PRELIMINARY STUDIES OF THE ANTIBACTERIAL ACTIVITIES OF COMBRETUM VENDAE LEAF EXTRACT

Abstract

The Combretaceae family has many pharmacological activities and bioactive compounds have been isolated from some of the species.1 No information is available on the anti-bacterial activities of Combretum vendae. This study investigates the effect of more polar leaf extracts of Combretum vendae on some bacteria associated with diarrhoea and inflammatory diseases (Eschericha coli, Enterococcus faecalis, Pseudomonas aeruginosa and Staphylococcus aureus). Milled samples of air dried leaves were extracted with 70% acetone acidified with 1% HCl, concentrated under vacuum and freeze-dried. The polyphenolic content of the extract was evaluated by Folin-Ciocalteau method. The antibacterial activities of the extract were determined in vitro and the minimum inhibitory concentrations (MIC) were assessed using the microplate dilution method2. Serial dilutions with a maximum concentration of 2.5 mg/ml and a minimum concentration of 0.02 mg/ml of the extract were made. Distilled water was used as negative control and gentamicin as positive control. Yield of extract was 38.88%; total phenol, 38.55 mg catechin equivalent/g; total tannin, 22.39 mg catechin equivalent/g; non tannin, 16.39 mg catechin equivalent/g. The MIC of extract against E. coli, E. faecalis, P. aeruginosa and S. aureus were 0.312 mg/ml, 0.156 mg/ml, 0.156 mg/ml and 0.156 mg/ml respectively. The results shows that polar Combretum vendae leaf extracts have some anti-bacterial activities that can be explored as alternative to existing antibacterial drugs. Tannins are implicated in non-specific antibacterial activity and tannin content in this extract is relatively high, the antibacterial activity may be attributed in part to the tannin content. References: 1 Eloff JN, Katerere DR, McGaw LJ (2008) J. Ethnopharmacology 119, 686-699 2 Eloff JN (1998) Planta Medica 54,711-714