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At least 109 records · Page 6Linked to original sources
PubMed2004

Electronic nose screening of limonene release from multicomponent essential oils encapsulated in pectin gels.

Multicomponent essential oils Tagetes Minuta and Poleo as well as pure limonene were encapsulated in Tween doped-high methoxylated pectin gels. Optical microscopy reveals that the obtained gels containing limonene consisted in a highly heterogeneous oil-in-water emulsion stabilised by the gelled medium. The influence of limonene encapsulation in pectin gelation kinetics and the gel structural properties were followed by dynamic rheological measurements. An electronic nose device developed in our laboratory was used to follow the flavour release of the three systems in order to discriminate the samples according to the main components released to the headspace. PCA and Neural Network Analysis allowed us to discriminate Tagetes Minuta from Poleo due to the difference in their limonene content. It is remarkable that the fingerprints of encapsulated complex mixtures differ from those obtained for the non-encapsulated oils, showing a preferential release of some components. In the case of limonene, the effect of the encapsulated concentration on the detected odour was also studied.

Cyclohexenes↗
PubMed1992

Benzaldehyde, citral, and d-limonene flavor perception in the presence of casein and whey proteins.

The effect of sodium caseinate and whey protein concentrate on benzaldehyde, d-limonene, and citral flavor intensity was determined by quantitative descriptive analysis deviation from reference using a 12-member trained panel. The concentrations for the benzaldehyde, d-limonene, and citral flavor intensity references were 17.8, 53.0, and 19.8 ppm, respectively. The concentration for both protein references was .25%. Flavored protein solutions were held for 17 h at 6 degrees C and contained benzaldehyde (17.8 ppm), d-limonene (53 ppm), or citral (19.8 ppm) and 2.5% sucrose with 0, .125, .25, or .5% protein. Benzaldehyde flavor intensity declined as the whey protein concentrate concentration increased from 0 to .5%. There was no significant difference in benzaldehyde flavor intensity with casein compared with the reference. The d-limonene flavor intensity declined as the protein concentration increased. Panelists found no significant drop in citral flavor intensity with casein or whey protein. Decreased benzaldehyde and d-limonene flavor intensity in the presence of whey protein concentrate or casein may be due to nonpolar interactions (casein), interaction with nonpolar binding sites, cysteine-aldehyde condensation, or Schiff base formation (whey protein concentrate).

Acyclic Monoterpenes↗
PubMed2004

Molecular cloning and identification of a novel oxygenase gene specifically induced during the growth of Rhodococcus sp. strain T104 on limonene.

Rhodococcus sp. strain T104 is able to utilize both limonene and biphenyl as growth substrates. Furthermore, T104 possesses separate pathways for the degradation of limonene and biphenyl. Previously, we found that a gene(s) involved in limonene degradation was also related to indigo-producing ability. To further corroborate this observation, we have cloned and sequenced a 8,842-bp genomic DNA region with four open reading frames, including one for indole oxygenase, which converts indole to indigo (a blue pigment), The reverse transcription PCR data demonstrated that the identified indole oxygenase gene is specifically induced by limonene, thereby implicating this gene in the degradation of limonene by T104.

Cloning, Molecular↗
PubMed1992

Influence of limonene and laurocapram on percutaneous absorption of nonsteroidal anti-inflammatory drugs.

The promoting effect of cyclic monoterpenes, 1% limonene (CAS 5989-27-5) and 1% cineole (CAS 470-82-6), on percutaneous absorption of nonsteroidal anti-inflammatory drugs was investigated in the rats. Compared with 1% laurocapram, drug absorption from the gel ointments was significantly more enhanced by addition of 1% limonene, while without any enhancer only ibuprofen penetrated across the skin in the limited amount. When using formulation with propylene glycol or 50% propylene glycolethanol solution, instead of carboxyvinyl polymer gel, percutaneous absorption significantly decreased and neither limonene nor cineole or laurocapram were capale to promote percutaneous absorption of flufenamic acid to sufficient serum level. Cineole and limonene were also evaluated in permeation experiments in vitro. Enhancement ability of limonene in the gel oinment was approximately 5 times higher comparing with enhancement ratio of cineole, while in 100% propylene glycol enhancement ability of both cyclic monoterpenes was equal. Good correlation was observed between in vivo and in vitro experiments. Evaluation of solubility proved that in the gel ointment simulated as water-ethanol solution were relatively best condition for percutaneous absorption of flufenamic acid when comparing with propylene glycol or 50% propylene glycol-ethanol solution.

Administration, Topical↗
PubMed2005

[Study on preparation technology of limonene dropping pills].

