Antioxidant and antiproliferative activities were examined for methanol (M), chloroform (C), ethyl acetate (E) and aqueous (A) extracts of Turbinaria ornata, Kappaphycus alvarezii, Acanthophora spicifera and Gracilaria corticata, using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, beta-carotene bleaching inhibition, ferrous ion chelation, total reducing activity and resazurin-based growth inhibition (in A549, HCT-15, MG-63 and PC-3 cell lines) assays. Higher growth inhibition was observed in A549 and MG-63 cells with higher values of total flavonoid content, DPPH radical scavenging and total reducing activities, and in PC-3 cells with higher beta-carotene bleaching inhibition. Positive correlation (P < 0.05) was observed between total phenolic content and total reducing activity. Although all seaweeds have been examined for antioxidant and brine shrimp cytotoxic activities, and for some, in some cancer cell lines, this is the first report of growth inhibition in the cell lines chosen for this study that represent highly prevalent cancers.
Although Turbinaria ornata, Kappaphycus alvarezii, Acanthophora spicifera and Gracilaria corticata have already been examined for various activities, including antioxidant and brine shrimp cytotoxicity, this is the first report of antiproliferative activity in the cell lines chosen for this study that represent highly prevalent cancers. Besides this, seaweeds like K. alvarezii find widespread use as thickening and gelling agents and A. spicifera is consumed in many parts of the world as food and a folklore remedy, including the Gulf of Mannar and Fiji. We hope that this report of antioxidant and antiproliferative activities of these four seaweeds will promote interest in their cultivation to further study their mechanism of cytotoxicity against the cell lines in this study to facilitate drug discovery efforts, besides the existing interest in them as nutraceuticals as well as food and fodder additives, among other applications.