Sesquiterpenes

Definition

Sesquiterpenes are a class of organic compounds that are composed of three isoprene units, resulting in a total of 15 carbon atoms. They are part of the larger group of terpenoids, which are a diverse family of natural products found in plants and some animals.

5 Must Know Facts For Your Next Test

1. Sesquiterpenes are the third-largest class of terpenes, after monoterpenes and diterpenes, and are known for their diverse and complex structures.
2. Many sesquiterpenes have been found to possess a wide range of biological activities, including antimicrobial, anti-inflammatory, and anticancer properties.
3. Sesquiterpenes are commonly found in essential oils, such as those extracted from plants like lavender, patchouli, and vetiver.
4. The biosynthesis of sesquiterpenes involves the condensation of three isoprene units, catalyzed by the enzyme sesquiterpene synthase.
5. Sesquiterpenes play important ecological roles, such as acting as plant defense compounds and attracting pollinators.

Review Questions

• Explain the structural relationship between sesquiterpenes and isoprene, and how this relates to their classification within the terpenoid family.
  • Sesquiterpenes are composed of three isoprene units, each consisting of five carbon atoms. This 15-carbon structure is what defines sesquiterpenes as a distinct class within the broader terpenoid family, which includes other terpene classes like monoterpenes and diterpenes that are built from different numbers of isoprene units. The shared isoprene building block is a key structural feature that links sesquiterpenes to the wider terpenoid group, as all terpenoids are derived from these fundamental five-carbon precursors.
• Describe the biological and ecological significance of sesquiterpenes, particularly in terms of their diverse functional roles in plants and other organisms.
  • Sesquiterpenes are known to exhibit a wide range of biological activities, including antimicrobial, anti-inflammatory, and anticancer properties. This makes them valuable compounds for potential therapeutic applications. Additionally, sesquiterpenes play important ecological roles, such as acting as plant defense compounds that deter herbivores or attract pollinators. The structural diversity of sesquiterpenes allows them to fulfill these diverse functional roles within the natural world, highlighting their importance as a class of terpenoid natural products.
• Analyze the biosynthetic pathway for sesquiterpenes and explain how the enzyme sesquiterpene synthase catalyzes the key step in their formation from isoprene precursors.
  • The biosynthesis of sesquiterpenes begins with the condensation of three isoprene units, which is catalyzed by the enzyme sesquiterpene synthase. This enzyme facilitates the complex cyclization and rearrangement reactions that transform the linear 15-carbon precursor into the diverse array of cyclic and acyclic sesquiterpene structures observed in nature. Understanding the mechanistic details of this sesquiterpene synthase-catalyzed step is crucial, as it represents the key branching point that determines the final structural and functional diversity of this important class of terpenoid natural products.

Related terms

Isoprene:

Isoprene is the fundamental building block of terpenes and terpenoids, consisting of a five-carbon molecule with the chemical formula C₅H₈.

Terpenes:

Terpenes are a large and diverse class of organic compounds, made up of multiple isoprene units, that are found in many plants and some insects.

Terpenoids:

Terpenoids are a class of naturally occurring organic chemicals derived from terpenes, which are themselves derived from five-carbon isoprene units.