Antioxidant peptide from Synechococcus marine microalgae with therapeutic potential against human colon adenocarcinoma

AK-12 peptide shows strong antioxidant activity through radical scavenging and metal ion chelation. Induces apoptosis in Caco-2 cells via the mitochondrial pathway, reducing Bcl-2 expression. Non-toxic, non-allergenic, and potentially suitable for oral use despite limited intestinal absorption. Promising bioactive ingredient for colon cancer management in functional foods. The research focuses on the peptide AILQSYSAGKTK (AK-12), synthesized from the marine microalga Synechococcus , to determine its antioxidant and apoptotic properties. Antioxidant activity is attributed to residues like tyrosine and glutamic acid, which chelate metal ions and neutralize free radicals. In silico analysis indicates that AK-12 is non-toxic, non-allergenic, and suitable for oral consumption, despite poor intestinal permeability. According to circular dichroism (CD) analysis, AK-12 predominantly adopts a random coil structure. AK-12 reduced Caco-2 cell viability in a dose-dependent manner and lowered intracellular ROS, confirming notable antioxidant activity. Molecular docking analysis indicated that AK-12 exhibits a strong binding affinity for Bcl-2, suggesting its potential to inhibit the protein’s anti-apoptotic functions. Flow cytometry confirmed that AK-12 induced apoptosis in Caco-2 cells dose-dependently. Flow cytometry indicated dose-dependent apoptosis, supported by RT-qPCR results showing upregulation of caspase-8 and caspase-9 mRNA, and a moderate increase in caspase-3. Western blot analysis further substantiated these findings by showing increased expression of Bax, and caspase-9, coupled with reduced Bcl-2 levels, confirming the mitochondrial pathway’s central role in apoptosis induction. These findings suggest that AK-12 has potential as a functional food ingredient for colon cancer treatment due to its dual antioxidant and pro-apoptotic activities.