Antioxidant potential of four flavonoids from Scutellaria baicalensis: a computational investigation on radical scavenging activity and enzyme inhibition

Abstract

Scutellaria baicalensis is widely known to contain various phytochemicals, with the most notable ones being flavonoids. The aim of this study was to assess the antioxidant properties of four characteristic flavonoids in Scutellaria baicalensis extracts, namely, baicalein, wogonin, baicalin, and wogonoside. A detailed density functional theory (DFT) was utilized to investigate structure–activity relationships and reaction pathways involved in radical scavenging reactions. It was found that the position and number of hydroxyl groups in the abovementioned compounds as well as the reaction environments have a significant impact on the thermodynamic parameters involved in HAT, SET-PT, and SPLET mechanisms. The order of radical scavenging activity for these investigated compounds was baicalein > baicalin > wogonin > wogonoside. The results showed that the 6-OH group of baicalein and baicalin can effectively scavenge ˙OOH radicals in the gas phase through HAT mechanism. Considering another major antioxidant pathway via the inhibition of ROS-producing enzymes, docking studies suggest that these investigated compounds exhibit good affinity toward myeloperoxidase (MPO), cytochrome P450 (CP450), NADPH oxidase (NOX), and xanthine oxidase (XO). These results indicate that baicalein, wogonin, baicalin, and wogonoside have potential as effective antioxidant therapies for diseases related to oxidative stress.