ANTIMICROBIAL, ANTIOXIDANT AND CYTOTOXIC EFFECTS OF THE BARK OF TERMINALIA ARJUNA

The aim of this study was to investigate the antimicrobial, antioxidant and cytotoxic effects of the bark of Terminalia arjuna. The plant part was extracted with methanol to yield the crude extract. The antimicrobial activity test of the methanol extract of the bark of Terminalia arjuna was done using disc diffusion method. Standard antibiotic discs of Kanamycin (30 μg/disc) were used as standard.  The crude extract was used at a concentration of 500μg/disc. All the microorganisms were susceptible in various degrees to the extract. The methanol extract was found to be moderately active against Staphylococus aereus, Bacillus megaterium, Bacillus subtilis Salmonella typhi, Escherichia coli and Pseudomonas aeruginosa. The zone of inhibition was found from 12 mm to 19 mm.  The crude methanol extract was again studied for investigating free radical scavenging potentiality and was subjected to this study with 2, 2-Diphenyl-1-picrylhydrazyl (DPPH). The methanol extract of the bark of the plant exhibited the potential free radical scavenging activity (antioxidant effect) having IC₅₀ value of 7.05 µg/ml. The cytotoxic activity of the crude methanol extract was determined by Brine Shrimp Lethality Bioassay. In this bioassay methanol extract showed positive results and the LC₅₀ was 6.163 µg/ml indicating that the some of the compounds of the extract are biologically active. From this experiment, it was reveled that the test sample showed different response at different concentrations. The mortality rate of brine shrimp was found to be increased with the increased concentrations of sample, and a plot of log of concentration versus percent mortality on the graph produced an approximate linear correlation.