tannins and Renal-Insufficiency

Chromium nephrotoxicity (CrNT) is thought to occur through the oxidant lesion mechanism. There is still a lack of specific remedies against CrNT. We primarily screened Chinese herbal medicines with a potential protective effect against CrNT, e.g., rhubarb (Rheum palmatum L.). However, the active constituents in rhubarb and its mechanisms remain unclear. In this study, the total rhubarb extract (TR) was successively separated into three parts: total anthraquinone extract (TA), total tannin extract (TT) and remaining component extract (RC). The effects of each extract on the potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity in rats were comparatively assessed. The results showed that only the administration of TT protected the kidney function in K(2)Cr(2)O(7)-injured rats. Besides, TT showed significant activity to scavenge hydroxyl radicals, which is considered to be the dominant lesion product generated by hexavalent chromium. TT also showed a reduced ability to transform toxic high valence chromium ions into non-toxic low valence ions. And TT was able to further precipitate chromium ions. These results suggested that rhubarb tannins treat CrNT as a free radical scavenger, reductant, and metal precipitant. The multiple protective routes of the plant tannins reveal a superior option for development into a promising natural remedy against CrNT. In addition, the opposite effects of rhubarb anthraquinones in treating CrNT were observed compared to rhubarb tannins, which suggested the duo-directional effects (Yin and Yang) of herbal medicines should be addressed.

Topics: Animals; Anthraquinones; Chromates; Drug Evaluation, Preclinical; Free Radical Scavengers; Kidney; Male; Phytotherapy; Potassium Compounds; Rats; Rats, Sprague-Dawley; Renal Insufficiency; Rheum; Tannins; Yin-Yang

The protective effect of green tea (Camellia sinensis) was tested against arsenic-induced toxicity. However, the possible role of tannins in green tea in alleviating hepatic and renal oxidative injury has also been studied. Administration of sodium arsenite (100 mg/kg/day) for 28 days in Sprague Dawley female rats resulted in significant reduction of biochemical parameters such as delta-aminolevulinic acid dehydratase (ALAD), reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD) and elevation of thiobarbituric acid reactive substances (TBARS) and the index of nitrite/nitrate (NOx) levels. The tissue arsenic burden was increased after arsenic exposure for a period of 28 days. Green tea crude fraction (GTC) co-treated with sodium arsenite for 28 days caused significant (p < .01) elevation of ALAD, GSH, GPx, SOD, and nitrate/nitrite levels and reduction of the TBARS level and tissue burden when compared to detannified green tea fraction (GTDT)-treated groups. The protective role of tannin-rich fraction of C. sinensis when compared to the detannified fraction was also confirmed by histological examinations. The greater activity of GTC than that of detannified green tea fraction correlates with the higher content of tannins in green tea. Overall, these results indicate that the tannin-rich green tea could have improved the defense mechanism against arsenic-induced oxidative stress and reduced the tissue arsenic burden.

Topics: Animals; Arsenic; Arsenic Poisoning; Arsenites; Biomarkers; Camellia sinensis; Chemical and Drug Induced Liver Injury; Dose-Response Relationship, Drug; Female; Kidney; Liver; Oxidative Stress; Phytotherapy; Plant Extracts; Plant Leaves; Porphobilinogen Synthase; Protective Agents; Random Allocation; Rats; Rats, Sprague-Dawley; Renal Insufficiency; Sodium Compounds; Tannins

The effects of a green tea tannin mixture and its individual tannin components on methylguanidine were examined in rats with renal failure. The green tea tannin mixture caused a dose-dependent decrease in methylguanidine, a substance which accumulates in the blood with the progression of renal failure. Among individual tannin components, the effect was most conspicuous with (-)-epigallocatechin 3-O-gallate and (-)-epicatechin 3-O-gallate, while other components not linked to gallic acid showed only weak effects. Thus, the effect on methylguanidine was found to vary among different types of tannin.

Topics: Adenine; Animals; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Male; Methylguanidine; Rats; Rats, Wistar; Renal Insufficiency; Tannins; Tea