Synthesis and biological activity of novel 2-(α- alkoxyimino)benzylpyridine derivatives as K+ channel openers

Article abstract of DOI:10.1248/cpb.45.1994

The search for novel K⁺ channel openers with a non-benzopyran skeleton, unlike cromakalim, led to the discovery of a new series of (Z)-2-(α- alkoxyimino)benzylpyridine derivatives. Synthesis was achieved by using a (Z)-dominant condensation reaction of henzoylpyridines with O- alkylhydroxylamines, followed by m-chloroperhenzoic acid (m-CPBA) oxidation. The compounds were tested for their vasorelaxant activity in tetraethylammonium chloride (TEA) and BaCl₂- and high KCl-induced contraction of rat aorta to identify potential K⁺ channel openers, and also for their effects on the coronary blood flow (CBF) after intracoronary injection in anesthetized dogs. A large number of the 2-(α- alkoxyimino)benzylpyridines strongly inhibited TEA and BaCl₂-induced contraction, had no effect on 80 mM KCl-induced contraction, and increased the CBF to more than 200% of the basal flow at 10-30μg/dog. In particular, (Z)-2-[5-bromo-α-(tert-butoxyimino)-4-fluoro-2-hydroxybenzyl]-3- hydroxypyridine 1-oxide (7d) showed highly potent vasorelaxant activity (EC₅₀=0.28μM) comparable to that of levcromakalim (EC₅₀=0.17 μM), and gave a significantly longer-lasting increase (T ( 1/4 ) = 30 min) in the CBF compared to levcromakalim, nicorandil, nitroglycerin, or diltiazem (T( 1/4 )=5.2, 0.9, 0.4, and 2.2 min, respectively). It also exhibited a stable and long-lasting hypotensive effect (over 7h) upon oral administration of 1 mg/kg in spontaneously hypertensive rats (SHRs).

Full text of DOI:10.1248/cpb.45.1994

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