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2. Upper rim site lipophilic calix[4]arenes as receptors for natural terpenes and functionally related solvent molecules: combined crystal structure and QMB sensor studyThis paper is dedicated to Prof. Alajos Kálmán on the occasion of his 75thbirthday, who performed prominent work in the fields of isostructurality, morphotropy and polymorphy.Electronic supplementary information (ESI) available: Additional structural data of the compounds studied by X-ray structural analysis (Tables S1 and S2) and isostructural calculations (Fig. S1–S6). CCDC reference numbers 780763–780768. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c0ce00696c
- Author
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Tobias Gruber, Conrad Fischer, Wilhelm Seichter, Petra Bombicz, and Edwin Weber
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HYDROPHOBIC surfaces , *QUARTZ crystal microbalances , *AROMATIC compounds , *TERPENES , *SOLVENTS , *CALIXARENES , *BUTANOL - Abstract
Three upper rim site lipophilic calix[4]arenes 1–3featuring different para-alkanoyl substituents at the phenolic moieties, i.e.n-hexanoyl, n-octanoyl and 3-cyclohexylpropanoyl groups, are reported to complex, aside from the common solvent molecule n-butanol, different keto and hydroxylic terpene guest molecules such as (−)-menthone, (−)-menthol or (+)-carvone in the solid state. Although for all six inclusion compounds described here, a strict 1 : 1 host : guest stoichiometry is observed, complementary size and polarity relationships between the cone shaped calixarene cavity and the guest molecule emerge from single crystal X-ray structural study. Dependent on the structure of the guest molecule, the calixarenes are arranged in a head-to-head or head-to-tail orientation in the crystalline packing, giving rise to capsular or otherwise deeply enclosed inclusion mode of the guest molecules, respectively. Furthermore, the O-acyl atoms of the calixarenes were found to be directly involved in host–guest interaction. In order to estimate the degree of isostructurality of the host frameworks and to examine the influence of the guest molecules on the solid-state conformation of these calixarene molecules, isostructurality comparison, cell similarity and molecular isometricity calculations were carried out revealing a rare case of supramolecular morphotropism for the pair of (−)-menthone and (−)-menthol inclusions of the n-hexanoyl substituted calixarene. Structure–inclusion property relationship was examined by QMB measurements of thin layers of the calixarenes. Vapor studies with different terpenes and common organic solvents show an increased affinity towards guest molecules with polar functionalities, whereas small solvent molecules like acetone are bound considerably better than the more bulky terpene molecules. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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3. Exploiting natural complexity for substrate controlled regioselectivity and stereoselectivity in tantalum catalysed hydroaminoalkylation.
- Author
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Zheng, Cameron H. M., Nadeau, Ben E., Trajano, Heather L., and Schafer, Laurel L.
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TANTALUM ,TURPENTINE ,MONOTERPENES ,STEREOELECTRONIC control ,STEREOSELECTIVE reactions ,ALKENES ,LIMONENE ,TERPENES ,CARYOPHYLLENE - Abstract
Naturally occurring and structurally diverse alkene-containing substrates, terpenes, provided a platform for establishing chemo-, regio-, and diastereoselective reactivity in tantalum catalysed hydroaminoalkylation. Naturally derived 1,3-butadienes revealed the unique regio- and diastereoselective (Z)-1,4-addition products accessible from isoprene and β-myrcene by hydroaminoalkylation. Selective terpene functionalisation, within an industrially produced turpentine mixture, demonstrates functionalisation specificity of β-pinene and limonene. Lastly, sesquiterpene functionalisation using β-caryophyllene and humulene provide rare examples of trisubstituted alkene reactivity in hydroaminoalkylation, by leveraging strainrelease and stereoelectronic effects to control chemoselectivity. As a result of these reactivity studies using natural substrates, new tools for understanding alkene electronic, strain, and stereoelectronic effects on chemo- and diastereoselectivity outcomes have revealed new mechanistic insights into hydroaminoalkylation. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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4. Comprehensive two-step supercritical fluid extraction for green isolation of volatiles and phenolic compounds from plant material.
