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

The current review outlines the distribution of flavonoids and phenolic acids in eleven species of Silphium (Asteraceae). The chemosystematic significance of these findings is discussed and compared with DNA and morphological-based assignments for eleven species. Special attention is given to the five flavonol triglycosides that were previously isolated and characterized from Silphium species: isorhamnetin 3-O-alpha-L-rhamnosyl (1""-->6")-O-beta-D-galactopyranoside 7-O-beta-L-apiofuranoside (1), quercetin 3-O-alpha-L-rhamnosyl (1"'-->6")-O-beta-D-galactopyranoside 7-O-beta-L-apiofuranoside (2), quercetin 3-O-beta-L-galactosyl (1"'-->6")-O-beta-D-rhamnopyranoside 7-O-alpha-L-apiofuranoside (3), kaempferol 3-O-beta-D-apiofuranoside 7-O-alpha-L-rhamnosyl (1""-6"')-O-beta-D-galactopyranoside (4) and kaempferol 3-O-beta-D-apiofuranoside 7-O-alpha-L-rhamnosyl (1""-->6"')-O-beta-D (2"'-O-E-caffeoylgalactopyranoside) (5). In addition, several other known mono and diglycosidic flavonoids, along with 18 phenolic acids, were also identified and the structures of all of the compounds were established by LC/MS and NMR spectral investigations.

Constituents of Chrysothamnus viscidiflorus.

A phytochemical investigation of the aerial parts of Chrysothamnus viscidiflorus var. viscidiflorus afforded three new [chrysothol (1), 2 and 4] and seven known compounds, including five sesquiterpenes, two cinnamic acid derivatives, two ketoalcohol derivatives and one coumarin glucoside. The structures of two previously reported compounds, 1b and 1c, were revised on the basis of chemical reaction. Structures of the compounds were determined by extensive NMR studies, including DEPT, COSY, NOE, HMQC, HMBC and X-ray analysis. The unpublished X-ray data of the known compounds 6 and 7 are reported. Compounds chrysothol (1), and 8-10 showed anti-cancer activity against human breast cancer cells.

Sylviside, a diterpene glucoside derivative from Gnaphalium sylvaticum.

A new diterpene glucoside (1), named sylviside, was isolated from the aerial parts of Gnaphalium sylvaticum. Its structure was elucidated as 2beta,15alpha,20alpha-trihydroxy-19,20-dicarboxy-ent-kaur-16-ene 2beta-O-(2'-angelate)-beta-D-glucopyranoside, on the basis of spectroscopic analysis ((1)H NMR, (13)C NMR, HMQC, HMBC, NOESY), and was confirmed by X-ray crystallographic analysis. Sylviside (1) displayed weak cytotoxicity against HeLa WT (human epitheloid cervical carcinoma) cells and was also evaluated for its effects on reversing multidrug resistance in HeLa cells overexpressing MDR1.

Nor-ent-kaurane diterpenes and hydroxylactones from Antennaria geyeri and Anaphalis margaritacea.

In a study of Pacific Northwest plants of the Asteraceae family, a nor-ent-kaurane diterpene and a known diterpene, both displaying antibacterial activities, were isolated together with scopoletin and sitosterol-3-O-beta-glucopyranoside from the aerial parts of Antennaria geyeri. Anaphalis margaritacea afforded two hydroxylactones. The structures were established by one and two dimensional NMR techniques, IR and CIMS.

Kaempferol triosides from Silphium perfoliatum.

Two apiose-containing kaempferol triosides, together with nine known flavonoids were isolated from the leaves of Silphium perfoliatum L. Their structures were elucidated by acid hydrolysis and spectroscopic methods including UV, LSI MS, FAB MS, CI MS, (1)H, (13)C and 2D-NMR, DEPT, HMQC and HMBC experiments. The two new compounds were identified as kaempferol 3-O-beta-D-apiofuranoside 7-O-alpha-L-rhamnosyl-(1""-->6"')-O-beta-D-galactopyranoside and kaempferol 3-O-beta-D-apiofuranoside 7-O-alpha-L-rhamnosyl-(1''''--> 6"')-O-beta-D (2"'-O-E-caffeoylgalactopyranoside).