Clerodane diterpenes, sometimes referred to as clerodane diterpenoids, are a large group of secondary metabolites that have been isolated from several hundreds of different plant species, as well as fungi, bacteria and marine sponges.
Classification
The clerodane diterpenes are classified into four groups
trans-
cis (TC),
trans-trans (TT),
cis-
cis (CC), and
cis-
trans (TC) based on the relative stereochemistry at the decalin junction (
trans or
cis) and the relative stereochemistry of the substituents at C-8 and C-9 (
trans or
cis). The absolute stereochemistry of the clerodanes is classified as
neo (shown below) or
ent-
neo (enantiomeric to
neo). The
neo-clerodanes share the same absolute stereochemistry as clerodin. Approximately 25% of clerodanes have the 5:10
cis ring junction. The remaining 75% have a
trans 5:10 ring junction.
Biosynthesis
They are structurally related to the bicyclic
labdane diterpenes. Its biosynthesis in plants (mostly present in the families
Lamiaceae and
Asteraceae) takes place in the
. 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 are repellent to herbivore predators (mostly insects and their larvae) or have a very bitter taste, such as
gymnocolin.
Some examples for clerodanes are I to V extracted from Ajuga like Ajuga remota, Ajuga ciliata, Ajuga decumbens, common skullcap ( Scutellaria galericulata), and Teucrium, cascarillin from Croton eluteria, 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.
See also
External links
