Flavonoids can replace alpha-tocopherol as an antioxidant.

Endogenous antioxidants such as the lipid-soluble vitamin E protect the cell membranes from oxidative damage. Glutathione seems to be able to regenerate alpha-tocopherol via a so-called free radical reductase. The transient protection by reduced glutathione (GSH) against lipid peroxidation in control liver microsomes is not observed in microsomes deficient in alpha-tocopherol. Introduction of antioxidant flavonoids, such as 7-monohydroxyethylrutoside, fisetin or naringenin, into the deficient microsomes restored the GSH-dependent protection, suggesting that flavonoids can take over the role of alpha-tocopherol as a chain-breaking antioxidant in liver microsomal membranes.