Limonene Oxide Research Articles

The effect of cadmium on growth and composition of essential oils of Mentha piperita L.

Cadmium is a non-essential element that induces various toxic responses in plants when accumulated above the threshold level. The aim of the present research was to study the effect of cadmium on growth factors, concentration of cadmium in the rhizomes and leaves, and quality and quantity of essential oils in the leaves of Mentha piperita L. The experiment was carried out in a completely randomized design with three replications. Rhizomes with uniform weight were planted in pots 30 × 50 × 35 cm. After foliation of all rhizomes, plants were irrigated every other day, for 2 months by different concentrations of CdCl2 (0, 100, 500, and 1000 µM). Results demonstrated that the minimum stem length and fresh and dry weight of leaves were achieved in the plants treated with CdCl2 (500 µM). With increasing the cadmium in treatments, the amount of cadmium in the rhizomes and leaves were also increased. In treatment of CdCl2 (1000 µM) the accumulation of cadmium in the leaves was more than the rhizomes. There were not significant differences in the essential oils contents between treatments. Analysis of the chemical composition of essential oils indicated that the main constituents of all treated plants were 1, 8 Cineole, Dihydrocarvon, Pulegone, and Carvone. Limonene oxide was observed only in the leaves of control plants.

Emergence of Hyper-Resistant Escherichia coli MG1655 Derivative Strains after Applying Sub-Inhibitory Doses of Individual Constituents of Essential Oils.

The improvement of food preservation by using essential oils (EOs) and their individual constituents (ICs) is attracting enormous interest worldwide. Until now, researchers considered that treatments with such antimicrobial compounds did not induce bacterial resistance via a phenotypic (i.e., transient) response. Nevertheless, the emergence of genotypic (i.e., stable) resistance after treatment with these compounds had not been previously tested. Our results confirm that growth of Escherichia coli MG1655 in presence of sub-inhibitory concentrations of the ICs carvacrol, citral, and (+)-limonene oxide do not increase resistance to further treatments with either the same IC (direct resistance) or with other preservation treatments (cross-resistance) such as heat or pulsed electric fields (PEF). Bacterial mutation frequency was likewise lower when those IC's were applied; however, after 10 days of re-culturing cells in presence of sub-inhibitory concentrations of the ICs, we were able to isolate several derivative strains (i.e., mutants) displaying an increased minimum inhibitory concentration to those ICs. Furthermore, when compared to the wild type (WT) strain, they also displayed direct resistance and cross-resistance. Derivative strains selected with carvacrol and citral also displayed morphological changes involving filamentation along with cell counts at late-stationary growth phase that were lower than the WT strain. In addition, co-cultures of each derivative strain with the WT strain resulted in a predominance of the original strain in absence of ICs, indicating that mutants would not out-compete WT cells under optimal growth conditions. Nevertheless, growth in the presence of ICs facilitated the selection of these resistant mutants. Thus, as a result, subsequent food preservation treatments of these bacterial cultures might be less effective than expected for WT cultures. In conclusion, this study recommends that treatment with ICs at sub-inhibitory concentrations should be generally avoided, since it could favor the emergence of hyper-resistant strains. To ascertain the true value of EOs and their ICs in the field of food preservation, further research thus needs to be conducted on the induction of increased transient and stable bacterial resistance via such antimicrobial compounds, as revealed in this study.

Changes in Volatile Compounds during Aging of Sweet Fennel Fruits-Comparison of Hydrodistillation and Static Headspace Sampling Methods

