Protective effect of triterpenes on calcium oxalate crystal-induced peroxidative changes in experimental urolithiasis

Naturally occurring pentacyclic triterpenes of plant origin have been identified as possessing a wide range of pharmacological effects. Lupeol (Lupa-21,20(29) dien, 3beta-ol) has been found to be efficient in reducing the risk of stone formation in animals by way of preventing crystal-induced tissue damage and dilution of urinary stone-forming constituents. In the present study, two structurally related triterpenes, lupeol and betulin (Lupa-20(29)ene-3,28 diol) were assessed for their antilithiatic effect. Foreign body implantation method followed by supplementation of ammonium oxalate was adapted to induce stone formation in the bladder. This led to elevated lipid peroxidation and depleted antioxidant status in the renal tissues. Both the triterpenes were equally efficient in minimizing crystal-induced renal peroxidative changes measured in terms of malondialdehyde and subsequent tissue damage. The antioxidant status, comprising of the enzymatic and non-enzymatic components, was found to be significantly depleted in the kidney and bladder of stone-forming animals. Both lupeol and betulin were comparable in their ability to restore the thiol status and the antioxidant enzymes like superoxide dismutase, catalase and glutathione peroxidase. The mechanism by which the two compounds render protection against oxalate-induced toxic manifestations and free radical production may involve the inhibition of calcium oxalate crystal aggregation and enhancement of the body defence systems. 2000 Academic Press.