Constituents of flowers of Paeoniaceae plants, Paeonia suffruticosa and Paeonia lactiflora

A new monoterpene glycoside, floralalbiflorin I (1), and a new flavonol glycoside, lactifloraoside I (2), were isolated from the flowers of Paeonia suffruticosa and Paeonia lactiflora (Paeoniaceae) together with 28 known compounds. The chemical structures of the isolated compounds were elucidated on the basis of chemical and physicochemical evidence. Among the major constituents of P. suffruticosa and P. lactiflora flowers, 1,2,3,4,6-penta-O-galloyl-β-d-glucopyranoside (10) [inhibition: 42.4% at 1 μM] and flavonoids having the catechol moiety showed significant inhibitory effect on Cu2+-induced low-density lipoprotein (LDL) oxidation.