Pinene Isomers Research Articles

Biotransformation as a source of potential controlling natural mixtures of Sitophilus zeamais

The mycelium of Pleurotus sapidus can be used as a biocatalyst for the organic biosynthesis due to the presence of enzymes such as lipoxygenases. The aim of this work was to improve the pesticide effect of α- and β-pinenes, the main components of Pinus spp. essential oils, to be used against pest through the bioconversion process. The lyophilized mycelium of P. sapidus was used as a biotransformation tool to upgrade the bioactivities of these monoterpene hydrocarbons. The biopesticide capacity of the mixtures of compounds obtained by bioconversion of pinene isomers was evaluated against Sitophilus zeamais. Additionally, the differences in the biotransformation products were determined. The mixture of α-pinene biotransformed products showed the best repellence against S. zeamais (RI100μL/L = −63.33 ± 15.85% at 120 min); however, both biotransformed mixtures presented low toxic effects (LC50 > 500 μL/L), while the pure compounds presented medium toxicities (LC50 α-pinene = 296.65 μL/L and LC50 β-pinene = 310.47 μL/L). Thus, the biotransformation of low-cost essential oils proves an alternative process to develop environmentally-friendly repellents by recycling forest industry side-streams.

Volatolomics of Three South African Helichrysum Species Grown in Pot under Protected Environment.

Helichrysum decorum DC, Helichrysum lepidissimum S. Moore, and Helichrysum umbraculigerum are three species traditionally used in the South African medicine. The present work deals with the investigation of the spontaneous emission and the essential oils obtained from these plants cultivated in open field under uniform conditions. Fractions of the volatile organic compounds of the three species were rich in monoterpene hydrocarbons, representing more than 70% of the total composition. Pinene isomers were the most representative compounds: β-pinene in H. decorum (53.0%), and α-pinene in H. lepidissimum (67.9%) and H. umbraculigerum (54.8%). These latter two species evidenced an important amount of sesquiterpene hydrocarbons (SH) especially represented by γ-curcumene (H. lepidissimum) and α- and β-selinene (H. umbraculigerum). On the contrary, in the EOs, sesquiterpenes compounds prevailed, representing more than 64% of the identified fraction to reach more than 82 and 87% in H. umbraculigerum and H. lepidissimum, respectively. Although the chemical classes and their relative abundances were comparable among the three species, the individual compounds of EOs showed large differences. In fact, caryophyllene oxide (26.7%) and γ-curcumene (17.4%) were the main constituents in H. decorum, and H. lepidissimum respectively, while neo-intermedeol (11.2%) and viridiflorol (10.6%) characterized H. umbraculigerum.

Dynamics of Isomeric and Enantiomeric Fractions of Pinene in Essential Oil of Picea abies Annual Needles during Growing Season.

Norway spruce (Picea abies (L.) H. Karst.) is one of the most important commercial tree species distributed naturally in the Boreal and subalpine forest zone of Europe. All parts of spruce trees, including needles, accumulate essential oils with a variety of chemical properties and ecological functions, such as modulating plant–insect communication. Annual needle samples from 15 trees (five from each of three habitats) of 15–17 years old were assayed for essential oils and their major compounds, including α-pinene, β-pinene, (1S)-(−)-α-pinene, and (1R)-(+)-α-pinene across a growing season. Results showed strong positive correlation between percentages of α- and β-pinene isomers (r = 0.69, p < 0.05) and between pinene isomers and essential oils: α-pinene correlated with essential oil stronger (r = 0.62, p < 0.05) than β-pinene (r = 0.33, p < 0.05). Correlation analyses performed with some weather conditions, including average monthly temperature, growing sum of effective temperatures over 5 °C, duration of sunshine, accumulated precipitation, relative humidity, and pressure, showed that temperature is the most important weather condition related to pinene dynamics: negative correlations of moderate strength were established between percentages of α- and β- pinenes and average monthly temperatures (r = −0.36, p < 0.01, n = 75 and r = −0.33, p < 0.01, n = 75, respectively). Out of pinene enantiomers, only (1S)-(−)-α-pinene showed some negative correlation with monthly temperature (r = −0.26, p < 0.05, n = 75). Different patterns of essential oil and pinene dynamics during growing season within separate habitats suggested that some genetic variables of Picea abies might be involved.

