Protective effect of ethyl acetate fraction of Biophytum sensitivum extract against sodium oxalate-induced urolithiasis in rats

The methanolic whole plant extract of Biophytum sensitivum (感应草gǎnyìng cǎo) has been found to possess antiurolithiatic effect. The present study was undertaken to evaluate the antiurolithiatic effect of some fractions of methanolic whole plant extract of B. sensitivum (MBS) in rats as a step toward activity-directed isolation of antiurolithiatic component. The MBS was successively extracted with dichloromethane, ethyl acetate, ethanol and water to obtain fractions. Sodium oxalate (70 mg/kg, i.p.) was administered to rats for seven days to develop calcium oxalate urolithiasis. These rats were treated with two doses (20 and 40 mg/kg, p.o.) of the fractions, 1 h before sodium oxalate injections. Antiurolithiatic activity was assessed by estimating biochemical changes in urine, serum and kidney homogenate along with histological changes in kidney tissue. Sodium oxalate administration caused biochemical alterations in urine which was found to be prevented significantly by the ethyl acetate fraction. Supplementation with ethyl acetate fraction prevented the elevation of serum creatinine, uric acid and blood urea nitrogen levels. The elevated calcium, oxalate and phosphate levels in the kidney tissue homogenate of lithiatic rats were significantly reduced by the treatment with ethyl acetate fraction. The ethyl acetate fraction also caused significant decrease in lipid peroxidation activity, accumulation of calcium oxalate deposits and histological changes in the kidney tissue. The results showed that the antiurolithiatic component of the methanolic whole plant extract of the plant is contained in the ethyl acetate fraction. The effect is attributed to its diuretic, antioxidant, nephroprotective properties and effect on lowering the concentration of urinary stone-forming constituents.