Three new phenylethanoid glycosides from Caryopteris incana and their antioxidative activity

Three new phenylethanoid glycosides, incanoside C, incanoside D and incanoside E were isolated together with one known glycoside, beta-D-fructofuranosyl-alpha-D-(6-O-[E]-sinapoyl) glucopyranoside from the whole plant of Caryopteris incana (THUNB.) Miq. On the basis of chemical and spectral analyses, the structures of the new compounds were elucidated to be 1-O-(3,4-dihydroxyphenyl)ethyl-O-beta-D-glucopyranosyl(1-->2)-alpha-L- rhamnopyranosyl(1-->3)-4-O-feruloyl-beta-D-glucopyranoside (incanoside C), 1-O-(3-hydroxy-4-methoxyphenyl)ethyl-O-beta-D-glucopyranosyl(1-->2)-alph a-L- rhamnopyranosyl(1-->3)-4-O-feruloyl-beta-D-glucopyranoside (incanoside D) and 1-O-(3methoxy-4-hydroxyphenyl)ethyl-O-beta-D-glucopyranosyl(1-->2) -alpha-L- rhamnopyranosyl(l-->3)-4-O-feruloyl-beta-D-glucopyranoside (incanoside E). The three new phenylethanoid glycosides exhibited radical scavenging activities against DPPH radical and inhibitory activities against the oxidation of linoleic acid.