The biosynthesis of thymol, carvacrol, and thymohydroquinone in Lamiaceae proceeds via cytochrome P450s and a short-chain dehydrogenase
Significance The monoterpene alcohols thymol, carvacrol, and thymohydroquinone are characteristic flavor compounds of thyme, oregano, and other Lamiaceae. These specialized metabolites are also valuable for their antibacterial, anti-spasmolytic, and antitumor activities. We elucidated the complete biosynthetic pathway of these compounds, which starts with the formation of γ-terpinene from geranyl diphosphate. The aromatic backbone of thymol and carvacrol is formed by P450 monooxygenases in combination with a dehydrogenase via an unstable intermediate. Additional P450s hydroxylate thymol and carvacrol to form thymohydroquinone. Our findings demonstrate a mechanism for the formation of phenolic monoterpenes that differs from previous predictions and provides targets for metabolic engineering of high-value terpenes in plants.
