Therapeutic Potential of (-)-Epigallocatechin 3-O-Gallate on Renal Damage in Diabetic Nephropathy Model Rats

Abstract

Previous investigations have demonstrated that green tea polyphenols and partially hydrolyzed guar gum as dietary fiber have antioxidative and hypolipidemic activity, respectively, supporting their reduction of risk factors in the course of diabetic nephropathy via a hypoglycemic effect and ameliorating the decline of renal function through their combined administration to rats with subtotal nephrectomy plus streptozotocin (STZ) injection. As a further study, we examined whether (Ϫ)-epigallocatechin 3-O-gallate (EGCg), the main polyphenolic compound, could ameliorate the development of diabetic nephropathy. Rats with subtotal nephrectomy plus STZ injection were orally administrated EGCg at doses of 25, 50, and 100 mg/kg body weight/day. After a 50-day administration period, EGCgtreated groups showed suppressed hyperglycemia, proteinuria, and lipid peroxidation, although there were only weak effects on the levels of serum creatinine and glycosylated protein. Furthermore, EGCg reduced renal advanced glycation endproduct accumulation and its related protein expression in the kidney cortex as well as associated pathological conditions. These results suggest that EGCg ameliorates glucose toxicity and renal injury, thus alleviating renal damage caused by abnormal glucose metabolism-associated oxidative stress involved in renal lesions of diabetic nephropathy.

High-dose green tea polyphenols induce nephrotoxicity in dextran sulfate sodium-induced colitis mice by down-regulation of antioxidant enzymes and heat-shock protein expressions

“…Moreover, a diet containing both GTPs and DSS dramatically increased serum creatinine (Fig. 4d), the most reliable biomarker of nephropathy (Nakagawa et al 2004;Yamabe et al 2006). Notably, both green tea extracts and DSS have been found to be widely distributed throughout a variety of organs in mice, including the liver and kidneys (Suganuma et al 1998;Kitajima et al 1999a, b).…”

Epigallocatechin-3-gallate inhibits IL-6 synthesis and suppresses transsignaling by enhancing soluble gp130 production

“…To study in vivo modulation of IL-6 by EGCG in rats, a daily i.p. injection of EGCG (100 mg/kg) based on an earlier study, which corresponds to 960 mg of human equivalent dose, was administered starting from day 7 to day 16 (23,24). Interestingly, the evaluation of serum IL-6, IL-1␤, and TNF-␣ levels at day 17 showed that EGCG treatment significantly inhibited IL-6 levels by almost 28% in serum with no change in the levels of IL-1␤ and TNF-␣ ( Fig.…”

Diabetes, Oxidative Stress and Tea

“…Black tea has been reported to be an efficient reducer of peroxidation of lipoproteins as well Vinson et al, 1998;Sur-Altiner et al, 2000;Yokozawa et al, 2002;Vinson et al, 2005;Alipoor et al, 2008). Some studies have investigated the effects of purified tea polyphenols and drawn similar results (Quine et al, 2005;Yamabe et al, 2006).…”