Academic literature on the topic 'Antibacterial Screening'

Plants from Northern Nigeria with a history of use in both human and veterinary traditional medicine have been investigated in vitro, for antiviral and antibacterial activity and their cytotoxicity against human cells in culture determined. Aqueous extracts were tested against poliovirus, astrovirus, human and Equine herpes simplex virus and canine and bovine parvovirus, using the microtitre plate inhibition test. Most of the extracts were non toxic to cells in culture and had activity against more than one virus at a dose rate of between 100 and 400 g/100. the most effective of the plant extracts were those of Bauhania thonningi, Anacardium occidentale, Boswelia dalzeilii, Dichrostacyls glomerata and Sterculia setigera, which were found to be active against all the viruses tested. In addition, most of the extracts were active against those Gram positive bacteria tested. Two of the plants, Anogeissus schimperi and Anacardium occidentale, had good antibacterial activity against the Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. Attempts were made to isolate and identify the active components in these extracts with activity against both viruses and bacteria using the gel filtration, ion-exchange chromatography and thin layer chromatography. Activities were associated with fractions identified as flavonoids, alkaloids, terpenoids and polyphenols and were found, either individually or in combination, to have antiviral action. A field trial of the active plant extracts was carried out using cattle with clinical diarrhoea and dysentery and comparing recovery patterns with similar administering extracts to cattle with clinically diagnosed diarrhoea animals treated with a broad spectrum gut-acting antibiotic, neomycin-sulphate. No significant difference (P=0.778) was seen between the extract and the antibiotic in efficacy of treatment.

The following study was conducted to investigate the antibacterial and feed additive potential of medicinal plants. Ethanol extracts of different medicinal plants including Curcuma longa (Turmeric), Zingiber officinale (Ginger), Piper nigrum (Black Pepper), Cinnamomum cassia (Cinnamon), Thymus vulgaris (Thyme), Laurus nobilis (Bay leaf), and Syzgium aromaticum (Clove) were tested using the disc diffusion method for their antimicrobial activity against the common poultry pathogens E. coli, S. typhimurium, E. faecium, and E. faecalis. Cinnamon extract (CE), at 130 mg/disk, exhibited antibacterial activity against E. coli, S. typhimurium, and E. faecalis. Thyme extract (TE), at 30 mg/disk, exhibited antibacterial activity against E. coli, E. faecium, and E. faecalis while the remaining medicinal plants extracts showed no activity. The minimum inhibitory concentration (MIC) of the cinnamon and thyme ranged from 31.25 to 250 mg/ml by the dilution method. From this in vitro antibacterial study, cinnamon and thyme were selected for a 21-d feeding trial in broilers to study their influence on feed consumption, body weight gain, and feed conversion. There were 6 dietary treatments groups: 1) negative control (NC) containing no plant extracts or antibiotic, 2) positive control (PC) containing BMD (bacitracin) at 50g/ton of feed, 3) Diet 1 plus low level of cinnamon extract (LCE) at 290 gm/100 kg of feed, 4) Diet 1 plus high level of cinnamon extract (HCE) at 580 gm/ 100 kg of feed, 5) Diet 1 plus low level of thyme extract (LTE) at 290 gm/100kg of feed, and 6) Diet 6 plus high level of thyme extract (HTE) at 580 gm/100 kg of feed. No significant changes in body weight gain were observed with the cinnamon extracts compared to the NC or PC at 7, 14, or 21 d. The HTE reduced body weight gain compare to the NC and PC at 7, 14, and 21 d (P < 0.02). No difference in feed efficiency was observed with any of the treatments except LCE which reduced feed efficiency compared to other treatments. No difference in feed consumption was found among any of the treatments. These results suggest that cinnamon and thyme have antibacterial activity in vitro, and thyme has an activity that reduces body weight. Since cinnamon caused no significant change in body weight gain compared to positive or negative controls, it warrants further study as a substitute for antibiotics in the diet.<br>Master of Science

Natural products and their derivatives have and are still used by humans for various health ailments due to their rich sources of drug discovery. New biologically active compounds from natural products play a key role in drug development. Marine sponges and their associated microbes contain a lot of bioactive compounds that are potential for drug development. These compounds produce chemical compounds with useful pharmaceutical properties such as antitumor, anti-infective, anti-inflammatory, and antibacterial properties. The main focus of this project was on the antibacterial activity of six different sponge specimens. The aim was to screen the antibacterial activity of the sponge specimen’s extracts. In order to do so, a Minimum Inhibitory Concentration assay was performed to screen the sponge's antibacterial activity against E. coli and S. aureus. Analytical HPLC was used for separation and Solid Phase Extraction (SPE) was used for determining the effect of salts towards the inhibition of anti-bacterial activity for two selected extracts. Ethanolic extract of Stylissa massa showed antibacterial activity against S. aureus. SPE would be a rapid purification step to remove the salts present in sponges at a high concentration but it has not shown a significant effect on the inhibition of antibacterial activity. However, further separation and purification need to be done to be able to completely screen for all the six different sponge specimens.

