ANTIBACTERIAL ACTIVITY OF FRACTIONS OF LEAF EXTRACT OF ANNONA SENEGALENSIS (PERS)

ABSTRACT Ethyl acetate, n-hexane, butanol and residual fractions from the ethanol (70%) E extracts of Annona senegalensis (Pers) leaves were evaluated for their antibacterial activity at 20 mg/ml against Escherichia coli, Salmonella typhi, Staphyloccocus aureus, Bacillus subtilis (clinical isolates) Escherichia coli ATGC25922 and Bacillus cereus NCIV6 using the agar well diffusion method. The antibiotics Augmentin and ampiclox were used as positive control while dimethylsulphoxide (DMSO) was used as negative control. The ethyl acetate fraction showed zone of inhibition against all the test bacteria (Escherichia col, 11.5mm; Staphyloccocus aureus, 11.5 mm; Salmonella typhi, 13.0 mm; Bacillus subtilis, 17.0mm; standard Escherichia coli ATGC25922, 11.5 mm and standard Bacillus cereus NCIV6, 15.5 mm). Ampiclox produced a zone of inhibition of more than 11 mm against all the organisms except Salmonella typhi and Staphyloccocus aureus while Augmentin produced zone of inhibition of more than 11 mm against all except Salmonella typhi. The ethanol extract showed activity against Bacillus subtilis (13.5 mm) and Bacillus cereus NCIV6 (15.5mm) with minimum inhibitory concentration of 2 mg/ml and have a bacteriostatic effect. The ethyl acetate fraction had a minimum inhibitory concentration of 2 mg/ml against all the test bacteria and showed a bactericidal effect against B. subtilis, S. aureus and B. cereus NCIV6 (all Gram- positive bacteria) and bacteriostatic effect against S. typhi and Escherichia coli (clinical isolate) and Escherichia coli ATGC25922 (all Gram- negative bacteria). The study indicated that extract of Annona senegalensis leaves possesses some antibacterial activity, especially against Gram positive bacteria and the ethyl acetate fraction possess the most broad and bactericidal activity thus validating the use of the leaves of the plant in traditional medicine to treat some infections.