The flavonoids and phenolic acids of the genus Silphium and their chemosystematic and medicinal value

My chemistry studies of the genus Silphium involved the flavonoids and phenolic acids among eleven species. In the course of these investigations, five new flavonol triglycosides were isolated and characterized: isorhamnetin 3-O-α-L-rhamnosyl (1'''→6'')- O-β-D-galactopyranoside 7-O-β-L-apiofuranoside (1A), quercetin 3-O-α-L-rhamnosyl (1'''→6'')-O-β-D-galactopyranoside 7-O-β-L-apiofuranoside (2A), quercetin 3-O-β-Lgalactosyl (1'''→6'')-O-β-D-rhamnopyranoside 7-O-α-L-apiofuranoside (3A), kaempferol 3-O-β-D-apiofuranoside 7-O-α-L-rhamnosyl (1''''→6''')-O-β-D-galactopyranoside (4A) and kaempferol 3-O-β-D-apiofuranoside 7-O-α-L-rhamnosyl (1''''→6''')-O-β-D (2'''-O-E- caffeoylgalactopyranoside) (5A). Many other known mono and diglycosidic flavonoids were also isolated and identified. The structures of all these compounds were established by chemical methods and spectral analyses using 1 H NMR, 13C NMR, HMQC, HMBC, ROESY, TOCSY and LC/MS techniques. The distribution of the flavonoids and phenolic acids in all eleven members were compared with Dr. Jennifer Clevinger’s DNA-based revision of the genus. In addition to the detailed chemical investigations, I present my evaluations of the chemosystematic and medicinal value of the compounds I characterized; moreover, the new flavonoids are now being made available for medicinal and pharmaceutical studies.