Covalent coupling fabrication of microporous organic network bonded capillary columns for gas chromatographic separation

Microporous organic networks (MONs) have shown great promise in separation science recently. Exploring novel, simple and convenient strategy to fabricate MONs coated capillary columns for gas chromatography (GC) still remains challenging but desirable for the development of MONs in chromatographic separation. To extend the potential application of MONs in separation science and to further develop novel method for the fabrication of MONs-based capillary columns, here we demonstrate a novel covalent coupling strategy to fabricate uniform MONs bonded capillary columns for GC separation of position isomers and hydrocarbons. The bare capillary column was firstly modified with (3-bromopropyl)trimethoxysilane to provide bromine sites for coupling with alkynyl monomers. The amino- and hydroxyl-functionalized MONs (MON-NH2 and MON-OH) were then directly grown onto the inner wall of the brominated capillary columns via the covalent coupling between bromine and alkynyl groups. The uniform MON-NH2 and MON-OH bonded capillary columns were obtained and showed good resolution for GC separation of dichlorobenzene, chlorotoluene, bromotoluene, and propylbenzene position isomers and many other hydrocarbons including linear alkanes, alkylbenzenes, pinene isomers, cyclohexane and benzene, ketones and aldehydes. The MONs bonded capillary columns also owned good lifetime and precision for dichlorobenzene isomers with the relative standard deviations (RSDs) of 0.2–0.3%, 1.2–2.1%, and 1.7–2.5% for retention time, peak height and peak area, respectively. In addition, the fabricated MON-NH2 and MON-OH bonded capillary columns offered better resolution than commercial InertCap-1, InertCap-5, InertCap-1701 and InertCap-WAX capillary columns for the separation of chlorotoluene and bromotoluene position isomers. These results revealed the feasibility of covalent coupling strategy to fabricate MONs-based stationary phases in GC, highlighting the potential of MONs in separation science.

In situ fabrication of microporous organic network coated capillary column for high resolution gas chromatographic separation of hydrocarbons.

Microporous organic networks (MONs) are a new class of porous materials synthesized via Sonogashira coupling reactions between organic building blocks. Here we report an in situ synthesis approach to fabricate MONs coated capillary column for high resolution GC separation of hydrocarbons. The McReynolds constant evaluation reveals the MONs coated capillary is a non-polar column. The MONs coated capillary column shows good resolution for GC separation of diverse important industrial hydrocarbons such as linear and branched alkanes, alkylbenzenes, pinene isomers, ethylbenzene and styrene, cyclohexane and benzene. The MONs coated capillary column gave a high column efficiency of 1542 plates per meter for hexane and good precision for replicate separations of the selected hydrocarbons with the RSDs of 0.2-0.3, 1.5-3.1, and 1.9-3.3% for retention time, peak height and peak area, respectively. The MONs coated capillary also offered better resolution than commercial Inert Cap-1 and Inert Cap-5 capillary columns for hexane and heptane isomers. These results reveal the potential of MONs as novel stationary phases in GC.

Preconditions for industrial use of foliage as felling by-product of Scots pine for essential oil production

The aim of the study was to analyse some preconditions for the industrial production of Scots pine (Pinus sylvestris L.) essential oils including effects of storage temperatures of harvested foliage on the percentages of essential oils, α- and β-pinenes, and an estimate of potential resources of the foliage obtained from by-products of forest felling. The hypothesis was tested whether uncommon winter temperatures could provide favourable storage conditions of pine foliage to produce essential oils without a loss of yield. The study revealed that neither of the tested storage conditions of pine foliage (one month at +4°C, and one month at −24°C) had adverse effects on the total yield of essential oils if compared to the freshly collected foliage. The essential oil yield varied within 0.43–0.64%, showing the highest amount after storage at +4°C. Percentages of α and β isomers of pinene, the main compound of the essential oils, did not change significantly after the storage at both temperatures. Independently of the storage conditions, the (1R)-(+)-α-pinene was more prevalent than (1S)-(−)-α-pinene: the chiral analysis showed that (+) enantiomer was 3.1–5.8 times more abundant than (−) enantiomer. The tested storage temperatures span over the common temperatures of winter time in the region, when forest felling is being performed, and occur more notably with the climate change. Nevertheless, this provide favourable preconditions to produce essential oils without a loss from a pine foliage which could be obtained in large amounts from by-products of forest felling. The equations developed by different authors for the estimation of pine foliage biomass in the study area were used, and it was estimated that a mature 1-m3-stem-volume pine tree produces at least 10kg of fresh foliage biomass. Considering that the rate of the final felling of mature pinewoods in Lithuania remains at the current level of 700,000m3 of stem wood a year, the total estimated harvest of foliage is 7000t. This amount of foliage contains at least 35t of essential oils or 17.4kg of essential oils per hectare of mature pinewood on average. The resources of such magnitude are available on a yearly basis.

