title: 7-Ethynylcoumarins: selective inhibitors of human cytochrome P450s 1A1 and 1A2.
abstract: To discover new selective mechanism-based P450 inhibitors, eight 7-ethynylcoumarin derivatives were prepared through a facile two-step synthetic route. Cytochrome P450 activity assays indicated that introduction of functional groups in the backbone of coumarin could enhance the inhibition activities toward P450s 1A1 and 1A2, providing good selectivity against P450s 2A6 and 2B1. The most potent product 7-ethynyl-3,4,8-trimethylcoumarin (7ETMC) showed IC(50) values of 0.46 μM and 0.50 μM for P450s 1A1 and 1A2 in the first six minutes, respectively, and did not show any inhibition activity for P450s 2A6 and 2B1 even at the dose of 50 μM. All of the inhibitors except 7-ethynyl-3-methyl-4-phenylcoumarin (7E3M4PC) showed mechanism-based inhibition of P450s 1A1 and 1A2. In order to explain this mechanistic difference in inhibitory activities, X-ray crystallography data were used to study the difference in conformation between 7E3M4PC and the other compounds studied. Docking simulations indicated that the binding orientations and affinities resulted in different behaviors of the inhibitors on P450 1A2. Specifically, 7E3M4PC with its two-plane structure fits into the P450 1A2's active site cavity with an orientation leading to no reactive binding, causing it to act as a competitive inhibitor.
authors.affiliation: Department of Chemistry, Xavier University of Louisiana, New Orleans, LA 70125, United States.
authors.forename: Jiawang
authors.initials: J
authors.lastname: Liu
authors.forename: Thong T
authors.initials: TT
authors.lastname: Nguyen
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Dupart
authors.forename: Jayalakshmi
authors.initials: J
authors.lastname: Sridhar
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Zhang
authors.forename: Naijue
authors.initials: N
authors.lastname: Zhu
authors.forename: Cheryl L Klein
authors.initials: CL
authors.lastname: Stevens
authors.forename: Maryam
authors.initials: M
authors.lastname: Foroozesh
mesh_terms: D020134:Catalytic Domain; D003374:Coumarins / Q000737:chemistry* / Q000494:pharmacology*; D018360:Crystallography, X-Ray; D019363:Cytochrome P-450 CYP1A1 / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2 / Q000737:chemistry / Q000378:metabolism; D065609:Cytochrome P-450 CYP1A2 Inhibitors; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D008958:Models, Molecular
chemical_list: C409442:7-ethynylcoumarin; D003374:Coumarins; D065609:Cytochrome P-450 CYP1A2 Inhibitors; D004791:Enzyme Inhibitors; D019363:Cytochrome P-450 CYP1A1; D019388:Cytochrome P-450 CYP1A2