Effect of Tannins in Green Tea on the Urinary Methylguanidine Excretion in Rats Indicating a Possible Radical Scavenging Action

Inhibitory Effect of Tannin in Green Tea on the Proliferation of Mesangial Cells

“…We have reported previously that both tannin mixture and (-)-epigallocatechin 3-O-gallate cause a significant de crease in the urinary excretion of methylguanidine in rats with renal failure [13]. Considering this together with the finding that active oxygen is involved in the mechanism of methylguanidine production, on the basis of our in vivo [21] and in vitro experiments [22], we conclude that tannin has a radical-scavenging action.…”

“…On the other hand, we have demonstrated previously that some oriental medicines or medical prescriptions and green tea work against the condition of chronic renal failure and inhibit its progression [3][4][5][6][7][8][9][10][11][12][13] and that the active compo nent responsible is tannin [12,13]. From the above-men tioned findings, we inferred that tannin has some influence on the onset of glomerulonephritis and glomerulosclerosis and the progression of glomerular disorder.…”

Activity of (−)-Epigallocatechin 3-O-Gallate against Oxidative Stress in Rats with Adenine-Induced Renal Failure

“…We also found that green tea polyphenols suppressed the progression of renal failure in nephrectomized rats, assessed by measuring renal functional parameters and histopathological examination, and concurrently elevated endogenous radical-scavenging enzyme activities in the kidney (2,4). In addition, the increased levels of uremic toxins, such as methylguanidine (MG), in patients on dialysis and animal models of renal failure were also significantly reduced by continuous treatment with green tea polyphenols (2,(5)(6)(7).…”

Antioxidant Properties of Green and Black Tea, and their Potential Ability to Retard the Progression of Eye Lens Cataract

“…Their effects on the oxidative damage to DNA and protein molecules have been less monitoredÐbarring some studies on cellular changes such as sister chromatid exchanges, micronuclei formation, micro®ltration of strand broken DNA, or 8-hydroxydeoxyguanidine adducts or excretion Yokozawa et al, 1992;Hasegawa et al, 1995;Leanderson, Faresjo and Tagesson, 1997;Wei et al, 1999). Direct molecular studies evaluating the protective action of tea components against protein and DNA damage would be of value in understanding the underlying mechanisms, particularly in relation to protein associated pathologies such as cataract or prion diseases (Balasubramanian, Chandani and Sivakama Sundari, 1998).…”