The Cytotoxic and Apoptotic Effects of the Brown Algae Colpomenia sinuosa are Mediated by the Generation of Reactive Oxygen Species

Brown algae are a novel resource of biogenic molecules, however few studies have been conducted in the Mediterranean to assess the cytotoxic mechanisms of algal-derived compounds. This study focuses on the antineoplastic activity of extracts from non-investigated algae of the Lebanese coast, Colpomenia sinuosa. Extracts' antineoplastic activities were evaluated by MTT and trypan blue on different tumorigenic cells. Results indicated that the most potent extract was obtained by soxhlet using dichloromethane:methanol solvent (DM soxhlet) against HCT-116. Wound healing assay confirmed that this extract decreased the migration potential of HCT-116 cells with minimal effects on non-tumorigenic cells. It also induced an increase in the subG1 population as determined by flow cytometry. Western blot analysis demonstrated that apoptosis in treated HCT-116 cells was induced via upregulation of p21 protein and downregulation of the anti-apoptotic Bcl 2, which led to caspases activation. The latter, catalyzes the degradation of PARP-1, and thus suppresses cancer proliferation. Morphological alterations, further confirmed apoptosis. A strong pro-oxidant activity evidenced by the enhanced generation of reactive oxygen species (ROS) was observed in HCT-116 treated cells. Interestingly, a strong antioxidant effectively blocked effect induced by the extract. These results indicate that C. sinuosa is a source of bioactive compounds possessing pro-apoptotic and anti-migratory efficacy.