OBJECTIVE: To study the technical preparation of limonene dropping pills. METHODS: Orthogonal test was applied to optimize the preparation of limonene dropping pills. RESULTS: The optimized project was as follow: the matrix contained PEG4000: PEG6000 (1:1.5); the refrigerant was liquid paraffin; the rate of limonene to matrix was 1:6 and the temperature of limonene was 70 degrees C; the internal and external diameter of burette was 2.0 mm and 2.4 mm, respectively; the burette was 4cm above the surface of refrigerant; drug was dropped into refrigerant of 15 degrees C at 45 drops per minute. CONCLUSION: The results provide the data for the ascertainment of shaping operation of limonene dropping pills at the manufacturing scale.

Analysis of Variance↗
PubMed2006

[Proliferation inhibition and apoptosis induction of K562 cells by D-limonene].

This study was aimed to investigate the effect of D-limonene on K562 leukemia cells and its mechanism. Inhibitory effect of D-limonene on proliferation of K562 leukemia cells was assayed by MTT method and cell apoptosis was detected by flow cytometry and DNA agarose gel electrophoresis, the morphologic change of K562 cells was observed by microscopy. The results showed that when K562 cells were treated with 0.125 - 1.0 mmol/L of D-limonene for 48 hours, the proliferation of K562 cells was obviously inhibited in dose-dependent manner. Typical morphological changes and the typical DNA ladder on agarose gel electrophoresis for analysis of cellular apoptosis were significantly appeared in D-limonene treated K562 cells. Simultaneously, the sub-G1 peak was found in FCM analysis. It is concluded that the D-limonene can inhibit proliferation of K562 cells in dose-dependent manner, cause cell detained at G1 phase and induce apoptosis of K562 cells.

Antineoplastic Agents↗
PubMed1996

Identification and characterization of limonene metabolites in patients with advanced cancer by liquid chromatography/mass spectrometry.

Limonene is a farnesyl transferase inhibitor that has shown antitumor properties. The drug had been given orally to cancer patients. Plasma and urine samples collected from the patients were examined by reversed-phase HPLC-atmospheric pressure chemical ionization and electrospray ionization MS. The drug underwent rapid conversion to hydroxylated and carboxylated derivatives. Characterization and structural elucidation of the metabolites were achieved by LC/MS and NMR. Five major metabolites were detected in the plasma extracts, namely limonene-1,2-diol, limonene-8,9-diol, perillic acid, an isomer of perillic acid, and dihydroperillic acid. Urinary metabolites comprised the glucuronides of the two isomers of perillic acid, dihydroperillic acid, limonene-8,9-diol, and a monohydroxylated limonene.

Adult↗
PubMed1992

Characterization and mechanism of (4S)-limonene synthase, a monoterpene cyclase from the glandular trichomes of peppermint (Mentha x piperita).

(4S)-Limonene synthase, a monoterpene cyclase isolated from the secretory cells of the glandular trichomes of Mentha x piperita (peppermint), catalyzes the cyclization of geranyl pyrophosphate to (4S)-limonene, a key intermediate in the biosynthesis of p-menthane monoterpenes in Mentha species. The enzyme synthesizes principally (-)-(4S)-limonene (greater than 94% of the total products), plus several other monoterpene olefins. The general properties of (4S)-limonene synthase resemble those of other monoterpene cyclases. The enzyme shows a pH optimum near 6.7, an isoelectric point of 4.35, and requires a divalent metal ion for catalysis, either Mg2+ or Mn2+, with Mn2+ preferred. The Km value measured for geranyl pyrophosphate was 1.8 microM. The activity of (4S)-limonene synthase was inhibited by sodium phosphate, sodium pyrophosphate, and reagents directed against the amino acids cysteine, methionine, and histidine. In the presence of Mn2+, geranyl pyrophosphate protected against cysteine-directed inhibition, suggesting that at least one cysteine residue is located at or near the active site. Experiments with alternate substrates and substrate analogs confirmed many elements of the proposed reaction mechanism, including the binding of geranyl pyrophosphate in the form of a complex with the divalent metal ion, the preliminary isomerization of geranyl pyrophosphate to linalyl pyrophosphate (a bound intermediate capable of cyclization), and the participation of a series of carbocation:pyrophosphate anion pairs in the reaction sequence.

Chromatography, DEAE-Cellulose↗
PubMed2005

Catalytic mechanism of limonene epoxide hydrolase, a theoretical study.

