# Litholytic Activities of Natural Bioactive Compounds and Their Mechanism Insights
## 3 Litholytic Activity of Flavonoids and Stilbenes
### In Vitro Investigations
#### 3.1.1 [PERSON] et al. [20] tested, _in vitro_, the effect of quercetin at different concentrations (0, 25, 50, and 100 \(\upmu\)M) on Madin-Darby canine kidney (MDCK) cells induced by sodium oxalate. Quercetin (at 100 \(\upmu\)M) significantly inhibited the decrease in the number of MDCK cells (between 70% and 80% of cell survival fraction at a concentration of 100 \(\upmu\)M). Furthermore, lipid peroxidation was evaluated by monitoring malondialdehydedehyde (MDA) production by oxalate at 1 mM. MDA production decreased significantly after 120 and 240 min of treatment with quercetin (at 100 \(\upmu\)M) compared to cells exposed to sodium oxalate (0.60 nmol/mg vs. 0.85 nmol/mg and 0.36 nmol/mg vs. 0.52 nmol/mg, respectively). In addition, the activity of catalase was restored. Moreover, less than 200 \(\upmu\)M of quercetin showed no toxic effect on MDCK cells. The authors of this report revealed that quercetin decreases the oxidative injury of oxalate through the antioxidant pathway [20].
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\begin{tabular}{c c c c} \hline \hline
**Compounds** & **Methods** & **Key Results** & **References** \\ \hline \multirow{4}{*}{Apigenin} & Hyperoxaluria induced by ethylene glycol & Decreased calcium levels in kidneys & \\  & (0.75\%) and ammonium chloride (2\%) in & Improved renal function & [9] \\  & rats for 1 week & Decomposition of kidney stones & \\  & Doses: 1.2, 2.4, and 4.8 mg/kg b.w & Increased urine calcium levels with increasing dose & \\ \hline \multirow{4}{*}{**Catechin**} & Reduced the overall number of crystals in vitro & & \\  & In vitro and in vivo crystallization induced by & Suppressed MCM-induced protein expression & \\  & melamine–cyanuric acid mixture & Decreased renal malondialdehydedehyde (MDA) and urinary & [10] \\  & Doses: 2.5 and 10 mg/kg b.w for 28 days & 8-isoprostine (8-IP) & \\  & Doses: 2.5 and 10 mg/kg b.w for 28 days & Improved the levels of antioxidant enzymes & \\  & Reduced the levels of renal crystals & \\ \cline{2-4}  & In vitro: crystallization induced by calcium & Prevented the mitochondrial membrane & \\  & oxalate monohydrate in NRK-52 cells & Prevented the expression of SOD, 4-HNE, cytochrome c, & \\  & In vivo: hyperoxaluria induced by & and cleaved caspase 3 & [11] \\  & ethylene glycol & Decreased the expression of superoxide dismutase, & \\  & Doses: 2.5 and 10 mg/kg/day for 14 days & malondialdehydedehyde, OPN, and 8-OHdG in rats & \\  & Prevented the EG-induced mitochondrial collapse in rats & \\ \hline \multirow{4}{*}{(-)Epicatechin} & In vitro struvit crystallization in the solution of & Accelerated struvite nucleation & \\  & artificial urine & Increased the mass of struvite & \\  & Spectrophotometric measurements and & Induced a change in color of urine & \\  & microscopic observations & Reduced the levels of MgCrit., MgHcit, and MgCr\({}_{2}\)O\({}_{4}\) & \\  & Doses: 125, 250, 500, and 1000 ug/mL & complexes formed in artificial urine & \\ \hline \multirow{4}{*}{Rutin} & Ethylene-glycol (0.75\%)- and ammonium & Restored the levels of calcium and oxalate to near normal & \\  & (1\%)-induced CaOx uro & Prevented lipid peroxidation & \\  & Dose: 20 mg/kg b.w for 28 days & Decreased tissue damage and the levels of CaOx in & \\  & & kidneys as compared to calculi-induced animals & \\  & & & \\ \cline{2-4}  & & Prevented increase in urine volume & \\  & & Prevented increase in and restored the calcium and & \\  & Ethylene-glycol (0.75\%)- and ammonium & oxalate to near normal & \\  & (1\%)-induced CaOx ucrolithiasis in rat daily & Reduced lipid peroxidation & \\  & for 28 days & Induced minimal kidney damage and histological & \\  & Dose: 20 mg/kg b.w & changes compared to the kidneys of & \\  & & & \\  & Dose: 20 mg/kg b.w & calculi-induced animals & \\  & & Decreased the levels of CaOx & \\ \hline \multirow{4}{*}{Hesperidin} & Fifty millilitutes of calcium chloride, 50 mL of & & \\  & sodium oxalate, and 50 mL of & Promoted the nucleation of crystal deposits & \\  & sodium oxalate, and 50 mL of & Increased the levels of CxM crystals and reduced their & \\  & solution (1 g/L) & size Inhibited CaOx crystal aggregation & \\  & Calculated the inhibition rate & & \\ \hline \multirow{4}{*}{Hesperidin} & Ethylene-glycol (0.5\%)- and vitamin-D3 & & \\  & (0.5 umol)-fed rats & Decreased the number of crystal deposits & \\  & Hyperoside and quercetin (ratio 1:1) at 20 mg/kg b.w & Increased significantly the SOD and catalase levels & [19] \\  & daily for 3 weeks & & \\ \hline \multirow{4}{*}{Quercetin} & In vitro: renal tubular cell injury induced by & & \\  & oxalate (MDCK cells) at doses 0, 25, 50, and & & \\  & 100 uM & & \\  & In vivo: sodium oxalate (3\%) induced urinary & Decreased catalase and superoxide dismutase activity & \\  & crystal deposit formation for 4 weeks & Decreased significantly the number of crystals in kidneys & \\  & Quercetin at 10 mg/kg daily for 4 weeks & & \\ \cline{2-4}  & Hyperoxaluria induced by potassium & Altered the increased lipid peroxidation and antioxidant & \\  & oxalate diet & depletion as compared with rats fed with KOCs & \\  & Quercetin at 10 mg/kg daily from 15 to 28 days & Reduced CaOx aggregation in urine and kidneys & \\  & Quercetin at 10 mg/kg daily from 15 to 28 days & Altered the expression of CaOX modulator genes and & \\  & antioxidant genes (GPx and SOD) & \\ \hline \multirow{4}{*}{Neprholithiasis induced by ethylene glycol (0.75\%)} & Increased urine volume & & \\  & Bycol (0.75\%) & Enhanced the excretion of calcium, oxalate, and & \\  & Dose: 2 mg/kg daily for 28 days & phosphate, and increased the levels of magnesium & \\ \cline{2-4}  & Reduced the levels of BUN and creatinine & & \\ \hline \hline \end{tabular}
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