Two extraction methods for subsequent gas chromatographic (GC) determination of volatiles from freshly harvested and aged fennel fruit samples (Foeniculum vulgare Mill.,ssp. vulgare var. dulce) have been compared. Hydrodistillation followed by GC-FID and GC-MS analysis was used as a standard method for essential oil characterization, while static headspace followed by GC (SHS-GC-FID) was used as a comparative method for determination of volatile components. As the fennel fruit ages, there is a gradual loss of the volatile components as indicated by the lower yield of essential oil and lower content of volatiles, as indicated by the alternative SHS-GC-FID analysis. Slight differences observed for the main components (trans-anethole, estragole, fenchone, and limonene) using the two methods are negligible, indicating that these volatiles did not undergo chemical transformation during the sample preparation procedures. A difference in anisaldehyde content was observed when the composition of the hydrodistilled essential oil was compared with the SHS-GC-FIDanalysis of volatiles and explanation for the variation of anisaldehyde content and the origin of other compounds was suggested. Comparison of the obtained results showed that limonene oxides, carvone and carveolare detectable in SHS-GC-FID analysis of the aged fennel fruits, while in hydrodistilled samples analyzed by GC-FID they were not present. Another observed difference was the appearance of products in significant amounts with higher retention times than trans-anethole, namely threo- and erythro-anethole β-hydroxymethylether and anethole glycol that are not detectable in the essential oil obtained by hydrodistillation. So, the relative abundance of the major components is comparable between these two methods for fennel seed up to 3 years from harvest and they can be used interchangeably depending on the purpose and amount of material. Furthermore, SHS-GC-FID can be used for assessment of maximum storage time and quality of fennel fruit suitable for human consumption.

Changes in Essential Oil Composition of Dill (Anethum graveolens L.) Grains in Response to Water Limitation and Nitrogen Fertilizer

In order to investigate the effects of irrigation and nitrogen fertilizer on essential oil composition of dill, this research was performed in 2010 at the Agricultural Research Farm of the University of Tabriz, Iran. The experiment was carried out as split plot on the basis of randomized complete block design with three replications. Irrigation treatments (irrigation after 70, 100 and 130 mm evaporation from class A pan) and nitrogen levels (0, 40, 80, 120 kgN/ha) were allocated to main and sub-plots, respectively. The essential oil from grains of dill was isolated by hydro distillation and analyzed by gas-chromatography (GC-MS). The main components of dill essential oil were found to be carvone (4.9 - 60.1 %), l-limonene (6.4 - 21.8 %), dillapiole (1.0-11.9 %), dihydrocarvone, apiole, l-phellandrene, hexacosane, octacosane, eicosane and anethole. The amount of cis-dihydrocarvone, trans- limonene oxide, limonene and dill ether were increased by water limitation. Nitrogen application increased carvone and dihydrocarvone in dill grains.

연속수증기증류추출법에 의한 오렌지와 자몽의 휘발성 유기화합물 확인

The volatile flavor components of the fruit pulp and peel of orange (Citrus sinensis) and grapefruit (Citrus paradisi) were extracted by simultaneous distillation-extraction (SDE) using a solvent mixture of n-pentane and diethyl ether (1:1, v/v) and analyzed by gas chromatography-mass spectrometry (GC-MS). The total volatile flavor contents in the pulp and peel of orange were 120.55 and 4,510.81 mg/kg, respectively, while those in the pulp and peel of grapefruit were 195.60 and 4,223.68 mg/kg, respectively. The monoterpene limonene was identified as the major voltile flavor compound in both orange and grapefruit, exhibiting contents of 65.32 and 3,008.10 mg/kg in the pulp and peel of orange, respectively, and 105.00 and 1,870.24 mg/kg in the pulp and peel of grapefruit, respectively. Limonene, sabinene, α-pinene, β-myrcene, linalool, (Z)-limonene oxide, and (E)-limonene oxide were the main volatile flavor components of both orange and grapefruit. The distinctive component of orange was valencene, while grapefruit contained (E)-caryophyllene and nootkatone. δ-3-Carene, α-terpinolene, borneol, citronellyl acetate, piperitone, and β-copaene were detected in orange but not in grapefruit. Conversely, grapefruit contained β-pinene, α-terpinyl acetate, bicyclogermacrene, nootkatol, β-cubebene, and sesquisabinene, while orange did not. Phenylacetaldehyde, camphor, limona ketone and (Z)-caryophyllene were identified in the pulp of both fruits, while α-thujene, citronellal, citronellol, α-sinensal, γ-muurolene and germacrene D were detected in the peel of both fresh fruit samples.

