Studies on the constituents of Vitex cannabifolia.

A new diterpenoid, named vitexilactone (I), was isolated together with a known iridoid glycoside, agnuside, a known flavonoid, artemetine, and p-hydroxybenzoic acid from the leaves of Vitex cannabifolia SIEB. et ZUCC. (Verbenaceae). The structure of vitexilactone was established as I by the chemical and spectral examinations.