- Author
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Pilařová, Veronika, Plachká, Kateřina, Herbsová, Diana, Kosturko, Štefan, Svec, Frantisek, and Nováková, Lucie
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SUPERCRITICAL fluid extraction ,PHENOLIC acids ,ORGANIC solvents ,SOLVENT extraction ,COMPLEX matrices ,CARBON dioxide ,TERPENES - Abstract
Extraction of compounds with different physicochemical properties from a complex matrix usually involves several individual steps and requires large volumes of organic solvents. In this pioneering study, we propose a comprehensive two-step supercritical fluid extraction using carbon dioxide, ethanol, and water. This novel approach allows the extraction of non-polar and polar analytes within one run in two consecutive steps. Indeed, the first step with a dominant amount of CO
2 with only 2% cosolvent allowed the selective extraction of non-polar volatile terpenes only in 20 min. The conditions were then automatically switched. Increasing the cosolvent volume in the extraction solvent up to 44% (v/v) resulted in the extraction of more polar compounds, including flavonoids and phenolic acids, in 60 min. Importantly, switching the supercritical fluid extraction (SFE) conditions does not require any manual intervention but results in two separate fractions containing target compounds with distinctly different physicochemical properties. The novel method was verified in terms of repeatability, accuracy, precision, and greenness. Two-step SFE was applied to seven plant species differing in volatile terpenes and phenolic profiles. The results proved that this concept is suitable for the analysis of complex plant samples. In addition, it enables a reduction in the toxic solvents consumption, extraction time, and manual intervention required for traditional extraction approaches when isolating different groups of metabolites. [ABSTRACT FROM AUTHOR]- Published
- 2024
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5. Catalytic prenylation of natural polyphenols.
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Du, Yi, Korchi, Iman, Rubtsov, Aleksandr E., and Malkov, Andrei V.
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POLYPHENOLS ,ISOPRENYLATION ,TERPENES ,FLAVONOIDS - Abstract
Prenylated polyphenols occur naturally and exhibit biological activity superior to the ubiquitous parent polyphenols. However, their low abundance limits the wider application of these derivatives. In this work, we present an expedient, single-step catalytic protocol for introducing terpene fragments into the aromatic rings of the widely available natural stilbenoids and flavonoids to upgrade their therapeutic potential. [ABSTRACT FROM AUTHOR]
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- 2023
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6. Reprogramming the metabolism of oleaginous yeast for sustainably biosynthesizing the anticarcinogen precursor germacrene A.
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Liu, Qi, Zhang, Ge, Su, Liqiu, Liu, Pi, Jia, Shiru, Wang, Qinhong, and Dai, Zongjie
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LIPID metabolism ,ACETYLCOENZYME A ,YEAST ,TERPENES ,BACKLASH (Engineering) ,CELL metabolism ,PHYTOREMEDIATION - Abstract
Due to the diverse structures and broad functions of terpenes, microbial biosynthesis of these compounds has been favored as a sustainable alternative to phytoextraction and chemosynthesis. Here, systematic metabolic engineering strategies were explored in the oleaginous yeast Yarrowia lipolytica for hyperproducing sesquiterpene germacrene A which serves as an important intermediate of numerous anticarcinogens. By identifying the most efficient germacrene A synthase to date, reconstructing the endogenous mevalonate pathway and extending the cytosolic acetyl-CoA pool by regulating lipid metabolism, the resulting strain overproduced 2.794 g L
−1 germacrene A in shake flasks, which represented a 38-fold improvement over the initial strain. The engineered strain was subsequently capable of producing 39 g L−1 germacrene A at a yield of 0.181 g g−1 glucose during optimized bioreactor fermentation, with this being the highest sesquiterpene production level reported to date for Y. lipolytica. These results demonstrate that reprogramming the metabolism of the host cell by systematic metabolic engineering plays an essential role in diverting its inherent metabolic fluxes for sesquiterpene biosynthesis and these approaches can be extensively applied for synthesizing natural terpenes. [ABSTRACT FROM AUTHOR]- Published
- 2023
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7. Repurposing the cellulase workhorse Trichoderma reesei as a ROBUST chassis for efficient terpene production.
