Vitamin E is a odorless and tasteless light yellow fat soluble vitamin with antioxidant, anticancer, anti-inflammatory and other functions. According to its molecular structure, it can be divided into two categories: tocopherols and tocotrienols. Each category is divided into four types based on the methyl position on the chromophore ring: alpha, beta, gamma, and delta [1-2]. Compounds related to tocopherols, such as tocotrienols, have a certain activity when the substituents are different, but the activity of tocopherols is significantly reduced.

Both tocopherol and tocotrienol have strong antioxidant effects. Due to the activity of alpha tocopherol transfer protein (alpha TP) and tocopherol binding protein (TBP) in the body, tocopherol is more easily absorbed and utilized by the body. Therefore, alpha tocopherol is considered to be the main manifestation of vitamin E's antioxidant activity in the body. Alpha tocopherol, with a molecular formula of C29H50O2 and a molecular weight of 430.5, is divided into two types based on its source: natural and synthetic, denoted as D-type and L-type, respectively. Natural alpha tocopherol is in the R conformation (RRR), while artificially synthesized alpha tocopherol is in the RS conformation (RRR, RSR, RRS, RSS, SRR, SSR, SRS, SSS). The conformation is related to its activity, and studies have found that only alpha tocopherol with 2R or more can be utilized and absorbed by the body. Therefore, natural alpha tocopherol has higher nutritional value and is safer than artificially synthesized alpha tocopherol