Discovery of N-(3-{4-[(3-Fluorobenzyl)oxy]phenoxy}propyl)-2-pyridin-4-ylacetamide as a Potent and Selective Reverse NCX Inhibitor

Abstract

Intracellular Ca2ϩ is of primary importance in the pathogenesis of ischemia and reperfusion injury in the myocardium. Recent studies have suggested that a massive Ca 2ϩ influx may occur as a consequence of Na ϩ -Ca 2ϩ exchange via the sodium-calcium exchanger (NCX) during reperfusion which, in turn, may be caused by an accumulation of Na ϩ via the sodium-hydrogen exchanger (NHE) during ischemia. 1,2)This results in an intracellular Ca 2ϩ overload, the detrimental effects of which include myocardial contracture, stunning, necrosis, and reperfusion arrhythmia.3-9) NCX functions in both reverse and forward modes, and it is well known that an overactive reverse NCX causes Ca 2ϩ overload. Inhibition of reverse NCX overactivity would effectively block this overload and prevent damage to the myocardium in ischemiareperfusion. Therefore, reverse NCX inhibitors are currently considered to be beneficial in treating disease states.10,11) Recently, quinazoline derivatives 12) and a series of benzyloxyphenyl derivatives [13][14][15][16] have been identified as NCX inhibitors. KB-R7943 (1) is one of the most widely known NCX inhibitors, and is used as a tool in heart and renal failure models, 17,18) and SEA0400 (2) is well known as a potent reverse NCX inhibitor that is efficacious in myocardial ischemia-reperfusion injury [19][20][21][22] (Fig. 1). We have recently discovered reverse NCX inhibitors, such as 3, which we have reported elesewhere. 16,23,24) To create potent and selective reverse NCX inhibitors, we have now designed a novel class of NCX inhibitors based on 3, and in this paper describe the results of our work on the synthesis and structure-activity relationships (SAR) of this novel class of benzyloxyphenyl derivatives. ChemistryCompounds 4a-e were converted into compounds 5a-e via O-alkylation with 1-(bromomethyl)-3-fluorobenzene. Desired compounds 6a-e were prepared from 5a-e by condensation with pyridin-4-ylmethylamine as shown in Chart 1. Intermediate 4e was synthesized from 7 via S-alkylation with the corresponding alkylbromide. Compounds 9a-c were obtained by O-alkylation of 8 15) with the corresponding alkylbromides followed by hydrolysis of the ester group. Compounds 10a-c were afforded by condensation with 9a-c and pyridin-4-ylmethylamine. Compound 8 was converted into a compound whose amino group was protected with a phthaloyl group, followed by deprotection of the phthaloyl group with hydrazine to give compound 11. Compound 12 was afforded via condensation of 11 with pyridin-4-ylacetic acid. Compound 13 was prepared by O-alkylation of 8 with tert-butyl(2-bromoethyl)carbamate followed by deprotection of the tert-butoxycarbonyl group. Desired compound 14 was obtained from 8 via condensation with bis(trichloromethyl)carbonate and pyridin-4-ylmethylamine. Results and DiscussionIn order to measure the inhibitory effect of the synthesized compounds on the reverse mode of NCX activity, an Na ϩ -dependent Ca 2ϩ influx assay was performed according to reported protocols, using 45 Ca and CCL39 cells stably expr...

Inhibition of β-Cell Sodium-Calcium Exchange Enhances Glucose-Dependent Elevations in Cytoplasmic Calcium and Insulin Secretion

“…The general consensus is that NCX1 inhibitors preferentially inhibit the inactivating Ca 2+ influx mode (RM) compared with the Ca 2+ efflux mode (FM) (13,15–18) that displays no inactivation. We have recently reported that, in contrast to the cardiac NCX1.1 splice variant, β-cell NCX1 splice variants (NCX1.3 and -1.7) exhibit significant inactivation during FM operation (Fig.…”

“…Thus, the identification of drugs with a greater selectivity for NCX1 inhibition over other ion transport pathways in the β-cell is a necessary first step in the advancement of β-cell NCX1 splice variants as novel therapeutic targets. In this latter regard, newer NCX inhibitors with a reported greater selectivity for NCX1 over other ion transport processes are in development for cardiovascular disease, and these inhibitors may also warrant further investigation for their splice variant selectivity and insulinotropic efficacy (13,15–18). …”

“…In this regard, pharmacological inhibitors have been developed as putative cardioprotective agents to reduce RM NCX1 activity and ameliorate the deleterious Ca 2+ c overload in cardiac tissue (12–14). While such NCX inhibitors favor pathophysiological cardiac RM NCX1 inhibition (13,15–18), their effects on the physiological Ca 2+ c extrusion via FM NCX1 activity in β-cells have not been determined. Theoretically, partial pharmacological inhibition of FM NCX1 activity in β-cells should delay Ca 2+ c clearance, leading to an increased Ca 2+ c exocytotic signal and enhanced insulin secretion that is sensitive to glucose.…”

Racemic total synthesis of dactyloidin and demethyldactyloidin through the dl-proline-catalyzed Knoevenagel condensation/[4 + 2] cycloaddition cascade

“…The deprotection of the methyl group of 16 was realized in 40% HBr Scheme 3. a) AlCl 3 (2.5 equiv), glutaric anhydride (1.0 equiv), anisole (excess), PhNO 2 , 100 o C, 3 h; b) H 2 (1 atm), Pd/C (10%), EtOH, rt, 12 h; c) 40% HBr, reflux, 12 h; d) H 2 SO 4 (1 drop/50 mL), EtOH, rt, 12 h; e) NaH (2.0 equiv), MOMCl (1.5 equiv), TBAB (0.06 equiv), THF, rt, 6 h; f) LiAlH 4 (1.0 equiv), THF, 0 °C to rt, 1 h; g) (COCl) 2 (2.0 equiv), DMSO (4.0 equiv), Et 3 N (8.0 equiv), CH 2 Cl 2 , -78 o C to rt, 15 min. aqueous according to the green procedure reported by Merschaert and co-workers [10] , and provided the desired product 17 with 95% yield after reflux for 12 h. Further esterification of 17 was promoted under sulfuric acid catalyzed condition and generated the known ester 18 [11] in 92% yield. The resulting phenol 18 was then subjected to MOM protection, LiAlH 4 reduction and Swern oxidation consequently to give targeted aldehyde 11 with 86% yield over 3 steps.…”

“…1 H NMR (300 MHz, CDCl 3 ): δ = 7.10 (d, J = 8.7 Hz, 2 H), 6.96 (dd, J = 8.7 Hz, J = 2.0 Hz, 2 H), 5.16 (s, 2 H), 3.64 (t, J = 6.6 Hz, 2 H), 2.58 (t, J = 7.6 Hz, 2 H), 1.62 (m, 4 H), 1.41 (m, 2 H); 13 C NMR (75 MHz, CDCl 3 ): δ = 155. 3, 136.0, 129.3, 116.2, 94.6, 62.9, 55.9, 35.0, 32.6, 31.4, 25.3 (11). To a solution of oxalyl chloride (5.1 g, 40 mmol) in CH 2 Cl 2 (100 mL) was added a solution of DMSO (6.0 mL, 80 mmol) in CH 2 Cl 2 (6.0 mL) dropwise over 10 min at −78 °C.…”