Flavonol Triglycosides from the Leaves of Silphium Albiflorum

In the course of chemotaxonomic studies of the genus Silphium two new and six known flavonol glycosides were isolated from the leaves of S. albiflorum. The structures of the new flavonoids were established by spectral analysis (1H NMR, 13C NMR, HMQC, HMBC, ROESY, TOCSY, MS) as isorhamnetin 3-O-α-L-rhamnosyl (1′“→6″)-O-β-D-galactopyranoside 7-O-β-D-apiofuranoside (1) and quercetin 3-O-α-L-rhamnosyl (1′“→6″)-O-β-D-galactopyranoside 7-O-β-D-apiofuranoside (2). LC-MS and LC-MSn (with post-column manganese complexation) were applied to elucidate the structures of some of the studied compounds.