The catalytic mechanism of limonene epoxide hydrolase (LEH) was investigated theoretically using the density functional theory method B3LYP. LEH is part of a novel limonene degradation pathway found in Rhodococcus erythropolis DCL14, where it catalyzes the hydrolysis of limonene-1,2-epoxide to give limonene-1,2-diol. The recent crystal structure of LEH was used to build a model of the LEH active site composed of five amino acids and a crystallographically observed water molecule. With this model, hydrolysis of different substrates was investigated. It is concluded that LEH employs a concerted general acid/general base-catalyzed reaction mechanism involving protonation of the substrate by Asp101, nucleophilic attack by water on the epoxide, and abstraction of a proton from water by Asp132. Furthermore, we provide an explanation for the experimentally observed regioselective hydrolysis of the four stereoisomers of limonene-1,2-epoxide.

Bacterial Proteins↗
PubMed2000

A single amino acid substitution (F363I) converts the regiochemistry of the spearmint (-)-limonene hydroxylase from a C6- to a C3-hydroxylase.

The essential oils of peppermint and spearmint are distinguished by the position of oxygenation on the constituent p-menthane monoterpenes. Peppermint produces monoterpenes bearing an oxygen at C3, whereas spearmint produces monoterpenes bearing an oxygen at C6. Branching of the monoterpene biosynthetic pathways in these species is determined by two distinct cytochrome P450s that catalyze the regiospecific hydroxylation of (-)-4S-limonene at C3 or C6 exclusively. cDNAs encoding the limonene-3-hydroxylase from peppermint and the limonene-6-hydroxylase from spearmint have been isolated, shown to be 70% identical at the amino acid level, and functionally expressed. A combination of domain swapping and reciprocal site-directed mutagenesis between these two enzymes demonstrated that the exchange of a single residue (F363I) in the spearmint limonene-6-hydroxylase led to complete conversion to the regiospecificity and catalytic efficiency of the peppermint limonene-3-hydroxylase.

Amino Acid Sequence↗
PubMed1980

Metabolism of limonene-1,2-epoxide in the rat.

1. The metabolism of limonene-1,2-epoxide was studied following intraperitoneal injection in rats and in rat liver homogenates. 2. Limonene-1,2-glycol was the only neutral metabolite detected. Major limonene metabolites, p-mentha-2,8-dien-1-alpha and -beta-ol and p-mentha-1,8-dien-6-alpha and -beta-ol were not observed. 3. Limonene-1,2-epoxide is not a major intermediate in limonene metabolism in the rat.

Animals↗
PubMed1993

4S-limonene synthase from the oil glands of spearmint (Mentha spicata). cDNA isolation, characterization, and bacterial expression of the catalytically active monoterpene cyclase.

The committed step in the biosynthesis of monoterpenes in mint (Mentha) species is the cyclization of geranyl pyrophosphate to the olefin (-)-4S-limonene catalyzed by limonene synthase (cyclase). Internal amino acid sequences of the purified enzyme from spearmint oil glands were utilized to design three distinct oligonucleotide probes. These probes were subsequently employed to screen a spearmint leaf cDNA library, and four clones were isolated. Three of these cDNA isolates were full-length and were functionally expressed in Escherichia coli, yielding a peptide that is immunologically recognized by polyclonal antibodies raised against the purified limonene synthase from spearmint and that is catalytically active in generating from geranyl pyrophosphate a product distribution identical to that of the native enzyme (principally limonene with small amounts of the coproducts alpha- and beta-pinene and myrcene). The longest open reading frame is 1800 nucleotides and the deduced amino acid sequence contains a putative plastidial transit peptide of approximately 90 amino acids and a mature protein of about 510 residues corresponding to the native enzyme. Several nucleotide differences in the 5'-untranslated region of all three full-length clones suggest the presence of several limonene synthase genes and/or alleles in the allotetraploid spearmint genome. Sequence comparisons with a sesquiterpene cyclase, epi-aristolochene synthase from tobacco, and a diterpene cyclase, casbene synthase from castor bean, demonstrated a significant degree of similarity between these three terpenoid cyclase types, the first three examples of this large family of catalysts to be described from higher plants.

Amino Acid Sequence↗
PubMed1999

Attenuation by d-limonene of sodium chloride-enhanced gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.

The effects of prolonged administration of d-limonene, a monocyclic monoterpene, on sodium chloride-enhanced induction of gastric carcinogenesis by N-methyl-N'-nitro-N-nitrosoguanidine, the labeling and apoptotic indices, and ornithine decarboxylase (ODC) activity of gastric cancers were investigated in Wistar rats. After 25 weeks of carcinogen treatment, rats were given chow pellets containing 10% sodium chloride and 1% limonene ad libitum. In week 52, the incidence of gastric cancers, the labeling index and ODC activity were significantly higher and the apoptotic index was significantly lower in rats given sodium chlolide than in untreated control rats. However, in rats given both sodium chloride and d-limonene, the incidence of gastric cancers, the labeling index and ODC activity were significantly lower and the apoptotic index was significantly higher than in rats given sodium chloride alone. Our findings suggest that limonene attenuates the gastric carcinogenesis enhanced by sodium chloride via increased apoptosis and decreased ODC activity in gastric cancers.

