Evaluation of antibacterial effects of chinaberry (Melia azedarach) against gram-positive and gram-negative bacteria

Melia azedarach L. (Meliaceae) is a deciduous tree that is native to northeastern India. The plant is widely distributed in northern Iran. In Iran it has been planted as an ornamental plant for several years. It has numerous common names such as, White cedar, Persian lilac, Tulip cedar and Chinaberry. The objective of present study was to evaluate the antibacterial effects of methanol extract of seed-fruits, leaves and flowers of chinaberry (M. azedarach) against strains of Pseudomonas syringae pv. syringae, Xanthomonas campestris pv. campestris, Rathayibacter tritici and Escherichia coli. In this study after obtaining methanol extract; the antibacterial activity was evaluated via growth inhibitory zone assay using disc diffusion experiments. Methanol at three concentrations ( 50, 100 and 150 mg/ml ) were evaluated as control. Antibacterial properties of this plant in other organs had a positive result. All extracts of the seed-fruits, leaves and flowers established significant antibacterial activity against tested phytopathogens. Size of growth inhibition zone in each of the factors A, B, C (organ, concentration and bacteria) showed a significant difference, while there was also a significant difference between types of organ and Bacteria in forming growth inhibitory zone. Results of this study strongly confirm that the seed-fruit extracts could be effective antibacterial compounds. Extracts from all of the organs showed an inhibitory effect on gram-positive and gram-negative plant pathogens.