Hypouricemic Effects of Armillaria mellea on Hyperuricemic Mice Regulated through OAT1 and CNT2

Ethanol and water extracts of Armillaria mellea were prepared by directly soaking A. mellea in ethanol (AME) at 65 ∘ C, followed by decocting the remains in water (AMW) at 85 ∘ C. Significantly, AME and AMW at 30, 60 and 120 mg/kg exhibited excellent hypouricemic actions, causing remarkable declines from hyperuricemic control (351 μ mol/L, P < 0 . 0 1 ) to 136, 130 and 115 μ mol/L and 250, 188 and 152 μ mol/L in serum uric acid, correspondingly. In contrast to the evident renal toxicity of allopurinol, these preparations showed little impacts. Moreover, they showed some inhibitory effect on XOD (xanthine oxidase) activity. Compared with hyperuricemic control, protein expressions of OAT1 (organic anion transporter 1) were significantly elevated in AME- and AMW-treated mice. The levels of GLUT9 (glucose transporter 9) expression were significantly decreased by AMW. CNT2 (concentrative nucleoside transporter 2), a key target for purine absorption in gastrointestinal tract was involved in this study, and was verified for its innovative role. Both AME and AMW down-regulated CNT2 proteins in the gastrointestinal tract in hyperuricemic mice. As they exhibited considerable inhibitory effects on XOD, we selected XOD as the target for virtual screening by using molecular docking, and four compounds were hit with high ranks. From the analysis, we concluded that hydrogen bond, Pi–Pi and Pi-sigma interactions might play important roles for their orientations and locations in XOD inhibition.