An Improved System to Evaluate Superoxide-Scavenging Effects of Bioflavonoids.

Yuanyong Yao, Shixue Chen, Hu Li

ChemistryOpen 2021 Apr

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The pyrogallol autoxidation method has been widely utilized to evaluate various antioxidants in antioxidative bioactivities. However, this method is generally not appropriate for estimating the . O2- radical scavenging capacity of bioflavonoids, as it enables bioflavonoids to generate . O2- radical in oxygen-alkaline (pH 8.2) surroundings. In the present study, an improved DMSO (dimethyl sulfoxide) system (pH 7.25, versus pH 8.2 of the pyrogallol autoxidation) was successfully developed to evaluate the . O2- radical scavenging capacity of bioflavonoids by EPR technique and using the spin trapping reagent DMPO (5,5-dimethyl-1-pyrroline-N-oxide). The non-protonic environment supplied by the system promotes the stabilization of the . O2- radical and therefore ensures a much more accurate measurement of . O2- radical scavenging capacity in bioflavonoids if compared to protonic solvents. The results demonstrated that the effects of scavenging . O2- radicals in natural bioflavonoids follows the order: dihydromyricetin>myricetin>quercetin>kaempferol>baicalein>chrysin, which are well associated with numbers of hydroxyl groups attached to their molecular skeletons and/or active H of their configurations. Interestingly, the higher superoxide-anion scavenging effect measured for dihydromyricetin with respect to myricetin is possibly attributed to the fact that dihydromyricetin can be transformed into myricetin in the presence of . O2- radical, resulting from the homolysis of active H donated from C3-H bond of DMY via . O2- radicals. © 2021 The Authors. Published by Wiley-VCH GmbH.

Citation

Yuanyong Yao, Shixue Chen, Hu Li. An Improved System to Evaluate Superoxide-Scavenging Effects of Bioflavonoids. ChemistryOpen. 2021 Apr;10(4):503-514