New Bisabolane-Type Sesquiterpenes from the Aerial Parts of Lippia dulcis

Abstract

Two new bisabolane-type sesquiterpenes, lippidulcine A (3) and epilippidulcine A (4), have been isolated from the aerial parts of Lippia dulcis TREV. along with five known flavonoids, cirsimaritin (5), salvigenin (6), eupatorin (7), 5-hydroxy-6,7,3′,4′-tetramethoxyflavone (8) and 5,3′-dihydroxy-6,7,4′,5′-tetramethoxyflavone (9), three known phenylethanoid glycosides, decaffeoylverbascoside (10), acteoside (11) and isoacteoside (12), and two known iridoid glucosides, 8-epiloganin (13) and lamiide (14). Their chemical structures have been determined on the basis of spectroscopic data. Among them, 5, 7, and 9 exhibited almost the same activity as that of α-tocopherol, and 10—12 were identified as stronger antioxidants than α-tocopherol using the ferric thiocyanate method.