Antibacterial activity of Avicennia marina leaves extract on Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa

Antibiotic resistance is one of the most common problems in medicine. Therefore discovering of new antibacterial components with least side effect is necessary. Based on the presence of biologically active constituents in Avicennia marina and its uses in alternative medicine, it is supposed that this plant has antibacterial effect. This study was designed as an "in vitro" study. In extraction procedure, 20% glycerin solution was utilized as solvent. In the screening step, S. aureus (ATCC 25923), E. coli (ATCC 25922) and P. aeruginosa (ATCC 27853) were exposed to extract with 90 mg/ml in concentration, separately. Thereafter, these three strains were examined with different concentrations of the extract to determine minimal bactericidal concentration (MBC). Also the effect of MBC was tested at time zero and after incubation time ranging from 2 to 24 hours. The MBCs on S. aureus, E. coli and P. aeruginosa were 7.9, 33.8 and 15.8 mg/ml, respectively. The minimum times necessary for effectiveness of extract were as follows: 24h for S. aureus, 8h for E. coli and 12h for P. aeruginosa. Avicennia marina leaves extract has a significant antibacterial effect on E. coli and P. aeruginosa as gram negative bacteria, and S. aureus as a gram positive bacterium.