Abstract
Curcumin, the yellow pigment in turmeric and curry, has antioxidative and anticarcinogenic activities. In this study, we investigated the pharmacokinetic properties of curcumin in mice. After i.p. administration of curcumin (0.1 g/kg) to mice, about 2.25 μg/ml of curcumin appeared in the plasma in the first 15 min. One hour after administration, the levels of curcumin in the intestines, spleen, liver, and kidneys were 177.04, 26.06, 26.90, and 7.51 μg/g, respectively. Only traces (0.41 μg/g) were observed in the brain at 1 h. To clarify the nature of the metabolites of curcumin, the plasma was analyzed by reversed-phase HPLC, and two putative conjugates were observed. Treatment of the plasma with β-glucuronidase resulted in a decrease in the concentrations of these two putative conjugates and the concomitant appearance of tetrahydrocurcumin (THC) and curcumin, respectively. To investigate the nature of these glucuronide conjugates in vivo, the plasma was analyzed by electrospray. The chemical structures of these metabolites, determined by mass spectrometry/mass spectrometry analysis, suggested that curcumin was first biotransformed to dihydrocurcumin and THC and that these compounds subsequently were converted to monoglucuronide conjugates. Because THC is one of the major metabolites of curcumin, we studied its stability at different pH values. THC was very stable in 0.1 M phosphate buffers of various pH values. Moreover, THC was more stable than curcumin in 0.1 M phosphate buffer, pH 7.2 (37°C). These results, together with previous findings, suggest that curcumin-glucuronoside, dihydrocurcumin-glucuronoside, THC-glucuronoside, and THC are major metabolites of curcumin in vivo.
Footnotes
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Send reprint requests to: Dr. Jen-Kun Lin, Institute of Biochemistry, College of Medicine, National Taiwan University, No. 1, Section 1, Jen-ai Road, Taipei, Taiwan, Republic of China.
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This study was supported by grants from the National Science Council (NSC 86–2621-B-002–008-Z and NSC 86–2314-B-002–04), the National Health Research Institute (DOH 86-HR-403), and the National Research Institute for Chinese Medicine (NRICM-87102).
- Abbreviations used are::
- THC
- tetrahydrocurcumin
- UGT
- UDP-glucuronosyltransferase UDPGT, uridine diphosphoglucuronsyltransferase
- CID
- collision-induced dissociation
- TLC
- thin-layer chromatography
- MS/MS
- mass spectrometry/mass spectrometry
- Received March 17, 1998.
- Accepted December 10, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
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