Determination of Antioxidant and Cytotoxic Activities of Red Seaweed, （Gracilaria manilaensis） against Different Cancer Cell Lines

Antioxidants play an important role in inhibiting and scavenging free radicals in human, providing protection against cellular damage in relation to cancer initiation. Seaweeds have been proved to have high antioxidant activity. Thus, this research was carried out to determine the antioxidant and anticancer properties of edible red seaweed, Gracilaria manilaensis （Gracilariales, Rhodophyta）. The extracts were prepared by Soxhlet extraction using organic solvents with different polarities. The antioxidant activities of extracts were determined in terms of their flee radical scavenging activity （RSA IC50） and total phenolic content （TPC）. The cytotoxic activity of extracts were tested against human ovarian cancer cell line （Caov-3）, human breast cancer cell line （MDA-MB-231 and MCF-7）, human cervical cell line （HeLa）, mouse fibroblast cell line （L929） and Madin-Darby canine kidney （MDCK） and the cell viability after 72 h incubation was determined by methylene blue assay. The findings showed that acetone extract has the lowest DPPH IC50 value followed by ethyl acetate extract. Both extracts also showed high values of TPC. Dichloromethane extract had the strongest cytotoxic on MDA-MB-231 （53.90 μg/mL ± 5.59 μg/mL） and HeLa （95.50 μg/mL）. While, acetone and ethyl acetate extracts were cytotoxic on MCF-7 （66.07 μg/mL） and Caov-3 （69.67 μg/mL ± 13.94 μg/mL）. It could be concluded that the antioxidant and cytotoxic activities of G. manilaensis were influenced by the types of solvents used and thus had a potential to develop as a cancer chemoprevention or anticancer agent against selected cancer.