Animals↗
PubMed1994

Limonene in expired lung air of patients with liver disease.

As part of an effort to examine the relationship between chemosensory disturbance and oral chemistry, we analyzed expired lung air samples from a series of 24 patients with liver disease and 24 healthy controls using gas chromatography-mass spectrometry. Compared to samples from controls, lung air from patients with liver disease contained unusually high levels of limonene, a monoterpene that is a major component of the essential oil of citrus fruits (0.1 vs 7.0 micrograms/20 liters for controls and patients). Only half the patients showed high levels of limonene. Patients with noncholestatic liver disease were significantly more likely to have elevated lung air limonene levels than those with cholestatic liver disease (0.2 vs 13.8 micrograms/20 liters). Responses to food frequency and dietary behavior questionnaires indicated a pattern of diet selection and food preferences that were consistent with a dietary origin for the limonene in these patients.

Air↗
PubMedDate not supplied

Influence of d-limonene on the transdermal penetration of felodipine.

Felodipine is a calcium antagonist, one of the dihydropyridines, with potential application in transdermal therapeutic systems (TTS). Earlier studies reported that the high lag time of this drug limited its potential development in a TTS. The present study analyzes the effect of d-limonene at concentrations of 0.5, 1, 5 and 10% on the transdermal penetration of this drug. The study was performed using a diffusion technique in vitro, with the skin of the hairless rat. d-Limonene significantly reduced the lag time (Tl) to 1.4 h at a concentration of 1% (compared with 9.8 h in its absence). Higher concentrations did not produce a significant decrease in the value of this parameter. The presence of d-limonene in the formulae produces an increase in the permeability constant (Kp) and the flux (J). The relation between this increase and the percentage of d-limonene was non-linear. An asymptotic value was obtained at a concentration of 5%, with increases of 993% and 1570% for Kp and J, respectively.

Administration, Cutaneous↗
PubMed2001

Bioconversion of limonene to increased concentrations of perillic acid by Pseudomonas putida GS1 in a fed-batch reactor.

Pseudomonas putida GS1 is able to convert limonene to perillic acid (up to 64 mM,(11 g/l) when the bacteria is cultivated in fed-batch culture with non-limiting amounts of glycerol. ammonium, and limonene. P. putida GS1 can use p-cymene as a single source of carbon and energy, and the enzymes that are responsible for the conversion of limonene to perillic acid belong to the degradation pathway of p-cymene. The p-cymene pathway of P putida GS1 is very similar, if not identical, to the cym pathway of P. putida F1. The latter strain, and a recombinant Escherichia coli strain that carried the genes of the cym pathway of P. putida Fl, also converted limonene to perillic acid. However, the final concentrations that were obtained in batch cultures with these two strains were lower than those obtained with P. putida GS1.

Bioreactors↗
PubMed1996

d-limonene mechanistic data and risk assessment: absolute species-specific cytotoxicity, enhanced cell proliferation, and tumor promotion.

d-Limonene produces tumors only in the kidneys of male rats in association with hyaline-droplet nephropathy, which is due to the accumulation of the rat-specific, low molecular weight protein alpha(2u)-globulin in the P2 segment cells of renal proximal tubules. Human urine contains no alpha(2u)-globulin and, compared with the male rat, much less protein and almost no low molecular weight protein. Genotoxicity tests for d-limonene are negative, and the mechanism of tumorigenesis involves tumor promotion and enhanced cell proliferation. There is no risk of cancer for humans from d-limonene, since the binding of d-limonene to alpha(2u)-globulin would not occur.

Animals↗
PubMed1995

Induction of protein droplet (alpha 2 mu-globulin) nephropathy in male rats after short-term dosage with 1,8-cineole and l-limonene.

As part of a series of short-term studies on peppermint oil constituents for their possible induction of the encephalopathy found with peppermint oil, 1,8-cineole and l-limonene were studied. Groups of 10 male Wistar rats were given 0, 500, or 1000 mg 1,8-cineole/kg body wt./day or 0, 800, or 1600 mg l-limonene/kg body wt./day for 28 days. 1,8-Cineole and l-limonene both induced accumulation of protein droplets containing alpha 2 mu-globulin in proximal tubular epithelial cells in male rats. These results suggest that both 1,8-cineole and l-limonene possibly belong to the group of chemicals characterized by their induction of excessive alpha 2 mu-globulin accumulation. Neither of the 2 substances induced encephalopathy.

Alpha-Globulins↗