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Xiao, Meili, Wang, Yinmei, Wang, Yan, Yan, Xing, Zhu, Zhihua, Tian, Ernuo, Yang, Chengshuai, Ma, Erdong, Zou, Gen, Zhou, Zhihua, and Wang, Pingping
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TERPENES ,TRICHODERMA reesei ,CELLULASE ,NATURAL products ,URIDINE ,AGRICULTURAL industries - Abstract
The comprehensive utilization of agro-industrial residues poses a persistent global challenge. Microbial fermentation is an efficient way to convert agro-industrial residues into valuable products. Trichoderma reesei is a traditional cellulase and other protein producer using agro-industrial residues as substrates. The potential of T. reesei as a chassis to produce small natural products remains untapped. Here, we successfully employed T. reesei to efficiently synthesize different terpene types. To optimize the chassis for metabolite synthesis, we deleted major (hemi-)cellulase genes along with the global regulator Lae1 to improve the efficiency of secondary metabolite biosynthesis, and overexpressed the constitutively activated transcriptional factor XYR1
A824V in MC3 (a uridine auxotrophic strain derived from T. reesei Rut-C30) to alleviate glucose repression. Through glucose, lactose, and corn steep as substrates, the production of ophiobolin F using the modified chassis was increased to 1187.06 mg L−1 in shake flask fermentation and up to 3072.45 mg L−1 under fed-batch fermentation. We further demonstrated the versatility of the Δlae1::xyr1/MC3-Δ10 chassis by successfully producing other fungal and plant terpenes. Collectively, our results demonstrated the potential of the Reducing Outflow and Broadened Upstream Substrate Type (ROBUST) T. reesei chassis for efficient terpene production utilizing agro-industrial residues, with important implications for terpene biosynthesis and sustainable biofabrication. [ABSTRACT FROM AUTHOR]- Published
- 2023
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8. A synergistic effect of hydrophobic deep eutectic solvents based on terpenoids and carboxylic acids for tetracycline microextraction.
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Cherkashina, Ksenia, Pochivalov, Aleksei, Simonova, Viktoria, Shakirova, Firuza, Shishov, Andrey, and Bulatov, Andrey
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TETRACYCLINES ,CHOLINE chloride ,EUTECTICS ,TETRACYCLINE ,HYDROPHOBIC interactions ,CARBOXYLIC acids ,TERPENES ,OCTANOIC acid - Abstract
Hydrophobic deep eutectic solvents were investigated for tetracycline microextraction. It was found that a deep eutectic solvent consisting of thymol and octanoic acid provided a synergistic effect on tetracycline extraction. In this paper, a novel liquid–liquid microextraction procedure for the HPLC-DAD determination of tetracyclines in milk samples was proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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9. Atrachinenynes A–D, four diacetylenic derivatives with unprecedented skeletons from the rhizomes of Atractylodes chinensis.
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Chen, Fei-Long, Liu, Dong-Li, Fu, Jing, Fu, Lu, Gao, Jin, Bai, Li-Ping, Zhang, Wei, Jiang, Zhi-Hong, and Zhu, Guo-Yuan
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DIELS-Alder reaction ,CIRCULAR dichroism ,BUTADIYNE ,TERPENES ,SKELETON - Abstract
Atrachinenynes A–D (1–4), four novel diacetylenic derivatives, were isolated for the first time from the rhizomes of Atractylodes chinensis. Compound 1 features a new C
26 skeleton with an unusual 8/6/6/5 tetracyclic ring system bearing a diacetylene sidechain. Compounds 2–4 are three novel diacetylenic terpenoids with an additional six-membered ring between terpenes and diacetylenes formed via a Diels–Alder reaction. The structures and the absolute configurations of 1–4 were elucidated by spectroscopic methods, electronic circular dichroism (ECD) calculations, and13 C quantum chemical calculations. Their plausible biogenetic pathways were also proposed. [ABSTRACT FROM AUTHOR]- Published
- 2022
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10. Hot off the press.
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Hill, Robert A. and Sutherland, Andrew
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NATURAL products ,X-ray imaging ,TERPENES ,GLYCOSIDES ,LACTONES - Abstract
A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as kadsuraol A from Kadsura longipedunculata. [ABSTRACT FROM AUTHOR]
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- 2018
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11. Selective separation of lactic, malic, and tartaric acids based on the hydrophobic deep eutectic solvents of terpenes and amides.
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Liu, Lijuan, Su, Benlong, Wei, Qifeng, and Ren, Xiulian
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TARTARIC acid ,TERPENES ,SOLVENTS ,SOLVENT extraction ,AMIDES ,EUTECTICS - Abstract
Inspired by traditional solvents for carboxylic acid extraction being not environmentally friendly, novel hydrophobic deep eutectic solvents (DESs) based on amides as hydrogen bond acceptors (HBAs) and terpenes as hydrogen bond donors (HBDs) were proposed as sustainable solvents. The structures were characterized by
1 H NMR and GC-MS, meanwhile the formation mechanism was revealed by electrostatic potential (ESP) analysis. In addition, the partition coefficients and separation factors of lactic, malic, and tartaric acids (LA, MA, and TA) in novel DESs were tested by a simple solvent extraction approach. What's more, the contributions of HBAs and HBDs in improving the selective separation of carboxylic acids were confirmed by multiscale exploration and experimental research. HBAs increase the partition coefficient via forming double hydrogen bonds with LA, MA, and TA. HBDs improve the selectivity by competition with these acids. This finding can serve as a blueprint for the design of greener solvents for the selective separation of carboxylic acids in bioprocesses. [ABSTRACT FROM AUTHOR]- Published
- 2021
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12. Production of plant volatile terpenoids (rose oil) by yeast cell factories.
