Investigation on antibacterial ability of acetone extract from leaves of Avicennia alba Blume growing in the Can Gio Mangrove Biosphere Reserve, Vietnam

The study aims were to investigate the antibacterial ability of Avicennia alba Blume leaves collected in An Nghia, Dan Xay, Long Hoa belonging to Can Gio Mangrove Biosphere Reserve, Vietnam. Sample leaf powder of A. alba was used to make acetone extracts. Investigation on antibacterial ability of the extracts was performed by using agar well diffusion method. The results showed that acetone extracts from A. alba leaves exhibited antibacterial activity against Gram (+) bacteria: Bacillus cereus and Staphylococcus aureus but no inhibitory effects on Gram (-) bacteria: Pseudomonas aeruginosa and Escherichia coli. Antibacterial strength of extract increased with increasing extract concentration. Leaf extracts of A. alba growing An Nghia had higher inhibitory effect of B. cereus than two others, while leaf extracts of A. alba growing Dan Xay was more effectively inhibitory against S. aureus than the others. Only extract of A. alba growing An Nghia at concentrations of 900 mg mL-1 and 1000 mg mL-1 and A. alba growing Dan Xay at concentration of 1000 mg mL-1 had moderately antibacterial strength against B. cereus and S. aureus. The other tested extracts of A. alba had antibacterial activity at weak level.