Inhibition of Cytochrome P450 2E1, Cytochrome P450 3A6 and Cytochrome P450 2A6 by Citrus Essential Oils

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Emily Ann Williamson (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Gregory Raner

Abstract: Cytochrome P450 enzymes in the liver catalyze reactions involving the reduction of molecular oxygen and the oxidation of organic substrates. In some cases the resulting products may have the potential to contribute to oxidative stress within this organ. Oxidative stress usually involves the generation of very reactive compounds that can damage cellular components and are therefore harmful to the body. These reactive compounds can include hydrogen peroxide, superoxide, hydroxyl radicals, and a host of other metabolic intermediates. Cytochrome P450 enzymes have been linked to increased development of oxidative stress in the liver of alcoholics. Cytochrome P4502E1 (CYP2E1) can cause mitochondrial stress and disruption via hydrogen peroxide productions which disturbs signaling pathways between cells. On the other hand, Cytochrome P4502A6 (CYP2A6) has been shown to activate several known potent carcinogens found in tobacco smoke. Cytochrome P4503A6 (CYP 3A6) is a widely recognized enzyme that plays a major role in the metabolism of pharmaceutical drugs, in fact more than 50% of all drugs are metabolized by this enzyme. The goal of this research was to determine if any of the nine citrus essential oils examined would inhibit any of the three Cytochrome P450 enzymes and if so then it would be determined how potent oil is and what type of inhibition it occurred. The results for CYP2E1 concluded that Citrus tangerine, tangerine, was the most potent inhibitor and inhibited through competitive inhibition. The results for CYP3A6 concluded that none of the nine citrus essential oils inhibited the activity of CYP3A6 at a good quality concentration. Lastly, the results for CYP2A6 concluded that both Citrus bergamia, bergamot, and Citrus aurantifolia, lime, were strong potent competitive inhibitors at low concentrations with a KI of 0.878 µg/mL and a KI of 0.045 µg/mL. The inhibition of CYP 2A6 has recently been identified as a possible therapeutic approach to smoking cessation, therefore giving significant importance to bergamot and lime oils and the compounds found in them.

Additional Information

Language: English
Date: 2010
Cytochrome P450, Cytochrome P450 2A6, Cytochrome P450 2E1, Cytochrome P450 3A6, Inhibition
Cytochrome P-450.
Enzyme inhibitors.
Cancer $x Prevention $x Research.

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