Organic aerosol molecular composition and gas–particle partitioning coefficients at a Mediterranean site (Corsica)

Molecular speciation of atmospheric organic matter was investigated during a short summer field campaign performed in a citrus fruit field in northern Corsica (June 2011). Aimedat assessing the performance on the field of newly developed analytical protocols, this work focuses on the molecular composition of both gas and particulate phases and provides an insight into partitioning behavior of the semi-volatile oxygenated fraction. Limonene ozonolysis tracers were specifically searched for, according to gas chromatography–mass spectrometry (GC–MS) data previously recorded for smog chamber experiments. A screening of other oxygenated species present in the field atmosphere was also performed. About sixty polar molecules were positively or tentatively identified in gas and/or particle phases. These molecules comprise a wide range of branched and linear, mono and di-carbonyls (C3–C7), mono and di-carboxylic acids (C3–C18), and compounds bearing up to three functionalities. Among these compounds, some can be specifically attributed to limonene oxidation and others can be related to α- or β-pinene oxidation. This provides an original snapshot of the organic matter composition at a Mediterranean site in summer. Furthermore, for compounds identified and quantified in both gaseous and particulate phases, an experimental gas/particle partitioning coefficient was determined. Several volatile products, which are not expected in the particulate phase assuming thermodynamic equilibrium, were nonetheless present in significant concentrations. Hypotheses are proposed to explain these observations, such as the possible aerosol viscosity that could hinder the theoretical equilibrium to be rapidly reached.

Bio-based polycarbonate from limonene oxide and CO2 with high molecular weight, excellent thermal resistance, hardness and transparency

Completely bio-based high molecular weight aliphatic poly(limonene carbonate) with excellent transparency, superior hardness compared to BPA-PC and a high Tg of 130 °C.

Uso de poliestireno expandido reciclado para la obtención de un recubrimiento anticorrosivo

Introduction. The use of organic solvents as raw material for diverse coatings applied in the prevention and control of corrosion in several industries and the high quantities of expanded polystyrene to be disposed after being used have generated a great controversy worldwide, as they have harmful effects on human health and on the environment. Objective. This study proposes the use of recycled expanded polystyrene, with limonene as a solvent, for its use as anti-corrosive. Materials and methods. Different formulas were developed, after being obtained corresponding to different quantities of recycled expanded polystyrene, limonene, titanium dioxide and zinc oxide, using a constant quantity of cobalt octoate as an additive. After preparing each formulation the anti-corrosive potential of the coating on carbon iron metal plates was assessed, by means of a salt spray chamber test. Result. By comparing the coating obtained with a commercial coating, in terms of efficiency and capacity to prevent and control corrosion, the conclusion is that the coating developed in this project only had a 10 % of its surface corroded, while the coating painted with the commercial coating had 50 % of its surface corroded. Conclusion. Good results in the anti-corrosion properties of the different coating formulations were obtained, thus making possible their use as anti-corrosive coating.

Litsea cubeba essential oil as the potential natural fumigant: Inhibition of Aspergillus flavus and AFB1 production in licorice

The study aimed to investigate the inhibitory activities of Litsea cubeba essential oil (LC-EO) on Aspergillus flavus and aflatoxin B1 production in licorice. The main chemical compositions of LC-EO, analyzed by gas chromatography–mass spectrometry (GC–MS), were (Z)-Limonene oxide (30.14%), (E)-Limonene oxide (27.92%) and D-Limonene (11.86%). The “ in vitro ” antifungal and antiaflatoxigenic properties of LC-EO were evaluated upon A. flavus. The headspace volatile assay showed more effective inhibition against A. flavus mycelial growth than contact assay with tested different concentrations of LC-EO. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of LC-EO were 0.5 and 1.0μL/mL with fumigation, respectively. The EO exhibited a high toxicity against three toxigenic isolates of A. flavus. Morphological investigation performed by the scanning electron microscopy (SEM) showed that the hyphae and conidiophores structures underwent alterations, following the treated with LC-EO. The fumigated hyphae grow abnormally, were introcession, enation and wilting of the cell surface, featuring the flat strip shape. Meanwhile, in view of the antifungal and antiaflatoxigenic activities, LC-EO was also assessed the inhibitory effect of AFB1 production “ in situ ” investigation on Chinese herbal medicines (CHMs) system by volatile assay. The results showed that LC-EO could strongly inhibit the accumulation of aflatoxin B1 in licorice after being inoculated and incubated with A. flavus for 20 days. Thus, LC-EO can potentially be used as a highly efficient and eco-friendly antifungal fumigant to control post-harvest fungi and AFB1 production in licorice in the storage process.

