Two new monoterpene lactones from Ligularia rumicifolia (J.R.Drumm.) S.W.Liu and their anti-proliferative activities

A phytochemical study of the EtOAc extract of Ligularia rumicifolia (J.R.Drumm.) S.W.Liu led to the isolation of two new monoterpene lactones (1-2) named (2S,3S,5R)-5-ethyl-2,3-dimethyl-6-oxoterahydro-2H-pyran-2-carboxylic acid and (2S,3S,5R)-5-ethyl-2,3-dimethyl-6-oxoterahydro-2H-pyran-2-carboxylic acid methyl ester, along with nine known compounds (3-11). All compounds were isolated from this species for the first time. Their structures were...