title: Enantioselectivity of some 1-[(benzofuran-2-yl) phenylmethyl] imidazoles as aromatase (P450AROM) inhibitors.
abstract: The enantioselectivity ratio ((+)-:(-)-forms) of three substituted 1-[(benzofuran-2-yl) phenylmethyl] imidazoles as inhibitors of aromatase (P450AROM) was 2.16, 12.3 and 1.0 for the 4-methyl-, 4-fluoro- and 4-chloro-substituted compounds, respectively. The (+/-)-compounds were all >1000 times more potent than (+/-)-aminoglutethimide (IC50 = 12 x 10(3) nM). High potency (5.3-65.0 nM) for all the enantiomers studied is unusual since activity usually resides in one form for chiral inhibitors of P450AROM. The 4-methyl derivative was fitted into the model [Furet, P., Batzl, C., Bhatnager, A.S., Francotte, E., Rihs, G. and Lang, M. (1993) J. Med. Chem. 36, pp. 1393-1400] for binding of S-(-)-fadrazole to the active site and the (R)- and (S)- forms both gave a good fitting pattern with (S)-(-)-fadrazole so accounting for their close activity. Docking of both forms into the active site model for P450AROM [Laughton, C.A., Zvelebil, M.J.J.M. and Neidel, S. (1993) J. Steroid Biochem. Mol. Biol. 44, pp. 399-407], using the orientation of (S)-(-)-fadrazole, gave similar strong binding along the position of the C and D rings of the steroid substrate and in the hydrophobic cavity below the A/B rings. The site was probed for group size accommodation using the less potent 4-phenyl analogue (IC50(+/-) = 242 nM): the (S)-form showed restricted access to the region under the A ring due to the extended bulk of the biphenyl group.
authors.affiliation: The Welsh School of Pharmacy, Cardiff University, UK.
authors.forename: G A
authors.initials: GA
authors.lastname: Khodarahmi
authors.forename: C A
authors.initials: CA
authors.lastname: Laughton
authors.forename: H J
authors.initials: HJ
authors.lastname: Smith
authors.forename: P J
authors.initials: PJ
authors.lastname: Nicholls
mesh_terms: D000818:Animals; D001141:Aromatase / Q000378:metabolism; D047072:Aromatase Inhibitors; D001665:Binding Sites; D003198:Computer Simulation; D017316:Fadrozole / Q000737:chemistry; D006801:Humans; D007093:Imidazoles / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D011485:Protein Binding; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: D047072:Aromatase Inhibitors; D007093:Imidazoles; D001141:Aromatase; D017316:Fadrozole