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PubMed1998

Biotransformation of (+)- and (-)-Limonene by the Larvae of Common Cutworm (Spodoptera litura).

(+)-Limonene was mixed in an artificial diet at a concentration of 1 mg/g of diet, and the diet was fed to the last instar larvae of common cutworm (Spodopteralitura). Metabolites were recovered from frass and analyzed spectroscopically. (+)-Limonene was transformed mainly to (+)-p-menth-1-ene-8,9-diol (uroterpenol) and (+)-p-mentha-1,8-dien-7-oic acid (perillic acid). Similarly, (-)-limonene was transformed mainly to (-)-p-menth-1-ene-8,9-diol (uroterpenol) and (-)-p-mentha-1,8-dien-7-oic acid (perillic acid). The results indicate that there is little difference in metabolic pathway between the (+)- and (-)-forms.

Journal Article↗
PubMed1999

Limonene synthase, the enzyme responsible for monoterpene biosynthesis in peppermint, is localized to leucoplasts of oil gland secretory cells

Circumstantial evidence based on ultrastructural correlation, specific labeling, and subcellular fractionation studies indicates that at least the early steps of monoterpene biosynthesis occur in plastids. (4S)-Limonene synthase, which is responsible for the first dedicated step of monoterpene biosynthesis in mint species, appears to be translated as a preprotein bearing a long plastidial transit peptide. Immunogold labeling using polyclonal antibodies raised to the native enzyme demonstrated the specific localization of limonene synthase to the leucoplasts of peppermint (Mentha x piperita) oil gland secretory cells during the period of essential oil production. Labeling was shown to be absent from all other plastid types examined, including the basal and stalk cell plastids of the secretory phase glandular trichomes. Furthermore, in vitro translation of the preprotein and import experiments with isolated pea chloroplasts were consistent in demonstrating import of the nascent protein to the plastid stroma and proteolytic processing to the mature enzyme at this site. These experiments confirm that the leucoplastidome of the oil gland secretory cells is the exclusive location of limonene synthase, and almost certainly the preceding steps of monoterpene biosynthesis, in peppermint leaves. However, succeeding steps of monoterpene metabolism in mint appear to occur outside the leucoplasts of oil gland cells.

Journal Article↗
PubMed1994

Prenylated proteins and lymphocyte proliferation: inhibition by d-limonene related monoterpenes.

The aim of the present study was to explore the role of post-translational isoprenoid modification of cellular proteins in the proliferation of human lymphocytes. We here report that treatment of phytohemagglutinin-stimulated peripheral blood mononuclear cells with monoterpenes including d-limonene, perillic acid and perillyl alcohol (0.5-5 mM) which selectively inhibit the isoprenylation of 21-26-kDa proteins resulted in a dose-dependent inhibition of DNA synthesis. Cell cycle analysis revealed that perillic acid arrested cells in G1 and prevented cells from entering S phase in a manner similar to that induced by the specific 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor, compactin. However, unlike compactin, the perillic acid-induced effects on lymphocyte proliferation were not prevented by addition of mevalonate. We also examined the incorporation of [3H]mevalonate into proteins in resting and phytohemagglutinin-stimulated lymphocytes during the first 30 h of culture. While in unstimulated lymphocytes radioactivity was predominantly incorporated into a cluster of 21-26-kDa proteins, mitogenic stimulation was associated with a striking increase in [3H]mevalonate incorporation into a protein (approximately 68 kDa) with migration characteristics similar to that of nuclear lamin B. Treatment of phytohemagglutinin-stimulated lymphocytes with 5 mM d-limonene, 2.5 mM perillic acid or 1.25 mM perillyl alcohol strongly suppressed [3H]mevalonate-labeling of proteins to a degree that correlated with the level of DNA synthesis inhibition. These findings suggest that those mevalonate-derived products required for lymphocyte proliferation may include one or more isoprenylated proteins and that the isoprenylation of these proteins is required for cell cycle progression.

Cell Cycle↗
PubMed1996

Antitumorigenic effects of limonene and perillyl alcohol against pancreatic and breast cancer.

