Demonstration that limonene is the first cyclic intermediate in the biosynthesis of oxygenated p-menthane monoterpenes in Mentha piperita and other Mentha species
The volatile oil of mature Mentha piperita (peppermint) leaves contains as major components the oxygenated p-menthane monoterpenes l-menthol (47%) and l-menthone (24%) as well as very low levels of the monoterpene olefins limonene (1%) and terpinolene (0.1%), which are considered to be probable precursors of the oxygenated derivatives. Immature leaves, which are actively synthesizing monoterpenes, produce an oil with comparatively higher levels of limonene approx.3%), and isolation of the pure olefin showed this compound to consist of approx.80% of the l-(4S)-enantiomer and approx.20% of the d-(4R)-enantiomer. The time course of incorporation of (U-/sup 14/C)sucrose into the monoterpenes of M. piperita shoot tips was consistent with the inital formation of limonene and its subsequent conversion to menthone via pulegone. d,l-(9-/sup 3/H)Limonene and (9,10-/sup 3/H)terpinolene were prepared and tested directly as precursors of oxygenated p-menthane monoterpenes in M. piperita shoot tips. Limonene was readily incorporated into pulegone, menthone, and other oxygenated derivatives, whereas terpinolene was not appreciably incorporated into these compounds. Similarly, d,l-(9-/sup 3/H)limonene was specifically incorporated into pulegone in Mentha pulegium and into the C-2-oxygenated derivative carvone in Mentha spicata, confirming the role of this olefin as the essential precursor of oxygenated p-menthane monoterpenes. Soluble enzyme preparations from the epidermis of immature M. piperita leaves converted the acyclic terpenoid precursor (1-/sup 3/H)geranyl pyrophosphate to limonene as the major cyclic product.
- Research Organization:
- Washington State Univ., Pullman
- DOE Contract Number:
- AM06-76RL02221; AT06-82ER12027
- OSTI ID:
- 6196202
- Journal Information:
- Arch. Biochem. Biophys.; (United States), Journal Name: Arch. Biochem. Biophys.; (United States) Vol. 220:1; ISSN ABBIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ALKENES
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
CARBON 14 COMPOUNDS
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
DEHYDROCYCLIZATION
ENZYMES
HYDROCARBONS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEAVES
ORGANIC COMPOUNDS
PLANTS
PRECURSOR
SYNTHESIS
TERPENES
TRACER TECHNIQUES
TRITIUM COMPOUNDS