Sesquiterpenes are a class of terpenes made up of three isoprene units (C₁₅H₂₄). They are a diverse group of natural compounds found in many plants, fungi, and some insects.
Key Features of Sesquiterpenes:
- Structure: Built from 15 carbon atoms (3 isoprene units).
- Forms: Can be linear, cyclic, bicyclic, or tricyclic.
- Volatility: Less volatile than monoterpenes (C₁₀H₁₆).
- Occurrence: Common in essential oils, resins, and defense secretions.
Examples:
- Farnesene – contributes to apple aroma.
- Humulene – found in hops (beer aroma).
- Bisabolol – in chamomile, with soothing effects.
- Caryophyllene – in black pepper and clove, has anti-inflammatory properties.
- Nerolidol – in ginger and tea tree oil, with antimicrobial activity.
Biological Roles:
- Plant defense against pathogens and herbivores.
- Signaling molecules in plant–plant and plant–insect interactions.
- Allelopathic effects (influencing neighboring plants).
Applications:
- Pharmaceuticals: Anti-inflammatory, anticancer, antimicrobial, and antimalarial properties.
- Fragrance industry: Perfumery and aromatherapy.
- Food & Beverages: Flavoring agents.