Perillyl alcohol is a natural product from cherries and other edible plants. Perillyl alcohol and d-limonene, a closely related dietary monoterpene, have chemotherapeutic activity against pancreatic, mammary, and prostatic tumors. In addition, perillyl alcohol, limonene, and other dietary monoterpenes have chemopreventive activity. Several mechanisms may account for the antitumorigenic effects of monoterpenes. For example, many monoterpenes inhibit the post-translational isoprenylation of cell growth-regulatory proteins such as Ras. Perillyl alcohol induces apoptosis without affecting the rate of DNA synthesis in both liver and pancreatic tumor cells. In addition, monoterpene-treated, regressing rat mammary tumors exhibit increased expression of transforming growth factor beta concomitant with tumor remodeling/redifferentiation to a more benign phenotype. Monoterpenes are effective, nontoxic dietary antitumor agents which act through a variety of mechanisms of action and hold promise as a novel class of antitumor drugs for human cancer.

Animals↗
PubMed2001

Chiral discrimination of limonene by use of beta-cyclodextrin-coated quartz-crystal-microbalances (QCMs) and data evaluation by artificial neuronal networks.

The enantiomeric composition of the chiral flavoring agent limonene was analyzed by means of a quartz-crystal microbalance (QCM) sensor. As chiral selectors three different modified beta-cyclodextrins were investigated. The selector molecules were applied as mixtures in different polysiloxane matrices. The chiral separation factors alpha for limonene obtained at 30 degrees C by gas chromatography and by use of the QCM sensor were comparable. Evaluation of sensor data was performed by use of an artificial neuronal network (ANN); this enabled prediction of the enantiomeric composition of the gas mixtures.

Cyclodextrins↗
PubMed2001

Biotransformation of limonene by Pseudomonas putida.

From a study of three fungal and 15 bacterial strains, it was observed that Pseudomonas putida MTCC 1072 oxidized limonene with the highest efficiency of. Fermentation of limonene by P. putida MTCC 1072 was conducted for 120 h at 30 degrees C at a fixed pH of 5.0. Major bioconversion products were isolated and characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy, and by elemental analysis. The bioconversion products were identified as perillyl alcohol and p-menth-1-ene-6,8-diol, and under optimum conditions the yields were 36% and 44%, respectively (a rate kinetic model indicated corresponding limiting yields of 44% and 56%). No further degradation of the products was observed using this bacteria.

Bacteria↗
PubMed2004

Changes in eye blink frequency as a measure of trigeminal stimulation by exposure to limonene oxidation products, isoprene oxidation products and nitrate radicals.

OBJECTIVES: To measure eye blink frequency as a measure of trigeminal stimulation of the eye. Human subjects were exposed to oxidation mixtures representative of reactive indoor pollutants and clean air, from which relative changes in blink frequencies were measured. METHOD: Male subjects ( n=8) were exposed for 20 min to limonene oxidation products (LOPs), isoprene oxidation products (IOPs), nitrate radicals (NO(3)), their residual reactants, and clean air at 20% relative humidity. A baseline blink frequency was measured prior to and following each exposure (2 x 8 min). The subjects were exposed locally in the non-dominant eye and single blind in random order. Blinking was video-recorded and evaluated for full sessions of 36 min while the subjects viewed an educational film. The initial terpene concentrations were one to two orders of magnitude higher than mean indoor concentrations. RESULTS: The mean blink frequency increased significantly during subjects' exposure to gas-phase oxidation products at lower part-per-billion (ppb) levels of LOPs, 42% ( P<0.0001) and NO(3), 21% ( P<0.022), compared with that at baseline. Neither the residual reactants nor clean air changed the blink frequency significantly. The findings coincided with qualitative reporting of weak eye irritation symptoms. CONCLUSIONS: Changes in blink frequency appear to be a promising measure of trigeminal stimulation from exposure to eye irritants in ppb levels. Gaseous products of limonene and ozone, and reactive radicals may cause eye irritation indoors.

Adult↗
PubMed2005

A novel psychrotrophic fungus, Mortierella minutissima, for D-limonene biotransformation.

