Limonene enantiomers

WUST, M., LITTLE, D. B, SCHALK, M., CROTEAU, R., Hydroxylation of limonene enantiomers and analogs by recombinant (-)-limonene 3- and 6-hydroxylases from mint (Mentha) species Evidence for catalysis within sterically constrained active sites, Arch. Biochem. Biophys., 2001,387,125-136. 

Limonene enantiomers activities were investigated on 25 different bacterial species. The results indicate that the (+) limonene was more active than the (-)-limonene. The (+)-limonene was active against the total of 22 species, whereas the (-)-enantiomer displayed activity only against 16 species [78]. Investigations into the activity of limonene enantiomers in relation to 20 laboratory strains of Listeria monocytogenes isolated from different foodstuffs were also carried out. 

Similarly as in the case of limonene enantiomers, investigations were carried out into the enantiomers of the a- pinene [79]. Activity investigations were performed in relation to 25 different bacteria species. 

The enantiomeric composition of monoterpene hydrocarbons in conifers and the receptor neuron discrimination of a -pinene and limonene enantiomers in the pine weevil Hylobius abietis) have been described [106]. The authors stated that one olfactory receptor neuron in the pine weevil showed a strong response to a -pinene. A markedly better response to (4-) than to (-)-a -pinene was elicited. Another olfactory receptor neuron responded strongly to limonene. This neuron responded more strongly to (-) than to (+)-limonene [106]. 

Wust, M. and R.B. Croteau (2002). Hydroxylation of specifically deuterated limonene enantiomers by cytochrome P450 limonene-6-hydroxylase reveals the mechanism of multiple product formation. Biochemistry 41, 1820-1827. 

Hydroxylation of limonene enantiomers and analogs by recombinant (-)-limonene 3- and... 

WIBE, A., BORG-KARLSON, A.-K., NORIN, T., MUSTAPARTA, H Enantiomeric composition of monoterpene hydrocarbons in some conifers and receptor neuron discrimination of alpha-pinene and limonene enantiomers in the pine weevil, Hylobius abietis, J. Chem. Ecol., 1998, 24, 273-287. 

More sensitive human noses can even distinguish between enantiomeric terpene hydrocarbons (i )-(+)-Limonene, the major constituent of the ethereal oil of mandarin peels, is recognized as a characteristic clean orange fragrance, while the (S)-(-)-enantiomer from the oil of fir-cones radiates a less pleasant orange odor with a touch of turpentine. Fig. 15 illustrates the sensitivity of the human olfactory organ by means of the limonene enantiomers between it may differentiate. 

Miyazawa, M., Shindo, M., and Shimada, T. (2002) Sex differences in the metabolism of (+) -and (-)-limonene enantiomers to carveol and perillyl alcohol derivatives by cytochrome P450 enzymes in rat liver micro-somes. 15(1) 15-20. 

The monocyclic monoterpene (+)- and (-)-limonene enantiomers have been shown to be present in orange peel Citrus aurantium L. sp. aurantium) and other plants and are extensively used as fragrances in household products and components of artificial essential oils. The (+)-limonene isomeric form is more abundantly present in plants than the racemic mixture and the (-)-limonene isomeric form (Wichtel, 2002). It has previously been shown that (+) limonene has chemopreventive activities in experimental animal models including rats and mice (Crowell et al., 1992). Because of the greater importance of (-i-)-limonene in the food and fragrance industry, only its metabolism and not that of (-)-limonene is described below. Several research groups have successfully described the biotransformation of ( f)-limonene in vitro (rat and human liver microsomes) and in vivo (rat, mice, guinea... 

Friedman, L. andJ. G. Miller, Science, 172, 1971, 1044-1046. (Incorrect smells of limonene enantiomers)... 

While i -(+)-limonene (134), for example, was completely and specifically converted by PenicilUum digitatum DSM 6284 to the corresponding a-terpineol enantiomer 135 [159,160], both limonene enantiomers were oxidized by Corynespora cassiicola DSM... 

The two enantiomers of limonene have completely different tastes. One has the taste of lemon (as the name implies) and the other of orange. Assign R or S forms tc the two enantiomers of limonene. 

Are the energies and dipole moments for the twc enantiomers of carvone (ibuprofen and limonene) the same or are they different Explain your result. 

