Antimicrobial activities and phytochemical properties of Annona muricata leaf

Annona muricata is a well-known economic and traditional plant of Nigeria. The study investigated the properties of constituents and antimicrobial activities of extracts of the leaf of A. muricata. The extracts were tested against Escherichia coli, Pseudomonas aeuroginosa, Staphylococcus aureus and Candida albicans by the agar well diffusion method at concentration of 20 mg/mL. The methanol (AM2) and ethyl acetate (AM4) extracts were characterized using UV and IR spectroscopy. The morphological structure of the A. muricata leaf was observed at a magnification of 20,000X using SEM and then subjected to EDX analysis. The results of the phytochemical screening revealed the presence of phenolic compounds, flavonoids, tannins, alkaloids, saponins and cardiac glycosides in the extracts. Anthraquinone was found absent. The ethyl acetate extract was found highly active against gram positive bacteria, S. aureus (ZI of 42 mm; AI = 1.31) and ampicillin resistant gram negative P. aeruginosa (ZI of 34 mm; AI = 1.13). The IR spectra of AM2 and AM4 extracts of A. muricata showed peaks at a frequency of 3377 cm-1 to 3440 cm-1 indicating the presence of a phenolic OH stretch. This supports the phenolics detected chemically. The UV spectrum of methanol extract showed peaks that are typical of flavonoids and phenolics. The SEM revealed the sizes of the leaf particles as inhomogeneous. EDX results showed high oxygen concentration of 73.5 % and carbon concentration of 26.5 %.The findings proved the anti-infective potential of Annona muricata leaf and established physico-chemical markers for the active extracts