The Chemical Constituents of Ajuga Plants. I. neo-Clerodanes from the Leaves of Ajuga nipponensis MAKINO

Abstract

Three new bitter principles, ajugamarin, dihydroajugamarin, and ajugamarin chlorohydrin, which belong to the neo-clerodane group of diterpenoids, have been isolated from the leaves of Ajuga nipponensis. The structures of these compounds were established by chemical and spectroscopic means. The absolute structure of ajugamarin was determined by the X-ray analysis of ajugamarin p-bromobenzoate. Ajugamarin chlorohydrin may have been formed by addition of hydrogen chloride to ajugamarin during the isolation procedure.