- Author
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Li, Rongsheng, Wang, Kou, Wang, Dong, Xu, Liping, Shi, Yusong, Dai, Zhubo, and Zhang, Xueli
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TERPENES ,DAMASK rose ,YEAST ,SYNTHETIC lubricants ,SYNTHETIC biology - Abstract
Plant volatile terpenoids (PVTs) are the main aroma components of flowers, fruits, and vegetables. Citronellol, geraniol, and nerol are the three major components of rose oil, which has wide applications in aromatherapy, perfumes, and cosmetics. However, the current production of rose oil through the distillation of flowers is not sustainable and cannot meet the increasing market demand. Here, we firstly reconstructed the biosynthetic pathway of citronellol in the platform yeast strain HP001, which overexpresses the MVA-pathway genes, resulting in the production of 7.87 mg L
−1 citronellol. To further increase the production, the native promoter of ERG20 was replaced by the promoter of ERG7, and the expression of the geraniol-synthesis module was enhanced. The resulting strain exhibited a remarkable 4450% increase of the citronellol titer, reaching 0.36 g L−1 in shake flasks and 6.37 g L−1 in a bioreactor. Furthermore, the entire synthetic pathways of these three rose oil monoterpenoids were reconstituted in yeast, resulting in Rose-yeast 1.0, with a titer of 124.0 mg L−1 in shake flasks and 4.87 g L−1 in a bioreactor. Rose-yeast 1.0 produced a synthetic rose oil comprising a correct ratio of citronellol (62.30%), geraniol (27.39%), and nerol (10.31%), closely matching that of Rosa × damascena MILLER. Additionally, the ERG7 promoter was inserted in front of the native ERG9 gene, and the metabolic flux of the sesquiterpenoid synthesis was assessed by introducing the biosynthetic pathways of nerolidol and valencene. The maximal titer of the resulting strain reached 912.72 mg L−1 nerolidol and 5.30 mg L−1 valencene in shake flasks. This synthetic biology platform for mono- and sesquiterpenoid production can serve as a basis for creating a sustainable microbial source of important PVTs. [ABSTRACT FROM AUTHOR]- Published
- 2021
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13. The incredible story of ophiobolin A and sphaeropsidin A: two fungal terpenes from wilt-inducing phytotoxins to promising anticancer compounds.
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Evidente, Antonio
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PHYTOTOXINS ,TERPENES ,CANKER (Plant disease) ,STRUCTURE-activity relationships ,ANTINEOPLASTIC agents ,HOST plants ,SALVINORIN A - Abstract
Covering: 2000 to 2023 This review presents the exceptional story of ophiobolin A (OphA) and sphaeropsidin A (SphA), a sesterterpene and a diterpene, respectively, which were initially isolated as fungal phytotoxins and subsequently shown to possess other interesting biological activities, including promising anticancer activities. Ophiobolin A is a phytotoxin produced by different fungal pathogens, all belonging to the Bipolaris genus. Initially, it was only known as a very dangerous phytotoxin produced by fungi attacking essential cereals, such as rice and barley. However, extensive and interesting studies were carried out to define its original carbon skeleton, which is characterized by a typical 5 : 8 : 5 ring system and shared with fusicoccins and cotylenins, and its phytotoxic activity on host and non-host plants. The biosynthesis of OphA was also defined by describing the different steps starting from mevalonate and through the rearrangement of the acyclic C-25 precursor lead the toxin is obtained. OphA was also produced as a bioherbicide from Drechslera gigantea and proposed for the biocontrol of the widespread and dangerous weed Digitaria sanguinaria. To date, more than sixty ophiobolins have been isolated from different fungi and their biological activities and structure–activity relationship investigated, which were also described using their hemisynthetic derivatives. In the last two decades, thorough studies have been performed on the potential anticancer activity of OphA and its original mode of action, attracting great interest from scientists. Sphaeropsidin A has a similar story. It was isolated as the main phytotoxin from Diplodia cupressi, the causal agent of Italian cypress canker disease, resulting in the loss of millions of plants in a few years in the Mediterranean basin. The damage to the forest, environment and ornamental heritage are noteworthy and economic losses are also suffered by tree nurseries and the wood industry. Six natural analogues of SphA were isolated and several interesting hemisynthetic derivatives were prepared to study its structure–activity relationship. Surprisingly, sphaeropsidin A showed other interesting biological activities, including antibiotic, antifungal, and antiviral. In the last decade, extensive studies have focused on the anticancer activity and original mode of action of SphA. Furthermore, specific hemisynthetic studies enable the preparation of derivatives of SphA, preserving its chromophore, which showed a noteworthy increase in anticancer activity. It has been demonstrated that ophiobolin A and sphaeropsidin A are promising natural products showing potent activity against some malignant cancers, such as brain glioblastoma and different melanomas. [ABSTRACT FROM AUTHOR]
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- 2024
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14. Class II terpene cyclases: structures, mechanisms, and engineering.
