Spearmint species

Interest in limonene synthase stems in part from the fact that (-)-limonene is the common precursor of menthol and carvone, respectively, of the essential oils of peppermint and spearmint species (Scheme 6) [79]. The cyclization leading to limonene is the simplest of all terpenoid cyclizations and the reaction has ample precedent in solvolytic model studies [58, 59, 80]. Thus, it is not... 

Historically, terpenes have enjoyed a role as symptom-relieving therapeutics. Camphor and carvone (spearmint oil) have been used as soothing agents in the past history of pharmaceutical compounds. More recently, the role of terpenes in biochemistry has been more fully appreciated. P-Carotene, for example, may be cleaved into two units of vitamin A. Other terpenes, such as geraniol, are now recognized as pheromones (a chemical secreted by one individual of a given species in order to elicit a response in another individual of the same species). Pheromones are of interest in medicinal chemistry for a variety of indications for instance, attractant pheromones can be used for the control of insects known to spread human disease. 

Therea renumerous species of mint including peppermint, Mcnf/zapipenta, spearmint, Mentha spicata, and cornmint, Mentha arvensis. Mentha piperita is actually a hybrid species bred from spearmint Mentha spicata and watermint Mentha aquatica. They all contain subspecies and chemotypes. Mints have a long tradition of culinary, fragrance, cosmetic and therapeutic applications. 

The formation of a hybrid combines, in a single species, the desirable characteristics of two or more separate species. An example is peppermint which is a hybrid between Watermint (Mentha aquatica) and Spearmint (Mentha spicata). In medicinal plant research the usual tactic is to combine ( cross ) a plant with a high % content of the desired compound with a related plant with high phytomass or bulk, thus giving a high overall yield. 

Flavor of Microbial Transformation Products. The flavor of terpenoids produced by microbial transformation was evaluated. (-)-Carvone (1) is well known as a spearmint flavor component. Transformation products (4 - 7) of 1 had peppermint-like flavor although these are slightly different to each other in terms of the odor quality. The metabolites, bottrospicatols (10a and 10b) Streptomyces species did not have a characteristic flavor but quite different activities (Figure 8). (+)-Bottrospicatal (15) which was produced by the oxidative reaction of (+)-bottrospicatol (10a) with CrOa in pyridine had a weak spice-flavor (slightly black-pepper like). The ester derivatives (13 in Figure 7) had a weak medicinal flavor. The flavor of acetyl ester (13a) was the strongest of all. 

Regiospecific hydroxylation of the monoter-pene (—)-46 -limonene at the C-3 or C-6-allylic positions to yield (—)-menthol (peppermint) or (—)-carvone (spearmint), respectively, is accomplished by the last two functionally characterized CYP71DS, the CYP71D13 and CYP79D18 found in commercial mint species (Mentha sp.) . 

In the previous above example, it was shown that two spearmint oils, which were produced from clonally reproduced distinctly different species of Mentha, produced oils whose compositions were simitar but could be differentiated however, the detailed oil compositionai data were not presented. To address this point, the analyus of oils that are known commercially as cedarwood will be the next subject of discussion. 

Spearmint oil. Besides peppermint oils, S. constitutes another important essential oil isolated from Mentha species. It has a typical warm, fresh, green-herby, caramel-mint-like odor and a warm, spicy-herby, somewhat bitter astringent taste. 

Production By steam distillation from the flowering shrub of the crisped or curled mint species Mentha spicata ( native spearmint ) and Mentha cardiaca ( Scotch spearmint ). The main areas of cultivation are the American states of Idaho, Oregon, and Washington as well as Indiana, Michigan, and Wisconsin ( Middle West ) oil production in 1992 was ca. 32001. It is also cultivated in smaller amounts in China and India production in 1992 ca. 500 t. 

The enzymes responsible for the hydroxylation of monoterpenes such as (— )-limonene (11) from peppermint Mentha piperita), spearmint Mentha spicata), and perilla Per-ilia frutescens) have been isolated and characterized (Karp et al., 1987,1990). Microsomal preparations from the epidermal oil glands of these plants catalyze the NADPH and 02-dependent allylic hydroxylation of (- )-(45)-limonene (the major olefinic constituent of each of the three species) at C-3, C-6, and C-7, respectively, to produce (- )-rra j-isopiper-itenol (34), (- )- m 5-carveol (35), and (- )-perillyl alcohol (36) (Fig. 19.9) (Karp et al., 1990). These transformations are the key steps in the biosynthesis of oxygenated monoterpenes in the respective species. The enzymes appear to be... 

Plants from some other plant families, e.g., Frulla-nitty Mttgnolitty and Ltturus contain SQTLs and may cause sensitization or cross-react with other SQTL-containing plants [67, 86]. Cross-reactions to carvone in spearmint [93] may occur as well. Patients may also react to Compositae plants to which they have never been exposed, as the same SQTL is sometimes found in multiple species [87]. 

The designation spearmint is applied commercially to several species and varieties of Mentha possessing a characteristic odor profile that is quite different from either peppermint or commint, although the plant form, its cultivation, and harvesting are very similar. The main species involved are the following ... 

There are considerable differences in the composition of the various mint oils, determined by species and environmental conditions during growth, harvesting, and postharvest handling. It is convenient to consider these oils in two groups (a) peppermint and (b) spearmint. Peppermint (M. piperita) and commint (M. arvensis) oils have much in common, the principle constituents of each being menthol, menthone, menthyl acetate, and other esters. It is the ratio of these components that determines their distinctive profiles. 

Monoterpenic ketones are frequently very important aromatic substances of many food raw materials, spices and medicinal herbs. Monocyclic ketone (-F)-carvone (8-50) is a key component of caraway and diU oils, where it is accompanied by (-F)-( )-dihydrocarvone, that is (lS,4S)-dihydrocarvone (8-50) that also possesses caraway odour. (-)-Carvone (8-50) is a typical component of spearmint essential oil, where it is accompanied by (-)-( )-dihydrocarvone, (lE,4E)-dihydrocarvone, which has the same odour (see Table 8.32). Isomeric ( )-menthone (8-50) and its precursor (-F)-pulegone (8-50) occur in the essential oils of the European pennyroyal Menthaptdegium, Lamiaceae), a traditional culinary herb and folk remedy, and other Mentha species (such as M. longifolia), as well as in marjoram essential oil. In the essential oil of mint, (-)-menthone is accompanied by (-F)-isomenthone (8-50) and other terpenoids. 

Carvone, also known as p-mentha-6,8-dien-2-one and carvol, is a material of commercial importance and has been reviewed by Clark (310). There are two enantiomers of which the (/ )-( )- is the commoner and is used in much greater quantities. If the stereochemistry is not specified, it is usually the (/ )-(—)-enantiomer, usually referred to as /-carvone, which is intended. Both isomers occur fairly widely in essential oils. The most significant natural sources of carvone are spearmint, dill, and caraway. The term spearmint is applied to various Mentha species including M. cardiaca, M. gracilis, M. spicata, and M. viridis and these usually contain 55-75% of the (/ )-( )-enantiomer (242). The (5)-(+)-enantiomer (243) is found in diU (Anethum graveolens) at levels of 30-65% and at 50-75% in caraway (Conan carvi). 

Closely related perennial aromatic herbs with runners or stolons by which they are propagated leaves of spearmint are sessile (no petioles), while those of peppermint and cornmint are petioled and short petioled, respectively up to about 1 m high cultivated worldwide. Each species has numerous varieties, strains, or chemotypes that produce essential oils with widely different chemical... 

---