In vitro evaluation of anti-colon cancer potential of crude extracts of fucoidan obtained from sargassum glaucescens pretreated by compressional-puffing

Abstract

Fucoidans constitute a family of fucose-rich sulfated polysaccharides, which possessmultiple characteristics, including antioxidant, antitumor, antivirus, anticoagulant, and anti-inflammatory properties. In addition, the incidence of colon cancer has risen rapidly worldwide. In the present study, fucoidan extracts were extracted from the Sargassum glaucescens (SG) pretreated by compressionalpuffing, and four fucoidans (SG1-SG4) were obtained with different puffing conditions. It was found that SG4 possessed the highest extraction yield, relatively high cytotoxicity against human colon carcinomaHT-29 cells, and relatively lowcytotoxicity to normal cells, as compared to the other extracted fucoidans. Moreover, SG4 caused cell cycle arrest of HT-29 cells at sub-G1, S, and G2/M phases. SG4 also induced HT-29 cellular apoptosis, as evidenced by the loss of mitochondrial membrane potential (MMP), increased cytochrome c release, activation of caspase-9 and -3, increased DNA fragmentation, and increased early and late apoptotic cells visualized by annexin V/propidium iodide (PI) assay. Additional biological experiments revealed that the Akt/mammalian target of rapamycin (mTOR)/S6 pathway is involved in SG4-induced apoptosis of HT-29 cells. These results clearly indicate that SG4 showed anti-colon cancer potential via the induction of cell cycle arrest and apoptosis, and thus may have a possible application as an adjuvant therapeutic agent in colon cancer treatment.