Antimicrobial, cytotoxic and antioxidant activities of Barringtonia acutangula (L)

Barringtonia acutangula (Indian Oak) is an important medicinal plant of Bangladesh and India for its antiasthmatic, anticold, antimalerial, antidiarrehal, antiprotozoal, antidysentery stimulating properties. The coarsely powdered stem bark of B. acutangula was extracted with petroleum ether, ethyl acetate and methanol for 8 days. The concentrated extract was then named as petroleum ether, ethyl acetate and methanol extracts respectively. The soluble portions were further fractionated with gel permeating chromatography using different solvent system. The extracts and compounds isolated from ethyl acetate were evaluated for their antibacterial, antifungal, cytotoxic and antioxidant activities. The antibacterial and antifungal activities were evaluated using the disc diffusion method using varied period of incubation while the screening of cytotoxic activity was done using brine shrimp lethality bioassay. In antibacterial testing, it was found that most microorganisms showed sensitivity to petroleum ether and ethyl acetate extracts while a large quantity of organism showed sensitivity to isolated compound from the extract. Besides, the ethyl acetate extract and its fraction 1, 2 has shown promising zone of inhibition against the fungi with few exception. In cytotoxicity test, the mortality rate of brine shrimp was found to be increased with the increase of the concentration for each sample. The LC50 values of plant ethyl acetate extract was found to be 12.58 µg/ml which clearly indicate that the extract was toxic to the brine shrimp. It was found that the methanol and ethyl acetate extracts showed higher free radicals scavenging activity with IC50 3.84 µg/ml and 9.83 µg/ml respectively. From this investigation it has been found that this plant showed a number of promising biological activities including antibacterial, antifungal cytotoxic and antioxidant. This is first report of the biological activity of the stem bark of B. acutangula. Therefore, further investigation is required to establish this plant as a good source of natural medicine.