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Pan, Xingming, Rudolf, Jeffrey D., and Dong, Liao-Bin
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CYCLASES ,TERPENES ,STRUCTURAL engineering ,NATURAL products ,ENGINEERING ,GIBBERELLINS ,DITERPENES - Abstract
Covering: up to July 2023 Terpene cyclases (TCs) catalyze some of the most complicated reactions in nature and are responsible for creating the skeletons of more than 95 000 terpenoid natural products. The canonical TCs are divided into two classes according to their structures, functions, and mechanisms. The class II TCs mediate acid–base-initiated cyclization reactions of isoprenoid diphosphates, terpenes without diphosphates (e.g., squalene or oxidosqualene), and prenyl moieties on meroterpenes. The past twenty years witnessed the emergence of many class II TCs, their reactions and their roles in biosynthesis. Class II TCs often act as one of the first steps in the biosynthesis of biologically active natural products including the gibberellin family of phytohormones and fungal meroterpenoids. Due to their mechanisms and biocatalytic potential, TCs elicit fervent attention in the biosynthetic and organic communities and provide great enthusiasm for enzyme engineering to construct novel and bioactive molecules. To engineer and expand the structural diversities of terpenoids, it is imperative to fully understand how these enzymes generate, precisely control, and quench the reactive carbocation intermediates. In this review, we summarize class II TCs from nature, including sesquiterpene, diterpene, triterpene, and meroterpenoid cyclases as well as noncanonical class II TCs and inspect their sequences, structures, mechanisms, and structure-guided engineering studies. [ABSTRACT FROM AUTHOR]
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- 2024
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15. Dimethyl sulfide facilitates acid catalysed ring opening of the bicyclic monoterpenes in crude sulfate turpentine to afford p-menthadienes in good yield.
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Tibbetts, Joshua D. and Bull, Steven D.
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TURPENTINE ,MONOTERPENES ,PINENE ,DIMETHYL sulfide ,SULFATES ,TERPENES ,HIGH temperature physics - Abstract
The potential of using turpentine for the production of biorenewable chemicals within a biorefinery context is discussed, focussing on the development of practical methodology to convert the bicyclic monoterpene components present in untreated crude sulfate turpentine into mixtures of synthetically useful p-menthadienes (p-MeDs) as feedstocks for chemical production. A simple and scalable biphasic acid catalysed ring-opening (ACRO) protocol employing recyclable 6 M aq. H
2 SO4 at 90 °C has been developed to transform the major bicyclic monoterpenes (β-pinene, α-pinene, and 3-carene) in untreated commercial crude sulfate turpentine (CST) into mixtures of monocyclic p-MeDs in >70% yield. Investigations using pure bicyclic monoterpenes reveal that the ∼3 mol% Me2 S present in CST plays a key role in increasing the rate and yield of these ACRO reactions. Reaction monitoring studies have identified the presence of induction periods and autocatalytic effects, as well as an intriguing time-dependent increase in p-MeD yield after all the bicyclic terpene substrate has been consumed. These effects have been explained using a mechanism that invokes reversible addition of Me2 S to the alkene bonds of monoterpenes to produce in situ generated sulfonium salts. These sulfonium salts then function as surfactants to increase the degree of mixing of the aqueous/terpene layers of the biphasic ACRO reaction, resulting in faster protonation of the alkene bonds of the bicyclic terpenes in the rate-determining step. The shorter reaction times of the Me2 S facilitated ACRO reactions of CST and gum turpentine enable better yields of p-MeDs to be obtained by minimising p-MeD losses to competing polymerisation pathways that occur at elevated temperatures over time. [ABSTRACT FROM AUTHOR]- Published
- 2021
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16. Monetary values estimates of solvent emissions.