The electrochemical discrimination of pinene enantiomers by a cyclodextrin metal-organic framework.

Pinene is a family of bicyclic monoterpenes found in nature, which exhibits important applications in chemical industry and biomedicine; however, the discrimination methods used for pinene enantiomers are still rare. The alpha- and beta-pinene enantiomers were recognized and discriminated via an electrochemical method for the first time based on a cyclodextrin metal-organic framework (CD-MOF) as an electrochemical chiral sensor.

CD-MOF: A Versatile Separation Medium.

Porous metal-organic frameworks (MOFs) have been studied in the context of a wide variety of applications, particularly in relation to molecular storage and separation sciences. Recently, we reported a green, renewable framework material composed of γ-cyclodextrin (γ-CD) and alkali metal salts--namely, CD-MOF. This porous material has been shown to facilitate the separation of mixtures of alkylaromatic compounds, including the BTEX mixture (benzene, toluene, ethylbenzene, and the regioisomers of xylene), into their pure components, in both the liquid and gas phases, in an energy-efficient manner which could have implications for the petrochemical industry. Here, we report the ability of CD-MOF to separate a wide variety of mixtures, including ethylbenzene from styrene, haloaromatics, terpinenes, pinenes and other chiral compounds. CD-MOF retains saturated compounds to a greater extent than their unsaturated analogues. Also, the location of a double bond within a molecule influences its retention within the extended framework, as revealed in the case of the structural isomers of pinene and terpinine, where the isomers with exocyclic double bonds are more highly retained than those with endocyclic double bonds. The ability of CD-MOF to separate various mono- and disubstituted haloaromatic compounds appears to be controlled by both the size of the halogen substituents and the strength of the noncovalent bonding interactions between the analyte and the framework, an observation which has been confirmed by molecular simulations. Since CD-MOF is a homochiral framework, it is also able to resolve the enantiomers of chiral analytes, including those of limonene and 1-phenylethanol. These findings could lead to cheaper and easier-to-prepare stationary phases for HPLC separations when compared with other chiral stationary phases, such as CD-bonded silica particles.

Effect of pinene isomers on germination and growth of maize

Terpenes, secondary metabolites that are present in the essential oils of aromatic plants, are responsible for the biochemical interaction between plants, known as allelopathy. Monoterpenes are a major component of essential oils. Pinene is a monoterpene well-known for its phytotoxic action, but little is known about the allelopathic effect of its isomers. The aim of this study is to determine the effect of pinene's structural isomers and enantioisomers [(−)-α-pinene; (+)-α-pinene; (−)-β-pinene and (+)-β-pinene] at 0.16 mM, on certain physiological parameters (growth, dry weight, phenol, photosynthetic pigments and abscisic acid content) in both the germination and growth of maize (Zea mays L.). In germination bioassays, neither of the α-pinene stereoisomers showed change when compared to the control with respect to seed vigour; but root growth was increased, while β-pinene (racemic mixture) inhibited germination and plant length. In the growth bioassay, all of the pinene isomers decreased the plant length. In general, β-pinene terpene was more phytotoxic than α-pinene in both bioassays. Differences in germination and growth of maize treated with the pinene isomers can be attributed to different action mechanisms which depends both on the growth phases of maize and on the particular pinene isomers.

Variation of Chemical and Morphological Characters of Leaves and Unripe Cones in Juniperus Communis

Abstract The variation of content of essential oil and pinene isomers and morphological parameters of leaves and unripe cones in Juniperus communis L. was studied. Leaves and cones were collected separate from 110 J. communis individuals in 11 different habitats throughout Lithuania. Essential oils were analysed by capillary gas chromatography (GC). The study showed more intensive essential oil accumulation and higher intraspecific variation of essential oil amount in unripe cones than in leaves. Significant differences between α- and β- pinene amounts were observed in J. communis. β-Pinene was detected in much higher quantities than α-pinene. Positive correlation was detected between pinene isomers in cones and leaves (r = 0.44, p &lt; 0.05 and r = 0.50, p &lt; 0.05, respectively) of the same tree showing pinene isomers common biosynthetic pathway. Significant differences between populations were characteristic of J. communis according to leaf length, unripe cones mass and essential oil yield in leaves, however, significant correlation was established between essential oil yield of leaves and habitat illumination (r = -0.67, p &lt; 0.05) and soil acidity (r = -0.80, p &lt; 0.05) only.

