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Detecting volatile organic compounds (VOCs) emitted from different plant species and their organs can provide valuable information about plant health and environmental factors that affect them. For example, limonene emission can be a biomarker to monitor plant health and detect stress. Traditional methods for VOC detection encounter challenges, prompting the proposal of novel approaches. In this study, we proposed integrating electrospinning, molecular imprinting, and conductive nanofibers to fabricate limonene sensors. In detail, polyvinylpyrrolidone (PVP) and polyacrylic acid (PAA) served here as fiber and cavity formers, respectively, with multiwalled carbon nanotubes (MWCNT) enhancing conductivity. We developed one-step monolithic molecularly imprinted fibers, where S(−)-limonene was the target molecule, using an electrospinning technique. The functional cavities were fixed using the UV curing method, followed by a target molecule washing. This procedure enabled the creation of recognition sites for limonene within the nanofiber matrix, enhancing sensor performance and streamlining manufacturing. Humidity was crucial for sensor working, with optimal conditions at about 50% RH. The sensors rapidly responded to S(−)-limonene, reaching a plateau within 200 s. Enhancing fiber density improved sensor performance, resulting in a lower limit of detection (LOD) of 137 ppb. However, excessive fiber density decreased accessibility to active sites, thus reducing sensitivity. Remarkably, the thinnest mat on the fibrous sensors created provided the highest selectivity to limonene (Selectivity Index: 72%) compared with other VOCs, such as EtOH (used as a solvent in nanofiber development), aromatic compounds (toluene), and two other monoterpenes (α-pinene and linalool) with similar structures. These findings underscored the potential of the proposed integrated approach for selective VOC detection in applications such as precision agriculture and environmental monitoring. [ABSTRACT FROM AUTHOR]

Nowadays, the effective processing of natural monoterpenes that constitute renewable biomass found in post-production waste into products that are starting materials for the synthesis of valuable compounds is a way to ensure independence from non-renewable fossil fuels and can contribute to reducing global carbon dioxide emissions. The presented research aims to determine, based on DFT calculations, the activity and reactivity of limonene, an organic substrate used in previous preparative analyses, in comparison to selected monoterpenes such as cymene, pinene, thymol, and menthol. The influence of the solvent model was also checked, and the bonds most susceptible to reaction were determined in the examined compounds. With regard to EHOMO, it was found that limonene reacts more easily than cymene or menthol but with more difficultly than thymol and pienene. The analysis of the global chemical reactivity descriptors "locates" the reactivity of limonene in the middle of the studied monoterpenes. It was observed that, among the tested compounds, the most reactive compound is thymol, while the least reactive is menthol. The demonstrated results can be a reference point for experimental work carried out using the discussed compounds, to focus research on those with the highest reactivity. [ABSTRACT FROM AUTHOR]

The preparation of sustainable polymers from renewable resources is a main task in modern polymer and materials chemistry. For this, terpenes, that have many functions in nature, are very important building blocks, e.g., due to their abundance, availability, structural diversity, and functionalities. Accordingly, many approaches have been and are currently developed for the utilization of many terpenes for the preparation of a variety of sustainable polymers and materials. These approaches are elucidated herein with a focus on different polymers (polyolefins, polyesters, polyamides, etc.) and their recent advances in synthesis and properties. [ABSTRACT FROM AUTHOR]

This review provides an overview of the biotransformation of limonene and α-pinene, which are commonly found in wood residues and citrus fruit by-products, to produce high-value-added products. Essential oils derived from various plant parts contain monoterpene hydrocarbons, such as limonene and pinenes which are often considered waste due to their low sensory activity, poor water solubility, and tendency to autoxidize and polymerise. However, these terpene hydrocarbons serve as ideal starting materials for microbial transformations. Moreover, agro-industrial byproducts can be employed as nutrient and substrate sources, reducing fermentation costs, and enhancing industrial viability. Terpenes, being secondary metabolites of plants, are abundant in byproducts generated during fruit and plant processing. Microbial cells offer advantages over enzymes due to their higher stability, rapid growth rates, and genetic engineering potential. Fermentation parameters can be easily manipulated to enhance strain performance in large-scale processes. The economic advantages of biotransformation are highlighted by comparing the prices of substrates and products. For instance, R-limonene, priced at US$ 34/L, can be transformed into carveol, valued at around US$ 530/L. This review emphasises the potential of biotransformation to produce high-value products from limonene and α-pinene molecules, particularly present in wood residues and citrus fruit by-products. The utilisation of microbial transformations, along with agro-industrial byproducts, presents a promising approach to extract value from waste materials and enhance the sustainability of the antimicrobial, the fragrance and flavour industry. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance is a worldwide problem that urges novel alternatives to treat infections. In attempts to find novel molecules, we assess the antimicrobial potential of seven essential oils (EO) of different plants (Pinus sylvestris, Citrus limon, Origanum vulgare, Cymbopogon martini, Cinnamomum cassia, Melaleuca alternifolia and Eucalyptus globulus) against two multidrug-resistant bacteria species, i.e. Neisseria gonorrhoeae and Streptococcus suis. EOs of P. sylvestris and C. limon revealed higher bactericidal activity (MIC ≤ 0.5 mg/mL) and capacity to rapidly disperse biofilms of several N. gonorrhoeae clinical isolates than other EOs. Examination of biofilms exposed to both EO by electron microscopy revealed a reduction of bacterial aggregates, high production of extracellular vesicles, and alteration of cell integrity. This activity was dose-dependent and was enhanced in DNase I-treated biofilms. Antibiotic susceptibility studies confirmed that both EOs affected the outer membrane permeability, and analysis of EO- susceptibility of an LPS-deficient mutant suggested that both EO target the LPS bilayer. Further analysis revealed that α- and β-pinene and d-limonene, components of both EO, contribute to such activity. EO of C. martini, C. cassia, and O. vulgare exhibited promising antimicrobial activity (MIC ≤ 0.5 mg/mL) against S. suis, but only EO of O. vulgare exhibited a high biofilm dispersal activity, which was also confirmed by electron microscopy studies. To conclude, the EO of P. sylvestris, C. limon and O. vulgare studied in this work exhibit bactericidal and anti-biofilm activities against gonococcus and streptococcus, respectively.

