells were cultured for seven weeks in woody plant (WP) media treated with either of those elicitors in various concentrations. The cells growth was observed and the alkaloids were analyzed by HPLC. Cells treated with MeJA failed to grow that led to the cell biomass insufficiency for alkaloids determination. It indicates that the cells are quite sensitive to even low concentration of MeJA that hampered the growth. Cells treated with the filtrate of Diaporthe sp. M13-Millipore filtered (S2M) gave the least cell biomass but presented the highest content of both alkaloids. Diaporthe sp. strain M-13 is stronger as elicitor than M-23 for this plant species. Filtrate of non-virulent fungi can elevate the biosynthesis of alkaloids. This reconfirms that cultured cells are capable to produce secondary metabolites and the productivity can be increased by using an appropriate elicitor.

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Ihara, Masataka, Nobuaki Taniguchi, and Keiichiro Fukumoto. "Synthesis of chiral intermediates of quinine alkaloids and (+)-dihydroantirhine." Journal of the Chemical Society, Perkin Transactions 1, no. 4 (1997): 365–70. http://dx.doi.org/10.1039/a606952e.

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Guo, Jing, Zi-Hui Lin, Kai-Bin Chen, Ying Xie, Albert S. C. Chan, Jiang Weng, and Gui Lu. "Asymmetric amination of 2-substituted indolin-3-ones catalyzed by natural cinchona alkaloids." Organic Chemistry Frontiers 4, no. 7 (2017): 1400–1406. http://dx.doi.org/10.1039/c7qo00129k.

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Igarashi, Junji, and Yuichi Kobayashi. "Improved synthesis of quinine alkaloids with the Teoc protective group." Tetrahedron Letters 46, no. 37 (September 2005): 6381–84. http://dx.doi.org/10.1016/j.tetlet.2005.06.171.

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IHARA, M., N. TANIGUCHI, and K. FUKUMOTO. "ChemInform Abstract: Synthesis of Chiral Intermediates of Quinine Alkaloids and (+)- Dihydroantirhine." ChemInform 28, no. 29 (August 3, 2010): no. http://dx.doi.org/10.1002/chin.199729215.

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Masturah, Markom, Kurnia Harlina Dewi, Nursyairah Jalil, Loh Wei Jia, Siti Rozaimah Sheikh Abdullah, and Idris Mushrifah. "Phytochemical Screening and Alkaloid Identification of Cabomba furcata." Advanced Materials Research 233-235 (May 2011): 971–76. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.971.

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Ekor Kucing (Cabomba furcata) is a dominating water plant, which is rapidly proliferating in Lake Chini, Pahang, Malaysia. If left uncontrolled, the prevalence of this plant would threaten other plants, such as by inhibiting the growth of lotus (Nelumbo niciferaandNympae lotus). It is also suspected as being a cause of pollution in Lake Chini. Steps to eradicate or controlC. furcataplants first require a comprehensive study of its phytochemical content through methods of chemical screening, extraction/fractionation and analysis of individual compounds. Phytochemical screening carried out on the extracts detected flavonoid, saponin and alkaloid groups, but not triterpene and tannin. Different extraction yields were obtained from various plant parts, with the highest yield (%g/g sample) obtained before and after alkaloid fractionation were from the leaf (10.1%, 6.9%), followed by stem (9.6%, 4.5%) and flower (0.8%, 0.5%). Identification of alkaloids inC. furcataextracts by TLC showed the presence of nicotine, tomatine, thebaine and quinine.

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Bucher, Christoph, Christof Sparr, W. Bernd Schweizer, and Ryan Gilmour. "Fluorinated Quinine Alkaloids: Synthesis, X-ray Structure Analysis and Antimalarial Parasite Chemotherapy." Chemistry - A European Journal 15, no. 31 (August 3, 2009): 7637–47. http://dx.doi.org/10.1002/chem.200900505.

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Fukumoto, Keiichiro, Nobuaki Taniguchi, and Masataka Ihara. "Conversion of the Synthetic Precursor for Ipecac and Corynanthe Alkaloids into Synthetic Intermediates of Quinine Alkaloids and (±)-Dihydroantirhine." HETEROCYCLES 33, no. 2 (1992): 545. http://dx.doi.org/10.3987/com-91-s98.

