Metabolism of xenobiotics and drugs<unk>  is involved in phase I xenobiotic and drug metabolism (one substrate of it is theophylline). It is inhibited by hesperetin (a flavonoid found in lime, sweet orange), fluoroquinolones and macrolides and induced by aromatic hydrocarbons.<unk>  is also known as AHH (aryl hydrocarbon hydroxylase). It is involved in the metabolic activation of aromatic hydrocarbons (polycyclic aromatic hydrocarbons, PAH), for example,benzoapyrene (BaP), by transforming it to an epoxide. In this reaction, the oxidation of benzoapyrene is catalysed by<unk>  to form BaP-7,8-epoxide, which can be further oxidized by epoxide hydrolase (EH) to form BaP-7,8-dihydrodiol. Finally,<unk>  catalyses this intermediate to form BaP-7,8-dihydrodiol-9,10-epoxide, which is a carcinogen. However, an in vivo experiment with gene-deficient mice has found that the hydroxylation of benzoapyrene by<unk>  can have an overall protective effect on the DNA, rather than contributing to potentially carcinogenic DNA modifications. This effect is likely due to the fact that<unk>  is highly active in the intestinal mucosa, and thus inhibits infiltration of ingested benzoapyrene carcinogen into the systemic circulation.<unk>  metabolism of various foreign agents to carcinogens has been implicated in the formation of various types of human cancer. Metabolism of endogenous agents<unk>  also metabolizes polyunsaturated fatty acids into signaling molecules that have physiological as well as pathological activities.<unk>  has monoxygenase activity in that it metabolizes arachidonic acid to 19-hydroxyeicosatetraenoic acid (19-HETE) (see 20-Hydroxyeicosatetraenoic acid) but also has epoxygenase activity in that it metabolizes docosahexaenoic acid to epoxides, primarily 19R,20S-epoxyeicosapentaenoic acid and 19S,20R-epoxyeicosapentaenoic acid isomers (termed 19,20-EDP) and similarly metabolizes eicosapentaenoic acid to epoxides, primarily 17R,18S-eicosatetraenic acid and 17S,18R-eicosatetraenic acid isomers (termed 17,18-EEQ). Synthesis of 12(S)-HETE by<unk>  has also been demonstrated. 19-HETE is an inhibitor of 20-HETE, a broadly active signaling molecule, e.g. it constricts arterioles, elevates blood pressure, promotes inflammation responses, and stimulates the growth of various types of tumor cells; however the in vivo ability and significance of 19-HETE in inhibiting 20-HETE has not been demonstrated (see 20-Hydroxyeicosatetraenoic acid). The EDP (see Epoxydocosapentaenoic acid) and EEQ (see epoxyeicosatetraenoic acid) metabolites have a broad range of activities. In various animal models and in vitro studies on animal and human tissues, they decrease hypertension and pain perception; suppress inflammation; inhibit angiogenesis, endothelial cell migration and endothelial cell proliferation; and inhibit the growth and metastasis of human breast and prostate cancer cell lines. It is suggested that the EDP and EEQ metabolites function in humans as they do in animal models and that, as products of the omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid, the EDP and EEQ metabolites contribute to many of the beneficial effects attributed to dietary omega-3 fatty acids. EDP and EEQ metabolites are short-lived, being inactivated within seconds or minutes of formation by epoxide hydrolases, particularly soluble epoxide hydrolase, and therefore act locally.<unk>  is one of the main extra-hepatic cytochrome P450 enzymes; it is not regarded as being a major contributor to forming the cited epoxides but could act locally in certain tissues such as the intestine and in certain cancers to do so.
CYP1A1
CYP1A2
CYP3A
CYP2C19
CYP3A4
CYP3A5
CYP2D6
CYP2J2