Sesquiterpene

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Sesquiterpenes are a class of terpenes that consist of three isoprene units and have the molecular formula C₁₅H₂₄. They are found naturally in plants and insects, and they often have strong odors, which makes them useful in perfumes and aromatherapy. Sesquiterpenes can be acyclic, monocyclic, bicyclic, or tricyclic.

Structure and Biosynthesis

Sesquiterpenes are built from three isoprene units, which are five-carbon molecules. The biosynthesis of sesquiterpenes involves the enzyme farnesyl pyrophosphate synthase, which catalyzes the formation of farnesyl pyrophosphate (FPP) from two molecules of dimethylallyl pyrophosphate (DMAPP) and one molecule of isopentenyl pyrophosphate (IPP). FPP is a key intermediate in the biosynthesis of sesquiterpenes.

Types of Sesquiterpenes

Sesquiterpenes can be classified into several types based on their structure:

• Acyclic sesquiterpenes: These have no rings in their structure. An example is farnesene.
• Monocyclic sesquiterpenes: These contain one ring. An example is zingiberene, found in ginger.
• Bicyclic sesquiterpenes: These contain two rings. An example is caryophyllene, found in clove oil.
• Tricyclic sesquiterpenes: These contain three rings. An example is longifolene, found in pine resin.

Functions and Uses

Sesquiterpenes play various roles in nature. In plants, they can act as phytoalexins, which are substances produced in response to pathogen attack. In insects, sesquiterpenes can function as pheromones.

In industry, sesquiterpenes are used in the production of fragrances, flavors, and pharmaceuticals. For example, artemisinin, a sesquiterpene lactone, is used as an antimalarial drug.

Examples of Sesquiterpenes

• Farnesene
• Zingiberene
• Caryophyllene
• Longifolene
• Artemisinin

See Also

• Monoterpene
• Diterpene
• Triterpene
• Terpenoid
• Essential oil