In Vivo Evidence of Antioxidant Activity from Dipeptides Synthesized from Spanish Dry-Cured Ham

Abstract Bioactive peptides from dry-cured ham have attracted interest as potential antioxidant ingredients. However, the specific contribution of dipeptides to this activity remains poorly characterized. In this study, we evaluated the safety and antioxidant capacity of ten synthesized dipeptides previously identified in a digested extract from dry-cured ham. Dipeptides were combined according to their relative proportion to obtain a stock solution (10 mg/mL), from which concentrations between 0.125 and 2.5 mg/mL were tested. Cell viability was evaluated in human colorectal Caco-2 cells using the MTT assay. Ex vivo antioxidant activity was determined in Caco-2 and human endothelial EA.hy926 cells, by quantifying reactive oxygen species (ROS) and antioxidant gene expression through directed transcriptomics. In vivo antioxidant activity was evaluated in Caenorhabditis elegans subjected to acute and chronic oxidative stress conditions. The dipeptide fraction maintained > 90% cell viability up to 1.0 mg/mL; however, higher concentrations decreased viability values by 65–78%. In both cellular-models, dipeptide treatments decreased ( P < 0.05) intracellular ROS generation compared to controls, with maximum reductions observed between 0.5 and 1.5 mg/mL. Caco-2 antioxidant gene profile was also found altered in the presence of 0.5 mg/mL dipeptides compared to control conditions. In C. elegans , exposure to the dipeptide fractions increased ( P < 0.05) survival under acute and chronic oxidative stress conditions. Pretreatment with 1.5 mg/mL dipeptides significantly increased the survival rate by 50% from 360 to 600 min after acute exposure. Under chronic stress, SR50 increased ( P < 0.05) survival rate from 3 to 5 days in peptide-treated nematodes. A significant reduction ( P < 0.05) in paraquat-induced intracellular ROS levels and modulation of key genes associated with the antioxidant response, including GST-4 and SOD-3 , were also observed. Taken together, these results demonstrate that dry-cured ham synthetic dipeptides (EE, IE, GA, VD, DA, DG, VG, PA, DV and ES) have biologically relevant antioxidant activity and support their application as functional ingredients aimed to protect against oxidative stress.