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Tobiszewski, Marek and Bystrzanowska, Marta
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ALIPHATIC hydrocarbons ,AROMATIC compounds ,ALIPHATIC alcohols ,TERPENES ,SOLVENTS ,ESTIMATES ,KETONES ,CARBON tetrachloride - Abstract
The impact values for the environmental emissions of 52 solvents are estimated and expressed in monetary units. The impact values of solvents present in the air are calculated on the basis of 13 impact indicators and additional 2 impact indicators for solvents present in water. These impact values are weighed with the results obtained with a multi-compartment distribution model, allowing the calculation of the fraction of solvent emitted to the environment present in each of the compartments. The results show that the impact values of solvent emissions are in the range of 0.7–1179.51 $ L
−1 , with a mean value of 20.69 $ L−1 , expressed in USD2019 . These impacts are considerably lower for short-chain aliphatic hydrocarbons, alcohols, ethers, aldehydes, ketones, and esters. High impact values are obtained for long-chain aliphatic hydrocarbons, aromatic hydrocarbons, terpenes, and an extremely high value for carbon tetrachloride. Monetary values calculated to assess the solvent emission impact have the advantage that they are quantitative and easily applicable. [ABSTRACT FROM AUTHOR]- Published
- 2020
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17. Unusual cyclic terpenoids with terminal pendant prenyl moieties: from occurrence to synthesis.
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Kulcitki, Veaceslav, Harghel, Petru, and Ungur, Nicon
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TERPENES ,CHEMICAL bonds ,PRENYLAMINE ,ELECTROPHILES ,CHEMICAL precursors - Abstract
Covering: 1966 up to the end of 2013 The paper reviews the known examples of cyclic terpenoids produced from open chain polyenic precursors by an “unusual” biosynthetic pathway, involving selective electrophilic attack on an internal double bond followed by cyclization. The resulting compounds possess cyclic backbones with pendant terminal prenyl groups. Synthetic approaches applied for the synthesis of such specifically functionalized compounds are also discussed, as well as biological activity of reported representatives. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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18. Biosourced terpenoids for the development of sustainable acrylic pressure-sensitive adhesives via emulsion polymerisation.
- Author
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Droesbeke, Martijn A., Simula, Alexandre, Asua, José M., and Du Prez, Filip E.
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PRESSURE-sensitive adhesives ,TERPENES ,SUSTAINABLE development ,POLYMERIZATION ,EMULSIONS ,EMULSION polymerization ,FOOD emulsions ,ACRYLATES - Abstract
The increasing regulations and restrictions in favour of a biobased and sustainable community could potentially harm the strong economic position of the polymer industry, which still heavily relyies on crude oil. The adhesive industry, in particular, is looking for more renewable alternatives and more environmentally friendly synthesis routes. In this work, (meth)acrylate derivatives of terpenoids, namely tetrahydrogeraniol, citronellol, menthol and isoborneol are introduced in the synthesis of waterborne pressure-sensitive adhesives (PSA) based on acrylic latexes via emulsion polymerisation. This industrially implemented setting enables the preparation of five different formulations with high biobased content with a renewable carbon content ranging from 70 to 100%. The biobased PSAs are found to be comparable in terms of tack, peel strength and shear resistance to a benchmark petroleum-derived commercial product. They show good adhesion properties on steel, glass and polyethylene surfaces. Moreover, the various formulations displayed different mechanical and adhesion properties, which make them attractive for a wide range of applications. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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19. Luminescent Zn(II) and Cd(II) complexes with chiral 2,2′-bipyridine ligands bearing natural monoterpene groups: synthesis, speciation in solution and photophysics.
- Author
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Kokina, Tatyana E., Rakhmanova, Marianna I., Shekhovtsov, Nikita A., Glinskaya, Ludmila A., Komarov, Vladislav Y., Agafontsev, Alexander M., Baranov, Andrey Y., Plyusnin, Pavel E., Sheludyakova, Liliya A., Tkachev, Alexey V., and Bushuev, Mark B.
