REVIEW: The new paradigm of curcumin and its anticancer activity

Curcumin, derived from the rhizome of Curcuma longa L. is used as a coloring and flavoring additive in many foods and has attracted interest because of its antioxidant activity, antiinflammatory and chemopreventive activities. Various curcumin-related phenols have also been found in edible or medicinal plants, especially in Zingiberaceae. Curcumin has a unique conjugated structure including two methoxylated phenols and an enol form of β-diketone, and the structure shows a typical radical trapping ability as a chain-breaking antioxidant. Curcumin has demonstrated anticarcinogenic effects in numerous animal models including skin and gastrointestinal carcinomas. Curcumin also inhibited benzo[a]pyren- or DMBA (7,12-dimethylbenz[a]anthracene)-induced skin cancer in a mice carcinogenesis model. Curcumin inhibits chemically induced carcinogenesis in the skin, forestomach, and colon when it is administered during initiation and/or postinitiation stages. Curcumin directly inhibited the activity of COX-2. The anti-inflammatory properties of curcumin have been attributed, at least in part, to suppression of PG synthesis. Curcumin also inhibited COX-2 transcription in bile acid and phorbol ester-treated gastrointestinal cell lines. Additionally, administration of curcumin into the rats during the initiation and postinitiation stages and throughout the promotion/progression stage increased apoptosis in the colon tumors. This article provide a mechanistic basis for the antioxidant, chemopreventive and antiinflammatory related-anticancer properties of curcumin.