Terpenes and isoprenoids: a wealth of compounds for global use Original paper

What was reviewed?

This narrative review, Terpenes and Isoprenoids, summarizes how plants biosynthesize and use terpenoid/isoprenoid compounds and why these molecules matter commercially and biologically. It explains the chemical “isoprene-unit” logic that organizes terpenoids from hemiterpenes (C5) to polyterpenes (>C40), and highlights the two precursor-producing pathways in plants—the cytosolic mevalonate (MVA) pathway and plastidic methylerythritol phosphate (MEP) pathway—both generating IPP and DMAPP as universal building blocks. The author also emphasizes how compartmentalization and terpene synthase diversity drive the enormous structural variety of terpenoids, and frames applications across pharmaceuticals, nutraceuticals, flavors/fragrances, cosmetics, and potential biofuels.

Who was reviewed?

No human participants were studied. Instead, the review synthesizes evidence across plants (especially higher plants), algae, bacteria, archaea, fungi/yeast, and animals to explain where terpene biosynthetic routes occur and how they evolved. It discusses plant cellular compartments (chloroplast, cytosol, and other organelles) as functional “sites” of terpene metabolism and notes expanding evidence that pathways and enzymes may exchange intermediates and localize beyond classic boundaries (e.g., movement of IPP/GPP across chloroplast envelopes; terpene synthases in mitochondria, peroxisomes, ER). The review also covers engineered microbial “factories” (e.g., E. coli, Saccharomyces cerevisiae, cyanobacteria, and Chlamydomonas) used for scalable terpenoid production when plant extraction is impractical.

Most important findings

The central message is that terpenes/isoprenoids are a chemically vast, evolutionarily important metabolite class that supports plant fitness (signaling, defense, acclimation) while also supplying major industrial value. Two key mechanistic points stand out: first, both MVA and MEP pathways converge on IPP/DMAPP precursors, enabling production of primary metabolites (chlorophyll phytol tails, carotenoids, quinone prenyl chains, sterols, hormones) and specialized secondary terpenoids (volatile mono-/sesquiterpenes, phytoalexins, latex/rubber). Second, terpenoid diversity is driven by terpene synthase enzyme specificity plus downstream “decorations” (secondary modifications), which creates thousands of structurally distinct molecules with distinct bioactivities and sensory properties. Clinically adjacent highlights include well-known terpene-derived drugs (e.g., taxol and artemisinin) and evidence that volatile terpenes (e.g., α-pinene, limonene, linalool) have anti-inflammatory/antioxidant activities and can influence neurological targets, including interest in Alzheimer’s related mechanisms. While this paper is not a microbiome study, it is relevant to microbiome-adjacent databases because many terpenes are antibacterial/antifungal, immunomodulatory, or metabolically active, meaning they can plausibly shape host–microbe ecosystems when used as dietary components, botanicals, or pharmaceuticals.

Key implications

For clinicians, the key implication is translational: terpenes/isoprenoids form a drug-and-bioactive “chemical universe” spanning pharmaceuticals, supplements, and inhaled/aroma exposures, with mechanistic hooks (anti-inflammatory signaling, antioxidant pathways, BBB permeability for some volatiles) that intersect chronic disease biology. For microbiome-aware practice and research, this review supports treating terpene exposure as a plausible ecological modifier—not because the paper measured microbiome changes, but because these compounds include antimicrobial and immunomodulatory activities and are increasingly manufacturable via engineered microbes, enabling controlled dosing and future microbiome-outcome trials.

Citation

Tetali SD. Terpenes and isoprenoids: a wealth of compounds for global use.Planta. 2019;249:1–8. doi:10.1007/s00425-018-3056-x.