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Tandi, Joni, Bella Melinda, Anita Purwantari, and Agustinus Widodo. "Analisis Kualitatif dan Kuantitatif Metabolit Sekunder Ekstrak Etanol Buah Okra (Abelmoschus esculentus L. Moench) dengan Metode Spektrofotometri UV-Vis." KOVALEN: Jurnal Riset Kimia 6, no. 1 (April 18, 2020): 74–80. http://dx.doi.org/10.22487/kovalen.2020.v6.i1.15044.

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This study aims to determine the content of secondary metabolites and the levels of total secondary metabolites in ethanol extract of Okra (Abelmoschus esculentus L. Moench) fruit with UV-Vis Spectrophotometry method. Okra (Abelmoschus esculentus L. Moench) fruit extract was prepared by maceration method with 96% ethanol. The extract was concentrated using a rotary evaporator that followed by a qualitative test for alkaloids, flavonoids, saponins, and tannins using suitable reagents with the test parameters, while for the qualitative assay using a UV-Vis Spectrophotometry. Qualitative analysis of alkaloids using test parameters of total alkaloids equivalent to quinine, flavonoid using parameter of total flavonoids equivalent to quercetin, saponin using parameters of standard saponins total from the Quillaja Bark, and tannin using test parameters of total tannins equivalent to tannic acid. Qualitative test results indicated that the ethanol extract of Okra fruit tested positive for alkaloids content wich characterized by the orange deposition, flavonoids characterized by the formation of an orange-yellow color, a stable foam for saponins and tannins marked in black. The quantitative analysis resulted alkaloids of 2228.06 mg/gram, flavonoids of 2.79 mg/gram, saponins of 10.03 mg/gram, and tannins of 1973.27 mg/gram. Keywords: Okra fruit, secondary metabolites, UV- Vis spectrophotometry, qualitative, quantitative.

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Nair, Jerald J., and Johannes van Staden. "Antiplasmodial Lycorane Alkaloid Principles of the Plant Family Amaryllidaceae." Planta Medica 85, no. 08 (March 25, 2019): 637–47. http://dx.doi.org/10.1055/a-0880-5414.

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AbstractThe spread of malaria is thought to have followed human expansion out of Africa some 60 – 80 thousand years ago. With its prevalence in pantropical countries of the world and epicenter localized in Africa, malaria is now considered an unnecessary burden to overworked and under-resourced healthcare structures. Plants have long afforded a fertile hunting ground for the search and identification of structurally diverse antimalarial agents, such as quinine and artemisinin. This survey examines the antiparasitic properties of the family Amaryllidaceae via the antiplasmodial activities demonstrated for its lycorane alkaloid principles. Of these, 24 were natural compounds identified in 20 species from 11 genera of the Amaryllidaceae family, whilst the remaining 28 were synthetically derived entities based on the lycorane skeleton. These were screened against ten different strains of the malarial parasite Plasmodium falciparum, wherein the parent compound lycorine was shown to be the most potent with an IC50 of 0.029 µg/mL in the FCR-3 strain seen to be the best. Structure-activity relationship studies revealed that good activities were detectable across both the natural compounds as well as the synthetically accessed derivatives. Such studies also highlighted that there are several inherent structural features that define the lycorane alkaloid antiplasmodial pharmacophore, such as the nature of its ring systems and properties of its substituents. Mechanistically, a limited number of studies confirmed that lycorane alkaloids manifest their action by targeting enzymes associated with the plasmodial FAS-II biosynthetic pathways. Overall, these alkaloids have provided useful, convenient, and accessible scaffolds for antimalarial-based drug discovery.

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Yang, Guan-Zhou, Jia-Kai Zhu, Xiao-Dan Yin, Yin-Fang Yan, Yu-Ling Wang, Xiao-Fei Shang, Ying-Qian Liu, Zhong-Min Zhao, Jing-Wen Peng, and Hua Liu. "Design, Synthesis, and Antifungal Evaluation of Novel Quinoline Derivatives Inspired from Natural Quinine Alkaloids." Journal of Agricultural and Food Chemistry 67, no. 41 (September 18, 2019): 11340–53. http://dx.doi.org/10.1021/acs.jafc.9b04224.

