Calmodulin discriminates between the two enantiomers of the receptor‐operated calcium channel blocker sk&f 96365: A study using ¹H‐NMR and chiral HPLC

Abstract

1H nuclear magnetic resonance at 360 MHz shows that SK&F 96365 (1-(beta-[3-(p-methoxyphenyl)-propyloxy]-p-methoxyphenethyl)-1H- imidazole hydrochloride), an antagonist of mammalian receptor-operated calcium channels, interacts with the calcium-binding regulatory protein calmodulin (CaM). This may be inferred by a number of chemical shift changes in the spectrum of the calcium-saturated protein induced by addition of the compound. Moreover, two well-resolved singlets corresponding to the 2-proton of the SK&F 96365 imidazolium moiety are observed in the spectrum over a wide range of protein:compound ratios. Separation of rac SK&F 96365 into its two enantiomers by high-performance liquid chromatography on a cellulose tris (4-methylbenzoate) column enabled us to show that the doubling of this NMR signal in the presence of CaM is due to a propensity of the protein to distinguish between the two optical isomers of the compound.

A Convenient Four-Step Synthesis of 1-{β-[3-(4-Methoxy-phenyl)Propoxy]-4-Methoxyphenethyl}-1H-Imidazole Hydrochloride as a Probing Tool for SOCE Assays

“…Compound 7 was prepared with an overall yield of 9%. The structure of 7 was confirmed by 1 H-NMR, and the data were in agreement with those previously described in literature [12]. 13 C-NMR, HRMS, and elemental analysis of 7 completed the data and are in accordance with this structure.…”

“…However, SKF-96365 is still used as a tool for the probing of receptor-mediated Ca 2+ entry processes, particularly in non-excitable cells [9][10][11]. To our surprise, the synthesis of SKF-96365 was not patented or not detailed in academic literature, but it is interesting to note that the enantiomers has been subjected to a chiral high pressure liquid chromatography (HPLC) study [12]. In this context and due to the recent interest of SKF-96365 for their anticancer effect in a mouse xenograph model [13], we developed efforts on a complete and detailed preparation of 1-{β-[3-(4-methoxy-phenyl)propoxy]-4-methoxyphenethyl}-1H-imidazole hydrochloride.…”

Inhibition by SK&F 96365 of Ca2+ current, IL‐2 production and activation in T lymphocytes

“…By repol-Additional suggestion that SK&F 96365 may inhibit Ca2m potential for channels by indirect means is provided by the observation nels may main-that this drug interacts with the Ca2l binding regulatory le of K+ chan-protein calmodulin as measured by 'H-nuclear magnetic Lssociated with resonance (n.m.r.) (Reid et al, 1990). Since calmodulin )ry to the Ca2"…”