Bio-screening of a few green seaweeds from India for their cytotoxic and antioxidant potential

Abstract

Seaweeds, raw, cooked, or dried, are used as food in many cultures, although not very popularly in India. Globally, several studies have indicated that seaweeds are a rich source of phenolic compounds and have antioxidant properties. Methanolic extracts (MEs) of five species of green seaweeds commonly found in India were screened for their cytotoxic activity by brine shrimp lethality assay and antioxidant properties using various in vitro assays, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, reducing power and metal ion chelating assays. A markedly variable, dose-dependent activity was observed in all the seaweed extracts relative to their total phenolic content. Statistical analysis indicated a significantly strong correlation between the DPPH radical scavenging activity and total phenolic content (R sup(2) = 0.88, P < 0.05) as well as reducing power and total phenolic content (R sup(2) = 0.99, P < 0.01) of the dry MEs. Also, a very poor correlation between total phenolic content and metal chelating activity (R sup(2) = 0.13, P > 0.05) was noted. None of the seaweed extracts were potently cytotoxic. The underlying results endorse seaweeds as a rich, novel source of antioxidant compounds needing systemic exploration.