Oxidations by the system “hydrogen peroxide–dinuclear manganese(IV) complex–carboxylic acid”Part 5. Epoxidation of olefins including natural terpenes

Dinuclear manganese(IV) complex [LMn(O)3MnL](PF6)2 (1, L = 1,4,7-trimethyl-1,4,7-triazacyclononane) efficiently catalyzes epoxidation of sterically accessible olefins, including natural compounds by hydrogen peroxide in acetonitrile at room temperature if a small amount of a carboxylic acid is present in the solution. The kinetics of dec-1-ene epoxidation and accompanying dioxygen evolution (catalase activity) under the action of this system in the presence of acetic acid has been studied. The initial rates of both epoxidation and O 2 evolution are proportional to the catalyst initial concentration. First order has been found for catalyst 1 for both processes, whereas the rate dependences of the dec-1-ene epoxidation is first order and the O 2 evolution is second order for H2O2. The epoxidation rate increases and the O2 evolution rate decreases with growing of acetic acid concentration. Zero order has been found for dec-1-ene in its epoxidation. The reaction proceeds with an induction period for a few minutes during which changes in the electronic spectra of the reaction solution are observed. It has been proposed that the processes of the alkane oxidation and dioxygen evolution on the one hand and of the olefin epoxidation on the other hand are induced by different intermediate species. An assumption has been made that the epoxidation occurs with participation of oxo-hydroxy Mn(V) derivative [LMn V ( O)(O)2(HO)Mn IV L] 2+ , whereas di(hydroperoxy) complex [LMn III (OOH)(O)2(HOO)Mn IV L] + is responsible for the alkane oxidation with simultaneous dioxygen evolution. The following equations for the initial rates were proposed for [CH 3CO2H] = 0.25 mol dm −3 : d[epoxide]/dt = keff (epoxide)[1][H2O2] with keff (epoxide) = 2.8–3.7 mol −1 dm 3 s −1 ; d[CyOOH]/dt = keff (CyOOH)[1][H2O2] 2 [CyH] with keff (CyOOH) = 4.1–6.2 mol −3 dm 9 s −1 ; d[O2]/dt = keff (O2)[1][H2O2] 2 with keff (O2) = 2.8–7.0 mol −2 dm 6 s −1 . Many different carboxylic acids were checked as cocatalysts and it has been found that oxalic acid acts with the highest efficiency in the epoxidation whereas the accompanying catalase activity of the system is very low in this case. It has been also demonstrated that complex 1 is unique catalyst because similar compounds containing only one Mn(IV) center (2) or dinuclear complex with bridging phenylboronic acid (3) are very poor catalysts in the olefin epoxidation. No epoxidation has been found when hydrogen peroxide was replaced by tert-butyl hydroperoxide. The system based on 1 ,H 2O2 and acetic and/or oxalic acid was employed for the efficient epoxidation of terpenes limonene, citral, carvone and linalool, while other terpenes containing sterically hindered double bonds (citronellal, - and -isomers of pinene) were epoxidized only with <15% yield. Using limonene as example, it has been demonstrated that regioselectivity of the epoxidation (predominant formation of product with addition of the O atom either to internal ring or external double bond) can be controlled by replacing acetic acid by oxalic acid. © 2004 Elsevier B.V. All rights reserved.

On the isomerization of β-pinene: a theoretical study

The β-pinene → α-pinene isomerization reaction was investigated at the HF, MP2 and MP4(SDQ) levels of theory, using the 6-31G, 6-31G(d), 6-31+G(d) and 6-311++G(d,p) basis set. The analysis of the intrinsic reaction coordinate has shown that this reaction takes place through a progressive intramolecular proton transfer. The use of different basis set and the inclusion of the electron correlation effects has little influence on the relative stability of the pinene isomers. Contrary to this, the effects of basis set and electron correlation, affects drastically, the energy barrier for the process, varying by 32.5 kcal/mol on going from HF/6-31G to MP2/6-311++G(d,p) levels of theory. The 6-31G basis set gave a completely different result at both HF and MP2 levels for the relative stability of the isomers. The analysis of the nature of the bonds and charge distribution in the transition state species, is shown in the formation of a π-allylic system with a three-center bond. A mechanism to the isomerization reaction assisted by transition metal compounds is given.

