ABSTRACT
Antioxidants possess the unique ability to neutralize free radicals, which are highly reactive molecules that result from oxidative processes and may contribute to DNA damage, carcinogenesis, inflammation, and photoaging of the skin. Polyphenols, or catechins, are plant-derived antioxidants with anti-inflammatory, photoprotective, and anti-carcinogenic properties. Green tea, the most well-studied type, contains significant amounts of polyphenols, which are known to reduce DNA damage, sunburn, inflammation, and erythema. The most potent catechin contained in green tea is epigallocatechin-3-gallate. Black tea, a fermented type, has been less extensively studied for its cutaneous effects. Research suggests that oral or topical black tea inhibits tumorigenesis. Its mechanisms of action, as demonstrated in murine models, include the inhibition of cell proliferation, apoptosis, tumorigenic cell-signaling kinases, transcription factors, and the inflammatory protein cyclooxygenase 2. Vitamin A, also known as retinol, is the cosmeceutical cousin of the prescription topical drug tretinoin.
