Effects of Functional Peptides Derived from Yam Dioscorin on Anti-aging Activities and Related Mechanisms

Yam tuber contained storage proteins, dioscorin, which was reported for the first time to have antioxidant activity by my Lab. The protease hydrolysates (peptic and tryptic hydrolysates) were also reported to have antioxidant and anti-radical activities, however, the active peptides were still under investigations. In our preliminary results, D-galactose was daily subcutaneous injection to dorsal necks of BALB/c mice for 10-weeks to induce oxidative damages, and at the 5th week dioscorin groups were daily oral administration till experimental ends together with daily galactose subcutaneous injection. It is found that plasma malondialdehyde (MDA) contents were significantly reduced and antioxidant parameters (such as GSH contents) were significantly elevated in dioscorin interventions compared to galactose group. It was assumed that some active peptides of dioscorin after being ingestion may be functioned to attenuate galactose-induced oxidative stresses. Therefore, a successive three-year project is proposed and the first year proposal is to use the computer-aided simulation for dioscorin hydrolysis by pepsin. Several peptide candidates are selected and synthesized to evaluate antioxidant activities; protection against methylglyoxal (MGO)- or advanced glycation end products (AGEs, from BSA/MGO)-induced HUVEC cells apoptosis or MPTP-induced SH-SY5Y cells apoptosis and their related mechanisms, which can select active peptides in advance for further animal model investigations. The second year proposal is to set up D-galactose-induced aging models and MPTP-induced Parkinson’s animal models. The Morris water maze, passive avoidance test, and rotarod performance test are used to evaluate effects of potential peptides in learning dysfunctions or degenerative disorders. Several biochemical parameters, oxidative stress index, antioxidant index, and AGEs levels, immunohistochemistry stains are also determined to overview the neuron protective functions of active peptides derived from dioscorin. The third year proposal is to use proteomics and genomics to observe the changes of participated proteins and genes in brains of MPTP-induced Parkinson’s animal models with or without active peptide oral administration. In the other hand, the transepithelial transport across Caco-2 cells are used to mimic active peptides in intestinal absorption and then checked by LC/MS/MS. These data might be references for healthy food developments in the future.