New acylated flavonol diglycosides of Cynanchum acutum

Abstract

Three new acylated flavonol diglycosides that were characterized as quercetin 3-O-(6'"-O-E-isoferuloyl)-sophoroside (1), quercetin 3-O-(6‴-O-Z-isoferuloyl)-sophoroside (2) and quercetin 3-O-[2″-O-(E-6‴-O-isoferuloyl)-β-D-glucopyranosyl] -β-Dgalactopyranoside (3), along with twelve known metabolites, have been isolated from the leaves of Cynanchum acutum L. The latter were identified as quercetin 3-O-β-D-neohesperidoside (4), rutin (5), quercetin 3-O-sophoroside (6), kaempferol 3-O-β-Drutinoside (7), quercitrin (8), isoquercitrin (9), hyperin (10), guaijaverin (11), quercetin 7-O-β-D-glucopyranoside (12), quercetin (13), scopoletin (14) and (E)-3-(3,4-dihydroxyphenyl)-propenoic acid (15). All metabolites have been isolated for the first time from the genus Cynanchum, except for 9 and 14. The structures were determined on the basis of chromatographic behavior, acid hydrolysis, chemical and physicochemical evidence (UV, HRESI-MS/MSn, 1H, 13C NMR, 1H-1H COSY, HSQC and HMBC). The chloroform extract and compounds 8 and 10 exhibited lethal effects towards brine shrimp, Artemia salina.