Effects of green tea on serum paraoxonase/arylesterase activities in streptozotocin-induced diabetic rats

In recent years, green tea has become a subject of interest because of its beneficial effects on human health. The purpose of this study was to determine the effects of green tea on serum paraoxonase/arylesterase activities and lipoprotein oxidizability in streptozotocin-induced diabetic rats (65 mg/kg [intraperitoneal]). Green tea was given in tap water (2%) for 3 and 6 weeks to control (CGT-3w and CGT-6w) and diabetic (DGT-3w and DGT-6w) rats, and they were compared with the control and diabetic groups (D-3w and D-6w), respectively. Serum insulin level was significantly increased in the DGT-6w group; serum lipid and plasma and tissue malondialdehyde levels were reduced in the DGT-3w and DGT-6w groups. Oxidizability of apolipoprotein B-containing lipoprotein fraction was found to be significantly reduced in the DGT-6w group. Serum total antioxidant capacity showed a significant increase in the CGT-6w and DGT-6w groups. Paraoxonase activity was significantly reduced in the D-3w and D-6w groups and increased in the DGT-6w group. We conclude that green tea might have antilryperlipidernic and antioxidative effects and may slow the progression of atherogenesis by reducing oxidation of lipoproteins and preserving paraoxonase activity. (c) 2005 Elsevier Inc. All rights reserved.