Fe/EuroPh catalysts for limonene oxidation to 1,2-epoxylimonene, its diol, carveol, carvone and perillyl alcohol

The catalysts in the form of an activated carbon EuroPh supported Fe were prepared and characterized structurally and chemically by XRD, nitrogen sorption, FESEM, EDX, and ICP-AES methods. The active phase was magnetite Fe3O4. The concentration of Fe in the catalysts was equal to 0.68, 1.32, 2.64wt%. The catalytic activity of the obtained catalysts was examined in limonene oxidation with hydrogen peroxide and tert-butyl hydroperoxide as oxidants. The studies were carried out in a batch reactor. The catalytic activity of the recovered catalysts was also tested. The research showed that all from the studied catalysts were active in the limonene oxidation. As a result of limonene oxidation the following products were mainly obtained: 1,2-epoxylimonene diol, carveol, carvone and perillyl alcohol – products with a great importance. The reused catalysts were characterized by considerably lover activity in the limonene oxidation than in the first run, especially when the oxidation was performed with t-butyl hydroperoxide.

The studies on the limonene oxidation over the microporous TS-1 catalyst

The studies on the oxidation of limonene with 60wt% hydrogen peroxide over the titanium silicalite TS-1 catalyst were carried out. The influence of the following parameters was examined: the temperature 0–120°C, the molar ratio of limonene/H2O2=1:2–5:1, methanol concentration 60–95wt%, TS-1 content 0.25–8wt% and the reaction time 15min to 11 days. The studies showed that the most beneficial conditions for the obtaining of high selectivity of 1,2-epoxylimonene, at simultaneously high values of the conversion of reactants and the efficiency of hydrogen peroxide, are as follows: the temperature 80°C, the molar ratio of limonene/H2O2=1:1, the methanol concentration 80wt%, the TS-1 content 3wt% and the reaction time 10 days. Moreover, the research showed that the process of limonene oxidation is very complicated, because during this process also other very useful oxygenated derivatives of limonene can be obtained, for example: perillyl alcohol, carveol, carvone and 1,2-epoxylimonene diol. The studies on the reuse of the TS-1 catalyst showed that it is very stable catalyst at the studied conditions and it can be recycled to the oxidation process at least three times.

Foeniculum sanguineum Triano y A. Pujadas (Apiaceae) nueva especie del suroeste de la Región Mediterránea

Se describe Foeniculum sanguineum Triano & A. Pujadas, sp. nov., del suroeste de la Región Mediterránea (España y Marruecos). Para su caracterización se ha realizado el análisis morfológico, citológico, fitoquímico y molecular. Se ha llevado a cabo el studio comparativo con Foeniculum vulgare Mill. La nueva especie F. sanguineum se distingue principalmente por sus pétalos rojos, polen rosado en fresco y por su estilopodio rojo. Es una especie diploide (2n= 22). Se ha encontrado una alta proporción de óxido de limoneno y piperitenona (ausente en F. vulgare) en la composición de aceite esencial de los frutos secos de F. sanguineum y una elevada cantidad (aproximadamente 50%) de α-felandreno en sus raíces y tallos. El análisis filogenético se realizó utilizando las secuencias del espaciador transcrito interno de ADN ribosomal nuclear (ITS) y las secuencias del gen cloroplástico rbcL. El análisis ITS apoya la existencia de la nueva especie, al tiempo que revela la divergencia de secuencias tanto a nivel intraespecífico como a nivel interespecífico. La divergencia de secuencia encontrada en el gen cloroplástico, aunque reducida a un nucleótido, proporcionó apoyo adicional para la caracterización de la nueva especie, para la que se propone el nombre de Foeniculum sanguineum.

The oxidation of limonene at raised pressure and over the various titanium-silicate catalysts

Abstract This work presents the studies on the oxidation of limonene with hydrogen peroxide and tert-butyl hydroperoxide (TBHP) in the presence of : TS-2, Ti-Beta, Ti-MCM-41 and Ti-MWW catalysts, at the autogenic pressure and atmospheric pressure. The examination were performed at the following conditions: the temperature of 140°C (studies in the autoclave) and 80°C (studies in glass reactor), the molar ratio of limonene/oxidant (H2O2 or WNTB) = 1:1, the methanol concentration 80 wt%, the catalyst content 3 wt%, the reaction time 3 h and the intensity of stirring 500 rpm. The analysis of the results showed that in process not only 1,2-epoxylimonene was formed but also: 1,2-epoxylimonene diol, carveol, carvone and perillyl alcohol but for 1,2-epoxylimonene obtaining the better method was the method at the autogenic pressure and in the presence of TBHP.

