Terpenoid

The terpenoids, also known as isoprenoids, are a class of naturally occurring organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeably with “terpenes”, terpenoids contain additional functional groups, usually containing oxygen.

Terpenoid Biosynthesis

• Terpenoids are derived from the 5-carbon compound isoprene.
• The hydrolysis of intermediates from geranyl pyrophosphate results in sesquiterpenoids.
• The hydrolysis of intermediates from farnesyl pyrophosphate leads to diterpenoids.
• Terpenoids can have different structures such as linear, acyclic, or monocyclic.
• The Salkowski test is used to identify the presence of terpenoids.

Terpenoid Uses

• Terpenoids constitute the largest class of plant secondary metabolites.
• They are used for their aromatic qualities and in traditional herbal remedies.
• Many terpenoids exhibit pharmacological bioactivity.
• Terpenoids play a role in plant defense and attraction for predators.
• They contribute to the scents and flavors of various plants.

Selected Terpenoids

• Paclitaxel is a diterpenoid anticancer drug.
• Terpineols are monoterpenoids.
• Humulones are sesquiterpenoids.
• Retinol is a diterpenoid.
• Limonin is a triterpenoid.

Terpenoid Testing and Identification

• Terpenoids combined with terpenes make up 80,000 compounds.
• Terpenoids represent approximately 60% of known natural products.
• Terpenoids can be classified based on their cyclic structures.
• The Salkowski test is a method to identify the presence of terpenoids.
• The biosynthesis of terpenoids involves the hydrolysis of intermediates.

References

• IUPAC Compendium of Chemical Terminology
• Structural and Chemical Biology of Terpenoid Cyclases
• Biochemistry of Terpenoids: Monoterpenes, Sesquiterpenes, Diterpenes
• Plant terpenes: defense responses, phylogenetic analysis, regulation, and clinical applications
• Terpenoids in pharmacognosy and their medicinal applications

Terpenoid Data Sources