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.
Eucommia ulmoides is a medicinal tree native to China, and its leaves are brewed into a healthy tea. In this study examined how harvesting E.ulmoides in the summer or fall affected the functional components, antioxidant activity, and anti-glycation activity of a hot water extract of E.ulmoides leaves. E.ulmoides leaves harvested in July 2012 served as summer leaves and leaves harvested in, November 2012 served as fall leaves. Results revealed that the total polyphenol content, the total flavonoid content, and the content of functional components (geniposidic acid, chlorogenic acid, and rutin) in E.ulmoides leaves decreased from summer to fall. Results revealed that the antioxidant activity of an extract of E.ulmoides leaves decreased substantially from summer to fall. This suggests that chlorogenic acid and rutin in E.ulmoides leaves are involved in the antioxidant activity of the extract. Results revealed that the antiglycation activity of an extract of E.ulmoides leaves decreased somewhat from summer to fall. Har vesting season had less of an effect on the anti-glycation activity of the extract than it had on the antioxidant activity of that extract. Results suggested that chlorogenic acid and rutin in E.ulmoides leaves inhibited the generation of fluorescent advanced glycation end products. Results suggested that the chlorogenic acid in E.ulmoides leaves cleaved α-dicarbonyl cross-links.
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