Studies on cardiac ingredients of plants. XI. synthesis of new bufotoxin homologues utilizing scillarenin (the genuine aglycone of proscillaridin), and their biological activities

Article abstract of DOI:10.1248/cpb.42.2256

New bufotoxin homologues (3) with various lengths of alkyl chain including longer ones thana suberoyl group at C-3 of the steroid nucleus were prepared from proscillaridin (1) via its genuine aglycone, scillarenin (2), in excellent yield. In the course of preparation, we established conditions for efficient enzymatic glycolysis of 1 to give 2 quantitatively. The pharmacological activities of the resulting bufotoxin homologues (3) were evaluated by measurement of the effect on smooth muscle using the mesenteric artery from spontaneously hypertensive rats, inhibitory: effect on Na⁺, K⁺-adenosine triphosphatase (ATPase) prepared from dog kidney, and positive inotropic effect (PIE) on isolated guinea-pig papillary muscle preparations; The bufotoxin homologues (3) showed only slight contraction of vascular muscle followed by a small-relaxation,in addition to the high Na⁺, K⁺-ATPase inhibitory activity and PIE comparable to those of clinically used ouabain, digoxin, and digitoxin. Those bufotoxin homologues (3) may be useful as cardiac agents with a minimal vascular contractile effect.

Full text of DOI:10.1248/cpb.42.2256

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