Investigation of Antibacterial, Cytotoxic and Antioxidant Properties of the Mangrove Plant Xylocarpus mekongensis

The plant (Xylocarpus mekongensis) of the Sundarbans mangrove origin was evaluated for its antibacterial, cytotoxic and antioxidant properties using methanolic and chloroformic leaf, stem and bark extracts, respectively. The methanolic extracts contained higher amount of total phenolics, flavonoids, tannins than the chloroformic extracts and the result was in correlation with their ferric reducing power ability as well. However, the chloroformic bark extract contained more potent DPPH free radical scavenging activity than others. Antibacterial activity of the extracts was determined against both Gram-positive (Micrococcus and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Vibrio cholerae, Salmonella typhimurium and Salmonella paratyphi) by disc diffusion assay and their zone of inhibitions (ZOI) were measured. Moreover, their minimum inhibitory concentrations (MIC) were determined by tube dilution method. Chloroformic bark and stem extracts showed strong inhibition to growth of P. aeruginosa (ZOI = 19 mm and MIC = 150 μg/ml) and S. aureus (ZOI = 19.5 mm and MIC = 250 μg/ml), respectively. All six extracts were subjected to brine shrimp lethality bioassay for possible measure of cytotoxicity. Concentration dependent increment in percentage mortality of brine Shrimp nauplii produced by the extracts indicated the presence of cytotoxic principles in these extractives. Therefore, Xylocarpus mekongensis showed antioxidant, antibacterial and cytotoxic activities.