The preventive effects of ethyl acetate fractions from aqueous and ethanolic extract of Nigella sativa L. seeds on calcium oxalate stones in Wistar rat

Various pharmacological effects of Nigella sativa including; anti-inflammatory and antimicrobial effects, disruption of kidney stone, lowering serum lipids and repairment of kidney tissues after nephrotoxicity, have been reported. The aim of this study was to investigate the preventive action of ethyl acetate fractions of aqueous-ethanolic extract of Nigella sativa seeds on calcium oxalate kidney stones in male rats. 31 male Wistar rats were randomly divided into four groups. All groups were studied during 28 days of experimental protocol. Healthy control group (1) received tap drinking water. Negative control group (2) received 1% ethylene glycol in drinking water. Groups 3 and 4 were treated with 1% ethylene glycol as well as ethyl acetate phase remnant and ethyl acetate fractions from aqueous and ethanolic extract of Nigella sativa L. seeds, respectively at equivalent dose of 250 mg/kg of total extract. Urine concentration of oxalate, citrate and calcium in days 0, 14 and 28, and also plasma concentration of magnesium and calcium in days 0 and 28, were measured. At the end of experiment, kidneys were removed for histopathologic study and examined for counting calcium oxalate deposits. Data were presented as Mean SEM and were analyzed by one way ANOVA and subsequently Tukey tests; p value less than 0.05 (p0.05) was considered significant. Results showed that the number of calcium oxalate crystals in group 2 vs. group 1 and 3 (without any crystals) significantly increased (p0.001), but there was no significant difference between groups 2 and 4. Urine oxalate concentration in day 28 increased significantly in groups 2, 3 and 4 (p0.05) in comparison with day 0, but urine calcium concentration in groups 3 and 4 at day 28 has no significant difference with day 0. The results of this study supported the inhibitory action of aqueous-ethanolic extract of Nigella sativa ethyl-acetate phase remnant on calcium oxalate kidney stones. However, ethyl acetate fraction of extract did not show a similar effect on kidney stones. Although the exact mechanism is not clear, but this action may be due to antioxidant, antilipid or anti-inflammatory properties of Nigella sativa seed. Therefore, Nigella sativa should be advised in treatment of human kidney stone disease.