Two acetophenone glucosides, cynanonesides A and B, from Cynanchum taiwanianum and revision of the structure for cynandione A

beta-Sitosterol, beta-amyrin, 4-hydroxyacetophenone, 3,4-dihydroxyacetophenone, sitosteryl 3-O-beta-D-glucopyranoside, cynandione A, and cynanonesides A (3) and B (4) were isolated from the roots of Cynanchum taiwanianum. The latter two compounds are new acetophenone glucosides, and their structures were elucidated on the basis of spectral and chemical evidence. Meanwhile, the structure of cynandione A, previously designated as 3',4-diacetyl-2,2',3,6'-tetrahydroxybiphenyl, has been revised as 2,3'-diacetyl-2',3,6,6'-tetrahydroxybiphenyl (9).