Abstract
Some kaurane diterpenoids were isolated from 3 species of the genus Sideritis (Lamiaceae) growing in the Eastern Mediterranean region. Sideritis libanotica subsp. libanotica contained siderol 2 and sideridiol 3. Sideritis erythrantha var. erythrantha yielded sideridiol 3. Sideritis perfoliata gave siderol 2, sideridiol 3 and sideritriol 4. The products are known as they occur in another species of Sideritis growing in Italy and in other species growing also in Turkey. The products are isolated for the first time from these 3 species. The taxonomic significance of these results is discussed.