New monoterpene glycoside esters and phenolic constituents of Paeoniae radix, and increase of water solubility of proanthocyanidins in the presence of paeoniflorin.

Seven new monoterpene glycoside esters related to paeoniflorin were isolated from Paeoniae Radix, together with polymeric proanthocyanidins, polygalloylglucoses and 48 known compounds (a benzoylsucrose, seven aromatic acids, adenosine, nine monoterpene glycosides, eight flavan-3-ols, a catechin dimer formed by oxidation, seven proanthocyanidins, three galloylsucroses, five galloylglucoses, and six ellagitannins). The structures of the new compounds were determined by spectral investigation including two-dimensional NMR techniques. In addition, increased water solubility of polymeric proanthocyanidin in the presence of paeoniflorin was examined by n-octanol-water partition and 1H-NMR spectral experiments.