Abstract
Curcumin, a constituent of the spice turmeric, has been shown to reduce the adenoma burden in rodent models of colorectal cancer accompanied by a reduction of levels of the oxidative DNA adduct 3-(2-deoxy-β-di-erythro-pentafuranosyl)-pyr[1,2-α]-purin-10(3H)one (M1G) and of expression of the enzyme cyclooxygenase-2 (COX-2). We tested the hypothesis that pharmacologically active levels of curcumin can be achieved in the colorectum of humans as measured by effects on levels of M1G and COX-2 protein. Patients with colorectal cancer ingested curcumin capsules (3,600, 1,800, or 450 mg daily) for 7 days. Biopsy samples of normal and malignant colorectal tissue, respectively, were obtained at diagnosis and at 6 to 7 hours after the last dose of curcumin. Blood was taken 1 hour after the last dose of curcumin. Curcumin and its metabolites were detected and quantitated by high-performance liquid chromatography with detection by UV spectrophotometry or mass spectrometry. M1G levels and COX-2 protein expression were measured by immunoslot blot and Western blotting, respectively. The concentrations of curcumin in normal and malignant colorectal tissue of patients receiving 3,600 mg of curcumin were 12.7 ± 5.7 and 7.7 ± 1.8 nmol/g, respectively. Curcumin sulfate and curcumin glucuronide were identified in the tissue of these patients. Trace levels of curcumin were found in the peripheral circulation. M1G levels were 2.5-fold higher in malignant tissue as compared with normal tissue (P < 0.05 by ANOVA). Administration of curcumin (3,600 mg) decreased M1G levels from 4.8 ± 2.9 adducts per 107 nucleotides in malignant colorectal tissue to 2.0 ± 1.8 adducts per 107 nucleotides (P < 0.05 by ANOVA). COX-2 protein levels in malignant colorectal tissue were not affected by curcumin. The results suggest that a daily dose of 3.6 g curcumin achieves pharmacologically efficacious levels in the colorectum with negligible distribution of curcumin outside the gut.
- Chemoprevention
- curcumin
- pharmacodynamics
Footnotes
↵3 Perkins et al., unpublished data.
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Grant support: UK Medical Research Council programme grant 1995, Association of International Cancer Research project grant 1998, and University Hospitals of Leicester Trust 2000.
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