In Vitro Cancer Chemopreventive Properties of Polysaccharide Extract from the Brown Alga, Sargassum Latifolium

Abstract Polysaccharides of edible algae attracted extensive interest due to their numerous biological activities. Sargassum latifolium (Turner) C. Agardh, belongs to Sargassaceae, is —a brown algae found in Egyptian Red Sea shores. This work is a novel attempt to explore the cancer chemopreventive activity of different fractions of water-soluble polysaccharide extract derived from S. latifolium. Estimation of cancer chemopreventive activity, specifically anti-initiation, including the modulation of carcinogen metabolism and the antioxidant capacity, revealed that E1 and E4 were potent anti-initiators, where they lead not only to an inhibition in the carcinogen activator cytochrome P450 1A (IC50 2.54 and 10.30 µg/ml, respectively), but also to an induction in the carcinogen detoxification enzymes glutathione-S-transferases (144 percent and 225 percent of the control, respectively). E1 and E4 inhibited 59 percent and 63 percent of the induced-DNA damage, as measured by comet assay. Similarly both E1 and E4 possessed potential anti-promoting properties as indicated by their anti-inflammatory activity. E1 and E4 enhanced the macrophage proliferation; however they dramatically inhibited the stimulated NO (30.7percent and 59.3 percent), TNF-a (38.2 percent and 54.9) and COX-2 (20 percent and 18 percent), respectively. E3 showed a selective cytotoxicity against lymphoblastic leukemia (1301 cells), while other fraction extracts had no cytotoxic effect against all tested cell lines. E3 led to a major disturbance in cell cycle including arrest in both S-phases in 1301 cells. This disturbance was associated with an induced-cell death due to apoptosis, but not necrosis. In conclusion, E1 and E4 are promising cancer chemopreventive fractions, since they had tumor anti- initiating activity via their protective modulation of carcinogen metabolism, and tumor anti-promoting activity via their anti-inflammatory activity, while E3 can be considered as a promising anti-cancer agent against leukemia. Keywords: Sargassum latifolium / Cytochrome P450 / Cancer chemoprevention / Anti-initiating / Anti promoting / Apoptosis. Amira M. Gamal-Eldeen a, Eman F. Ahmed b, Mona A. Abo-Zeid c