Nowadays, the effective processing of natural monoterpenes that constitute renewable biomass found in post-production waste into products that are starting materials for the synthesis of valuable compounds is a way to ensure independence from non-renewable fossil fuels and can contribute to reducing global carbon dioxide emissions. The presented research aims to determine, based on DFT calculations, the activity and reactivity of limonene, an organic substrate used in previous preparative analyses, in comparison to selected monoterpenes such as cymene, pinene, thymol, and menthol. The influence of the solvent model was also checked, and the bonds most susceptible to reaction were determined in the examined compounds. With regard to EHOMO, it was found that limonene reacts more easily than cymene or menthol but with more difficultly than thymol and pienene. The analysis of the global chemical reactivity descriptors “locates” the reactivity of limonene in the middle of the studied monoterpenes. It was observed that, among the tested compounds, the most reactive compound is thymol, while the least reactive is menthol. The demonstrated results can be a reference point for experimental work carried out using the discussed compounds, to focus research on those with the highest reactivity.

We have performed the first comparative analysis of the potential of two physiologically-diverse model cyanobacteria, Synechococcus PCC 7002 (S.7002) and Synechococcus elongatus PCC 7942 (S.7942), for the photosynthetic production of four chemically-different high-value terpenes: two monoterpenes limonene and pinene, and two sesquiterpenes bisabolene and farnesene. We showed, for the first time, that S.7002 and S.7942 can produce farnesene and bisabolene, respectively. Both cyanobacteria produced farnesene (S.7942 produced more efficiently than S.7002) more efficiently than the other tested terpenes (especially pinene, the weakest produced terpene). S.7002 produced limonene more efficiently than bisabolene, whereas S.7942 produced bisabolene more efficiently than limonene. These findings suggest that S.7942 is better suited to produce sesquiterpenes than monoterpenes. Interestingly, higher levels of terpenes were produced by S.7942 and S.7002 expressing a terpene-synthase gene from both an RSF1010-derived replicating plasmid and a neutral chromosomal site, as compared to either the plasmid alone or the chromosome alone. These results suggest that in both cyanobacteria, the production of terpenes is more limited by the activity of terpene synthases than the abundance of terpene precursors. Finally, higher levels of terpenes were produced by S.7002 growing on urea (a frequent pollutant) as compared to nitrate or ammonium, the standard nitrogen sources for cyanobacteria. [ABSTRACT FROM AUTHOR]

Mastic oil (MO) is extracted from the resin of the bark of Pistacia lentiscus var. chia, a tree abundantly grown in the Greek island of Chios. Various biological activities, such as antimicrobial, anticancer and antioxidant, have been associated with the dietary intake of MO. However, little is known about MO's potential anti-inflammatory effects, while some of its main chemical constituents were reported to exert significant anti-inflammatory activity. This study aims to assay the bioactivity of MO on in vitro and in vivo experimental inflammation models, in particular on LPS-stimulated RAW264.7 macrophages, murine primary peritoneal macrophages and a model of zymosan-induced peritonitis in BALB/c mice. The per os administration of MO inhibited the recruitment of macrophages into the peritoneal cavity of zymosan-treated mice, but did not affect neutrophil mobilisation or the levels of IL-6 or TNF-α in the peritoneal fluid. Similarly, IL-6 and TNF-α secretion in primary LPS-stimulated macrophages was not affected by MO, but the levels of phosphoproteins that activate inflammation in macrophages were differentially regulated. Finally, MO and some of its individual constituents reduced nitric oxide (NO), prostaglandin E2 and TNF-α levels in supernatants of LPS-stimulated RAW264.7 cells and inhibited their phagocytosis rate. Our data imply that MO may promote an anti-inflammatory transition in macrophages due to the combined bioactivities of its individual constituents. Thus, as a mixture of various compounds, MO seems to affect multiple molecular mechanisms that are involved in the development of inflammation. Therefore, more research, focusing on MO's individual constituents and employing various pre-clinical inflammation models that activate different mechanisms, is required for a detailed investigation of the oil's potential anti-inflammatory activity. [ABSTRACT FROM AUTHOR]

Terpene epoxides such as limonene dioxide are known as a very important intermediates for developing biological resins such as non-isocyanate polyurethanes. Recently, the dimethyldioxirane (DMDO) epoxidation technique has attracted attention and studies are being carried out to epoxidize terpenes. This study focuses on the epoxidation of hydrophobic terpene such as limonene and pinene by DMDO generated in-situ in a microemulsion system, examining the efficacy of cetyltrimethylammonium hydrogen sulfate (CTAHS) as a surfactant to homogenize the limonene and pinene in the aqueous reaction medium. The application of CTAHS showed a significant advantage for the epoxidation reaction. 100% limonene dioxide (LDO) and α-pinene oxide yields are obtained with molar ratios of only 1.6 for oxone/limonene and 0.9 for oxone/α-pinene respectively, after 30 min. The application of CTAHS resulted in a significant reduction in acetone content so that it just plays the role of a catalyst; Only an acetone/water volume ratio of up to 1:9 was sufficient to obtain these results. The reaction volume is therefore completely reduced and the amount of oxone required is almost 50% less than with the conventional biphasic organic solvent/water reaction medium. The separation of the epoxides from the aqueous medium and the surfactant (CTAHS) is easily done by liquid-liquid extraction. The main advantages of this technology are the use of acetone as a catalyst, which can be recycled indefinitely, the high selectivity of the epoxides without any by-products and the exclusion of the use of any organic solvent. [Display omitted] • Epoxidation of limonene and pinene by dioxirane generated from oxone. • Limonene dioxide and pinene oxide as bio-monomers or green monomers. • Green epoxides for the synthesis of green resins or polycarbonates. • Free-catalyst synthesis of green epoxides by dimethyl dioxirane. • Epoxidation of limonene and pinene in microemulsions by dioxirane. [ABSTRACT FROM AUTHOR]

