Fennel and raspberry leaf as possible inhibitors of acetaminophen oxidation.
In addition to CYP2E1, several CYP isoenzymes, notably CYP1A2, 2D6, and 3A4, are suggested to contribute in acetaminophen oxidation and formation of the hepatotoxic metabolite N-acetyl-p-benzoquinone imine (NAPQI). The in vitro CYP2E1 inhibitory potentials of fennel and raspberry leaf, herbs previously found to inhibit CYP1A2, 2D6, and 3A4 activities in vitro, were investigated. Extracts from commercially available herbal products were incubated with recombinant cDNA-expressed human CYP2E1. A validated LC/MS/MS methodology was applied for determination of 6-hydroxychlorzoxazone formation with disulfiram used as a positive inhibitory control. CYP2E1 IC50 inhibition constants were found to be 23 ± 4 and 27 ± 5 µg/ml for fennel and raspberry leaf, respectively, constants significantly lower than those presented in the literature for other herbal extracts. Together with previous findings, the presented in vitro data for CYP2E1 inhibition suggest that fennel and raspberry leaf have a significant potential of inhibiting all the major metabolic pathways for acetaminophen oxidation and NAPQI formation. Both herbs should be further investigated for their in vivo ability of inhibiting acetaminophen oxidation and NAPQI formation.
Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology (NTNU), Norway.
Astrid Jordet
AJ
Langhammer
Odd Georg
OG
Nilsen
D000082:Acetaminophen / Q000378:metabolism*; D016227:Benzoquinones / Q000378:metabolism; D002753:Chlorzoxazone / Q000031:analogs & derivatives / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2 / Q000378:metabolism; D065609:Cytochrome P-450 CYP1A2 Inhibitors / Q000494:pharmacology*; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism; D065691:Cytochrome P-450 CYP2E1 Inhibitors / Q000494:pharmacology*; D030001:Foeniculum / Q000737:chemistry*; D006801:Humans; D007097:Imines / Q000378:metabolism; D008658:Inactivation, Metabolic; D020128:Inhibitory Concentration 50; D010084:Oxidation-Reduction; D018515:Plant Leaves / Q000737:chemistry; D065856:Rubus / Q000737:chemistry*
D016227:Benzoquinones; D065609:Cytochrome P-450 CYP1A2 Inhibitors; D065691:Cytochrome P-450 CYP2E1 Inhibitors; D007097:Imines; C039289:6-hydroxychlorzoxazone; D000082:Acetaminophen; D019392:Cytochrome P-450 CYP2E1; C504573:CYP1A2 protein, human; D019388:Cytochrome P-450 CYP1A2; C028473:N-acetyl-4-benzoquinoneimine; D002753:Chlorzoxazone
CYP inhibition; acetaminophen; fennel; herb-drug interactions; in vitro; raspberry leaf