Effects on the Cytochrome P450 Enzyme System

In vivo tests performed using human test subjects taking 1000 mg curcumin once daily for 14 continuous days showed that curcumin inhibited the cytochrome P450 enzyme CYP1A2 by 28.6% and induced CYP2A6 by 48.9%. [4]

Curcumin was found to inhibit CYP3A4 in the small intestine but induce it in the liver and kidneys in rats in vivo.[3]

Curcuminoids were found to inhibit human CYP2C19, CYP2B6, and CYP3A4 in vitro with IC50 values ranging from 0.99 +/- 0.04 to 25.3 +/- 1.3 microM. CYP2D6, CYP1A2, and CYP2E1 activities were less affected (IC50 values > 60 microM).[2]

Rats fed a diet of 1% turmeric showed inhibition of CYP1A1, CYP1A2 and CYP2B1.[1]

Effects on Other Enzymes and Biological Compounds

Curcuminoids were found to inhibit human UGT and SULT in vitro.[2]

Curcumin was found to inhibit intestinal P-glycoprotein (P-gp) and induce hepatic P-glycoprotein in rats in vivo.[3]

In one study curcumin was found to inhibit glutathione S-transferase (GST) by 96% and reduce levels of glutathione by 50% in vitro.[5]

1. Food Chem Toxicol. 2001 Jun;39(6):541-7.
Inhibition of cytochrome P450 isozymes by curcumins in vitro and in vivo. Thapliyal R, Maru GB; Carcinogenesis Division, Cancer Research Institute, Tata Memorial Centre, Mumbai-400 012, Parel, India. PubMed PMID: 11346483
2. Drug Metab Dispos. 2008 Aug;36(8):1594-605. doi: 10.1124/dmd.108.020552. Epub 2008 May 14;
Curcuminoids inhibit multiple human cytochromes P450, UDP-glucuronosyltransferase, and sulfotransferase enzymes, whereas piperine is a relatively selective CYP3A4 inhibitor. Volak LP, Ghirmai S, Cashman JR, Court MH; Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts 02111, USA. PubMed PMID: 18480186
3. Drug Metab Dispos. 2007 Jan;35(1):110-5. Epub 2006 Oct 18.
Impact of curcumin-induced changes in P-glycoprotein and CYP3A expression on the pharmacokinetics of peroral celiprolol and midazolam in rats. Zhang W, Tan TM, Lim LY; Pharmacy M315, School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia; PubMed PMID: 17050652
4. Plant polyphenol curcumin significantly affects CYP1A2 and CYP2A6 activity in healthy, male Chinese volunteers;
Ann Pharmacother. 2010 Jun;44(6):1038-45. doi: 10.1345/aph.1M533. Epub 2010 May 18; Chen Y, Liu WH, Chen BL, Fan L, Han Y, Wang G, Hu DL, Tan ZR, Zhou G, Cao S, Zhou HH; Institute of Clinical Pharmacology, Central South University, Changsha, Hunan, China. PubMed PMID: 20484172
5. Inhibition of glutathione S-transferase activity in human melanoma cells by alpha,beta-unsaturated carbonyl derivatives. Effects of acrolein, cinnamaldehyde, citral, crotonaldehyde, curcumin, ethacrynic acid, and trans-2-hexenal.
Iersel ML, Ploemen JP, Struik I, van Amersfoort C, Keyzer AE, Schefferlie JG, van Bladeren PJ. PubMed PMID 8950226
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