Secondary organic aerosol (SOA) contributes significantly to ambient fine particulate matter that affects climate and human health. Monoterpenes represent an important class of biogenic volatile organic compounds (VOCs) and their oxidation by nitrate radicals poses a substantial source of SOA globally. Here, we investigate the formation and properties of SOA from nitrate radical oxidation of two common monoterpenes, α-pinene and limonene. When two monoterpenes are oxidized simultaneously, we observe a ~50% enhancement in the formation of SOA from α-pinene and a ~20% reduction in limonene SOA formation. The change in SOA yields is accompanied by pronounced changes in aerosol chemical composition and volatility. These non-linear effects are not observed in a sequential oxidation experiment. Our results highlight that unlike currently assumed in atmospheric models, the interaction of products formed from individual VOCs should be accounted for to accurately describe SOA formation and its climate and health impacts. Tiny airborne particles play a critical role in two major environmental issues: climate change and air pollution. Our study highlights the important, yet often overlooked non-linear interaction of organic compounds on the formation of such particles. [ABSTRACT FROM AUTHOR]

Background: The robust model cyanobacterium Synechocystis PCC 6803 is increasingly explored for its potential to use solar energy, water and atmospheric CO2 for the carbon-neutral production of terpenes, the high-value chemicals that can be used for the production of drugs, favors, fragrances and biofuels. However, as terpenes are chemically diverse, it is extremely difcult to predict whether Synechocystis is a suitable chassis for the photosynthetic production of various terpenes or only a few of them. Results: We have performed the frst-time engineering and comparative analysis of the best-studied cyanobacterium Synechocystis PCC 6803 for the photosynthetic production of fve chemically diverse high-value terpenes: two monoterpenes (C10H16) limonene (cyclic molecule) and pinene (bicyclic), and three sesquiterpenes (C15H24) bisabolene (cyclic), farnesene (linear) and santalene (cyclic). All terpene producers appeared to grow well and to be genetically stable, as shown by the absence of changes in their production levels during the 5--9-month periods of their sub-cultivation under photoautotrophic conditions). We also found that Synechocystis PCC 6803 can efciently and stably produce farnesene and santalene, which had never been produced before by this model organism or any other cyanobacteria, respectively. Similar production levels were observed for cells growing on nitrate (the standard nitrogen source for cyanobacteria) or urea (cheaper than nitrate). Furthermore, higher levels of farnesene were produced by cloning the heterologous farnesene synthase gene in a RSF1010-derived replicating plasmid as compared to the well-used slr0168 neutral cloning site of the chromosome. Conclusions: Altogether, the present results indicate that Synechocystis PCC 6803 is better suited to produce sesquiterpenes (particularly farnesene, the most highly produced terpene of this study) than monoterpenes (especially pinene). [ABSTRACT FROM AUTHOR]

Terpenoids are a large variety of natural products with remarkable diverse biological functions, and have a wide range of applications in flavors, pharmaceuticals, biofuels, pigments, and so on. However, limited production of terpenoids from natural resources constrains their use of bulk commodity products. In vivo synthetic biosystem, harnessing living organisms to produce terpenoids, has been broadly used and in-depth reviewed for terpenoids production, which has inherent weaknesses, such as slow reaction rate, low product yield, toxic intermediates, and high separation cost. In vitro synthetic biosystem, harboring numerous enzymes and/or coenzymes assembled into an in vitro enzymatic bioreactions, can obviate part of problems associated with in vivo style. In this review, the general design of in vitro synthetic biosystem is presented with seven supporting examples: mevalonate, isoprene, limonene, pinene, farnesene, amorpha-4,11-diene and taxadiene. The efforts for the large-scale implementation of in vitro synthetic biosystem have been addressed to enzymes engineering, computational modeling and cofactors recycle. The review also discusses the challenges and solutions for the large-scale implementation of in vitro synthetic biosystem around enzymes stability and cofactors recycle. This review may suggest in vitro synthetic biosystems become a realistic option for the production of diverse valuable terpenoids, even expand to other commodity chemicals. [ABSTRACT FROM AUTHOR]

The Aristotelia alkaloids are a family of monoterpene indole alkaloids possessing a characteristic azabicyclononane scaffold, which has been assembled by several synthetic methods. Herein we review those approaches that have adopted a biomimetic approach to unite heterocyclic synthons with chiral-pool monoterpenes. Throughout this discussion, the tendency of monoterpenes like α-pinene and limonene to undergo racemization is highlighted, revealing the challenges in developing stereospecific syntheses of these alkaloids. Finally, we provide a brief discussion of how these synthetic efforts have enabled the structural confirmation and elucidation of the Aristotelia alkaloids' absolute configurations, including our own recent efforts to employ bioactivity data to deduce the naturally occurring configuration of the quinoline alkaloid aristoquinoline. 1 Introduction 2 Mercury-Mediated Ritter-Like Reactions 3 Brønsted Acid Mediated Ritter-Like Reactions 4 Synthesis of Aristoquinoline: Ritter-Like Reaction Approach 5 Aza-Prins-Type Reaction in the Synthesis of Aristotelia Alkaloids 6 Determination of Naturally Occurring Absolute Stereochemistry 7 Conclusions [ABSTRACT FROM AUTHOR]

Isomerization of α-pinene epoxide was performed over several Fe or Cu supported on MCM-41 and SBA-15 catalysts. The effect of the metal loading and polarity of the solvent on substrate conversion and selectivity was analyzed. It was found that materials containing Fe are more active but less selective to campholenic aldehyde and trans- carveol than materials with Cu, difference that was related with the size of the metal oxide particles and strength/type of the acid sites. An increasing of the solvent polarity decreases formation of campholenic aldehyde, the most desirable compound from α-pinene epoxide. Also, it was showed that trans- carveol is an intermediate in the production of p- cymene. Selectivity to campholenic aldehyde up to 82% can be achieved over Cu/MCM-41 as heterogeneous catalyst at soft reaction conditions (70 °C, 2.5 h, 25 mg, 750 rpm, toluene as solvent). From limonene epoxide isomerization over Fe/SBA-15, dihydrocarvone and limonene-1,2-diol production depended on the type of solvent. An increasing of polarity of the solvent, appears to increase selectivity to dihydrocarvone while limonene-1,2-diol is favored with solvents of lower polarity (mainly cyclohexane and hexane). Reuse of Fe materials were also tested for both monoterpene epoxides showing that Fe supported on MCM-41 and SBA-15 can be used several times (up to 5 times) without any loss of catalytic activity for the synthesis of campholenic aldehyde from α-pinene epoxide and dihydrocarvone (and limonene-1,2-diol) from limonene epoxide. [Display omitted] • Campholenic aldehyde is obtained from α-pinene epoxide using non-polar solvents. • tert -Butanol and ethyl acetate seems to block active sites of Cu supported materials. • Fe/SBA-15 is active for limonene epoxide isomerization. • Synthesis of fine chemicals from monoterpene epoxides using a green process. • Fe loading in MCM-41 and SBA-15 does not affect selectivity to campholenic aldehyde. [ABSTRACT FROM AUTHOR]