Hydrophobic effect of silica functionalized with silylated Ti-salicylaldimine complex on limonene oxidation by aqueous hydrogen peroxide

This research work describes the effect of hydrophobicity in inducing the diffusion of alkene substrates to the catalytic active sites. The aim of this research is to improve the catalytic activity by tailoring the degree of hydrophobicity of the catalyst. Silica functionalized with solid non-silylated Ti-salicylaldimine complex was prepared at room temperature by mixing imine ligand and Ti(IV) sulphate solution. The amorphous, solid complex formed was further silylated with octadecyltrimethoxysilane (OTMS) to induce hydrophobicity. The composition of the resulting silica functionalized with silylated Ti-salicylaldimine complex was varied with Ti:OTMS molar ratio in the range of 1:1/4 to 1:4 at room temperature. The successful attachment of alkylsilyl groups to silica functionalized with Ti-salicylaldimine complex was proven by the FTIR and 29Si solid state NMR spectra. The FTIR spectra showed increasing peak area for sp 3 C-H stretching mode (ca. 2919 cm−1 and 2850 cm−1) and decreasing peak area for Si-OH band with increasing amount of OTMS. TGA showed less water content with higher amount of alkylsilyl groups in the catalyst. This is in agreement with the lower kinetic rate of water adsorption capacity for the hydrophobic catalysts prepared. It was observed that the hydrophobic, silica functionalized with silylated Ti-salicylaldimine complex exhibited higher substrate conversion and reusability compared to the non-silylated catalyst. Silica functionalization with silylated Ti-salicylaldimine complex was varied with octadecyltrimethoxysilane (OTMS) concentration to induce hydrophobicity. It was found that the higher degree of hydrophobicity has decreased the water content. Hence, the catalytic activity and TON for Ti increased. It showed that the surface property is important in the design of catalysts.

Heterogeneous radical-generating catalysts based on cationic surfactants

Proceeding from the earlier finding that cationic surfactants are capable of forming mixed micelles with amphiphilic hydroperoxides (LOOH) and catalyzing their decomposition to free radicals, heterogeneous catalysts for the radical degradation of LOOH have been prepared by depositing the cationic surfactant cetyltrimethylammonium bromide (CTAB) onto the solid supports montmorillonite (M1), microcrystalline cellulose (Cel1), and chitosan (Chi1). The performance of the obtained colloid catalysts in generating radicals in a hydroperoxide-containing medium decreases in the order Cel1 > Chi1 > M1 for the radical chain styrene polymerization process in the presence of cumyl hydroperoxide or row Cel1 > M1 > Chi1 in the case of limonene oxidation. The low activity of M1 in the initiation of polymerization is probably due to partial heterolytic decomposition of cumyl hydroperoxide on montmorillonite to give phenol.

Efficient Epoxide Hydrolase Catalyzed Resolutions of (+)‐ and (−)‐cis/trans‐Limonene Oxides

AbstractThe synthesis of enantiomerically pure cis‐ and trans‐limonene oxides and their corresponding diols from easily accessible raw materials has been of much interest for a long time. A straightforward one‐step biocatalytic resolution of the (+)‐cis/trans limonene oxide and the (−)‐cis/trans‐limonene oxide has been investigated. Epoxide hydrolases showing complementary stereoselectivity were recombinantly expressed in Escherichia coli, which allowed easy purification. The conditions for the selective epoxide hydrolase catalyzed ring‐opening reactions have been optimized and enabled the preparation of all limonene oxide enantiomers. The described utilization of recombinant epoxide hydrolases for the synthesis of all limonene oxide enantiomers was superior to chemical routes and represents a highly resource‐efficient one‐step preparation.