- Subjects
ZINC compounds synthesis ,LIGANDS (Chemistry) ,ZINC porphyrins ,CHEMICAL speciation ,EXCITED states ,HYDROGEN bonding ,TERPENES ,ZINC ferrites - Abstract
Mononuclear zinc(II) and cadmium(II) complexes, ZnLCl
2 (1), CdLCl2 (2), ZnL1 Cl2 ·2H2 O (3), and CdL1 Cl2 ·2H2 O (4), with chiral ligands containing a 2,2′-bipyridine moiety and natural terpene (+)-limonene (L) or (+)-3-carene (L1 ) moieties were synthesized. In these complexes the L and L1 ligands are shown to coordinate Zn2+ and Cd2+ ions through the 2,2′-bipyridine moiety. The acetamide group of the ligands interacts with M2+ ions by forming N⋯M2+ and C=O⋯M2+ contacts and N–H⋯Cl hydrogen bonds with coordinated Cl− ions. In solutions the complexes have several conformers differing by the degree of the turn of the acetamide moiety relative to the ligand core and the type of its interaction with the coordination core. The ligands and complexes exhibit luminescence with the quantum yield increasing in the order: ligand < cadmium(II) complex < zinc(II) complex. The complexes 3 and 4 demostrate excitation wavelength independent single-channel fluorescence. As opposed to 3 and 4, the complexes 1 and 2 demonstrate excitation wavelength dependent emission with nanosecond and microsecond lifetimes of the excited states. According to our TD-DFT calculations, an interplay of ligand centered and halide to ligand transitions facilitates two deactivation channels in 1 and 2: S1 –S0 and T1 –S0 . [ABSTRACT FROM AUTHOR]- Published
- 2020
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20. Analysis of the volatile monoterpene composition of citrus essential oils by photoelectron spectroscopy employing continuously monitored dynamic headspace sampling.
- Author
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Ganjitabar, Hassan, Hadidi, Rim, Garcia, Gustavo A., Nahon, Laurent, and Powis, Ivan
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ESSENTIAL oils ,PHOTOELECTRON spectroscopy ,MONOTERPENES ,CITRUS ,PHOTOELECTRON spectra ,TERPENES - Abstract
A new photoelectron spectroscopic method permitting a quantitative analysis of the volatile headspace of several essential oils is presented and discussed. In particular, we focus on the monoterpene compounds, which are known to be the dominant volatile components in many such oils. The photoelectron spectra of the monoterpene constituents may be effectively isolated by accepting for analysis only those electrons that accompany the production of m/z = 136 ions, and by using low photon energies that restrict cation fragmentation. The monoterpene isomers are then identified and quantified by regression modelling using a library of terpene standard spectra. An advantage of this approach is that pre-concentration of the volatile vapour is not required, and all steps are performed at ambient temperature, avoiding the possible deleterious effects (such as isomerisation/decomposition) that may sometimes arise in gas chromatographic (GC) procedures. As a proof-of-principle demonstration, three citrus oils (lemon, lime, bergamot) are analysed with this approach and the results are compared with reported GC composition profiles obtained for these oils. Potential advantages of the methodology that include multiplex detection and real-time, in situ analysis are identified and discussed. Alternative and faster experimental implementations concerning laboratory-based ionization and detection schemes are proposed and considered, as is the possibility of a straightforward extension towards simultaneous determination of enantiomeric excesses. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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21. Limonene as a natural product extraction solvent.
- Author
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Pagliaro, Mario, Fabiano-Tixier, Anne-Sylvie, and Ciriminna, Rosaria
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NATURAL products ,SOLVENT extraction ,LIMONENE ,TERPENES ,MANUFACTURING processes ,RESEARCH teams - Abstract
First reported in 2004, and subsequently advanced by Chemat's team and other research teams in the following two decades, the use of D -limonene as a natural product extraction solvent offers multiple benefits that go beyond its environmentally benign nature. Following a review of the main research achievements concerning the use of this biosolvent in the extraction of widely different natural products, we offer a comprehensive perspective including usually neglected economic and safety aspects. The study concludes by identifying three main research outcomes and providing two guidelines to bioeconomy practitioners willing to use this terpene in new natural production extraction and production processes. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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22. Hot off the press.
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Hill, Robert A. and Sutherland, Andrew
- Subjects
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X-ray crystallography , *CHEMICAL structure , *GLYCOSIDE synthesis , *PENICILLIUM , *TERPENES - Abstract
A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as macrophilone A from Macrorhynchia philippina. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
23. Solvent from forestry biomass. Pinane a stable terpene derived from pine tree byproducts to substitute n-hexane for the extraction of bioactive compounds.