Rice is a broad-spectrum meal consumed annually in large amounts. Ready-to-eat rice is a member of dishes with a high risk of contamination. The present study aimed to increase the safety and shelflife of ready-to-eat rice during temporary storage. To prepare a mixture for extraction, three spices were chosen ginger: thyme:coriander (1:2:1). Two types of extract were prepared, aromatic and water extracts. The bioactive aromatic extract was preserved by encapsulation using chitosan nanoparticle preparation, while water extracts were prepared by warm diffusion. The aromatic extract possessed volatiles with antimicrobial features, including α-pinene, cymene, camphor, 1, 8 cineol, and limonene. The results expressed the extracts' better antifungal and antibacterial effect, with a distinguishing aromatic one. Water extract was recorded as being rich in phenolic and flavonoids, like Salysilic, p-hydroxybenzoic acid, ferulic, Luteolin 7 glucoside, and quercitin. These molecules play functionality for microbial inhibition in the simulated media. Ready-to-eat rice shelflife was extended by applying the aromatic extract of the encapsulated mixture at the late stage of cooking and before packaging. It can preserve the samples for up to five days at room temperature and up to eight days of refrigerator storage (8 °C). However, water extract had lower activity as antibacterial and antifungal than the aromatic one. Again, water extract activity reduces fungal citrinin secretion by low efficiency more than the aromatic extract. These results recommended the addition of aromatic extract to the ready-to-eat rice meals as a final additive just before packaging. [ABSTRACT FROM AUTHOR]

We have performed the first comparative analysis of the potential of two physiologically-diverse model cyanobacteria, Synechococcus PCC 7002 (S.7002) and Synechococcus elongatus PCC 7942 (S.7942), for the photosynthetic production of four chemically-different high-value terpenes: two monoterpenes limonene and pinene, and two sesquiterpenes bisabolene and farnesene. We showed, for the first time, that S.7002 and S.7942 can produce farnesene and bisabolene, respectively. Both cyanobacteria produced farnesene (S.7942 produced more efficiently than S.7002) more efficiently than the other tested terpenes (especially pinene, the weakest produced terpene). S.7002 produced limonene more efficiently than bisabolene, whereas S.7942 produced bisabolene more efficiently than limonene. These findings suggest that S.7942 is better suited to produce sesquiterpenes than monoterpenes. Interestingly, higher levels of terpenes were produced by S.7942 and S.7002 expressing a terpene-synthase gene from both an RSF1010-derived replicating plasmid and a neutral chromosomal site, as compared to either the plasmid alone or the chromosome alone. These results suggest that in both cyanobacteria, the production of terpenes is more limited by the activity of terpene synthases than the abundance of terpene precursors. Finally, higher levels of terpenes were produced by S.7002 growing on urea (a frequent pollutant) as compared to nitrate or ammonium, the standard nitrogen sources for cyanobacteria.

Members of the Abies genus (Pinaceae) have been used in traditional medicines in their natural ranges, and essential oils derived from Abies species have found use in aromatic therapy. In this work, the foliar (leaves and twigs) essential oil of Abies concolor have been obtained from mature trees growing in southwestern Idaho and analyzed using gas chromatographic techniques. The essential oils were rich in α-pinene (15.2-20.5%), camphene (7.5-10.2%), β-pinene (24.2-25.6%), δ-3-carene (5.5-6.5%), limonene (5.4-6.9%), and bornyl acetate (14.6-22.1%). The dominant enantiomers for the major terpenoids were (+)-α-pinene, (–)-camphene, (–)-β-pinene, (+)-δ-3-carene, (–)-limonene, and (–)-bornyl acetate. The essential oil compositions are qualitatively similar to other Abies species, but the enantiomeric distributions for α-pinene, β-pinene, and camphene did reveal notable variation between Abies essential oils. [ABSTRACT FROM AUTHOR]

The volatile components of kuromoji oil (Lindera umbellata Thunb.) obtained in Shizuoka Pref. were analyzed by GC/MS. Linalool, a-pinene, limonene, camphene, cis- and trans-dihydrocarvone, 1,8-cineol, 4-terpinenol, a-terpineol, piperitone, geranyl acetate, geraniol, and trans-nerolidol were identified as major components. Using enantio-MDGC-MS, the enantiomeric ratio ((R)-(-) vs (S)-(+)) of linalool in this oil was determined to be 67.8/32.2. Touch care treatment while sniffing this oil was done on cancer patients. We found that the relaxation effect persisted longer after the treatment compared to treatment without aroma. [ABSTRACT FROM AUTHOR]