Of 98 strains of moulds, isolated from arctic soils, Mortierella minutissima 01, grew the best on agar plates with limonene vapor. Perillyl alcohol and perillic acid were the main products of limonene biotransformation. Maximal yield of perillyl alcohol (125 mg l(-1)) occurred in medium containing 0.8% substrate, at 15 degrees C, pH 6 and after 4-5 d.

Biotransformation↗
PubMed1996

Inhibition of metabolic activation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone by limonene.

Previous work by others shows that d-limonene (LIM) inhibits carcinogen-induced lung tumorigenesis in mice and strongly suggests that LIM can inhibit the metabolic activation of nitrosamines such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Thus, in the current study, the ability of LIM and other monoterpenes to inhibit the activation of the tobacco-specific NNK was examined in murine pulmonary and hepatic microsomes after addition in vitro or administration in vivo. LIM inhibited the metabolic activation of NNK in both pulmonary and hepatic microsomes. Perillyl alcohol was a more potent inhibitor than LIM, while p-menth-1-ene was equipotent with LIM. After administration of LIM, limonene 1,2-oxide, or perillyl alcohol in vivo, significant inhibition of cytochrome P450-mediated metabolites (NNK N-oxide and HPB) was found at 1 and 4 h after administration of monoterpene. These results indicate that LIM and other monoterpenes are effective inhibitors of NNK metabolic activation, and that other monoterpenes such as perillyl alcohol may be effective chemopreventive agents against NNK-induced lung tumorigenesis.

Animals↗
PubMed1998

Mechanisms of percutaneous absorption of tamoxifen by terpenes: eugenol, D-limonene and menthone.

The effect of chemical penetration enhancers (e.g., eugenol, d-limonene and menthone in combination with 50% ethanol) on the in vitro percutaneous absorption of tamoxifen through porcine epidermis has been investigated. The above enhancers significantly increased (p<0.05) the permeability coefficient of tamoxifen in comparison with the control (50% ethanol). Fourier transform infrared spectroscopy (FT-IR) was employed to investigate the biophysical changes in the stratum corneum (SC) lipids by the enhancer(s). FT-IR results showed that the treatment of the SC with enhancers did not produce a blue shift in the asymmetric and symmetric C-H stretching peak positions. However, all of the above enhancers showed a decrease in peak heights and areas for both asymmetric and symmetric C-H stretching absorbances in comparison with the untreated SC. A decrease in peak heights and areas is a measure of lipid extraction. Partitioning of tamoxifen to powdered SC from control and enhancer solutions was also determined. FT-IR and partitioning studies reveal that the enhancement in the permeability coefficient of tamoxifen by eugenol and d-limonene is due to lipid extraction and improvement in the partitioning of the drug to the SC. However, menthone enhanced the permeability of tamoxifen by increasing extraction of the SC lipids and not by improving the partitioning of the drug to the SC.

Animals↗
PubMed2002

Influence of limonene on the bioavailability of nicardipine hydrochloride from membrane-moderated transdermal therapeutic systems in human volunteers.

The aim of the present study was to develop a membrane-moderated transdermal therapeutic system (TTS) of nicardipine hydrochloride using 2%w/w hydroxy propyl cellulose (HPC) gel as a reservoir system containing 4%w/w of limonene as a penetration enhancer. The permeability flux of nicardipine hydrochloride through ethylene vinyl acetate (EVA) copolymer membrane was found to increase with an increase in vinyl acetate (VA) content in the copolymer. The effect of various pressure-sensitive adhesives (MA-31, MA-38 or TACKWHITE A 4MED) on the permeability of nicardipine hydrochloride through EVA membrane 2825 (28% w/w VA) or membrane/skin composite was also studied. The results showed that nicardipine hydrochloride permeability through EVA 2825 membrane coated with TACKWHITE 4A MED/skin composite was higher than that coated with MA-31or MA-38. Thus a new TTS for nicardipine hydrochloride was formulated using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE 4A MED and 2%w/w HPC gel as reservoir containing 4%w/w of limonene as a penetration enhancer. The bioavailability studies in healthy human volunteers indicated that the TTS of nicardipine hydrochloride, designed in the present study, provided steady state plasma concentration of the drug with minimal fluctuations for 20 h with improved bioavailability in comparison with the immediate release capsule dosage form.

