Evaluation of antimicrobial activity and phytochemical composition of some fractions of methanol stem bark extract of Diospyros mespiliformis

Abstract

The aim of this study was to determine the active phytochemical(s) most probably responsible for microbial inhibitions, following a bioassay guided protocol. Column chromatographic fractions (AG) obtained from n-Butanol partitioned portion of stem bark extract of Diospyros mespiliformis were analyzed for phytochemical composition. These were subjected to antimicrobial activity tests on clinical isolates of Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Klebsiella pneumoniae and Candida albicans. Phytochemical screening conducted on the column fraction E revealed the presence of tannins, free anthraquinones, cardiac glycosides, saponins, terpenoids, and flavonoids. The anti-microbial test results from fractions A, B, F and G, obtained showed no inhibition against most of the micro-organisms tested, while fractions C, D and E showed significant (P<0.05) activities with diameters of inhibition zone of inhibition ranging from 15.00±1.00 mm to 13.00±6.67 mm against Streptococcus pyogenes at all the concentrations tested (50, 12.5, 6.25 mg/ml equivalent to 3, 1.5 and 0.75 mg/disc). The column fraction E showed the highest inhibition zones with broader concentration dependent pattern with MIC at 12.5 mg/ml. The findings from this study showed the presence of bio-active components against Streptococcus pyogenes with relative higher potency in fraction E. Based on this findings, it can be surmised that Fraction E with significant dose-dependent activity is expected to revealed a potent broad-spectrum antimicrobial agent and thus recommended for further purification stages towards compound(s) isolation of a novel antimicrobial agent.

Keywords: Antimicrobial, Diospyros mespiliformis, Phytochemical, Potency, Stem Bark