Curcuma spp. contain
turmerin,
essential oils, and
curcuminoids, including
curcumin.
Curcumin [1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] is regarded as the most biologically active constituent of the spice turmeric and it comprises 2-8% of most turmeric preparations. Preclinical data from animal models and phase I clinical studies performed with human volunteers and patients with
cancer have demonstrated low systemic bioavailability following oral dosing. Efficient first-pass metabolism and some degree of intestinal metabolism, particularly glucuronidation and sulfation of
curcumin, might explain its poor systemic availability when administered via the oral route. A daily oral dose of 3.6 g of
curcumin is compatible with detectable levels of the parent compound in colorectal tissue from patients with
cancer. The levels demonstrated might be sufficient to exert pharmacological activity. There appears to be negligible distribution of the parent
drug to hepatic tissue or other tissues beyond the gastrointestinal tract.
Curcumin possesses wide-ranging anti-inflammatory and anticancer properties. Many of these
biological activities can be attributed to its potent
antioxidant capacity at neutral and acidic pH, its inhibition of cell signaling pathways at multiple levels, its diverse effects on cellular
enzymes, and its effects on cell adhesion and angiogenesis. In particular,
curcumin's ability to alter gene transcription and induce apoptosis in preclinical models advocates its potential utility in
cancer chemoprevention and
chemotherapy. With regard to considerable public and scientific interest in the use of
phytochemicals derived from dietary components to combat or prevent human diseases,
curcumin is currently a leading agent.