Abstract

IN VITRO ANTIBACTERIAL ACTIVITES, SAFETY STUDIES AND PHYTOCHEMICAL SCREENING OF DREGEA SCHIMPERI CLARK (ASCLEPIADACEAE) EXTRACTS

Onyancha Jared M.*, Wakori E.W.T., Moriasi Gervason A., Waiganjo Bibianne W., Kisengi John M., Arara Lameck N. and Ng’etich Japhet K.

Abstract

Plants synthesize phytochemical compounds for protection against environmental stress and diseases. Some of the phytochemicals are used for curative and preventive medicine. Over 90% plants produce phytochemicals that are used in traditional medicine to treat diseases in human and veterinary diseases. Since a great percentage of these plant materials used lack sufficient scientific data to back their healing claims, the objective of this study was to evaluate antimicrobial, cytotoxic and phytochemical properties of methanolic and water extracts of Dregea schimpheri extracts. Disc diffusion method was used to assay for antimicrobial activities of the methanolic and waterextracts of leaves and husks. The microorganismsagainst which the extracts were tested were Staphylococcus aureus, Micrococcus luteus, Bacillus pumilus, Pseudomonas aerugnosa and Escherichia coli. Cytotoxicity of the extracts was determined by use of brine shrimp lethality test. Qualitative phytochemical screening of the husks and leaves was performed using standard phytochemical tests. Antibacterial results were tabulated as mean zone of inhibition ± SEM while LC50 values for brine shrimp lethality test were estimated using Graphed Prism Version 5 statistical software. Phytochemical screening observations were also tabulated. Most extracts exhibited antibacterial activity, on the other hand water and methanol husk extracts of D. schimperi were found to be cytotoxic (LC50 ˂100 μg/ml) while all leaf extracts had moderate to low toxicity. Alkaloids, phenols, tannins were observed in both leaf and husk powders. However, saponins and anthraquinones were present in leaf extracts but absent in the husks. The antibacterial and cytotoxic activities are attributed to the presence of these secondary metabolites. Further studies aimed at isolating the bioactive compounds with antibacterial and cytotoxic properties are recommended. In vitro and in vivo toxicity studies are also necessary.

Keywords: Disc diffusion, Zone of inhibition, Brine shrimp lethality test, LC50.