Evaluation of antioxidant and anti-cancer properties of bioactive peptides extracted from two marine species on colon cancer HCT-116 cell line

Colon cancer is one of the most common types of gastrointestinal malignancies, with oxidative stress and redox imbalance playing critical roles in its progression. This study investigates the antioxidant properties and cytotoxic and apoptotic effects of bioactive peptides derived from mullet fish (Liza klunzingeri) and Vannamei shrimp (Litopenaeus vannamei) on colon cancer cells (HCT-116). The antioxidant activity of peptides was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, total antioxidant capacity (TAC), and nitric oxide (NO-) measurement, while cytotoxic effects were assessed using the Neutral Red Assay and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Apoptosis was evaluated using acridine orange/ethidium bromide staining, and redox changes were assessed. The results demonstrated that peptides derived from mullet exhibited significantly higher antioxidant activity in terms of TAC and NO levels compared to shrimp-derived peptides (p < 0.05). Cytotoxicity assays revealed a dose-dependent reduction in cancer cell viability, with an IC50 value of 1.2 mg/mL after 24 hours, indicating potent cytotoxic and apoptotic effects. Furthermore, mullet-derived peptides significantly elevated NO levels while reducing glutathione content and catalase (CAT) activity in cancer cells (p < 0.05). Both mullet and shrimp peptides induced apoptosis in HCT-116 cells, with mullet peptides exerting a more pronounced effect (p < 0.05). These findings suggest that by reducing antioxidant capacity and inhibiting the proliferation of colon cancer cells, mullet-derived peptides may enhance the susceptibility of cancer cells to endogenous defense mechanisms.