Phytochemical screening and antimicrobial activity of <i>Cassia obtusifolia</i> leaf extracts

Abstract

Cassia obtusifolia is a plant which plays an important role in the traditional system of holistic health and herbal medicine in Africa. In this study phytochemical constituents and antimicrobial activity of Cassia obtusifolia leaf extracts were investigated. The leaf powder of Cassia obtusifolia was macerated with methanol and then fractionated with petroleum ether, dichloro methane and ethyl acetate. The extract and fractions were subjected to phytochemical analysis to detect the presence of secondary metabolites by using standard procedures. The extract and fractions were further subjected to antimicrobial activity against ten microorganisms namely Staphylococcus aureus, Escherichia coli, Aspergillus flavus, Aspergillus niger, Klebsiella pneumoniae, Streptococcus pyogenes, Proteus mirabilis, Salmonella typhi, Shigella dysentriae and Pseudomonas aeruginosa. The result of phytochemical analysis indicated the presence of saponins, tannins, steroids, flavonoids, glycosides, triterpenoids and alkaloids. The antimicrobial susceptibility study showed dose-dependent pattern. The ethyl acetate extract had the highest activity with the zone of inhibition of 20mm against Staphylococcus aureus at a concentration of 4000 μg /mL and a minimum inhibitory concentration at 1000 μg/ml, followed by dichloromethane extract which had zone of inhibition of 19mm against E.coli. Still at same concentration an inhibition zone of 18mm was recorded against E.coli, S.dysenteriae and S.typhi from the ethyl acetate and methanol extracts respectively. The lowest zone of inhibition (9mm) at that concentration recorded against Aspergillus niger was from methanol extract. This study showed interesting correlation between the phytochemical and biological activities hence, findings from this study, justifies the traditional use of the plant in treatment of various diseases.