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Kirk, K., H. Y. Wong, B. C. Elford, C. I. Newbold, and J. C. Ellory. "Enhanced choline and Rb+ transport in human erythrocytes infected with the malaria parasite Plasmodium falciparum." Biochemical Journal 278, no. 2 (September 1, 1991): 521–25. http://dx.doi.org/10.1042/bj2780521.

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Human erythrocytes infected in vitro with the malaria parasite Plasmodium falciparum showed a markedly increased rate of choline influx compared with normal cells. Choline transport into uninfected cells (cultured in parallel with infected cells) obeyed Michaelis-Menten kinetics (Km approximately 11 microM). In malaria-parasite-infected cells there was an additional choline-transport component which failed to saturate at extracellular concentrations of up to 500 microM. This component was less sensitive than the endogenous transporter to inhibition by the Cinchona bark alkaloids quinine, quinidine, cinchonine and cinchonidine, but showed a much greater sensitivity than the native system to inhibition by piperine. The sensitivity of the induced choline transport to these reagents was similar to that of the malaria-induced (ouabain- and bumetanide-resistant) Rb(+)-transport pathway; however, the relative magnitudes of the piperine-sensitive choline and Rb+ fluxes in malaria-parasite-infected cells varied between cultures. This suggests either that the enhanced transport of the two cations was via functionally distinct (albeit pharmacologically similar) pathways, or that the transport was mediated by a pathway with variable substrate selectivity.

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Eiden, Fritz. "ChemInform Abstract: Quinine and Other Cinchona Alkaloids. Part 2. Spatial Structure of the Quinoline Derivatives." ChemInform 30, no. 20 (June 15, 2010): no. http://dx.doi.org/10.1002/chin.199920303.

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Eiden, Fritz. "ChemInform Abstract: Quinine and Other Cinchona Alkaloids. Part 1. From the Isolation to the Structural Elucidation." ChemInform 30, no. 12 (June 17, 2010): no. http://dx.doi.org/10.1002/chin.199912323.

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Eiden, Fritz. "ChemInform Abstract: Quinine and Other Cinchona Alkaloids. Part 3. From Total Syntheses of Quinoline Cinchona Alkaloids via Preparation of More Active Antimalarials to the Investigation of the Indole Cinchona Alkaloids." ChemInform 30, no. 21 (June 15, 2010): no. http://dx.doi.org/10.1002/chin.199921289.

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Gao, Xinya, Qiang Jiao, Bingqian Zhou, Qimei Liu, and Dangquan Zhang. "Diverse bioactive components from Ginkgo biloba fruit." Thermal Science 24, no. 3 Part A (2020): 1753–60. http://dx.doi.org/10.2298/tsci190623048g.

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The fruit of Ginkgo biloba is widely concerned because of its high economic and medical value. In this study, efficient extraction methods were used to identify the bioactive components in the fruit of Ginkgo biloba. The bioactive constituents of Ginkgo biloba fruit were identified and the uses of these bioactive components were discussed. There are more than 160 kinds of chemical extracts in Ginkgo biloba fruit. It mainly contains flavonoids, terpenes, phenols, alkaloids, polyisopentene, quinine acid, linoleic acid, monoxalic acid, gingol, gingosterone and other substances. It contains a variety of substances, and has many applications in anti-bacterial, anti-tumor, lipid-lowering and other aspects. The results suggested that Ginkgo biloba fruit has great potential in chemical raw materials, biological health care, biomedical treatment, aroma and bioenergy.

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Iyekowa, Osaro, and Mary Olire Edema. "Chemosuppressive activities in in vivo studies of Plasmodium falciparum-infected mice using isolated oil of Stigmaphyllon ovatum (Amazon vine) Cav." Ovidius University Annals of Chemistry 28, no. 1 (February 23, 2017): 1–6. http://dx.doi.org/10.1515/auoc-2017-0001.

