Multisubstrate inhibitors of dopamine .beta.-hydroxylase. 2. Structure-activity relationships at the phenethylamine binding site
摘要:
1-Aralkylimidazole-2-thiones have been shown to be potent multisubstrate inhibitors of dopamine beta-hydroxylase (DBH; EC 1.14.17.1). In the present study, a series of 1-benzylimidazole-2-thiones was prepared to explore the effects of substitution in the benzyl ring on the inhibition of DBH. A detailed structure-activity relationship for in vitro activity was discovered and this was shown by a modified Hansch analysis to correlate (r = 0.91) with four key structural features of the benzyl ring: the presence of a hydroxyl at the 4-position, molar refractivity at the 3-, 4-, and 5-positions, inductive effects of the substituents at the 3-, 4-, and 5-positions, and pi-electron density. The affinity (Kis) of eight substituted inhibitors for DBH was shown to correlate (r = 0.75) with the affinity (KD) of comparably substituted tyramines for the ternary DBH-oxygen-tyramine complex. This correlate is used to support the hypothesis that binding of inhibitor to DBH occurs in a fashion that mimics the binding of tyramine substrates. The most potent inhibitors were selected for study in vivo in the spontaneously hypertensive rat model of hypertension. The changes in vascular dopamine and norepinephrine levels that resulted from oral administration of the inhibitors corresponded to the observed reduction in mean arterial blood pressure. A divergence between in vitro potency and in vivo efficacy upon oral dosing was noted and is suggested to result from an in vivo metabolic conjugation of the phenolic group of inhibitor.
Nucleophilic Trifluoromethylation of Imines under Acidic Conditions
作者:Vitalij V. Levin、Alexander D. Dilman、Pavel A. Belyakov、Marina I. Struchkova、Vladimir A. Tartakovsky
DOI:10.1002/ejoc.200800820
日期:2008.11
A general method for the trifluoromethylation of imines by using Me3SiCF3 under acidic conditions is described. The reaction is promoted by hydrofluoric acid generated in situ from KHF2 and either TFA or TfOH. A new chemoselectivity pattern was achieved, as the C=N bond was found to be more reactivate than the carbonyl group. The trifluoromethylation reaction is believed to proceed by concerted transfer
Multisubstrate inhibitors of dopamine .beta.-hydroxylase. 1. Some 1-phenyl and 1-phenyl-bridged derivatives of imidazole-2-thione
作者:Lawrence I. Kruse、Carl Kaiser、Walter E. DeWolf、James S. Frazee、Eleanor Garvey、Eileen L. Hilbert、Wayne A. Faulkner、Kathryn E. Flaim、John L. Sawyer、Barry A. Berkowitz
DOI:10.1021/jm00162a008
日期:1986.12
The synthesis and characterization of some 1-(phenylalkyl)imidazole-2-thiones as a novel class of "multisubstrate" inhibitors of dopamine beta-hydroxylase (DBH) are described. These inhibitors incorporate structural features that resemble both tyramine and oxygen substrates, and as evidenced by steady-state kinetics, they appear to bind both the phenethylamine binding site and the active site copper atom(s) in DBH. A series of structural congeners that incorporate different bridging chain lengths between the phenyl ring (dopamine mimic) and the imidazole-2-thione group (oxygen mimic) define the optimum distance for inhibitory potency and the likely intersite distance in the DBH active site. Additional bridging analogues were prepared to determine the active site bulk tolerance and the effects of heteroatom replacement.