Glutathione S‐transferase (GST) M1 and Tl polymorphism influence plasma antioxidant status of Korean smokers after grape juice supplementation

Abstract

Grape juice is a rich source of polyphenols, which have antioxidant properties. Glutathione S‐transferase (GST) belongs to a multigene family of phase II enzymes, which are involved in detoxification and function as antioxidants. In this study, we examined whether daily supplementation of grape juice can modulate the levels of plasma antioxidants, lipid profiles and conjugated dienes (CD), which are markers of lipid peroxidation, and whether this modulation can be affected by the GSTM1 and T1 polymorphisms. 95 male smokers received 480 ml/day of grape juice for 8 weeks, and blood samples were drawn before and after this 8 week period. Plasma levels of γ‐tocopherol increased and plasma CD decreased only in the GSTM1‐null genotype when compared to the GSTM1‐ present genotype after supplementation (p<0.05). Supplementation did not change the plasma levels of the other antioxidants and lipid profiles in GSTM1‐null or present genotypes. There were no significant changes in the plasma levels of antioxidants and lipid profiles for the GSTT1‐null or present genotypes after supplementation. Our findings suggest that supplementation of grape juice might increase plasma γ‐tocopherol levels and decrease lipid peroxidation in smokers with a GSTM1‐null genotype. (This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2011‐0003613)).