Characterization of some flavonoids from the leaves of Annona squamosa and stem Bark of Borassus aethiopium and their Biological Activity

Abstract

Phytochemical screening the leaves of Annona squamosa and the stem bark of Borassus aethiopum revealed the presence of flavonoids, tannins, alkaloids and glycosides in both species. A silica gel column eluted with methanol: ethyl acetate in order of increasing polarity followed by a Sephadex column allowed isolation of compound I from the stem bark of Borassus aethiopum , while paper chromatography allowed isolation of three components : II, III(from Borassus aethiopum) and IV from leaves of Annona squamosa .The structures of the isolates were deduced on the basis of their spectral data(UV,NMR and MS).

I

II

iv

III

IV

The methanolic fractions of both species were evaluated ,in vitro, for their potential antimicrobial activity against six standard human pathogens(Gram positive: Staphylococcus aureus and Bacillus subtilis; Gram negative : Escherichia coli and Pseudomonasa aeruginosa and the fungi Candida albicans and Aspergillus niger) using the cup plate agar diffusion bioassay . Different antimicrobial responses were observed. The activity ranged from high to moderate. Since the biological activity of flavonoids is well documented now, the bioactivity of these extracts could possibly be due to their flavonoid content .