Screening and Molecular Identification of Marine Sponges with Cytotoxic Activities, Collected from Gulf of Mannar, Indian Ocean

The marine environment, a rich source of biological and chemical diversity, offers tremendous scope for discovering novel metabolites with pharmacological activities. Marine invertebrates, especially sponges, have gained more attention in drug discovery programmes since they exhibit unique metabolic and physiological capabilities and an extraordinarily symbiotic association with diverse bacterial communities. The present study focuses on screening the cytotoxic activity of the methanolic extracts of sponges against the Non-Small Cell Lung Cancer (NSCLC) cell line, NCI-H460. In the bioactivity screening, two sponges (IOS-11 and IOS-12) were found with potent cytotoxic activity. The sponge IOS-12 showed almost complete cell growth inhibition (99 %) at 50 μg/ml and 80 % inhibition at 5 μg/ml; whereas IOS-11 showed cell growth inhibition of 96 % and 77 % at 50 μg/ml and at 5 μg/ml, respectively. Amplification of the mitochondrial cytochrome C oxidase subunit I (COI) and subsequent nucleotide analysis enabled the identification of sponge samples, IOS-11 and IOS-12, as Rhabdastrella globostellata and Halichondria sp., respectively. The study concludes that the two marine sponges, Rhabdastrella globostellata and Halichondria sp., possess excellent cytotoxic activities and could be considered good candidates for the isolation of anticancer compounds with biomedical applications. The isolation, purification and structural elucidation of the lead molecules from these sponges are ongoing studies, which might yield potential new compounds with promising cytotoxic activities.