Reaction Kinetics of Trans-Sobrerol and 8-p-Menthen-1,2-diol with Hydroxyl Radical in Aqueous Solution: A Combined Experimental and Theoretical Study

Trans-sobrerol (Sob) and 8-p-menthen-1,2-diol (Limo-diol) are the primary products in the atmospheric oxidation of β-pinene and limonene, respectively. Because of their low volatility, they associate more likely to the liquid particles in the atmosphere, where they are subject to the aqueous phase oxidation by the atmospheric oxidants. In this work, through experimental and theoretical study, we first provide the rate constants of Sob and Limo-diol reacting with hydroxyl radical (·OH) in aqueous solution at room temperature of 304±3 K and 1 atm pressure, which are (3.05±0.5)×109 and (4.57±0.2)×109 L/(mol·s), respectively. Quantum chemistry calculations have also been employed to demonstrate the solvent effect on the rate constants in aqueous phase and the calculated results agree well with the measurements. Some reaction products have been identified based on liquid chromatography combined with mass spectroscopy and theoretical calculations.

Dynamics in Polysaccharide Glasses and Their Impact on the Stability of Encapsulated Flavors

The aim of this work is to examine the correlation between measured instability of model flavor compounds in glassy matrices with the calorimetric relaxation times of the matrices. Spray-dried carbohydrate matrices were chosen as the model compounds for this study. Enthalpy relaxation times were determined for spray-dried carbohydrate matrices using differential and isothermal calorimetric methods. The losses of the volatile methyl acetate, ethyl acetate and limonene, as well as formation of limonene oxidation products, were measured by gas chromatography. Storage conditions were 30 and 40 °C, with samples equilibrated with 11, 23, 33 and 43 % RH at each temperature. A comparison of the relaxation times for temperatures below Tg was made using Modulated DSC (MDSC) and a Thermal Activity Monitor (TAM). TAM yields significantly lower values for relaxation times implying that it is capturing some of the faster dynamics as well as dynamics that are activated near Tg. However, plots of relaxation times as determined by both techniques versus temperature appear to converge at Tg. An increase in the relative humidity results in moderately higher loss of volatiles (methyl acetate, ethyl acetate and limonene) and greater oxidation rates. In general, there is a good correlation between relaxation time and stability, with greater enthalpy relaxation time associated with better stability. Enthalpy relaxation time appears to be a useful predictor of stability for both loss of volatiles and oxidation of limonene.

Crystallization of Alternating Limonene Oxide/Carbon Dioxide Copolymers: Determination of the Crystal Structure of Stereocomplex Poly(limonene carbonate)

The crystal structure of the alternating copolymer of limonene epoxide and carbon dioxide has been studied. Highly stereoregular and regioregular alternating copolymers have been prepared starting from cis/trans mixtures of both enantiopure (R) and (S) isomers of 1-methyl-4-(1-methylvinyl)-7-oxabicyclo[4.1.0] heptane (limonene oxide) using a β-diiminate zinc complex under mild conditions of temperature and pressure, to yield enantiopure poly(1S,2S,4R-limonene carbonate) (PRLC) and poly(1R,2R,4S-limonene carbonate) (PSLC) products, respectively. Attempts to crystallize the pure enatiomers failed, whereas racemic mixtures readily crystallize from solution, forming racemic crystals. In the crystals, enantiomorphic chains are packed in an orthorhombic unit cell with axes a = 9.71 ± 0.05 A, b = 10.68 ± 0.05 A, and c = 11.31 ± 0.05 A (chain axis) according to the space group Pbc21 and 2 chains (4 monomeric units)/unit cell. The chain periodicity c of 11.31 A can be accounted for by a s(2/1) helical conformation...

Effect of mercaptoethanol on the hydrocarbon oxidation and cis—trans-isomerization of unsaturated lipids

The kinetics of the oxidation of ethylbenzene, limonene, and methyl linoleate containing mercaptoethanol additives were studied, as well as cis—trans-isomerization of the double bonds in methyl linoleate. Mercaptoethanol (RSH) additives were found to accelerate the oxidation of hydrocarbons and methyl linoleate due to the reaction of RSH with hydroperoxides (primary oxidation products) resulting in a low yield of free radicals. The cis—trans-isomerization catalyzed by thiyl radicals produced in the exchange radical reactions with RSH decelerates in the presence of oxygen.