Protective effect of morus nigra extract on stone formation in rats with ethylene glycol-induced nephrolithiasis

Background: Many herbal products are used in the prevention of stone disease in our country and in the world. Whether these herbal products are beneficial or not, they should be demonstrated by scientific studies. M. nigra is a fruit with high antioxidant activity that contains phenols and flavonoids. The aim of the study is to investigate that M. nigra has a protective effect in stone formation by comparing it with potassium citrate. Material and Methods: Twenty-eight Wistar-type rats obtained from Experimental Animals Research Center of Bolu Abant Izzet Baysal University were divided into four groups. Group I as the control group was fed with only water, Group II was fed with 0.75% of ethylene glycol, Group II was fed with 0.75% of ethylene glycol and 0.4 mEq/day of potassium citrate per rat, and Group IV was fed with 0.75% of ethylene glycol and 800 mg/kg/day of M. nigra extract per rat for 28 days by oral gavage under laboratory conditions. At the end of 28 days, rats were taken into metabolic cages for 24-hour urine collection. Afterwards, the rats were sacrificed and serum Urea, Cr, Na, Ca, Mg, K, Cl, Total Thiol, Native Thiol, Disulphite and urine crystal, leukocytes, pH were studied. Crystal structures of kidney tissues were examined in histological sections. Results: The disulfide level of the ethylene glycol group (40±6.33 µmol/L) was significantly higher than that potassium citrate group (32.17±4.48 µmol/L) (p=0.04). Disulfide values of M. nigra group (37.67±6.09 µmol/L) were lower than the ethylene glycol group, although there was no significant difference. Crystal density of urine in the M. nigra group was statistically significantly lower [289 (19-340) n/µL] than ethylene glycol group [1099 (507-1178) n/µL] (p=0.016). Conclusion: It was observed that M. nigra significantly reduced the crystal density of urine and pathological kidney sections , and decreased oxidative parameters in serum analysis via its antioxidative activity. Keywords: Morus nigra, Nephrolithiasis, Crystallization, Kidney Stone, Thiol-Disulfide, Potassium Citrate