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AbstractProblem: In sub-Saharan Africa, malaria remains one of the leading health problems. This situation has been aggravated by the increasing spread of drug-resistant Plasmodium falciparum strains. The study was conducted to determine the chemosuppressive activities in in vivo studies of Plasmodium falciparum-infected mice with isolated oil of Stigmaphyllon ovatum leaves used in the traditional treatment of malaria in Nigeria. Methodology: The plant leaves were collected, dried, pulverized and extracted in Soxhlet extractor with hexane solvent. The crude extract was concentrated using a rotary evaporator and phytochemical screening performed using standard methods. Isolation of oil from hexane extract was done using vacuum liquid chromatography while characterization was done by gas chromatography-mass spectrometry (GC-MS). Chemosuppressive activities were conducted along with quinine to determine the antimalarial potency in Plasmodium falciparum- infected BALB/c albino mice. Findings: Glycosides, saponins, phenolics, and alkaloids among others were present. Components detected from the isolated yellow oil of S. ovatum were 9-octadecenoic acid (oleic acid) (Rt:20.0, 19.37%), an unsaturated fatty acid, squalene (Rt:25.6, 4.58%), a terpene; 7-tetradecenal (Rt:22.6, 2.40%), an aldehyde and alicyclic compounds like bicycle (3,10) hexan-3-one (Rt:16.7, 0.22%). Quinine-treated mice exhibited the lowest parasite counts of 0.27±0.01 (83.82% mean chemosuppression) at day 4 of therapy while the lowest parasite counts for the isolated oil was 0.95±0.05 (42.92% mean chemosuppression) at day 4 of therapy. Conclusion: The chemosuppressive activities revealed that the isolated oil exhibit significant suppression (P<0.05) of Plasmodium falciparum when compared with the standard, quinine which was evident by the photomicrograph results. This work corroborates the local use of the plants for the treatment of malaria in Southern Nigeria.

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Blom, T. J. M., T. B. van Vliet, J. Schripsema, J. Val, F. van Iren, R. Verpoorte, and K. R. Libbenga. "Uptake and Accumulation of the Alkaloids Quinine and Cinchonamine in Cultured Cells of Cinchona robusta and Catharanthus roseus." Journal of Plant Physiology 138, no. 4 (August 1991): 436–42. http://dx.doi.org/10.1016/s0176-1617(11)80519-5.

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Hubel, Roland, Kurt Polborn, and Wolfgang Beck. "Cinchona Alkaloids as Versatile Ambivalent Ligands – Coordination of Transition Metals to the Four Potential Donor Sites of Quinine." European Journal of Inorganic Chemistry 1999, no. 3 (March 1999): 471–82. http://dx.doi.org/10.1002/(sici)1099-0682(199903)1999:3<471::aid-ejic471>3.0.co;2-h.

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Nawaz, Sarfraz A., Muhammad Ayaz, Wolfgang Brandt, Ludger A. Wessjohann, and Bernhard Westermann. "Cation–π and π–π stacking interactions allow selective inhibition of butyrylcholinesterase by modified quinine and cinchonidine alkaloids." Biochemical and Biophysical Research Communications 404, no. 4 (January 2011): 935–40. http://dx.doi.org/10.1016/j.bbrc.2010.12.084.

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Swamy, C. T. "An Overview of COVID-19 and the Potential Plant Harboured Secondary Metabolites against SARS-CoV-2: A Review." Journal of Pure and Applied Microbiology 15, no. 3 (August 28, 2021): 1059–71. http://dx.doi.org/10.22207/jpam.15.3.52.

