Isoswertiajaponin 2′’-O-β-arabinopyranoside and other flavone-C-glycosides from the Antarctic grass Deschampsia antarctica
The major flavonoid constituents of the Antarctic grass, Deschampsia antarctica, are shown to be the C-glycosylflavones, isoswertiajaponin (7-O-methylorientin) 2′'-O-β-arabinopyranoside and orientin. These are accompanied by lower levels of orientin 2′'-O-arabinopyranoside, isoswertisin (7-O-methylvitexin) 2′'-O-β-arabinopyranoside, acylated derivatives, isoswertisin, isoswertiajaponin and tricin. A preliminary study suggests that the overall level of flavonoids in Deschampsia increases during the Antarctic mid-summer.