DPPH radical-scavenging effect on some constituents from the aerial parts of Lippia triphylla.

Lippia triphylla (L'HER) O. KUNTZE: (Verbenaceae; common name, Lemon Verbena) is used in Peru as a spice and herb tea for the prevention of arteriosclerosis. From the aerial parts of this plant, 25 known compounds--3 phenylpropanoid glucosides, 7 flavonoids, 5 phenylethanoid glycosides, 5 lignans, 2 sesquiterpenoids, and 3 triterpenoids--were isolated, and their chemical structures were elucidated on the basis of physical and spectral data. Among them, 19 aromatic compounds were examined for their scavenging effect on the stable free radical 1,1-diphenyl-2-picrylhydrazyl--4 phenylethanoid glycosides and 5 lignans indicated a potent scavenging effect. Of note, the EC(50) values of two phenylethanoid glycosides reached almost thrice that of alpha-tocopherol.