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

Abstract

The chemical structure of glycoside H₁ (I), C₅₆H₉₀O₂₄, mp 182°, [α]²⁴_D-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 (1_dig→4_cym)-β-D-cymaropyranoside](20)-[β-D-glucopyranosyl (1_glu→6_glu)-β-D-glucopyranosyl (1_glu→2_dig)-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.