Drug-resistant pathogenic and opportunistic bacteria are increasing in occurrence and prevalence, and pose a dangerous threat to human health. In the search for novel antibiotics with which to combat this threat, plants, specifically those used in traditional medicine with ascribed antibacterial properties, offer a promising and potentially vast source of such therapeutic compounds. The purpose of this study was therefore to screen chemical extracts created from various plant species for antibacterial properties versus pathogenic bacterial species. In the course of these antibacterial assays, we successfully identified a methanol extract derived from Artemisia tridentata tridentata plant material as capable of inhibiting the growth of the opportunistic pathogen Staphylococcus aureus. Three sub-fractions were created using hexane, ethyl acetate and water solvents. Each of these extracts displayed significant antibacterial activity versus a wild-type strain over a period of six hours, at concentrations as low as 62.5 µg/ml. The extracts also demonstrated an enhancement of antibiotic effects when combined with ampicillin, G418 sulfate or amikacin, for a period of up to twelve hours. Though the efficacy of the extracts was lessened when tested against an ampicillin-resistant strain, significant enhancement of the efficacy of this antibiotic was still observed. Gas chromatography-mass spectrometry analysis of these three extracts revealed the sesquiterpene lactone achillin as present in each. Column chromatography of the hexane extract resulted in a fraction retaining its antibacterial activity, and still containing this compound, further implicating it as responsible for the antibacterial activity of this plant. The results of serial dilution and plating of extract-treated samples, along with those of ethidium bromide assays and transmission electron microscopy analysis, indicated a bacteriostatic mechanism of action involving disruption of the bacterial membrane, which is in agreement with the literature on the antibacterial properties of this plant, and those of sesquiterpene lactones, respectively. We therefore conclude that achillin, likely produced as a secondary metabolite by Artemisia tridentata tridentata, possesses growth inhibitory properties versus Staphylococcus aureus, and should be isolated and studied further for the purposes of evaluating its potential use, either as a stand-alone antibiotic, or as an adjunctive therapeutic, in the treatment of drug-resistant bacterial pathogens.

>Magister Scientiae - MSc<br>Nanotechnology has emerged as an elementary division of modern science and stemmed directly from green chemistry twelve basic concepts, it receives global attention due to its unique character and ample applications. It also has great potential to mitigate the challenges they face in various fields, especially medical sector. Nanodrugs are increasingly considered as a potential candidate to carry therapeutic agents safely into a targeted compartment in an organ, particular tissue or cell. In this study, twenty (20) Libyan plants were selected and evaluated for their potential to synthesis gold and silver nanoparticles. The screening of the different plant extracts was performed using 96 well plate method at 25 °C and 70 °C. The NPs formation was confirmed and characterized using UV- Vis, DLS, HR-TEM and EDX. A well-defined NPs were obtained at high temperature (70 °C). The Au NPs had an average diameter of 92 nm at 25 °C and 66 nm at 70 °C. The zeta potential values were observed to be negative (-14 to -24) and indicate the stability of the Au NPs. The HR-TEM showed polydispersity, which decreased at higher temperature (70 °C). The stability of Au NPs in nutrient broth prior was conducted as well. All the Au NPs under study showed stability, only minimal changes in the UV-Vis spectra can be observed. Two plant extract viz Pistacia atlantica, Junipers phoenicea showed consistent results and forming stable and smaller NPs compared to others, both of the plant extracts and the corresponding NPs were tested against Streptococcus mutans and showed MIC value ~ 49 g/mL. In case of silver NPs, two plant extracts viz J. phoenicea, Rosmarinus officinalis, showed superior results than the others; both plants produced stable and small Ag NPs. The antibacterial activity against S. mutans demonstrated MIC valus ~ 50 g/mL. The synthesised NPs showed a promising bioactivity for developments of new antibacterial agents against S. mutans strains. Dose-dependent activity was observed for the tested NPs.