The inhibitory kinetics of vitamins B9, C, E, and D3 on bovine xanthine oxidase: Gout treatment

Over-consumption of foods high in purines like seafood, red meat, and alcoholic beverages leads to hyperuricemia causing gout attacks. Xanthine oxidase was reported responsible for the overproduction of uric acid.We intend to test in silico and in vitro, the inhibition effect of four vitamins against bovine milk xanthine oxidase (BXO). We performed Molecular docking with GOLD v4.0, and the biological activity prediction with the PASS server. The best-selected vitamins were chosen based on their best PLPchem score. The BXO constant Km and Vmax were determined in vitro, and then the vitamins were tested for their inhibition effect to BXO. Furthermore, the inhibition constant Ki of each inhibitor were determined using Dixon method, the vitamins chosen were vitamin E, vitamin B9, vitamin D3, and vitamin C.The in silico results show that the tested vitamins were the best inhibitors model with PLPchem scores up to 70 comparing to the control. The in vitro results show that BXO have a Km value of 163.55 μM with Vmax of 37 U, vitamins B9, E, C, and D3 were potent inhibitors to BXO with an IC50 of 34.10 ± 0.21, 36.68 ± 1.50, 39.01 ± 0.02, and 100.28 ± 0.33 μM, respectively comparing to the control (32.03 ± 0.73 μM). The kinetic study shows that all tested vitamins were Non-competitive inhibitors, the Ki values were 15 ± 1.76 μM, 29 ± 1.06 μM, 12 ± 1.41 μM, and 20 ± 0.71 μM, for respectively vitamins B9, E, C, and D3.The obtained results promise an excellent strategy using vitamins to enhance immunity, treat hyperuricemia, and minimize the usual drug side effects.