INHIBITORY EFFECTS OF ANCHUSA AZUREA EXTRACTS ON XANTHINE OXIDASE ACTIVITY AND ITS HYPOURICEMIC EFFECTS ON MICE

Objective: The aim of the present study was to determine the effects of the polyphenols and flavonoids from Anchusa azurea on XO activities in vitro and on serum and liver uric acid levels in normal and potassium oxonate-induced hyper uricemic mice. In addition, the renal function of the mice after flavonoid administration was estimated by the determination of blood urea and creatinine analysis.Methods: In the present study, Anchusa azurea were extracted with solvent of varying polarity allowed its separation into four subfractions: crude extract (Cr) chloroform extract (ChE), ethyl acetate extract (AcE), and aqueous extracts (AqE). Total polyphenol and flavonoids contents of Anchusa azurea extracts were determined. The inhibitory activity of the extracts on the XO was evaluated and the type of inhibition was determined. Hyperuricemia is induced by intraperitoneally injection of potassium oxonate, the uric acid, urea and creatinine were measured in serum and supernatant of the liver. The effect of the extracts on renal function was evaluated. The rate of urea and creatinine levels can be indicators for the assessment of renal function.Results: AcE were the richest in polyphenols and ChE was the richest fraction in flavonoids. The inhibitory activity of the extracts on the XO was evaluated, the results obtained showed that the inhibition is dose-dependent and ChE and AcE have the best inhibitory effect (IC50= 0.334±0.006 and 0.263±0.002 mg/ml, respectively), and both showed a noncompetitive type of inhibition. For antihyperuricemic effect, AqE and CrE caused a decrease in serum uric acid (a decrease of 66%) followed by ChE with a percentage of 29.22 %. The AcE keeps almost the same value of uric acid of "PO" group. For the supernatant, only CrE caused a significant decrease of liver uric acid (18.5±4.83 mg/l). This decrease can be explained by the significant inhibition of the XO by inhibition of the synthesis pathways of uric acid. Comparing the urea level of "OP" group (0.48 g/l), only extracts CrE-AA, AqE-AA (0.41g/l, 0.39 g/l) decreased the level of urea significantly (P ≤ 0.05) to the normal values of urea (0.34 g/l), we can conclude that the rate of urea and creatinine after treatment with plant extracts are normal and that the results of this study indicate the absence of renal damage in miceConclusion: Anchusa azurea fractions have a strong inhibitory effect on xanthine oxidase and also have a significant lowering effect on serum and liver creatinine and urea levels in hyper uricemic mice.Â

Kinetics of Inhibition of Xanthine Oxidase by Lycium arabicum and its Protective Effect against Oxonate- Induced Hyperuricemia and Renal Dysfunction in Mice

Purpose: To evaluate the in-vitro inhibition of xanthine oxidase (purified from bovine milk) by extracts of Lycium arabicum, as well as it is in vivo hypouricemic and renal protective effects.Methods: Four extracts of Lycium arabicum, methanol (CrE), chloroform (ChE), ethyl acetate (EaE) and aqueous (AqE) extracts, were screened for their total phenolics and potential inhibitory effects on purified bovine milk xanthine oxidase (XO) activity by measuring the formation of uric acid or superoxide radical. The mode of inhibition was investigated and compared with the standard drugs, allopurinol, quercitin and catechin. To evaluate their hypouricemic effect, the extracts were administered to potassium oxonate-induced hyperuricemic mice at a dose of 50 mg/kg body weight.Results: The results showed that EaE had the highest content of phenolic compounds and was the most potent inhibitor of uric acid formation (IC50 = 0.017 ± 0.001 mg/mL) and formation of superoxide (IC50 = 0.035 ± 0.001 mg/ml). Lineweaver-Burk analysis showed that CrE and EaE inhibited XO competitively, whereas the inhibitory activities exerted by ChE and AqE were of a mixed type. Intraperetoneal injection of L. arabicum extracts (50 mg/kg) elicited hypouricemic actions in hyperuricemic mice. Hyperuricemic mice presented a serum uric acid concentration of 4.71 ± 0.29 mg/L but this was reduced to 1.78 ± 0.11 mg/L by EaE, which was the most potent hyporuricemic extract.Conclusion: L. arabicum fractions have a strong inhibitory effect on xanthine oxidase and and also have a significantly lowering effect on serum and liver creatinine and urea levels in hyperuricemic mice.Keywords: Lycium arabicum, Uric acid, Creatinine, Superoxide, Phenolic compounds, Flavonoids, Hyperuricemi