Phytoecdysteroid and Clerodane Content in Three Wild Ajuga Species in Israel

Many species of the genus Ajuga (family Lamiaceae) contain phytoecdysteroids and clerodane diterpenes. Phytoecdysteroids are triterpene-derived analogues of steroid hormones that control molting and metamorphosis in arthropods, whereas clerodanes deter phytophagous insects. We identified and quantified phytoecdysteroid and clerodane contents in three Ajuga plant species in Israel. Leaves and roots of Ajuga iva, Ajuga chamaepitys (Ajuga chia), and Ajuga orientalis were collected from three different populations. Using liquid chromatography-time of flight-mass spectrometry analysis, we identified three phytoecdysteroids: 20-hydroxyecdysone (ecdysterone), makisterone A, and cyasterone and two clerodanes: dihydroajugapitin and columbin. Their contents varied significantly among plant species, organs, and populations. The highest concentrations of 20-hydroxyecdysone, makisterone A, and cyasterone were recorded in leaves and roots of A. iva. Cyasterone content tended to be higher in leaves of A. chamaepitys. Clerodane concentrations were generally negligible or nonexistent. Dihydroajugapitin concentrations were highest in A. iva leaves but were lower or undetectable in the roots and in the other two species. Columbin concentration was similar in all species and organs. Phytoecdysteroid contents also varied among populations within species. Because phytoecdysteroids have disruptive effects on phytophagous insect growth, the potential role of extracts of A. iva in pest-management programs is of interest.