Potential clinical relevance of Buchholzia coriacea: in vitro antimicrobial characteristics of the methanol leaf extract.

BACKGROUND

Buchholzia coriacea is acclaimed to be efficacious in several microbial infections and traditionally used for the treatment of diarrhoea and respiratory infections, among others, thereby, raising its potential relevance in the search for new antimicrobial agents. This study evaluated the phytochemical constituents, in-vitro antimicrobial activities and Minimum Inhibitory Concentration (MIC) of the methanol leaf extract of B. coriacea at lower concentrations in comparison with standard drugs.

METHODS

The leaves of B. coriacea were harvested, air-dried, pulverized and extracted exhaustively by cold maceration using methanol. Using agar-well diffusion method, antimicrobial screening was done at various concentrations (ranging between 11.9 mg/ml and 190 mg/ml), after phytochemical screening of the dried extract. Further, antimicrobial effects of the extract on test organisms - Klebsiella spp, Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Candida albicans, were compared to ciprofloxacin and gentamicin.

RESULTS

Tannins, saponins, cardenolides, terpenoids and reducing sugars were present in the extract. Klebsiella spp (0-24 mm) had the highest inhibition zone diametre for the extract, while E. coli (2-20 mm), and C. albican (2-11 mm) were most sensitive at much lower concentration, and no inhibitory effect was observed against Bacillus subtilis (0-0 mm). The MIC was lowest for Klebsiella spp (12.59 mg/ml) and S. aureus (12.59 mg/ml), while E.coli had higher MIC (15.85 mg/ml). Ciprofloxacin and gentamycin had significantly (P < 0.001) lower MIC than the extract for the test organisms.

CONCLUSION

The methanol leaf extract of B. coriacea comprised several phytochemicals at various concentrations and exhibited appreciable concentration-dependent antimicrobial activities. However, ciprofloxacin and gentamycin showed activity against the test bacteria at significantly lower concentrations than the extract. Nonetheless, the methanol leaf extract of B. coriacea having shown a relatively modest broad-spectrum antimicrobial activity, may be further evaluated for potential pharmaceutical formulations.