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The SARS-CoV-2 virus causes COVID-19, a pandemic disease, and it is called the novel coronavirus. It belongs to the Coronaviridae family and has been plagued the world since the end of 2019. Viral infection to the lungs causes fluid filling and breathing difficulties, which leads to pneumonia. Pneumonia progresses to ARDS (Acute Respiratory Distress Syndrome), in which fluid fills the air sac and seeps from the pulmonary veins. In the current scenario, several vaccines have been used to control the pandemic worldwide. Even though vaccines are available and their effectiveness is short, it may be helpful to curb the pandemic, but long-term protection is inevitable when we look for other options. Plants have diversified components such as primary and secondary metabolites. These molecules show several activities such as anti-microbial, anti-cancer, anti-helminthic. In addition, these molecules have good binding ability to the SARS-CoV-2 virus proteins such as RdRp (RNA-dependent RNA polymerase), Mpro (Main Protease), etc. Therefore, these herbal molecules could probably be used to control the COVID-19. However, pre-requisite tests, such as cytotoxicity, in vivo, and human experimental studies, are required before plant molecules can be used as potent drugs. Plant metabolites such as alkaloids, isoquinoline ß-carboline, and quinoline alkaloids such as skimmianine, quinine, cinchonine, and dictamine are present in plants and used in a traditional medicinal system.

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E. Denmark, Scott. "Deconstructing Quinine. Part 1. Toward an Understanding of the Remarkable Performance of Cinchona Alkaloids in Asymmetric Phase Transfer Catalysis." HETEROCYCLES 82, no. 2 (2010): 1527. http://dx.doi.org/10.3987/com-10-s(e)108.

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Sowunmi, A., L. A. Salako, O. J. Laoye, and A. F. Aderounmu. "Combination of quinine, quinidine and cinchonine for the treatment of acute falciparum malaria: correlation with the susceptibility of Plasmodium falciparum to the cinchona alkaloids in vitro." Transactions of the Royal Society of Tropical Medicine and Hygiene 84, no. 5 (September 1990): 626–29. http://dx.doi.org/10.1016/0035-9203(90)90127-z.

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Hisaki, Ichiro, Eri Hiraishi, Toshiyuki Sasaki, Hideo Orita, Seiji Tsuzuki, Norimitsu Tohnai, and Mikiji Miyata. "Crystal Structure of Quinine: The Effects of Vinyl and Methoxy Groups on Molecular Assemblies of Cinchona Alkaloids Cannot Be Ignored." Chemistry - An Asian Journal 7, no. 11 (August 22, 2012): 2607–14. http://dx.doi.org/10.1002/asia.201200566.

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CHAPMAN, R. F., A. ASCOLI-CHRISTENSEN, and P. R. WHITE. "Sensory Coding For Feeding Deterrence in the Grasshopper Schistocerca Americana." Journal of Experimental Biology 158, no. 1 (July 1, 1991): 241–59. http://dx.doi.org/10.1242/jeb.158.1.241.

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The electrophysiological responses of sensilla on the tibia of Schistocerca americana (Drury) to six compounds were examined. All the compounds were shown to cause feeding deterrence at high concentrations. Nicotine hydrogen tartrate, quinine, hordenine (all alkaloids) and salicin (a phenolic glycoside) all stimulated one cell in each sensillum. This was shown by differential adaptation experiments to be the same cell. In some sensilla this cell also responded to linamarin (a cyanogenic glycoside). Earlier work had shown that the activity of this cell was correlated with feeding deterrence. However, canavanine (a nonprotein amino acid) did not stimulate this cell, although it caused feeding deterrence. All the compounds, except salicin, produced a marked depression in the activity of cells responding to sucrose, and at higher concentrations of the compounds this inhibition was almost complete. The activity of the deterrent cell and inhibition of the activity of sucrose-sensitive cells appear to act together to produce the behavioural effects of most chemicals, but canavanine appears to act only by suppressing the activity of other cells and salicin primarily through activity of the deterrent cell. In addition, quinine disrupts the activity of all the cells and in its presence the deterrent cell adapts very slowly so that the message signalling deterrence is sustained. At low concentrations, salicin, and probably hordenine, increased the duration of feeding. In the case of hordenine this was due to an increase in the firing rate of sucrose-sensitive neurones; with salicin the increase was associated with a high threshold of response and a rapid rate of adaptation of the deterrent cell. Thus, similar behavioural effects are produced by a variety of sensory phenomena with each compound acting in a slightly different manner from the others.

