Anticancer effect of marine bivalves derived polysaccharides against human cancer cells

In recent decades, studies on cancer prophylactics and therapeutics with development of novel anticancer drugs have garnered interest on a global scale. The diverse marine environment is a major source of biocompounds and has been acknowledged as an important platform for drug discovery. A wide variety of novel agents in the form of protein, polysaccharide, polypeptide and steroid from marine microbes, plants and animals are under preclinical and clinical evaluation as potential anticancer drugs. Polysaccharides, with their manifold structures and side groups, have been extensively investigated in biomedical and pharmaceutical fields. The present study investigates the potential of polysaccharides extracted by enzyme hydrolysis from five marine bivalves to inhibit human cancer cells. Cytotoxicity of crude polysaccharides was analyzed using a normal cell line (vero). Antiproliferative effect of polysaccharides on the breast (MDA-MB-231), cervical (HeLa), liver (HepG2) and colon (HT-29) cancer was evaluated by 3-(4, 5 dimethylthiazol-2-yl)-2, 5- diphenyltetrazolium bromide assay (MTT). The polysaccharides from different bivalve species showed varied results on different cell lines but highest inhibitory activity was observed in the polysaccharide of Donax variabilis with IC50 at the concentration 350 μg/mL in MDA-MB-231 and HeLa cells, 400 μg/mL in HepG2 cells and 200 μg/mL in HT-29 cells. Apoptosis-related characteristics were observed by cell morphological observation and nuclear morphological analysis by propidium iodide staining. The late stages of apoptosis were detected by dual acridine orange/ethidium bromide staining and confirmed by DNA fragmentation assay and MMP using Rhodamine 123 stainings. The results obtained substantiate that novel polysaccharides from marine bivalves are potent antiproliferative agents and further studies might unveil a promising anticancer drug.