Major structural types
While squalene, the parent of all triterpenoids, is a linear acyclic compound, the majority of triterpeneoids exist in cyclic forms, penta- and
tetracyclic triterpenes being the major types. Within these cyclic triterpenoids distinct structural variations lead to several structural classes of
triterpenoids. Some of the major structures types of triterpenoids are
shown below.
Tetracyclic triterpenes
Apotirucallane
Cucurbitane
O
H
H
O
OAc
O
H
O
H
Azadirachtol
OH
H
H
O
H
O
OH
OAc
Cucurbitacin E
Occurs in the family Cucurbitaceae
Cycloartane
Dammarane
O
H
H
H
H
H
Cycloartenol
Precursor of phytosterols
H
H
H
O
H
H
OH
Dammarenediols
Euphane
Lanostane
H
O
H
H
OH
Corollatadiol
O
H
H
H
H
Lanosterol
Prostostane and fusidane
OAc
H
O
H
O
H
H
O
O
H
H
Fusidic acid
An antibiotic
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CH6 NATURAL PRODUCT CHEMISTRY