Studies on the constituents of Leonotis nepetaefolia

Abstract

Three antioxidative phenylethanoid glycosides and two new iridoid glycosides, along with three known iridoids were isolated from the African medicinal plant, Leonotis nepetaefolia R. BR. (Labiatae). The new iridoid glycosides were established as 10-O-(trans-3,4-dimethoxycinnamoyl)geniposidic acid and 10-O-(p-hydroxybenzoyl)geniposidic acid. Antioxidative activities of the compounds were measured by α,α-diphenyl-β-picrylhydrazyl (DPPH) method, and the three known phenylethanoid glycosides, acteoside, martynoside and lavandulifolioside showed strong antioxidative activity.