Monoterpene Synthases of Loblolly Pine (Pinus taeda) Produce Pinene Isomers and Enantiomers

The turpentine fraction of conifer oleoresin is a complex mixture of monoterpene olefins and plays important roles in defense and in the mediation of chemical communication between conifer hosts and insect predators. The stereochemistry of the turpentine monoterpenes is critical in these interactions, influencing host recognition, toxicity, and potency of derived pheromones, and the stereochemical composition of these compounds lends insight into their biogenetic origin, with implications for the numbers and types of enzymes responsible and their corresponding genes. Analysis of the oleoresin from several tissues of loblolly pine (Pinus taeda) showed the derived turpentine to consist mainly of (+)-(3R:5R)-α-pinene and (−)-(3S:5S)-β-pinene. Cell-free extracts from xylem tissue yielded three monoterpene synthases which together account for the monoterpene isomer and enantiomer content of the turpentine of this tissue. The major products of these enzymes, produced from the universal precursor of monoterpenes, geranyl diphosphate, were shown to be (+)-α-pinene, (−)-α-pinene, and (−)-β-pinene, respectively. In most properties (molecular mass of ∼60 kDa, Km for geranyl diphosphate of 3 μM, requirement for monovalent and divalent cations), these enzymes resemble other monoterpene synthases from conifer species.

Effect of selected monoterpenes on methane oxidation, denitrification, and aerobic metabolism by bacteria in pure culture.

Selected monoterpenes inhibited methane oxidation by methanotrophs (Methylosinus trichosporium OB3b, Methylobacter luteus), denitrification by environmental isolates, and aerobic metabolism by several heterotrophic pure cultures. Inhibition occurred to various extents and was transient. Complete inhibition of methane oxidation by Methylosinus trichosporium OB3b with 1.1 mM (-)-alpha-pinene lasted for more than 2 days with a culture of optical density of 0.05 before activity resumed. Inhibition was greater under conditions under which particulate methane monooxygenase was expressed. No apparent consumption or conversion of monoterpenes by methanotrophs was detected by gas chromatography, and the reason that transient inhibition occurs is not clear. Aerobic metabolism by several heterotrophs was much less sensitive than methanotrophy was; Escherichia coli (optical density, 0.01), for example, was not affected by up to 7.3 mM (-)-alpha-pinene. The degree of inhibition was monoterpene and species dependent. Denitrification by isolates from a polluted sediment was not inhibited by 3.7 mM (-)-alpha-pinene, gamma-terpinene, or beta-myrcene, whereas 50 to 100% inhibition was observed for isolates from a temperate swamp soil. The inhibitory effect of monoterpenes on methane oxidation was greatest with unsaturated, cyclic hydrocarbon forms [e.g., (-)-alpha-pinene, (S)-(-)-limonene, (R)-(+)-limonene, and gamma-terpinene]. Lower levels of inhibition occurred with oxide and alcohol derivatives [(R)-(+)-limonene oxide, alpha-pinene oxide, linalool, alpha-terpineol] and a noncyclic hydrocarbon (beta-myrcene). Isomers of pinene inhibited activity to different extents. Given their natural sources, monoterpenes may be significant factors affecting bacterial activities in nature.

Infinite-dilution activity coefficients for systems with α- and β-pinene

Proust, P., Meyer, E. and Jaque, Z., 1992. Infinite-dilution activity coefficients for systems with α- and β-pinene. Fluid Phase Equilibria, 73: 139-146. Infinite-dilution activity coefficients for binary systems with α- or β-pinene and several organic solvents have been determined by means of the differential ebulliometry technique. The following solvents were included: cyclohexane, cyclohexene, n-heptane, 1-octene, benzene, toluene, ethylbenzene, 1-butanol and anisole. Experiments were performed at temperature levels of 65 ° C and 80 ° C, and 80 ° C and 100 ° C, respectively, depending on the nature of the solvent and solute, using modified Swietoslawski ebulliometers. Except for the systems of both pinene isomers with 1-butanol or anisole, small positive deviations from ideal-solution behaviour were observed.