In order to isolate and purify the reference compounds and improve the quality standard of ethnic medicine of Radix of Cynanchum otophyllum, the ethanol extracts were isolated by column chromatography onsilica gel, C₁₈ reverse-phase silica gel, and semi-preparative HPLC. Twelve compounds were isolated and their structures were elucidated as 2,4-dihydroxy-6-methoxyphenylethanone(1), 4,6-dihydroxy-2-methoxyphenylethanone(2), p-hydroxyacetophenone(3), baishouwubenzophenone(4), 2,4-dihydroxyacetophenone(5), 2,5-dihydroxyacetophenone(6), otophylloside A(7),otophylloside B(8), caudatin-3-O-β-D-cymaropyranosyl-(1→4)-β-D-digitoxopyranoside(9),caudatin-3-O-β-D-glucopyranosyl-(1→4)-β-D-oleandropyranosyl-(1→4)-β-D-cymaropyranosyl-(1→4)-β-D-digitoxopyranoside(10),qingyangshengenin-3-O-β-D-oleandropyranosyl-(1→4)-β-D-cymaropyranoside(11),caudatin-3-O-β-D-oleandropyranosyl-(1→4)-β-D-cymaropyranosyl-(1→4)-β-D-cymaropyranoside(12) on the basis of spectral analysis. Compounds 1 and 2 were isolated from the genus Cynanchum for the first time, and compounds 3-4, 9-12 were obtained from this plant for the first time.These compounds are main active components of Radix of C.otophyllum and can be used as reference substances for the quality control of this ethnic medicine.
Keywords: C21 steroid glycosides; Cynanchum; Cynanchum otophyllum; acetophenones; chemical constituents.
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