The phytochemical and anti-microbial potential of the extracts from the fruit pulp of Landlphia owariensis
The phytochemical composition and antimicrobial potential of extracts of fruit pulp of Landolphia owariensis was investigated. L. owariensis mesocarp flour was obtained by oven drying at 500C and pulverized while microwave assisted extraction was used to obtain hexane, chloroform, ethyl acetate and methanol extracts, which were concentrated in vacuo using microwave and thereafter air dried at ambient temperature. Antimicrobial sensitivity tests on fourteen (14) human pathogenic microorganisms were performed using diffusion method while minimum inhibitory concentration (MIC) and minimum bacterial/fungal concentration (MBC/MFC) tests were performed using dilution method. The oven dried L. owariensis fruit pulp flour contained 12.45±0.03 mg/100 g tannins and 6.39±2.78 mg/100 g total flavonoids but low levels of anthraquinones, alkaloids, cyanogenic glycosides, saponins, steroids and terpenes. The phytosterols consisted of cholesterol, cholestanol, campesterol, stigmasterol, beta sitosterol and tocopherol with stigmasterol being the most abundant (1.06±0.21 mg/100 g). The flavonoids constituents included orientin, isovitexin and keampferol. Microbiological analysis of hexane, chloroform, ethyl acetate and methanol extracts of L. owariensis fruit pulp showed antimicrobial activities against S. aureus, S. pyogenes, S. typhi, S. dysenteriae, K.pneumoniea, C. albicans, C. krusei, C. stellatoidea and M. rubrum. Chloroform extract exhibited the highest zones of inhibition, followed by hexane and ethyl acetate extracts while methanol extract had least diameter of zones of inhibition. Also ethyl acetate extract was more potent (2.5-5 mg/mL), followed by chloroform and methanol extracts while hexane extract had the least potency (5-10 mg/mL) level. Similarly, ethyl acetate extract was most effective (5-10 mg/mL) in inhibiting bacterial/fungal growth. L. owariensis fruit pulp flour and extracts contained important secondary metabolites that may account for its antimicrobial activities.
Keywords: Landolphia owariensis, phytochemicals, anti-microbial activities, flavonoids, phytosterols