A clerodane diterpene, also called a clerodanoid, is a bicyclic 20-carbon terpene compound. It is a rare form of diterpene and is structurally related to the bicyclic labdane diterpenes. Its biosynthesis in plants (mostly present in the families Lamiaceae and Asteraceae) takes place in the chloroplasts. Some forms can be useful intermediates in organic synthesis. Some clerodanes like clerodin (3-desoxy-caryoptinol) from the leaves of Clerodendrum infortunatum (Verbenaceae) have anthelminthic properties, others like ajugarins are repellent to herbivore predators (mostly insects and their larvae) or have a very bitter taste, such as gymnocolin.
Some examples for clerodanes are ajugarins I to V extracted from bugleweeds like Ajuga remota, Ajuga ciliata, Ajuga decumbens, common skullcap (Scutellaria galericulata), and germanders (Teucrium sp.), cascarillin from Croton eleuteria, columbins from Jateorhiza columba, Jateorhiza palmata and guduchi (Tinospora cordifolia), gymnocolin from Gymnocolea inflata, hardwickiic acid from Hardwickia species (Fabaceae). Neo-clerodane diterpenes can have hallucinogenic properties such as salvinorin A, a trans-neoclerodane diterpene from Salvia divinorum.