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Menezes Filho, Antonio Carlos Pereira de, and Carlos Frederico de Souza Castro. "Análise Fitoquímica dos Extratos Etanólicos de Euphorbia splendens (Borjer ex. Hooke) e Hyptis suaveolens (L.) Poit." Ensaios e Ciência: Ciências Biológicas, Agrárias e da Saúde 23, no. 2 (December 9, 2019): 98. http://dx.doi.org/10.17921/1415-6938.2019v23n2p98-103.

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Há séculos plantas são utilizadas como meio para tratar doenças que afligem os humanos e animais, no entanto, ainda pouco se conhece sobre os efeitos fitoterapêuticos de plantas utilizadas no paisagismo e como invasoras de áreas de pastagens. Este estudo objetivou avaliar, por meio de análises fitoquímicas preliminares, os principais grupos químicos que compõem os extratos etanólicos de Euphorbia splendens, planta ornamental utilizada em vias públicas e Hyptis suaveolens, conhecida por mata-pasto, amplamente encontrada em pastagens do Cerrado. Foram preparados extratos etanólicos das raízes, das folhas, das flores e das sementes, os quais foram avaliados por testes de identificação para compostos, ácidos orgânicos, açúcares redutores e não redutores, alcaloides, flavonoides, saponinas espumídicas, cumarinas, glicosídeos cardíacos, fenólicos simples, taninos, polissacarídeos, purinas, catequinas, derivados de quininas, depsídeos e depsidonas, compostos antraquinônicos e duplas olefínicas. Os resultados foram positivos para ambas as espécies para ácidos orgânicos, açúcares redutores e não redutores, alcaloides, flavonoides, saponinas, cumarinas, glicosídeos cardíacos, fenólicos, taninos condensados, depsídeos e depsidonas e duplas olefínicas. Não foram observados resultados positivos para benzoquinonas, naftoquinonas, fenantraquinonas e antraquinonas. Estas análises preliminares resultaram em importantes dados sobre a composição fitoquímica das espécies E. splendens e H. suaveolens. Palavras-chave: Ácidos Orgânicos. Açúcares Redutores. Cumarinas. Abstract Plants have for centuries been used as a means to treat diseases that afflict humans and animals, but little is known about the phytotherapeutic effects of plants used in landscaping and as pasture areas invaders. The objective of this study was to evaluate the main chemical groups that compose the ethanolic extracts of Euphorbia splendens, an ornamental plant used in public roads and Hyptis suaveolens, known as mata-pasto, widely found in pastures of Cerrado, through preliminary phytochemical analyzes. Ethanolic extracts of roots, leaves, flowers and seeds were prepared and tested for compounds, organic acids, reducing and non-reducing sugars, alkaloids, flavonoids, foamy saponins, coumarins, cardiac glycosides, simple phenolics, tannins, polysaccharides, purines, catechins, quinine derivatives, depsides and depsidones, anthraquinone compounds and olefinic doublets. The results were positive for both species for organic acids, reducing and non-reducing sugars, alkaloids, flavonoids, saponins, coumarins, cardiac glycosides, phenolics, condensed tannins, depsides and depsidones and olefinic doubles. No positive results were observed for benzoquinones, naphthoquinones, phenanthraquinones, and anthraquinones. These preliminary analyzes resulted in important data on the phytochemical composition of the species Euphorbia splendens and Hyptis suaveolens. Keywords: Coumarins. Organic Acids. Reducing Sugars.

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Pussard, Eric, Celine Straczek, Idrissa Kaboré, Auguste Bicaba, Tatiana Balima-Koussoube, Patrice Bouree, and Hubert Barennes. "Dose-Dependent Resorption of Quinine after Intrarectal Administration to Children with Moderate Plasmodium falciparum Malaria." Antimicrobial Agents and Chemotherapy 48, no. 11 (November 2004): 4422–26. http://dx.doi.org/10.1128/aac.48.11.4422-4426.2004.

