Background: Nowadays, numerous studies have been conducted on the use of bioactive compounds as anti-cancer agents regarding their antioxidant activities. The current study aimed to assess the anti-cancer and anti-oxidant activities of organic and water extracts of brown algae (Cystoseira indica) collected from the shores of Chabahar, Iran. Materials and Methods: The extraction was performed based on the method of immersion by n-hexane, ethanol, methanol, chloroform and distilled water as solvent during 24 hours. The reducing power, free radical (DPPH) scavenging activity, metal chelating activity and cytotoxicity against colorectal cancer cells were examined by the MTT test. Results: The chloroform extract showed the best reducing power compared to the other infusions, with an average of 0.36±0.02 µg/µL. Also, chloroform extract showed the best metal chelating activity with an average of 62.18±0.86 µg/µL (P<0.05). The best free radical scavenging activity observed in the ethanol and methanol extracts with concentrations of 15.83 and 33.21 µg/µL, respectively; the inhibitory activity of methanol extracts was better than ethanol extract (P<0.05). Regarding the anti-cancer properties, methanol extract (30±1.33 µg/µL) showed the greatest effect on cancer cell death and the water extract showed the least effect (66.67±1.11 µg/µL) (P<0.05). Conclusion: The extract of the brown algae (Cystoseira indica) can be proposed as an antioxidant and anticancer compound for preclinical and clinical studies