Administration, Cutaneous↗
PubMed1999

Novel limonene phosphonate and farnesyl diphosphate analogues: design, synthesis, and evaluation as potential protein-farnesyl transferase inhibitors.

Limonene and its metabolite perillyl alcohol are naturally-occurring isoprenoids that block the growth of cancer cells both in vitro and in vivo. This cytostatic effect appears to be due, at least in part, to the fact that these compounds are weak yet selective and non-toxic inhibitors of protein prenylation. Protein-farnesyl transferase (FTase), the enzyme responsible for protein farnesylation, has become a key target for the rational design of cancer chemotherapeutic agents. Therefore, several alpha-hydroxyphosphonate derivatives of limonene were designed and synthesized as potentially more potent FTase inhibitors. A noteworthy feature of the synthesis was the use of trimethylsilyl triflate as a mild, neutral deprotection method for the preparation of sensitive phosphonates from the corresponding tert-butyl phosphonate esters. Evaluation of these compounds demonstrates that they are exceptionally poor FTase inhibitors in vitro (IC50 > or = 3 mM) and they have no effect on protein farnesylation in cells. In contrast, farnesyl phosphonyl(methyl)phosphinate, a diphosphate-modified derivative of the natural substrate farnesyl diphosphate, is a very potent FTase inhibitor in vitro (Ki=23 nM).

Alkyl and Aryl Transferases↗
PubMed2002

Degradation of the adsorbent Tenax TA by nitrogen oxides, ozone, hydrogen peroxide, OH radical, and limonene oxidation products.

The degradation of the adsorbent Tenax TA was studied qualitatively by sampling oxidants common in indoor air followed by thermal desorption and gas chromatography. A total of 25 degradation products were identified. Several degradation products not reported previously were identified: 9 for nitrogen dioxide; 11 for ozone; 2 for hydrogen peroxide; 12 for hydroxyl radical; 1 for ozone-limonene mixtures, but none for nitrogen oxide. Whereas ozone shows a complex degradation of the adsorbent, hydrogen peroxide and limonene--ozone mixtures show few products. Nitrogen dioxide and the hydroxyl radical behave almost identically and produce 2,6-diphenyl-p-benzoquinone as the major degradation product. Reactant specific degradation products were identified for ozone (11) and nitrogen dioxide (1).

Air Pollutants↗
PubMed2006

Impact of humidity on the ozone initiated oxidation of limonene, delta3-carene, and alpha-pinene.

The effect of water on the initial secondary organic aerosol (SOA) formation from gas-phase ozonolysis of limonene, delta3-carene, and alpha-pinene (-3 and approximately 1.5 x 10(11) molecule cm(-3) reacted) has been investigated in a flow reactor at controlled relative humidity (RH), temperature (298 +/- 0.4 K), and reaction time (270 +/- 2 s). Low amounts of terpene converted minimize the impact of secondary reactions. A comparison of the SOA formation from the three terpenes was made for initial rate of reactions being around 7.5 x 10(8) and 15 x 10(8) molecule cm(-3) s(-1). The most efficient species in producing SOA was limonene, while alpha-pinene was the least efficient. The results showed that an enhancement in water vapor concentration (<2-85% RH) caused an increase in both integrated mass (M10-300nm) and total number (N10-300nm). The effect on number and mass were a factor of 2-3 and 4-8, respectively. Physical water up-take can partly explain the increase in mass, but not the observed increase in number. Therefore it was concluded that the increase in water concentration must, by a gas-phase reaction, produce more low volatility product(s).

Air Pollutants↗
PubMed2006

Changes in membrane fatty acids composition of microbial cells induced by addiction of thymol, carvacrol, limonene, cinnamaldehyde, and eugenol in the growing media.

