Effects of the dipeptides comprising leucine and lysine on lifespan and age-related stress in Caenorhabditis elegans .

The aging process is affected by various stressors. An increase in oxidative stress is related to the impairment of physiological functions and enhancement of glycative stress. Food-derived bioactive peptides have various physiological functions, including antioxidant activities. Dipeptides comprising Leu and Lys (LK and KL, respectively) have been isolated from foods; however, their physiological properties remain unclear. In this study, we investigated the antioxidant/antiglycation activity of dipeptides and their antiaging effects using Caenorhabditis elegans ( C .  elegans ). Both dipeptides showed antioxidant activities against several reactive oxygen species (ROS) in vitro. In particular, the scavenging activity of LK against superoxide radicals was higher than KL did. Moreover, dipeptides suppressed advanced glycation end products (AGEs) formation in the BSA-glucose model. In the lifespan assays using wild-type C .  elegans , both LK and KL significantly prolonged the mean lifespan by 20.9% and 11.7%, respectively. In addition, LK decreased intracellular ROS and superoxide radical levels in C .  elegans . Blue autofluorescence, an indicator of glycation in C .  elegans with age, was also suppressed by LK. These results suggest that dipeptides, notably LK, show an antiaging effect by suppressing oxidative and glycative stress. Our findings suggest that such dipeptides can be used as a novel functional food ingredient. Food-derived dipeptide Leu-Lys (LK) and Lys-Leu (KL) exert antioxidant and antiglycation activity in vitro. Treatment with LK prolonged the mean lifespan and maximum lifespan of C .  elegans more than that of KL. Intracellular ROS and blue autofluorescence levels (indicator of aging) were suppressed by LK.