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ABSTRACT The pharmacokinetics of increasing doses of an intrarectal Cinchona alkaloid combination containing 96.1% quinine, 2.5% quinidine, 0.68% cinchonine, and 0.67% cinchonidine (Quinimax) was compared to that of parenteral regimens in 60 children with moderate malaria. Quinine exhibited a nonlinear pharmacokinetics, suggesting a saturation of rectal resorption. When early rejections appeared, blood quinine concentrations decreased by 30 to 50% and were restored by an immediate half-dose administration of the drug. Rectal administration of doses of 16 or 20 mg/kg of body weight led to concentration-time profiles in blood similar to those of parenteral regimens and could be an early treatment of childhood malaria.

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Ihara, Masataka, Kazuharu Noguchi, Keiichiro Fukumoto, and Tetsuji Kametani. "Conversion of indoles into quinolines through the n-1-c-2 fission by singlet-oxygen as a model experiment of biomimetic synthesis of quinine alkaloids." Tetrahedron 41, no. 11 (January 1985): 2109–14. http://dx.doi.org/10.1016/s0040-4020(01)96581-0.

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McCoy, Kevin, Sateesh Gudapati, Lawrence He, Elaina Horlander, David Kartchner, Soham Kulkarni, Nidhi Mehra, et al. "Biomedical Text Link Prediction for Drug Discovery: A Case Study with COVID-19." Pharmaceutics 13, no. 6 (May 26, 2021): 794. http://dx.doi.org/10.3390/pharmaceutics13060794.

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Link prediction in artificial intelligence is used to identify missing links or derive future relationships that can occur in complex networks. A link prediction model was developed using the complex heterogeneous biomedical knowledge graph, SemNet, to predict missing links in biomedical literature for drug discovery. A web application visualized knowledge graph embeddings and link prediction results using TransE, CompleX, and RotatE based methods. The link prediction model achieved up to 0.44 hits@10 on the entity prediction tasks. The recent outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as COVID-19, served as a case study to demonstrate the efficacy of link prediction modeling for drug discovery. The link prediction algorithm guided identification and ranking of repurposed drug candidates for SARS-CoV-2 primarily by text mining biomedical literature from previous coronaviruses, including SARS and middle east respiratory syndrome (MERS). Repurposed drugs included potential primary SARS-CoV-2 treatment, adjunctive therapies, or therapeutics to treat side effects. The link prediction accuracy for nodes ranked highly for SARS coronavirus was 0.875 as calculated by human in the loop validation on existing COVID-19 specific data sets. Drug classes predicted as highly ranked include anti-inflammatory, nucleoside analogs, protease inhibitors, antimalarials, envelope proteins, and glycoproteins. Examples of highly ranked predicted links to SARS-CoV-2: human leukocyte interferon, recombinant interferon-gamma, cyclosporine, antiviral therapy, zidovudine, chloroquine, vaccination, methotrexate, artemisinin, alkaloids, glycyrrhizic acid, quinine, flavonoids, amprenavir, suramin, complement system proteins, fluoroquinolones, bone marrow transplantation, albuterol, ciprofloxacin, quinolone antibacterial agents, and hydroxymethylglutaryl-CoA reductase inhibitors. Approximately 40% of identified drugs were not previously connected to SARS, such as edetic acid or biotin. In summary, link prediction can effectively suggest repurposed drugs for emergent diseases.

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Adiukwu, Paul Chukwuemeka, and MO Tebogo. "Chromatography and mass spectroscopy analysis of bioactive principles from Vernonia amygdalina leaf aqueous extract." African Journal of Food, Agriculture, Nutrition and Development 21, no. 103 (September 27, 2021): 18501–17. http://dx.doi.org/10.18697/ajfand.103.19720.

