Cyanobacteria of the Indian Sundarbans: A Potential Source of Powerful Therapeutic Agents

Mangrove forests occupy the estuarine ecotone and harbor a wide range of microorganisms along with a rich diversity of flora and fauna. Marine and estuarine organisms are known to produce unique molecules due to the aggressive, exigent, and competitive surroundings that are unlike those produced in the terrestrial environment. Marine cyanobacteria are a vast resource for new bioactive natural products useful in the development of therapeutics. The Sundarbans mangrove ecosystem harbours various unique microorganisms having different interesting properties. Discovery of a unique alkaline serine protease enzyme tolerant to bleach, detergent, high salt concentration and solvent, isolation and identification of obligatelyhalophilic,euryhaline novel cyanobacteria from intertidal soil surface of the Sundarbans and identification of a pair of novel Streptomyces represent a few of the ongoing endeavors undertaken to explore the mostly untapped microbial diversity of the Sundarbans. This study focuses on two novel strains of cyanobacteria isolated from the intertidal soil surface biofilm of the Indian Sundarbans, which were cultivated on a large scale to yield a significant quantity of biomass for the extraction of secondary metabolites. The cyanobacterial biomass was extracted with a range of polar and non-polar solvents and the ethyl acetate fractions showed significant anti- angiogenic activity when tested against sunitinib (a protein kinase inhibitor). The extracts also showed significantly greater anti- inflammatory activity compared to dexamethasone, which has been shown to reduce the 28 day mortality rate of patients affected by COVID- 19.