The oxidation of biogenic and anthropogenic compounds leads to the formation of secondary organic aerosol mass (SOA). The present study aims to investigate α -pinene, limonene, and m -cresol with regards to their SOA formation potential dependent on relative humidity (RH) under night- (NO 3 radicals) and daytime conditions (OH radicals) and the resulting chemical composition. It was found that SOA formation potential of limonene with NO 3 under dry conditions significantly exceeds that of the OH-radical reaction, with SOA yields of 15–30 % and 10–21 %, respectively. Additionally, the nocturnal SOA yield was found to be very sensitive towards RH, yielding more SOA under dry conditions. In contrast, the SOA formation potential of α -pinene with NO 3 slightly exceeds that of the OH-radical reaction, independent from RH. On average, α -pinene yielded SOA with about 6–7 % from NO 3 radicals and 3–4 % from OH-radical reaction. Surprisingly, unexpectedly high SOA yields were found for m -cresol oxidation with OH radicals (3–9 %), with the highest yield under elevated RH (9 %), which is most likely attributable to a higher fraction of 3-methyl-6-nitro-catechol (MNC). While α -pinene and m -cresol SOA was found to be mainly composed of water-soluble compounds, 50–68 % of nocturnal SOA and 22–39 % of daytime limonene SOA are water-insoluble. The fraction of SOA-bound peroxides which originated from α -pinene varied between 2 and 80 % as a function of RH. Furthermore, SOA from α -pinene revealed pinonic acid as the most important particle-phase constituent under day- and nighttime conditions with a fraction of 1–4 %. Other compounds detected are norpinonic acid (0.05–1.1 % mass fraction), terpenylic acid (0.1–1.1 % mass fraction), pinic acid (0.1–1.8 % mass fraction), and 3-methyl-1,2,3-tricarboxylic acid (0.05–0.5 % mass fraction). All marker compounds showed higher fractions under dry conditions when formed during daytime and showed almost no RH effect when formed during night. [ABSTRACT FROM AUTHOR]

Chloropinane and chloromenthene, synthesized from pinene and limonene, respectively, were compared with their non-halogenated analogs and n-hexane for their ability to solubilize natural products of interest such as β-carotenoids, vanillin, and rosmarinic acid. Chloropinane was six times more efficient than hexane for β-carotene solubilization. Chloromenthene was 15 times better than hexane. Vanillin was 20 times more soluble in chloropinane than in hexane. Chloropinane and chloromenthene were 3.5 and 2 times more efficient than hexane for rosmarinic acid solubilization. Obtained from pinene and limonene, two very abundant natural products, and even from their waste byproducts, chloropinane and chloromenthene can be an alternative to solvents from non-renewable resources.

We report the dehydration and isomerization of renewable perillyl alcohol to industrially useful p‐cymene in 91% yield utilizing 2.0 mol% para‐toluenesulfonic acid (pTsOH) catalyst at 110 °C as a 3.0 M solution in toluene. Lower reaction temperatures, catalyst loadings, and/or starting concentrations resulted in lower yields of p‐cymene as well as longer reaction times. Conversion of perillyl alcohol to p‐cymene yielded atom and carbon economies of 88.1% and 100% as well as an E‐factor of 2.7, thereby indicating that the process was both green and sustainable. A lower yield of 86% was observed when the reaction was performed neat, but a lower E‐factor of 0.4 indicated that neat conditions were more desirable from an environmental perspective. Application of the optimized parameters to 3.0 M solutions of dl‐limonene led predominantly to oligomerization (92%) as opposed to dehydroisomerization (5%), which was attributed to the strong Brønsted acidity of pTsOH. In addition, camphene (44%), terpinene isomers (15%), and limonene (14%) were obtained when dehydroisomerization was attempted on 3.0 M solutions of α‐ and β‐pinene, which was once again attributed to the acidity of the catalyst. Oligomerization was strongly favored when dehydroisomerization of dl‐limonene, α‐ and β‐pinene was attempted neat. In summary, synthesis of renewable p‐cymene was readily achieved from perillyl alcohol with catalytic pTsOH but competing side reactions suppressed yield when dehydroisomerization of dl‐limonene, α‐ and β‐pinene was attempted due to the strong Brønsted acidity of the catalyst. [ABSTRACT FROM AUTHOR]

Headspace volatiles (HS) and hydrodistilled essential oils (EO) of fresh aerial parts of Artemisia annua L. and A. scoparia Waldst. et Kit., were analyzed by GC-MS/FID. Artemisia ketone was found to be the most abundant component among the EO volatiles (55.8 %), as well as among HS (52.1 %) of A. annua. Additionally, in both A. annua samples, EO and HS, α-pinene (12.7 and 24.2 %, respectively) was found in high percentage. On the other hand, it has been determined that the dominant components of A. scoparia EO and HS were different; in the essential oil capillene (63.8 %) was found as the main constituent, while β-pinene (26.1 %), (Z)-β-ocimene (23.8 %) and limonene (10.7 %) were the major components among the HS. This is the first report on the composition of HS volatiles of the A. annua and A. scoparia obtained by direct static headspace. [ABSTRACT FROM AUTHOR]

The evaluation of the technical and economic separation of the monoterpenes α‐pinene and d‐limonene from essential oils, carried out by computational simulation of the vacuum fractional distillation in continuous and batch mode from samples of turpentine and citrus oils, was developed using Aspen Plus® software combined with estimations of operational expenses (OPEX) and capital expenses (CAPEX) based on the Guthrie method. The production of d‐limonene and α‐pinene with high purity from the essential oils is a technically feasible process. From the economic point of view and based on the average annual import costs of turpentine and orange oils in Colombia, it was found that the selling prices of α‐pinene and d‐limonene obtained from the distillation module cost analysis depend on the daily production and can be minimized if essential oils are preliminary extracted from local industrial wastes. [ABSTRACT FROM AUTHOR]

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• Ferrierite-type zeolite was dealuminated by solutions of hydrochloric acid. • The samples were highly crystalline and contained Brønsted and Lewis acid sites. • Initial reaction rate and turnover frequency of α-pinene at 348–363 K were estimated. • Selectivity to camphene and limonene was in the range of 77–98.9 %. Ferrierite-type zeolite (Zeolyst Intern.) with Si/Al = 10 was dealuminated sequentially using solutions of hydrochloric acid of different concentrations. The course of dealumination was followed by XRD, XPS, sorption of nitrogen, scanning electron microscopy, FTIR, and solid-state 29Si, 27Al and 1H MAS NMR. The dealuminated samples retained high crystallinity and revealed good sorption properties. The tetrahedrally coordinated aluminium in ferrierite was distributed between T B sites located in the main channels and T A ones siting in hidden positions. It was shown that dealumination removed aluminium from ferrierite in a non-random manner; up to 60% of aluminium was removed from T B and up to 19-% from T A sites. The amount and strength of Brønsted acid sites decreased with dealumination. The samples were tested in the liquid-phase isomerization α-pinene at 348–363 K; camphene and limonene were the main products. The initial reaction rates and turnover frequencies have been estimated and compared to other zeolite catalysts. The selectivity to camphene and limonene was in the range of 77–98.9 %. [ABSTRACT FROM AUTHOR]

