benzofurans nor-sesquiterpenoids from petasites hybridus rhizomes and absolute configuration by circular dichroism

Petasites hybridus (l.) g.gaertn., b.mey. & scherb. has been used as a medicine for different illnesses. a phytochemical study on hexane extract has been carried out using normal phase silica gel column and rp-hplc chromatography. five sesquiterpenoids were isolated, purified, and identified from hexane extract. the structures were elucidated by applying extensive 1d and 2d nmr and hresi-tofms spectroscopy. in addition, circular dichroism (cd) spectra were applied to determine absolute configurations of constituents. two never described benzofuran nor-sesquiterpenes (2s,3s)-5’-acetyl-(z)-3-(acetoxymethyl) but-2-enoate tremetone) (4) and (2r,3r)-5’-acetyl-(z)-3-(acetoxymethyl) but-2-enoate-7-hydroxytremetone (5) as well as euparin (1), (2s,3r)-3,6-dihydroxytremetone (2), and (2s,3s)-3,6-dihydroxytremetone (3) were isolated from the rhizome of petasites hybridus, a species in flora of iran. also, the euparin content of the meoh extracts of seven populations of iran was measured by hplc-pda. notably, isolated euparin was the main constituent of iranian p. hybridus varying between 2.7 and 9.7 μg/mg among samples.