There are hundreds, probably thousands, of different substancses that can act as antioxidants. The most familiar ones are vitamin C, vitamin E, polyphenols, and many more.
Polyphenols are known as flavonoids, are divided into flavonols, flavones, catechines, flavonones, anthocyanidins, and isoflavonoids. They are synthesized by plants as a response to mitigate cellular damage due to oxidative conditions.
Polyphenols are generally multi-functional, strong antioxidants. Besides OH- radicals, polyphenols are believed to quench singlet oxygen, superoxide anion radicals, and peroxide radicals.
Moreover, polyphenolic compounds also possess anti-inflammatory and other properties beneficial for aged and damaged skin.
Distinct combinations of topical antioxidants have shown significantly enhanced synergetic photo-protective effect as compared to single antioxidants.