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, β-D-fructofuranosyl-α-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-β-D-glucopyranosyl(1→2)-α-L-rhamnopyranosyl(1→3)-4-O-feruloyl-β-D-glucopyranoside (incanoside C), 1-O-(3-hydroxy-4-methoxyphenyl)ethyl-O-β-D-glucopyranosyl(1→2)-α-L-rhamnopyranosyl(1→3)-4-O-feruloyl-β-D-glucopyranoside (incanoside D) and 1-O-(3-methoxy-4-hydroxyphenyl)ethyl-O-β-D-glucopyranosyl(1→2)-α-L-rhamnopyranosyl(1→3)-4-O-feruloyl-β-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.