Paeonianins A-E, new dimeric and monomeric ellagitannins from the fruits of Paeonia lactiflora.

Four new dimeric ellagitannins, paeonianins A-D (2-5), were isolated from the fruits of Paeonia lactiflora, together with a new ellagitannin monomer, paeonianin E (1). Their structures were determined by spectroscopic methods. Paeonianins A-D (2-5) are positional isomers formed by condensation of pentagalloyl-beta-D-glucose (8) with 5-desgalloylstachyurin (6) or casuariin (7). Paeonianin E is a C-glycosidic ellagitannin having a gallic acid methyl ester moiety at the glucose C-1 position. This is the first report of the isolation of dimeric ellagitannins from a plant in the family Paeoniaceae.