Major active compounds from essential oils are well-known to possess antimicrobial activity against both pathogen and spoilage microorganisms. The aim of this work was to determine the alteration of the membrane fatty acid profile as an adaptive mechanism of the cells in the presence of a sublethal concentration of antimicrobial compound in response to a stress condition. Methanolic solutions of thymol, carvacrol, limonene, cinnamaldehyde, and eugenol were added into growth media of Escherichia coli O157:H7, Salmonella enterica serovar typhimurium, Pseudomonas fluorescens, Brochothrix thermosphacta, and Staphylococcus aureus strains. Fatty acid extraction and gas chromatographic analysis were performed to assess changes in membrane fatty acid composition. Substantial changes were observed on the long chain unsaturated fatty acids when the E. coli and Salmonella strains grew in the presence of limonene and cinnamaldehyde and carvacrol and eugenol, respectively. All compounds influenced the fatty acid profile of B. thermosphacta, while Pseudomonas and S. aureus strains did not show substantial changes in their fatty acid compositions.

Acrolein↗
PubMed2006

Diffusion of limonene in polyethylene.

Diffusion coefficients of limonene in various linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE) resins have been determined from sorption data using a thermogravimetric methodology. From these data, one can determine whether polymer synthesis parameters such as the choice of catalytic process or co-monomer result in substantial differences in how much food packaging additives might migrate to food. For example, LLDPE is currently manufactured using either one of two distinct catalytic processes: Ziegler-Natta (ZN) and metallocene, a single-site catalyst. ZN catalysis is a heterogeneous process that has dominated polyolefin synthesis over the last half-century. It involves a transition metal compound containing a metal-carbon bond that can handle repeated insertion of olefin units. In contrast, metallocene catalysis has fewer than 20 years of history, but has generated much interest due to its ability to produce highly stereospecific polymers at a very high yield. In addition to high stereospecificity, metallocene-catalysed polymers are significantly lower in polydispersity than traditional ZN counterparts. Absorption and desorption testing of heat-pressed films made from LLDPE and LDPE resins of varying processing parameters indicates that diffusion coefficients of limonene in these resins do not change substantially.

Absorption↗
PubMedDate not supplied

Formulation and evaluation of limonene-based membrane-moderated transdermal therapeutic system of nimodipine.

The aim of the present study was to design a membrane-moderated transdermal therapeutic system (TTS) of nimodipine using 2% w/w hydroxypropyl methylcellulose (HPMC) gel as a reservoir system containing 4% w/w of limonene as a penetration enhancer. The permeability flux of nimodipine through ethylene vinyl acetate (EVA) copolymer membrane was found to increase with an increase in vinyl acetate content in the copolymer (9 to 28%). The effect of pressure-sensitive adhesives such as TACKITE A 4MED on the permeability of nimodipine through EVA membrane 2825 (28% w/w vinyl acetate) or membrane/rat skin composite also was studied. The permeability flux of nimodipine from the chosen EVA 2825 (with 28% vinyl acetate content) was 159.72 +/- 1.96 microg/cm2/hr, and this flux further decreased to 141.85 +/- 1.54 microg/cm2/hr on application of pressure-sensitive adhesive (TACKWHITE A 4MED). However, the transdermal permeability flux of nimodipine across EVA 2825 membrane coated with TACKWHITE A 4MED/rat skin composite was found to be 126.59 +/- 2.72 microg/cm2/hr, which is 1.3-fold greater than the required flux. Thus, a new transdermal therapeutic system for nimodipine was formulated using EVA 2825 membrane coated with a pressure-sensitive adhesive TACKWHITE 4A MED and 2% w/w HPMC gel as reservoir containing 4% w/w of limonene as a penetration enhancer. The bioavailability studies in healthy human volunteers indicated that the TTS of nimodipine, designed in the present study, provided steady-state plasma concentration of the drug with minimal fluctuations for 20 hr with improved bioavailability in comparison with the immediate release tablet dosage form.

Adjuvants, Pharmaceutic↗
PubMed2003

Solubilization of (+)-limonene by anionic/cationic mixed surfactant systems.

The combined effects of sodium n-octyl sulfate (SOS) and cetyltrimethylammonium bromide (CTAB) on the solubilization of (+)-limonene in aqueous solution were studied using a headspace gas chromatography technique. The findings showed the mixing of SOS and CTAB resulted in positive synergistic effects on the solubility of (+)-limonene. The positive synergistic effects are explained from the perspective of the phase behavior of this mixed surfactant system.

Alkanesulfonic Acids↗