Influence on the oxidized protein hydrolase (OPH) activity of herbal tea extract.

抄録

Glycative stress is a comprehensive concept meaning biological stress caused by the formation and accumulation of advanced glycation end products (AGEs). The increase of glycative stress leads to the risk of onset and development of aging, diabetic complications, Alzheimer’s, and arteriosclerosis. The countermeasures against glycative stress are called anti-glycation, which includes inhibitions of postprandial hyperglycemia and glycation, the decrease of AGEs, and the lowering of dietary-derived AGEs. Oxidized protein hydrolase (OPH) is a kind of protease which is the decrease of aged protein and AGEs and is broadly distributed within living tissues. In this research, for the purpose of investigating components which decrease glycative stress, the effect of herb tea extracts on OPH activity were verified. The extracts of 58 products (38 categories) of herbal teas on OPH activity and OPH activity enhancing action was recognized in 47 herbal tea products (81%). OPH activity was observed in 34 categories (89%) of herbal tea. On the other hand, the extracts of 12 products inhibited OPH activity. Green tea (unfermented tea) and black tea (fermented tea) derived from Camellia sinesis showed an inhibitory effect; however, houji tea (roasted green tea) and pu-er tea (late fermented tea) enhanced the activity. The comparison of utilized portions of herbal teas in which an OPH activity enhancing action was observed showed that seed tea had a stronger influence than leaf tea. The active components enhancing OPH activity are possibly included in various plants. It was found that the roasting and fermenting process for tea leaves have an influence on OPH activity. It is possible that herbal teas could prevent the accumulation of aged protein and AGEs by enhancing OPH activity, and as a result, contribute to the prevention of the progression of aging caused by glycative stress.