Constituents of Chinese Crude Drug “Wujiapi.” V. On the Structure of Glycoside H1 of Bei-Wujiapi

The chemical structure of glycoside H1 (I), C56H90O24, mp 182°, [α]24D-22. 83°(EtOH), which was isolated from Bei-Wujiapi (cortex of Periploca sepittm BGE.), was established to be Δ5-pregnene-3β, 20α-diol (3)-[2-O-acetyl-β-D-digitalopyranosyl (1dig→4cym)-β-D-cymaropyranoside](20)-[β-D-glucopyranosyl (1glu→6glu)-β-D-glucopyranosyl (1glu→2dig)-β-D-digitalopyranoside].It should be noted that glycoside H1 is the first example of the pregnane type glycoside whose sugar moiety links to both C-3 and C-20 hydroxyl groups of the aglycone and that the sugar sequences of Asclepiadaceous glycosides are ruled by certain regularity, such as aglycone-(2, 6-dideoxysugar or its 3-O-methyl derivative) 0-l-(6-deoxysugar or its 3-Omethyl derivatives) o_m-(glucose) o-n.