Title : Antimicrobial properties of Tanzanian combretum species
Abstract:
Combretum species are well known and documented in treatment of broad-range of ailments, including microbial infections. Previous studies have shown that extracts of few investigated Tanzanian Combretum species have significant antifungal activity. The studies however did not cover all Combretum species found in Tanzania, or go further in identifying the active compounds.
This study aimed to collect and extract Combretum species found in Tanzania for the purpose of evaluating their antimicrobial activity and isolate active secondary metabolites from the most active species
Combretum species were collected from different regions of Tanzania and extracted by cold maceration at room temperature using 95% ethanol. Antimicrobial activity of extracts and secondary metabolites were carried out using disc-diffusion and broth microdilution methods. Isolation of secondary metabolites was done on the most active extracts using chromatographic methods and identification was done by spectroscopic methods.
A total of 83 samples from twenty-four Combretum species were collected and extracted. Antimicrobial tests showed that 41 extracts had activity to at least one microbe, with best activity displayed by C. apiculatum and C. mole, with inhibition zone of 12.5 mm and 11.0 mm respectively against S. aureus, at 1 mg/disc. Eleven secondary metabolites were isolated and identified as quercitrin, afzelin, apigenin, mollic acid, musambin C, 24-epiquadrangularic acid M, musambin B, flavogallonic acid dilactone, combreglutinin, terflavin A, and terchebulin. Terchebulin had the best antifungal activity of 64 μg/ml against C. albicans.
Antimicrobial activity displayed by the extracts and the isolated secondary metabolites from the Combretum species support traditional use of Combretum species in treatment of microbial infections.
Keywords: Combretum, antimicrobial, secondary metabolites
