Effect of Green Tea on Porcine Intestinal Glutamate Carboxypeptidase II Activity

抄録

Food folates exist mainly as pteroylpolyglutamate, which is degraded to a monoglutamyl form by glutamate carboxypeptidase II (GCPII) in the intestine before absorption. Green tea is a traditional and widely consumed drink all over the world and one of the major sources of food folates. In this study, we examined the influence of food, including green tea, on porcine GCPII activity in vitro. Several foods were selected and their extracts were prepared in order to examine the influence on GCPII activity. The food extracts were included in the reaction mixture for the analysis of GCPII activity at the level of 10%. Little inhibition of GCPII activity was exhibited in extracts of cabbage, lettuce and spinach. In contrast, this activity was significantly inhibited by extracts of orange juice (68.6% of no addition), tomatoes (66.9%) and green tea (35.6%). The activity was inhibited in a concentration-dependent manner by the extract of green tea. These results indicate that green tea may partially influence folate bioavailability through the inhibition of GCPII.