An Improved Test Method for Assaying the Inhibition of Bioflavonoids on Xanthine Oxidase Activity in vitro

Graphical The test method for assaying inhibitory effects of bioflavonoids on xanhine oxidase in vitro has been improved successfully with the equipment of UV-Vis technique. In the improved test method, there is a micro-environment surrounding XOD has been created in the presence of •O 2 - , which is similar to that of in vivo . Simultaneously, the inhibition of dihydromyricetin as a chiral flavonoid was effectively assayed by the improved test method, indicating dihydromyricetin enabling to be a potent inhibitor of XOD, resulting from the selective transformation of DMY to MY occurred. The difference on inhibitory effects of bioflavonoids inhibiting XOD activity assayed by varying test methods cause of us to be further in consideration. The reported test method creating a micro-environment surrounding XOD in the absence of ⋅O 2 − , which is seemly different from the assay in vivo . So, the vitro test method for assaying XOD activity is necessary to be improved for selection of potential inhibitors in the presence of ⋅O 2 − . The inhibitory results demonstrated that bioflavonoids of MY, DMY, QUE and LUT are capable to be on effective IC 50 values, but others are not. As well, their resulting inhibitions determined by the improved test method are much less than that reported in the literature, indicating that their chemical affinities with XOD become weaker. Moreover, DMY assayed on the inhibitions of XOD in the improved test method performs to be a better inhibitor, as compared to the assay of the reported test methods. Abasing on the transformation of DMY into MY in the presence of ⋅O 2 − , the good inhibition of DMY on XOD activity can be explained by the synergistic effect of MY.