Evaluation of Mangifera indica for antimicrobial activity
The leaves of Mangifera indica were subjected to ethanol extraction and the extracts fractioned by suspending the extract in 20% ethanol and partitioned with different organic solvents (n-hexane, chloroform, ethyl acetate) in order of increasing polarity. Standard methods were used for both extraction and phytochemical screening. Modified agar well diffusion method was adopted for screening the antimicrobial activities. The test was carried out in triplicates. The test organisms were S. aureus, S. epidermidis, P. aeruginosa, E. coli, K. pneumoniae, P. mirabilis, P. vulgaris and C. albicans. The leaf extract was phytochemically screened and revealed the presence of Flavonoid, Alkaloid, Tannins, Steroid, Saponins, Cardiac glycosides, Anthraquinone, Triterpenoids. The chloroform leaf extract showed strong antimicrobial activity on both gram positive and gram negative organisms; followed by the aqueous extract. The ethyl acetate leaf extract ranked third. n-hexane leaf extract had the least antimicrobial activity. The 100 mg/ml concentration exerted a broad spectrum antimicrobial activity with the highest diameter zone of inhibition of 18mm against Staphylococcus aureus and Klebsiella pneumoniae. This activity was followed by the 50 mg/ml and 25 mg/ml concentrations in that order. Fifty (50) mg/ml exerted the diameter zones of inhibitions of 10.5 mm while 25 mg/ml concentrations exerted the diameter zones of inhibitions of 7.5 mm. Also the least antimicrobial activity was exerted by the 25 mg/ml concentration, followed by the 50 mg/ml concentration with diameter zones of inhibitions of 4 mm and 7.5mm respectively, against S. epidermidis and C. albicans and some Gram negative organisms. The data obtained showed broad spectrum activities with increasing diameter zone of inhibitions at increasing concentrations, which showed that the inhibitory effects of the extracts were not only solvent dependent but also concentration dependent (Figures 1 – 8). The extracts were subjected to MIC evaluation and the findings showed that E. coli and K. pneumoniae were the most sensitive. The MBC showed no value. This study shows that the leaves of M. indica when purified to the appropriate pharmacological level, contain some active principles with antimicrobial potential that will be useful in preventing and curing diseases.
Keywords: M. oleifera, Antimicrobial, Phytochemical, Infectious isolates