Anticancer Activity of a Water-soluble Polysaccharide Isolated from Korean Capsosiphon fulvescens

다국어 초록 (Multilingual Abstract)

Seaweed extracts have been reported for their diverse biological and pharmacological activities including immunomodulating, anticoagulaning, anticancer activities, etc. Capsosiphon fulvescens (CF) is a green alga that is widely ditributed in the Southern coastal area of Korea. Crude polysaccharides were obtained from the CF collected at a coastal area of Wando, Korea by extraction in acidic condition (0.01 N HCl) and 75% ethanol precipitaion. After removal of alginate by CaCl2 precipitaion, it was futher purified by DEAE-cellulose column chromatography and its chemical components and anticancer activity was determined. Monosaccharide composition analysis by TLC and HPEAC-PAD showed that this polysaccharide consist of Rha, Man and Xyl as the major neutral sugars, with the mole ratios of 4.1:1.0:3.7, respectively, suggesting that it is a mannoxylorhamnan type polysaccharide. This polysaccharide (1 mg/ml) was shown to effectively scavenge nitrite up to 40% at pH 3. The effects of this polysccharide on the cell viability of 4 cancer cell types, human prostate cancer cell (PC-3), human lung cancer cell (A-549), human colon cancer cell (HT-29), and human gastric cancer cell (MK-N-45), were evaluated by MTT assay. It showed most significant cytotoxicity against HT-29 cells among cancer cell lines tested. This polysaccharide significantly induced the cleavage of PARP, caspase 8 and caspase 9, and also enhanced the phosphorylation of p38 in a dose-dependant manner. However, it was shown to reduce the AKT phosphorylation and mitochondrial membrane charge causing mitochondrial dysfunction. Taken collectively, these results demonstated that a watersoluble polysaccharide isolated from the sporophyll of Korean Capsosiphon fulvescens inhibits proliferation of HT-29 cells by activation of apoptotic pathway, suggesting that this polysaccharide can be a good candidate for the development of a potent anti-cancer agent against human colon cancer.