Cardiac glycoside-like structure and function of 5.beta.,14.beta.-pregnanes

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Abstract
5.beta.-Reduction and 14.beta.-substitution convert the planar progesterone molecule to the cardiac glycoside configuration.sbd.A and D rings of the steroid moiety are bent toward the .alpha.-face relative to the B and C rings. Potency of the 5.beta.,14.beta.-derivative in a [3H]ouabain binding assay or its ability to inhibit the sodium pump in red blood cells is enhanced by 3.beta.-hydroxylation, 20.beta.-hydroxylation, and 3.beta.-glycosidation. Synthesis of 14,20.beta.-dihydroxy-3.beta.-(.beta.-D-glucopyranosyloxy)-5.beta.,14.beta.-pregnane from digitoxin is described. The glucoside is 1/20 as potent as ouabain and elicits prominent, sustained, positive inotropy in isolated cardiac muscle.