Definition of Terpenoids
Terpenoids, or isoprenoids, are a diverse class of naturally occurring organic compounds derived from five-carbon isoprene units.
They undergo modifications like oxidation and rearrangement, resulting in varied structures and functions.
Structure and Classification
Based on isoprene units:
Monoterpenoids: C₁₀ (2 units)
Sesquiterpenoids: C₁₅ (3 units)
Diterpenoids: C₂₀ (4 units)
Triterpenoids: C₃₀ (6 units)
Tetraterpenoids: C₄₀ (8 units)
Polyterpenoids: >C₄₀
Biosynthesis
Produced via:
Mevalonate Pathway: In cytosol of eukaryotes and some prokaryotes.
MEP Pathway: In plastids of plants and most bacteria.
Both pathways generate isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP).
Occurrence in Nature
Widely found in plants, contributing to aromas, flavors, and colors. Also present in animals, fungi, and some bacteria.
Common sources include essential oils, resins, and waxes.
Biological Activities and Uses
Ecological Roles: Defense against herbivores/pathogens; attract pollinators.
Pharmaceuticals: Medicinal properties like anti-inflammatory and anticancer (e.g., paclitaxel, artemisinin).
Industrial Applications: Fragrances, flavorings, solvents, and synthetic material precursors.
Examples
Menthol: Monoterpenoid in mint oils, provides cooling sensation.
Citral: Monoterpenoid with a strong lemon scent, used in fragrances and flavorings.
Artemisinin: Sesquiterpenoid with potent anti-malarial properties.