The Yemeni Brown Algae Exhibit High Anticancer Activity Independent of Its Antioxidant Capability.

The aim of this study was to investigate the anticancer and antioxidant activities as well as the safety of the brown algae of the Western seacoast of Yemen. Cytotoxicity of methanol extract of and several of its fractions, petroleum ether, chloroform, ethyl acetate, n-butanol, and aqueous extracts against seven different cancer cell lines was determined by crystal violet staining. The antioxidant activity was also assessed using the DPPH radical scavenging assay. Acute toxicity study was performed on rats at increasing doses of the methanol extract. Extracts of exerted a significant dose-dependent cytotoxicity on the seven tumor cell lines but were generally more selective on MCF-7 and PC-3. Among all fractions, the chloroform fraction of the displayed the highest cytotoxic activity and was most effective in MCF-7, PC3, and CACO cells (IC = 1.93 ± 0.25, 2.2 ± 0.18, and 2.71 ± 0.53 g/mL, respectively). The petroleum ether fraction was also effective, particularly against MCF-7 and PC-3 (IC = 4.77 ± 0.51 and 3.93 ± 0.51 g/mL, respectively) whereas the activity of the ethyl acetate fraction was more pronounced against HepG2 and CACO (IC = 5.06 ± 0.21 and 5.06 ± 0.23 g/mL, respectively). Of all the extracts tested, the crude methanolic extract of the algae exhibited only a modest antioxidant potential (IC = 204.6 ± 8.3 g/mL). Doses as high as 5000 mg/kg body weight of methanolic extracts were safe and well tolerated by rats. The overall results showed that exhibited a significant cytotoxic activity probably due to the occurrence of nonpolar cytotoxic compounds, which is independent of its antioxidant capability.