The present study investigated the chemical composition of essential oil extracted from Elsholtzia fruticosa, and evaluated the biological activities of the essential oil and its main components against Ditylenchus destructor. The essential oil of E. fruticosa was obtained by hydrodistillation and analyzed by GC/ MS. Twenty-three components of essential oil were identified. The most abundant compounds were eucalyptol (40.1%), γ-terpinene (15.8%), limonene (9.3%) and β-pinene (5.2%). Essential oil and three major constituents (eucalyptol, γ-terpinene, and limonene) were tested for their biological activities against D. destructor. The results showed that the essential oil, eucalyptol, γ-terpinene, and limonene exhibited a strong effect of suppression against D. destructor (EC50/24h = 0.16, 0.27, 0.36 and 0.23 mg/ml, respectively). The essential oil, eucalyptol, ã-terpinene, and limonene also possessed the obvious nematicidal activities against D. destructor (LC50/24h = 0.18, 0.46, 0.66 and 0.38 mg/ml, respectively). The essential oil and main components described herein merit further study as potential botanical nematicides against D. destructor. [ABSTRACT FROM AUTHOR]

Organic nitrate esters are key products of terpene oxidation in the atmosphere. We report here the preparation and purification of nine nitrate esters derived from (+)-3-carene, limonene, α -pinene, β -pinene and perillic alcohol. The availability of these compounds will enable detailed investigations into the structure–reactivity relationships of aerosol formation and processing and will allow individual investigations into aqueous-phase reactions of organic nitrate esters. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance is a worldwide problem that urges novel alternatives to treat infections. In attempts to find novel molecules, we assess the antimicrobial potential of seven essential oils (EO) of different plants (Pinus sylvestris, Citrus limon, Origanum vulgare, Cymbopogon martini, Cinnamomum cassia, Melaleuca alternifolia and Eucalyptus globulus) against two multidrug-resistant bacteria species, i.e. Neisseria gonorrhoeae and Streptococcus suis. EOs of P. sylvestris and C. limon revealed higher bactericidal activity (MIC ≤ 0.5 mg/mL) and capacity to rapidly disperse biofilms of several N. gonorrhoeae clinical isolates than other EOs. Examination of biofilms exposed to both EO by electron microscopy revealed a reduction of bacterial aggregates, high production of extracellular vesicles, and alteration of cell integrity. This activity was dose-dependent and was enhanced in DNase I-treated biofilms. Antibiotic susceptibility studies confirmed that both EOs affected the outer membrane permeability, and analysis of EO- susceptibility of an LPS-deficient mutant suggested that both EO target the LPS bilayer. Further analysis revealed that α- and β-pinene and d -limonene, components of both EO, contribute to such activity. EO of C. martini , C. cassia, and O. vulgare exhibited promising antimicrobial activity (MIC ≤ 0.5 mg/mL) against S. suis , but only EO of O. vulgare exhibited a high biofilm dispersal activity, which was also confirmed by electron microscopy studies. To conclude, the EO of P. sylvestris, C. limon and O. vulgare studied in this work exhibit bactericidal and anti-biofilm activities against gonococcus and streptococcus, respectively. [Display omitted] • Essential oils of Pinus sylvestris and Citrus limon have bactericidal activity against drug-resistant Neisseria gonorrhoeae strains. • Essential oils of Pinus sylvestris and Citrus limon have high capacity to disperse gonococci biofilms. • α- and β-pinene and d -limonene are bioactive components of Essential oils of Pinus sylvestris and Citrus limon. • Essential oils of Origanum vulgare have bactericidal and biofilm dispersal activity against Streptococcus suis. [ABSTRACT FROM AUTHOR]

• Enzyme-aided pressing alters the volatile composition of blackcurrant juice. • Sensory properties of juice were modified by enzyme-aided berry pressing. • Pasteurization does not produce significant changes in odor. • Storage temperature impacts on volatiles and the sensory properties of the juice. • Light exposure does not affect the volatile composition of juice. Blackcurrant juices were prepared without enzyme (NEB-juice) and with conventional enzyme-aided berry pressing (EB-juice). Juices were pasteurized and stored at ambient temperature (in light and dark conditions) and at +4 °C for a 1-year period of time. Volatile composition and odor attributes were followed by HS–SPME–GC–MS and a sensory panel, respectively. Volatiles were decreased in the EB-juice, showing 100-fold lower contents of the main terpenoids, e.g., α-pinene, δ-3-carene, limonene, terpinolene, bornyl acetate and β-caryophyllene; whereas esters, such as methyl butanoate and ethyl butanoate, showed 2- and 4-fold lower contents for the EB-juice. Pasteurization produced minor changes in both juices. Volatiles decreased during storage at room temperature while at +4 °C esters and eucalyptol were kept at 100%. The descriptive sensory analysis reported a significant decrease (p < 0.05) of the berry-like odor after 12-month storage at RT. Storage at +4 °C for 12 months did not affect the odor quality. [ABSTRACT FROM AUTHOR]

A new time-integrated thermal desorption technique has been developed that can be used with selected ion flow tube mass spectrometry, TI-TD/SIFT-MS, for off-line quantitative analyses of VOCs accumulated onto sorbents. Using a slow desorption temperature ramp, the absolute amounts of desorbed compounds can be quantified in real time by SIFT-MS and constitutional isomers can be separated. To facilitate application of this technique to environmental atmospheric monitoring, method parameters were optimised for quantification of the three common atmospheric monoterpenes: β-pinene, R-limonene and 3-carene. Three sorbent types, Tenax TA, Tenax GR and Porapak Q, were tested under 26 different desorption conditions determined by the "design of experiment", DOE, systematic approach. The optimal combination of type of sorbent, bed length, sampling flow rate, sample volume and the initial desorption temperature was determined from the experimental results by ANOVA. It was found that Porapak Q exhibited better efficiency of sample collection and further extraction for total monoterpene concentration measurements. On the other hand, Tenax GR or TA enabled separation of all three monoterpenes. The results of this laboratory study were tested with the sample accumulated from a branch of a Pinus nigra tree. [ABSTRACT FROM AUTHOR]

