Acylated flavonol glycosides from Larix needles

Abstract

Kaempferol-3-p-coumarylglucoside (KCG) was isolated from ether fractions of acetone-extracted freeze-dried needles of all larch species investigated. In each case, KCG was found as one of the main flavonoids, whereas often a variety of closely related, acylated flavonoids was present in either low to very low concentration. For example, the KCG complex of L. leptolepis needles on alkaline hydrolysis produced traces of ferulic acid besides p-coumaric acid, indicating the possible presence of a kaempferol- 3-ferulylglycoside (KFG). Because of the low concentration, KFG could not be isolated from L. leptolepis needles, but was obtained from L. decidua, a species with lower concentrations of KCG. Freeze-dried needles of L. decidua were KCA. Traces of KCA were also found in needles extracted with 70% EtOH; chlorophyll etc. was of L. laricina. removed with CCl₄, and the extract was separated on a polyamide column and on paper. In addition to KCG, 4 new acylated glycosides were isolated and identified by standard methods as: the 3- ferulylglucosides of kaempferol, quercetin, iso- rhamnetin and syringetin. A fifth compound could not be completely freed from KCG, but was iden- tified as kaempferol-3-p-coumarylarabinoside-KCA. Traces of KCA were also found in needles of L. Laricina.