Studies have shown that the production and reaction of excess free radicals and reactive oxygen species are closely related to the occurrence and development of many diseases and the aging process of organisms when the homeostasis is disturbed. Free radical reactive oxygen species can destroy biological macromolecules (such as proteins, enzymes and DNA, etc.), causing mutations or breaks in DNA, and the destruction of functional proteins and membrane structures. Free radicals damage the body, is an important incentive to accelerate the aging of human body. Supplementation of antioxidant nutrients helps to reduce oxidative damage and delay it. Therefore, it is of great significance to search for antioxidant foods and Chinese herbs that can effectively remove free radical activity for the protection of human health.

The mechanism of scavenging free radicals by natural products is very complex. Generally, it is related to the antioxidant active substances rich in natural products. The antioxidant substances in the body are supplemented by highly active antioxidant components in natural products (such as flavonoids, tannins, unsaturated fatty acids, vitamins, etc.), so as to improve the activity of endogenous antioxidant enzymes in the body. To prevent the formation of free radical chain reactions and further damage. It has been reported that flavonoids and phenolic compounds have the scavenging effect on free radicals. In addition, structural factors related to antioxidant activity, such as the number and location of phenolic hydroxyl groups and the steric hindrance generated by the combination of monomers, have a certain relationship with the strength of free radical scavenging ability. For example, catechins and their oxides contain multiple free phenolic hydroxyl groups. With a strong ability to provide hydrogen protons, so that the highly oxidizing free radical reduction, so as to terminate the free radical chain reaction, to achieve the purpose of eliminating free radicals.