L-carvone

Other synthetics with cost advantages and large volume productions are L-carvone [6485-40-17, the primary component in natural spearmint essence D-carvone [2244-16-8], the primary component in natural diU and caraway anethol [4180-23-8], in place of anise and fennel spices and smaller amounts of thymol [89-83-8] replacing thyme and disulfide synthetics for onion and gadic. AH of these synthetics must be labeled as artificial which may limit their use among consumers. 

The main constituents of spearmint oil are /-carvone (Fig. 13.12.7) and /-limonene (Fig. 13.12.8). Oil of spearmint contains from 45 to 60% l-carvone, 6 to 20% of alcohols, and 4 to 20% of esters and terpenes, mainly /-limonene and cineole (see Fig. 13.12.4)J2J The optically isomeric form of carvone, d-carvone, is found in oil of caraway and oil of dill. Carvone appears to co-occur with limonene when present in a plant. 

The hydrogenation of the monoterpenes (—)- and (-l-)-carvone was studied extensively. Several microorganisms were used in these reductions. They catalyzed the production of all possible stereoisomers, but some of them only in small quantities. The distribution of the products depended on the catalyst applied116. 

The linear sequence starts from (-l-)-carvone (67) (Scheme 12). Establishing the quaternary center at Cl was achieved via a successive enolate alkyla-tion/hydroxyalkylation to furnish hydroxyketone 68. Reduction of the enone... 

Humans,mole rats" and squirrel monkeys" can distinguish between suprathreshold concentrations of the two enantiomers of carvone. The (47 )(—)-carvone is detected at lower concentrations than the (45) (-l-)-carvone by humans. At equivalent suprathreshold concentrations some individuals perceive (45) (-f)-carvone to be more intense than its... 

This strategy was utilized in the 1970s to isolate olfactory cilia (64). Later the technique was utilized to j pare olfactory cilia from frog, where it was demonstrated that GTP was required for stimulation of adenylate cyclase by odorants. Four chemicals, citral, L-carvone, 1,8-cineole and amyl acetate, were used either individually or in a mixture, and adenylate cyclase was measured (65). Maximal stimulation by the mixture of 4 odorants was 2.3-fold above the GTP-stimulated value. In further studies a total of 65 odorants were tested individually with frog and rat cilia (66). These results indicated that only about a third of the odorants tested stimulated adenylate cyclase by meaningful amounts, with 6 stimulating by 45-65%. 

Cancer-risk-diet relationship, 262 Canonical correlation analysis, 104 Capsaicin, 15-16 N-(Carboxymethyl)chitosan, preservation of meat flavor, 73 Carrageenan, fat replacement in ground beef, 73-75 Carry-over, description, 57 Carry-through, description, 57 Carvone, headspace analysis, 24,25/ L-Carvone, chemicals resulting in anosmias, 211... 

The main renewable resource for L-carvone is spearmint oil (Mentha spicata), which contains up to 75% of this flavour chemical. There also exists a synthetic process for the manufacturing of L-carvone, which is based on (-t)-limonene, which is available as a by-product of the citrus juice industry as a major component of orange peel oil (Scheme 13.4). The synthesis was developed in the nineteenth century and starts with the reaction of (-t)-limonene and nitrosyl chloride, which ensures the asymmetry of the ring. Treatment with base of the nitrosyl chloride adduct results in elimination of hydrogen chloride and rearrangement of the nitrosyl function to an oxime. Acid treatment of the oxime finally results in l-carvone. 

Scheme 13.4 Chemical synthesis of l-carvone from (+)-limonene...

Caraway Carum carvi (Apiaceae) (-l-)-carvone, (+)-hmonene... 

C. Samples were withdrawn every two days from the samples stored at 45 C and every three days from the samples stored at 37 C. Pulled samples were stored in screw cap vials at 0 C until analsis by gas chromatography (GC). The products were monitored for the formation of limonene-1,2-epoxide and L-carvone, both oxidation products of d-limonene (3). 

Worm M, Jeep S, Sterry W, Zuberbier T. Perioral contact dermatitis caused by L-carvone in toothpaste. Contact Dermatitis 1998 38(6) 338. 

L-Carvone Warm-herbaceous, breadhke, spicy, spearmint Spearmint (Mentha spicata)... 

For example, spearmint leaves and caraway seeds respectively contain L-carvone and D-carvone - enantiomers of carvone. These smell different to most people because our taste receptors also contain chiral molecules which behave differently in the presence of different enantiomers. 

The three most important cyclic monoterpenes are L-menthol, l-carvone and a-terpineol (including its esters). L-Menthol occurs in a number of mint oils and is used not only for its minty odour, but also,... 

---