Yokozawa Takako, Rhyu Dong Young, Cho Eun Ju, Aoyagi Kazumasa
Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan.
Free Radic Res. 2003 May;37(5):561-71. doi: 10.1080/1071576031000083134.
The protective effect of (-)-epicatechin 3-O-galate (ECg) against peroxynitrite (ONOO-)-mediated damage was examined using an animal model and a cell culture system. In rats subjected to lipopolysaccharide (LPS) administration plus ischemia-reperfusion, the plasma 3-nitrotyrosine level an indicator of ONOO- production in vivo, was elevated, whereas it declined significantly and dose-dependently after the oral administration of ECg at doses of 10 and 20 micromoles/kg body weight/day for 20 days prior to the process. Moreover, oral administration of ECg significantly enhanced the activities of the antioxidant enzymes, superoxide dismutase, catalase and glutathione peroxidase, and the antioxidant glutathione, showing enhancement of the biological defense system against the damage induced by ONOO-. In addition, the significant increase in the renal mitochondrial thiobarbituric acid-reactive substance level of LPS and ischemic-reperfused control rats was attenuated in rats given ECg. Furthermore, the elevations in the plasma urea nitrogen and creatinine (Cr) levels and the urinary methylguanidine/Cr ratio induced by the procedure were attenuated markedly after oral administration of ECg, implying amelioration of renal impairment. The addition of ECg (25 or 125 microM) prior to 3-morpholinosydnonimine (SIN-1, 800 microM) exposure reduced ONOO- formation and increased the viability of cultured renal epithelial (LLC-PK1) cells in a dose-dependent manner. In particular, ECg inhibited ONOO(-)-mediated apoptotic cell death, which was confirmed by decreases in the DNA fragmentation rate and the presence of apoptotic morphological changes, i.e. small nuclei and nuclear fragmentation. Furthermore, adding ECg before SIN-1 treatment regulated the cell cycle by enhancing G2/M phase arrest. This study provides evidence that ECg has protective activity against the renal damage induced by excessive ONOO- in cellular and in vivo systems.