Although the different enantiomers of a chiral molecule have the same physical properties, they usually have different biological properties. For example, the (+) enantiomer of limonene has the odor of oranges, but the (-) enantiomer has the odor of pine trees. 

Numerous examples of the different biological effects of enantiomers are available. One of the enantiomers of limonene smells of lemons, the other of oranges one of carvone smells of caraway, the other of spearmint These differences obviously have important... 

Both the (+)- and (-)- enantiomers of limonene were transformed by larvae of the cutworm Spodop-tera litura (Miyazawa et al. 1998). For both of them the reactions involved are (a) dihydroxylation between C-8 and C-9 and (b) oxidation of the C-1 methyl group to carboxyl. These transformations were not dependent on the intestinal microflora in contrast to the transformation of a-terpinene to p-mentha-l,3-dien-7-ol and p-cymene whose formation could be attributed to the intestinal flora. 

The two pinenes are obtained from Crude Sulfate Turpentine (CST), which is a side product of the sulfate cellulose process from pine trees. Limonene is present in orange and lemon peels [which provide different enantiomers/ )], and is a cheap by-product of the citrus industry. 

The LIS (Lanthanide Induced Shift) NMR technique is useful for such analysis25 and the separation of olefin enantiomers such as limonene, a-camphene and /J-pinene has been performed upon addition of silver salts such as Ag(fod) or Ag(hfc) to the commonly used lanthanide chiral salts such as Ln(tfc )3 or Ln(hfc)3, where fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyloctanedione, hfc = heptafluoro-3-butyrylcam-phorato and tfc = trifluoroacetylcamphorato. 

Another group of bicyclic aliphatic phosphines has been introduced by Sasol [15], Their ligands are based on addition of PH3 to limonene (the R-enantiomer). A mixture of two diastereomeric compounds is obtained due to the two configurations of the methyl group at the C-4 position (Figure 7.9). The Lim-H compounds obtained can be functionalised at the phosphorus atom with the usual radical reactions with alkenes or substitution reactions of their conjugate bases formed after treatment with BuLi with electrophiles. 

Another illustration of the use of such a biocatalytic approach was the synthesis of either enantiomer of a-bisabolol, one of these stereoisomers (out of four) which is of industrial value for the cosmetic industry. This approach was based on the diastereoselective hydrolysis of a mixture of oxirane-diastereoiso-mers obtained from (R)- or (S)-limonene [68]. Thus,starting from (S)-hmonene, the biohydrolysis of the mixture of (4S,81 S)-epoxides led to unreacted (4S,8S)-epoxide and (4S,8i )-diol. The former showed a diastereomeric purity (> 95%) and was chemically transformed into (4S,8S)-a-bisabolol. The formed diol... 

Attempts to investigate boll weevil (Anthonomus grandis) pheromone biosynthesis have identified isomerization, dehydration, and oxidation of the pheromone alcohols, and anticipated allylic oxidation of myrcene and limonene, but no evidence for the cyclization of acyclic precursors. The aggregation pheromones of bark beetles have been reviewed. Ips calligraphus responds to ipsdienol only in the presence of the c/5-verbenol (32) large additional concentrations of the enantiomer (l/ ,4i ,5/ )-(32) reduce beetle response. 5-(-)-Ipsenol, the pheromone of Ips grandicollis, increases the response of /. avulsus to its own pheromone ipsdienol. ... 

It was also reported that there were slight differences in the activity of enantiomers. (R)-(-i-)-Limonene and (iI)-(-t)-carvone were more biologically active than their isomers (S)-(-)-limonene and (S)-(-)-carvone [115],... 

Limonene is a monoterpene that occurs in citrus fruits. Two enantiomers of limonene produce two distinct flavours (—)-limonene is responsible for the flavour of lemons and (+)-limonene for orange. Similarly, one enantiomeric form of carvone is the cause of caraway flavour, while the other enantiomer has the essence of spearmint. 

Optical rotation measures the degree that light is rotated (see Table Gl.5.7 in Anticipated Results). In citrus oils, d-limonene is the major enantiomer in the sample. Since other optically active compounds are often present in racemic mixtures, there is no net rotation and thus they are ignored. If a compound is a racemic mixture, the polarimeter will not give a reading. Readings can be verified with known standards. 

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