ANTI-MICROBIAL, ANTI-OXIDANT AND PHYTOCHEMICAL PROFILING OF AVICENNIA MARINA AND AVICENNIA ALBA, THE DOMINANT MANGROVE FLORAL SPECIES OF INDIAN SUNDARBANS.

The Indian Sundarbans represents one of the taxonomically diverse and physico-chemically dynamic ecosystems of the Indian sub-continent supporting around 34 species of true mangrove flora out of which members of the Avicenniaceae family are the second most dominant. This salt-tolerant mangrove community experiences inundation and exposure twice a day during high and low tides, and therefore is unique in comparison to the normal terrestrial flora. In the last decade, there is an outburst of multi-drug resistant (MDR) microbial pathogens owing to antibiotic overuse in disease therapeutics, and therefore the need of the hour is to look for alternative medicine. Interestingly, recent studies have revealed the use of mangroves in traditional therapeutics. In view of this scenario, we investigated the anti-microbial, anti-oxidant and phytochemical profiles of the two major mangrove species (Avicennia marina and Avicennia alba) of Indian Sundarbans. Although, anti-microbial and phytochemical screening of mangroves were conducted by several researchers in Indian Sundarbans, however, the present study has its own merit in the sense that both clinical and environmental MDR bacterial pathogens have been used to evaluate the potential of the mangrove species in alternative drug therapeutics. Crude solvent extracts of the vegetative tissue parts of the two mangrove plant species were prepared in n-hexane. The anti-bacterial activity of the tissue extracts of A. marina and A. alba was tested via disc diffusion assay using five environmental MDR pathogenic bacterial strains (Stenotrophomonas maltophilia, E. coli strain BGW1, E. coli strain BMW1, Citrobacter sp. and Pseudomonas sp.) and three clinically isolated MDR human pathogens (Proteus vulgaris, Salmonella typhi and Staphylococcus aureus) among others with A. marina tissue (stems and leaves) extracts displaying the strongest activity. Consistent with this data, the highest total anti-oxidant activity was also accounted in A. marina tissue extracts. We also compared essential phytochemicals among the two mangroves and noticed the presence of flavonoids, steroids, tannins, terpenoids, xanthoproteins, saponins, and cardiac glycosides. Together, our findings showed that the members of the Avicenniaceae family as potential sources of biologically active compounds and therefore, suggest their potential especially A. marina in alternative disease therapeutics.