Antioxidant properties of plant extracts Since the introduction of the free radical (tripheylemthylradical) theory in 1900, the study of free radicals has gradually deepened. Traditionally synthesized antioxidants have strong antioxidant capacity, but long-term consumption has potential toxicity, and some may even cause teratogenic and carcinogenic effects, so they are increasingly rejected by people; while bee pollen is collected by bees from flowers. Pollen grains, which contain flavonoids, vitamins, hormones, nucleic acids, enzymes and trace elements, have anti-aging effects and are good antioxidant foods. The antioxidant effects of Pueraria lobata, Eucommia ulmoides, 枸 杞, 椇 茯, 茯 苓, schisandra, apricot, bamboo leaves, lemon, citrus and propolis have been experimentally proven. Therefore, screening substances with antioxidant and free radical scavenging activity from natural products is of great significance to the food and pharmaceutical industries.
The mechanism of scavenging free radicals by plant extracts showed that in the case of imbalance of the homeostasis of the organism, the production and reaction of excess free radicals and reactive oxygen species in the body are closely related to the occurrence and development of many diseases and the aging process of organisms. Free radical reactive oxygen species destroy biological macromolecules (such as proteins, enzymes, and DNA), causing DNA mutations or breaks, disruption of functional proteins and membrane structures. Free radical damage to the body is an important incentive to accelerate human aging. Supplementing antioxidant nutrients helps to reduce oxidative damage and delay. Therefore, the search for antioxidant foods and Chinese herbal medicines that can effectively scavenge free radical activity is of great significance for protecting human health.
The mechanism by which natural products scavenge free radicals is complex, generally related to the antioxidant active substances rich in natural products, through the high-activity antioxidants contained in natural products (such as flavonoids, tannins, unsaturated). Fatty acids, vitamins, etc.) to supplement the body's antioxidants, to enhance the body's endogenous antioxidant enzyme activity, to prevent the formation of free radical chain reaction and further damage. It has been reported that flavonoids and phenolic compounds have a scavenging effect on free radicals. In addition, structural factors related to antioxidant activity, such as the number and position of phenolic hydroxyl groups, and the steric hindrance and scavenging caused by the combination of monomers There is a certain relationship between the strength of free radicals. For example, catechins and their oxides contain multiple free phenolic hydroxyl groups, which have a strong ability to provide hydrogen protons, which can reduce the highly oxidative free radicals and thus terminate. The free radical chain reaction achieves the purpose of scavenging free radicals.