Essential oils from flowers and leaves of Grindelia integrifolia DC. were investigated for the first time in terms of chemical composition and antimicrobial activity. The GC-FID/MS analysis allowed for the identification of 58 and 72 volatiles, comprising 92.4 and 90.1% of the oils, respectively. The major components of the flower oil were α-pinene (34.9%) and limonene (13.1%), while myrcene (16.9%), spathulenol (12.3%), β-eudesmol (11.9%) and limonene (10.1%) dominated among the leaf volatiles. The antimicrobial activity, evaluated against 12 selected bacteria and fungus, was found moderate, with the strongest effect of both oils observed against C. albicans (MIC = MBC: 0.63 and 0.31 mg/mL for flower and leaf oil, respectively). [ABSTRACT FROM AUTHOR]

The chemical constituents of the essential oils hydrodistilled from rhizome parts of Hedychium greenii W.W. Sm. and Hedychium gracile Roxb, of family Zingiberaceae, growing in India, were analysed for the first time by GC-FID and GC-MS, respectively. A total of 30 and 29 components representing 99.62 and 96.74% of the total oil were identified in the essential oils of H. greenii and H. gracile, respectively. The major components of H. greenii were bornyl acetate (31.32%), α-pinene (14.49%), camphene (12.81%) and limonene (10.55%), whereas H. gracile was dominated by β-pinene (25.24%), γ-terpinene (24.62%), terpinen-4-ol (14.87%) and 1,8-cineole (7.51%). Essential oils were assessed for antioxidant potential using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay. H. greenii oil exhibited stronger antioxidant potential as compared to H. gracile oil and butylated hydroxytoluene (BHT). Thus, H. greenii rhizome oil has the potential to be used as an alternative source of antioxidant. [ABSTRACT FROM AUTHOR]

Abstract Bio-derived solvents such as ρ-cymene , d-limonene and α-pinene represent feasible alternatives to n-hexane for the extraction of vegetable oils. However, the large-scale utilization of these solvents is still limited mainly owing to their high boiling points and latent heats of vaporization. In this work, the performance of composite polydimethylsiloxane/polyacrylonitrile (PDMS/PAN) organic solvent nanofiltration membranes in the recovery of these solvents from their binary mixtures with canola oil is investigated. The sorption isotherms of the mixtures were first studied using free-standing PDMS films and the multicomponent Flory–Huggins model used to determine the resulting interaction parameters. The partial solvent uptake decreased with increasing oil concentration in the mixture. On the other hand, the partial oil uptake in the solvent mixture was higher than that of the pure oil which was attributed to the swelling effects induced by solvents. The effects of feed concentration (10–30 wt% oil), feed temperature (25–40 °C), transmembrane pressure (5–30 bar), and cross-flow velocity (18–52 cm s−1) on the membrane performance were then studied in a cross-flow membrane setup. Maxwell–Stefan formulations were combined with the ternary Flory–Huggins solubility model to successfully describe these flux data. Highlights • Sorption isotherms determined for 10 and 30 wt% canola oil in terpene mixtures into PDMS films. • Sorption data predicted by a ternary Flory–Huggins model. • Nanofiltration flux and rejection of these oil and terpene mixtures measured through PDMS films. • Flux data fitted to a Maxwell–Stefan ternary mixture diffusion model. [ABSTRACT FROM AUTHOR]

The article offers information on a study related to monoterpene hydrocarbons found in almost every essential oils. Topics discussed include monoterpenes as molecules containing only 10 carbon atoms, which makes them small and light and known as skin penetration enhancers; properties for limonene as well as a- and β-pinene; and knowing the composition of an essential oil also gives valuable clues for safety, shelf life, and storage.

Background: Montanoa guatemalensis is a small to medium-sized tree in the Asteraceae that grows in Central America from Mexico south through Costa Rica. There have been no previous investigations on the essential oil of this tree. Methods: The leaf essential oils of M. guatemalensis were obtained from different individual trees growing in Monteverde, Costa Rica, in two different years, and were analyzed by gas chromatography—mass spectrometry. Results: The leaf oils from 2008 were rich in sesquiterpenoids, dominated by α-selinene, β-selinene, and cyclocolorenone, with lesser amounts of the monoterpenes α-pinene and limonene. In contrast, the samples from 2009 showed no α- or β-selinene, but large concentrations of trans-muurola-4(14),5-diene, β-cadinene, and cyclocolorenone, along with greater concentrations of α-pinene and limonene. The leaf oils were screened for cytotoxic and antimicrobial activities and did show selective cytotoxic activity on MDA-MB-231 breast tumor cells. Conclusion: M. guatemalensis leaf oil, rich in cyclocolorenone, α-selinene, and β-selinene, showed selective in vitro cytotoxic activity to MDA-MB-231 cells. The plant may be a good source of cyclocolorenone.

