Antimicrobial activity of the crude extracts and five flavonoids from the twigs of Dorstenia barteri (Moraceae).
ABSTRACT The aim of this study was to evaluate the antimicrobial activity of the crude extract of the twigs of Dorstenia barteri (DBT) as well as that of four of the five flavonoids isolated from this extract. Gram-positive bacteria (six species), Gram-negative bacteria (12 species) and fungi (four species) were used. The agar disc diffusion test was used to determine the sensitivity of the tested samples while the well micro-dilution was used to determine the minimal inhibition concentrations (MIC) and the minimal microbicidal concentration (MMC) of the active samples. The results of the disc diffusion assay showed that DBT, isobavachalcone (1), and kanzonol C (4) prevented the growth of all the 22 tested microbial species. Other compounds showed selective activity. The inhibitory activity of the most active compounds namely compounds 1 and 4 was noted on 86.4% of the tested microorganisms and that of 4-hydroxylonchocarpin (3) was observed on 72.7%. This lowest MIC value of 19.06microg/ml was observed with the crude extract on seven microorganisms namely Citrobacter freundii, Enterobacter aerogens, Proteus mirabilis, Proteus vulgaris, Bacillus megaterium, Bacillus stearothermophilus and Candida albicans. For the tested compounds, the lowest MIC value of 0.3microg/ml (on six of the 22 organisms tested) was obtained only with compound 1, which appeared as the most active compound. This lowest MIC value (0.3microg/ml) is about 4-fold lower than that of the RA, indicating the powerful and very interesting antimicrobial potential of isobavachalcone (1). The antimicrobial activities of DBT, as well as that of compounds 1, 3, 4, amentoflavone (5) are being reported for the first time. The overall results provide promising baseline information for the potential use of the crude extracts from DBT as well as some of the isolated compounds in the treatment of bacterial and fungal infections.
Full-textDOI: · Available from: Victor Kuete, Jul 07, 2015
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ABSTRACT: This study was designed to evaluate the antimycobacterial, antibacterial and antifungal activities of the methanol extract from the stem bark of Thecacoris annobonae Pax & K. Hoffm, that of aristolochic acid I (1) and other isolated compounds. The microplate alamar blue assay (MABA) and the broth microdilution method were used to determine the minimal inhibitory concentration (MIC) and minimal microbicidal concentration (MMC) of the above samples. The H+-ATPase-mediated proton pumping assay was used to evaluate a possible mechanism of action for both the methanol extract and aristolochic acid I. The results of the MIC determinations showed that the methanol extract and aristolochic acid I prevent the growth of all studied organisms. The results obtained in this study also showed that the methanol extract as well as aristolochic acid I inhibited the H+-ATPase activity. The overall results provided evidence that the methanol extract of T. annobonae might be a potential source of new antimicrobial drug against tuberculosis, and some bacterial and fungal diseases, but should be consumed with caution, bearing in mind that the main active component, aristolochic acid I is a potentially toxic compound.South African Journal of Botany 07/2013; DOI:10.1016/j.sajb.2010.04.003 · 1.34 Impact Factor
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ABSTRACT: Deguelia duckeana is popularly known as timbó and used by indigenous people as ictiotoxic. On account of there being no literature pertaining to the chemical profile or biological activity of this plant, the hexane, methanol and aqueous crude extracts from leaves, stems and roots were assayed that presented very high cytotoxic potential against Artemia salina, achieving 100% mortality in up to 5.0 µg mL(-1) concentration, but lower antioxidant potential on 2,2-diphenyl-1-picryl-hydrazyl and Fe(3+)/Phenanthroline assays. The phytochemical analysis of crude extracts showed the presence of flavonoids and related compounds as major constituents as well as steroids in all of them, and tannins in polar extracts. All the extracts were assayed for antibacterial activity but only the hexane extract of stems showed moderate activity on Staphylococcus aureus, which was fractionated and yielded a mixture of 3,5,4'-trimethoxy-4-prenylstilbene, lonchocarpine, 4-hydroxylonchocarpine and derricidine, reported for the first time in D. duckeana and other fraction with β-sitosterol and stigmasterol mixture.Natural product research 10/2012; 27(4-5). DOI:10.1080/14786419.2012.733387 · 1.23 Impact Factor
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ABSTRACT: Background information: Plants produce hosts of secondary metabolites that help them to fight off infections. However these phytochemicals have also been found to inadvertently protect humans against infections and are therefore a current subject in bio-prospecting for new therapeutic leads. Objectives: The aim of this study was to investigate the antibacterial properties of organic solvent root extracts of Indigofera lupatana Baker F. Methods: Powdered sample of I. lupatana Baker F. roots were sequentially extracted using hexane, ethyl acetate and dichloromethane solvents. The resultant fractions were subjected to anti-bacterial assay. Results: The fractions showed the highest activity against Bacillus subtilis (28.5 ± 0.3mm), Staphylococcus aureus (22.6 ± 0.1mm), Bacillus cereus (22.0 ± 0.3mm), Escherichia coli (21.7 ± 0.7mm), Pseudomonas aeruginosa (21.5 ± 0.9mm), Salmonella typhimurium (17.3 ± 0.3mm), Klebsiella pneumonia (10.6 ± 0.9mm) and Proteus mirabilis (10.4± 1.1mm). The MIC ranged from between 21.9 to over 750mg/ml. The activity was greater among the Gram positive bacteria than Gram negative bacteria. Discussion: These results demonstrate that Indigofera lupatana Baker F. can be used as an alternative source of new, effective drug(s) against the tested microbes because it demonstrated anti-bacterial efficacy.