title: Potent inhibition of CYP1A2 by Frutinone A, an active ingredient of the broad spectrum antimicrobial herbal extract from P. fruticosa.
abstract: 1. Frutinone is an active ingredient extracted from the lipophilic fraction of the Polygala Fruticosa demonstrating various antibacterial and fungal properties. The aim of this study was to characterize its metabolism in an effort to understand metabolism based drug-herb interactions. 2. In vitro metabolic clearance and metabolite identification studies were done using cryopreserved hepatocytes. Reaction phenotyping and inhibition studies were done using human liver microsomes and recombinant cytochrome P450s (CYPs). Frutinone A-CYP1A2 interactions were rationalized using docking simulations. 3. Hepatic clearance was predicted to be low (7.17 mL/min/kg), with reaction phenotyping studies indicating no clearance by the enzymes tested. Frutinone was identified as a potent inhibitor of CYP1A2 with moderate effects on CYP2C19, 2C9, 2D6 and 3A4. CYP1A2 inhibition was reversible and characterised by an IC(50) of 0.56 µM. Inhibition was differential showing mixed (K(i) = 0.48 µM) and competitive (K(i) = 0.31 µM) inhibition with 3-cyano-7-ethoxycoumarin and ethoxyresorufin, respectively. Two binding sites, one for inhibitors and the other for substrates were identified in silico. 4. The potent CYP1A2 inhibition by Frutinone A could be predictive of the potential drug-herb interaction risk in the use of herbal extracts from P. fruticosa. The data suggest future pharmacological research on this chromocoumarin should take metabolic properties into account.
authors.affiliation: Department of DMPK/PD-BAC, African Institute of Biomedical Science & Technology (AIBST), Harare, Zimbabwe.
authors.forename: Roslyn S
authors.initials: RS
authors.lastname: Thelingwani
authors.forename: Kariema
authors.initials: K
authors.lastname: Dhansay
authors.forename: Peter
authors.initials: P
authors.lastname: Smith
authors.forename: Kelly
authors.initials: K
authors.lastname: Chibale
authors.forename: Collen M
authors.initials: CM
authors.lastname: Masimirembwa
mesh_terms: D000890:Anti-Infective Agents / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology*; D020134:Catalytic Domain; D002867:Chromones / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology*; D003374:Coumarins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D015925:Cryopreservation; D019388:Cytochrome P-450 CYP1A2 / Q000378:metabolism; D065609:Cytochrome P-450 CYP1A2 Inhibitors; D004353:Drug Evaluation, Preclinical; D004791:Enzyme Inhibitors / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D007700:Kinetics; D013058:Mass Spectrometry; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D062105:Molecular Docking Simulation; D009570:Nitriles / Q000378:metabolism; D010078:Oxazines / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry*; D031801:Polygala / Q000737:chemistry*; D015203:Reproducibility of Results; D013379:Substrate Specificity / Q000187:drug effects; D013997:Time Factors
chemical_list: D000890:Anti-Infective Agents; D002867:Chromones; D003374:Coumarins; D065609:Cytochrome P-450 CYP1A2 Inhibitors; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D009570:Nitriles; D010078:Oxazines; D010936:Plant Extracts; C581826:frutinone A; C057714:3-cyano-7-ethoxycoumarin; C007649:ethoxyresorufin; D019388:Cytochrome P-450 CYP1A2