The volatile oils ofEucalyptus camaldulensisleaves harvested in three agro-ecological areas in Senegal were analysed by GC-FID and GC-MS. The yields ranged from 0.5 to 1.0%. Qualitative and quantitative differences were determined in the composition according to leave sources. The main compounds of Saint-Louis oils were: 1,8-cineole (69.3–73.0%) and limonene (12.4–13.5%), whereas those from Kaolack were characterized by p-cymene (28.4–32.6%), 1,8-cineole (16.8–20.0%), α-pinene (8.7–11.6%) and limonene (7.8–8.3%), while those plants from Dakar revealed high content of β-pinene (25.3–34.4%) and α-eudesmol (12.3–20.6%). During drying of leaves, the proportions of all major compounds (except limonene) increased and were optimal after 2 h hydrodistillation. As in oils, 1,8-cineole was the major compound in hydrosols from Saint-Louis and Kaolack (77.3% and 39.0%, respectively), Dakar floral water showed: α-terpineol (20.3%), 1,8-cineole (12.6%), trans-pinocarveol (9.9%) and α-eudesmol (9.8%) as major compounds.E. camaldulensisfrom Saint-Louis is a source of essential oils that could be used in pharmaceutical and cosmetic applications. [ABSTRACT FROM PUBLISHER]

This work presents the studies on the isomerization of alpha-pinene in the presence of Ti-SBA-15 catalysts with different titanium contents: 0.75, 0.90, 1.10, and 3.10 wt%, as established by the EDX method, and 0.60, 0.76, 1.08, and 2.53 wt%, as measured by the ICP-AES method. These catalysts were prepared by the hydrothermal method and were characterized by the followed instrumental techniques: XRD, UV-Vis, FT-IR, SEM, ICP-AES, EDX, TEM, and AFM. Additionally, textural parameters were determined by N 2 adsorption/desorption. Preliminary studies showed that the most active catalyst was the material prepared from the crystallization gel with the molar ratio of Si:Ti = 20:1. This catalyst was further used for the detailed studies on α-pinene isomerization according to the following parameters: temperature range of 20–200 °C, 0.5–20 wt% catalyst content, and reaction times from 15 min to 24 h. The optimal conditions for α-pinene isomerization were determined on the basis of its conversion and the selectivity of the produced camphene. This study also showed that the process of α-pinene isomerization is complex because subsequent reactions occurred during the process. [ABSTRACT FROM AUTHOR]

Anthropogenic emissions such as NOx and SO2 influence the biogenic secondary organic aerosol (SOA) formation, but detailed mechanisms and effects are still elusive. We studied the effects of NOx and SO2 on the SOA formation from the photooxidation of α-pinene and limonene at ambient relevant NOx and SO2 concentrations (NOx : < 1to 20 ppb, SO2: < 0.05 to 15 ppb). In these experiments, monoterpene oxidation was dominated by OH oxidation.We found that SO2 induced nucleation and enhanced SOA mass formation. NOx strongly suppressed not only new particle formation but also SOA mass yield. However, in the presence of SO2 which induced a high number concentration of particles after oxidation to H2SO4, the suppression of the mass yield of SOA by NOx was completely or partly compensated for. This indicates that the suppression of SOA yield by NOx was largely due to the suppressed new particle formation, leading to a lack of particle surface for the organics to condense on and thus a significant influence of vapor wall loss on SOA mass yield. By compensating for the suppressing effect on nucleation of NOx , SO2 also compensated for the suppressing effect on SOA yield. Aerosol mass spectrometer data show that increasing NOx enhanced nitrate formation. The majority of the nitrate was organic nitrate (57– 77 %), even in low-NOx conditions (< ~1 ppb). Organic nitrate contributed 7–26% of total organics assuming a molecular weight of 200 g mol-1. SOA from α-pinene photooxidation at high NOx had a generally lower hydrogen to carbon ratio (H = C), compared to low NOx . The NOx dependence of the chemical composition can be attributed to the NOx dependence of the branching ratio of the RO2 loss reactions, leading to a lower fraction of organic hydroperoxides and higher fractions of organic nitrates at high NOx . While NOx suppressed new particle formation and SOA mass formation, SO2 can compensate for such effects, and the combining effect of SO2 and NOx may have an important influence on SOA formation affected by interactions of biogenic volatile organic compounds (VOCs) with anthropogenic emissions. [ABSTRACT FROM AUTHOR]

From oxidation over a FePcCl16-NH2-SiO2 catalyst and tert-butyl hydroperoxide (TBHP) as oxidant, verbenone, α-pinene epoxide, and verbenol were obtained from α-pinene while carvone, limonene 1,2-epoxide and carveol were produced from limonene. TBHP decomposes into O2, tert-butanol, and di- tert-butyl peroxide (DTBP). With the aim to perform a batch-reactor conceptual design, α-pinene and limonene oxidation was thermodynamically analyzed. Standard enthalpy and entropy of formation, liquid heat capacity, enthalpy of reaction and vaporization, and Gibbs free energy were determined by group contribution methods using Aspen Plus® simulation. Although the results depend on the method, it was found that α-pinene and limonene oxidations were exothermic and spontaneous at the selected reaction temperature. However, TBHP decomposition into O2, tert-butanol, and DTBP was an endothermic reaction. [ABSTRACT FROM AUTHOR]

Cadmium oxide supported on silica is a highly active and selective bifunctional catalyst for the clean synthesis of p-cymene using dehydroisomerization of cyclic monoterpenes such as α-pinene, β-pinene, limonene, α-terpinene, γ-terpinene, and terpinolene. The dehydroisomerization occurs via acid-redox bifunctional catalysis at the gas-solid interface involving isomerization of monoterpenes to p-menthadienes on acid sites of silica support followed by p-menthadiene dehydrogenation to p-cymene on oxo-metal sites of CdO. The less reactive bicyclic monoterpenes, such as α-pinene and β-pinene, give 91–95% p-cymene yields at 325–375 °C, whereas more reactive monocyclic monoterpenes, such as limonene, α-terpinene, γ-terpinene, and terpinolene, give a 100% yield at 200–250 °C. To the best of our knowledge, CdO/SiO 2 has the highest efficiency in monoterpene-to-p-cymene dehydroisomerization among the catalysts reported so far. The catalyst was characterized by BET, TGA, XRD, DRIFTS, H 2 -TPR, and ICP–OES. [Display omitted] • CdO/SiO 2 is a new efficient catalyst for terpene-to-p-cymene dehydroisomerization. • Wide range of terpenes studied: α-pinene, β-pinene, limonene, α-terpinene, γ-terpinene, and terpinolene. • p-Cymene yields range from 91% to 100% at 100% terpene conversion depending on terpene. • CdO/SiO 2 outperforms other catalysts reported so far for this reaction. • The results are consistent with acid-redox bifunctional reaction mechanism. [ABSTRACT FROM AUTHOR]