5-Allyl-1-methoxy-2,3-dihydroxybenzene

Identification and characterization of reactive metabolites in myristicin-mediated mechanism-based inhibition of CYP1A2.[Pubmed:26091900]

Chem Biol Interact. 2015 Jul 25;237:133-40.

Myristicin belongs to the methylenedioxyphenyl or allyl-benzene family of compounds, which are found widely in plants of the Umbelliferae family, such as parsley and carrot. Myristicin is also the major active component in the essential oils of mace and nutmeg. However, this compound can cause adverse reactions, particularly when taken inappropriately or in overdoses. One important source of toxicity of natural products arises from their metabolic biotransformations into reactive metabolites. Myristicin contains a methylenedioxyphenyl substructure, and this specific structural feature may allow compounds to cause a mechanism-based inhibition of cytochrome P450 enzymes and produce reactive metabolites. Therefore, the aim of this work was to identify whether the role of myristicin in CYP enzyme inhibition is mechanism-based inhibition and to gain further information regarding the structure of the resulting reactive metabolites. CYP cocktail assays showed that myristicin most significantly inhibits CYP1A2 among five CYP enzymes (CYP1A2, CYP2D6, CYP2E1, CYP3A4 and CYP2C19) from human liver microsomes. The 3.21-fold IC50 shift value of CYP1A2 indicates that myristicin may be a mechanism-based inhibitor of CYP1A2. Next, reduced glutathione was shown to block the inhibition of CYP1A2, indicating that myristicin utilized a mechanism-based inhibition. Phase I metabolism assays identified two metabolites, 5-Allyl-1-methoxy-2,3-dihydroxybenzene (M1) and 1'-hydroxymyristicin or 2',3'-epoxy-myristicin (M2). Reduced glutathione capturing assays captured the glutathione-M1 adduct, and the reactive metabolites were identified using UPLC-MS(2) as a quinone and its tautomer. Thus, it was concluded that myristicin is a mechanism-based inhibitor of CYP1A2, and the reactive metabolites are quinone tautomers. Additionally, the cleavage process of the glutathione-M1 adduct was analyzed in further detail. This study provides additional information on the metabolic mechanism of myristicin inhibition and improves risk evaluation for this compound.

Roles of human liver cytochrome P450 3A4 and 1A2 enzymes in the oxidation of myristicin.[Pubmed:12523956]

Toxicol Lett. 2003 Feb 3;137(3):143-50.

The aim of this work was to identify the form(s) of human liver cytochrome P450 (CYP) involved in the hepatic transformation of myristicin to its major metabolite, 5-Allyl-1-methoxy-2,3-dihydroxybenzene. When microsomes prepared from different human liver samples were compared, the activity of 5-Allyl-1-methoxy-2,3-dihydroxybenzene formation was well correlated (r(2)=0.87) with nifedipine oxidation (a marker of CYP3A4). With a microsomal sample having high CYP3A4 activity, microsomal oxidation of myristicin to the major metabolite (5-Allyl-1-methoxy-2,3-dihydroxybenzene) was markedly inhibited by gestodene and ketoconazole, selective inhibitors of CYP3A enzymes, but not by any of several other P450 inhibitors. Antibodies raised against CYPs 3A4 and 1A2 could also inhibit the oxidation of myristicin, but antibodies recognizing other CYPs had no effect. The oxidation of myristicin to 5-Allyl-1-methoxy-2,3-dihydroxybenzene was catalyzed by purified bacterial recombinant CYPs 3A4 and 1A2. These results provide evidence that CYP3A4 (and possibly other CYP3A enzymes) and CYP1A2 play roles in the formation of the major metabolite, 5-Allyl-1-methoxy-2,3-dihydroxybenzene.

In vitro and in vivo metabolism of myristicin in the rat.[Pubmed:9521577]

J Chromatogr B Biomed Sci Appl. 1998 Feb 13;705(2):367-72.

Myristicin [5-allyl-1-methoxy-2,3-(methylenedioxy)benzene] is a flavoring plant constituent and has been known to produce significant psychopharmacological responses as well as insecticidal activity. From in vitro and in vivo metabolism of myristicin, the two metabolites 5-Allyl-1-methoxy-2,3-dihydroxybenzene and 1'-hydroxymyristicin were identified using GC-MS after derivatization of sample matrices with a mixture of BSTFA-TMCS. Those metabolites from in vitro study were also confirmed in urine after an oral administration of myrisitcin to rats, and enzymatic hydrolysis of urine suggested that these metabolites were excreted as conjugated forms as well.