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Application of medicinal plants in managing disease conditions is a practice as old as mankind. Its use in today’s healthcare has increased astronomically when compared to any other era. National policies, which integrate herbal products in healthcare systems, and the increasing presence of herbal clinics have become the order in many countries. Despite the ease of accessibility and affordability, the use of products from medicinal plants as phyto-medicines is threatened by the inability to maximize the benefits. This is due to inadequate qualitative and quantitative data necessary for proper application and regulation. Vernonia amygdalina, a herb widely used by ethnics in diverse forms of health management, is one such medicinal plant. This study was designed to determine referenceable values for the ethno formulation of the herb which is usually prepared as the aqueous extract of the leaf. Standard techniques and procedures were employed for this study. Fractionation of the extract was carried out using facilitated column chromatography. Pure principles of fractionates were separated with gas chromatography and identified using hyphenated mass spectrometer based on their relative abundance. The obtained chromatogram and spectra of principles were elucidated by relating data to the Mass Spectral Database with Automatic Mass Spectra Deconvolution & Identification System (AMDIS). Preliminary screening of extract indicated the absence of quinine but presence of alkaloids, tannins and saponins. Aqueous extraction produced 18 % (w/w) yield. The accelerated column chromatography produced a yield in the ratio of four to six to nine for the chloroform, chloroform/methanol and methanol effluents, respectively. Data obtained from the AMDIS elucidation showed the presence of eleven principles, which includes 1, 2, 3, 4-Butanetetrol; 1, 2-Benzenediol; and Caprolactam among others. Some of the properties and bioactivities of these principles have been reported in previous literature. Findings suggest that bioactivity common with some of these principles is consistent with previous literature on the use of the herb, and demonstrates reasons for the folkloric application.

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Knölker, Hans-Joachim, Arnold Braier, Dirk J. Bröcher, Simon Cämmerer, Wolfgang Fröhner, Peter Gonser, Holger Hermann, Daniela Herzberg, Kethiri R. Reddy, and Guy Rohde. "Recent applications of tricarbonyliron-diene complexes to organic synthesis." Pure and Applied Chemistry 73, no. 7 (July 1, 2001): 1075–86. http://dx.doi.org/10.1351/pac200173071075.

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The present review describes some of our recent applications of tricarbonyliron-diene chemistry to organic synthesis. It focuses on the selective synthesis of tricarbonyliron-diene complexes including the asymmetric catalytic complexation of prochiral cyclohexa-1,3-dienes, the enantioselective synthesis of carbazole-3,4-quinone alkaloids, and the iron-mediated synthesis of corannulene and yohimbane alkaloids.

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Iribarren, Iñigo, and Cristina Trujillo. "Improving phase-transfer catalysis by enhancing non-covalent interactions." Physical Chemistry Chemical Physics 22, no. 37 (2020): 21015–21. http://dx.doi.org/10.1039/d0cp02012e.

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A theoretical study of the interactions established between an alkaloid quinine-derived PTC and different anions of interest was performed. Ion pairing competes with an intermolecular hydrogen bond between the PT counteranion and potential HB donors.

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S.*, Abdul Nasar, and Narasegowda P. N. "Physico-chemical and phytochemical evaluation of Aloe acutissima leaves." International Journal of Bioassays 5, no. 06 (May 31, 2016): 4633. http://dx.doi.org/10.21746/ijbio.2016.06.0010.

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Aloe acutissima is a fast growing shrub belonging to the family Xanthorrhoeaceae. This plant is a point of concern as it has profound importance in the field of pharmacology. The secondary metabolites obtained from this plant viz., alkaloids, flavonoids, steroids, quinines, glycosides, tannins, saponins, terpenoids, phenols, proteins, oils and free fatty acids serves as a medicinal tool to mankind. The study comprises of physico-chemical and phytochemical evaluation of leaves of Aloe acutissima by using standard methods. Physico-chemical parameters such as percentage of loss on drying (LOD), ash values, extractive values were determined. Phytochemical evaluation was carried out to detect the presence of alkaloids, carbohydrates, tannins, saponins, flavonoids, quinines, glycosides, terpenoids, phenols, couramins, acids, proteins, oils and free fatty acids in different extracts of Aloe acutissima leaf powder. Estimation of Phenols, Tannin, flavonoids, Alkaloids, steroids and ascorbic acid content of Aloe acutissima leaves were also carried out. Thus the present study revealing the physico-chemical data and phytochemical analysis of leaves of Aloe acutissima is useful for further studies of pharmacological parameters which is helpful for the future at large.

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Journal articles on the topic 'Quinine alkaloids'

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