Antioxidant potential of Ulva rigida extracts: protection of HeLa cells against H₂O₂ cytotoxicity.

The rising demand for natural antioxidants instead of synthetic materials, especially in biomedical applications, has led to increased interest in the search for bioactive compounds with potent antioxidant activity. In the present study, we tested the antioxidant effect of both a crude extract and an ethanol precipitate of Ulva rigida in HeLa cells exposed to hydrogen peroxide (H₂O₂). HeLa cells treated with H₂O₂ (1 mmol l⁻¹ for 3 h) exhibited significant damage to their morphology, a significant decrease in cell survival, and a remarkable leakage of lactate dehydrogenase (LDH). However, the co-exposure of cells to H₂O₂ and the crude extract or ethanol precipitate of U. rigida induced fewer morphological cytotoxic effects, a significant increase in cell viability, and a significant decrease in LDH release. Biochemical studies have demonstrated that U. rigida extracts have a strong radicalscavenging activity and contain protein, sugar, and phenolic content. The overall results suggest that U. rigida extracts protect HeLa cells from death induced by oxidative stress, and it is likely that these effects are related to the phenolic, protein, and polysaccharide compounds contained in this alga. Hence, U. rigida can be used to treat diseases ascribed to oxidative disorders.