- Author
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Yara-Varón, E., Fabiano-Tixier, A. S., Chemat, F., Balcells, M., Canela-Garayoa, R., Touaibia, M., Selka, A., and Bily, Antoine
- Subjects
TERPENES ,BIOACTIVE compounds ,SOLVENTS - Abstract
The ability to be used as an alternative solvent of a cis-rich pinane (cis/trans: 7/3), which was obtained for the first time at the multigram scale through an environmentally friendly catalytic hydrogenation of α/β-pinenes or turpentine oil under neat conditions over a Pd/C catalyst, was investigated and compared to n-hexane for the extraction of several bioactive compounds. Experimental evaluation as well as a simulation of the cis-rich pinane extraction capacity have been undertaken. The predictive approach was performed using the simulation software COSMO-RS (conductor like screening model for realistic solvents), which uses a statistical thermodynamics approach based on the result of quantum chemical calculation, for the understanding of dissolving mechanism. COSMO-RS simulation showed that the bio-based solvent is a good solvent to solubilize carotenoids, oil from rapeseed and aromas from caraway seeds. The experimental results indicated that the highest carotenoid yield was obtained with the cis-rich pinane with 95.4% of the maximum carotenoid content in carrots while n-hexane was only able to extract 78.1% of them. With respect to the extraction of oil from rapeseeds, both solvents showed similar extraction yields and no differences were observed in the fatty acid profiles. In relation to the aromas, the characterization of the essential oil extracted by the two solvents showed a similar composition, where carvone (64%) was the main component followed by limonene (34%). No selectivity of the solvents was observed for any of the two major compounds. The results indicate that the bio-based solvent could be a promising solvent for n-hexane substitution. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
24. Sustainable cycloaliphatic polyurethanes: from synthesis to applications.
- Author
-
Mouren, Agathe and Avérous, Luc
- Subjects
TERPENES ,POLYURETHANES ,PLASTIC scrap ,GAS prices ,ALIPHATIC compounds ,PRICE fluctuations ,PLASTICS ,POLYURETHANE elastomers - Abstract
Polyurethanes (PUs) are a versatile and major polymer family, mainly produced via polyaddition between polyols and polyisocyanates. A large variety of fossil-based building blocks is commonly used to develop a wide range of macromolecular architectures with specific properties. Due to environmental concerns, legislation, rarefaction of some petrol fractions and price fluctuation, sustainable feedstocks are attracting significant attention, e.g., plastic waste and biobased resources from biomass. Consequently, various sustainable building blocks are available to develop new renewable macromolecular architectures such as aromatics, linear aliphatics and cycloaliphatics. Meanwhile, the relationship between the chemical structures of these building blocks and properties of the final PUs can be determined. For instance, aromatic building blocks are remarkable to endow materials with rigidity, hydrophobicity, fire resistance, chemical and thermal stability, whereas acyclic aliphatics endow them with oxidation and UV light resistance, flexibility and transparency. Cycloaliphatics are very interesting as they combine most of the advantages of linear aliphatic and aromatic compounds. This original and unique review presents a comprehensive overview of the synthesis of sustainable cycloaliphatic PUs using various renewable products such as biobased terpenes, carbohydrates, fatty acids and cholesterol and/or plastic waste. Herein, we summarize the chemical modification of the main sustainable cycloaliphatic feedstocks, synthesis of PUs using these building blocks and their corresponding properties and subsequently present their major applications in hot-topic fields, including building, transportation, packaging and biomedicine. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
25. Characterization of carotenoids in soil bacteria and investigation of their photodegradation by UVA radiation via resonance Raman spectroscopy.
- Author
-
Kumar B. N., Vinay, Kampe, Bernd, Rösch, Petra, and Popp, Jürgen
- Subjects
CAROTENOIDS ,BIOLOGICAL pigments ,TERPENES ,CHEMICAL decomposition ,PHOTODEGRADATION - Abstract
A soil habitat consists of an enormous number of pigmented bacteria with the pigments mainly composed of diverse carotenoids. Most of the pigmented bacteria in the top layer of the soil are photoprotected from exposure to huge amounts of UVA radiation on a daily basis by these carotenoids. The photostability of these carotenoids depends heavily on the presence of specific features like a carbonyl group or an ionone ring system on its overall structure. Resonance Raman spectroscopy is one of the most sensitive and powerful techniques to detect and characterize these carotenoids and also monitor processes associated with them in their native system at a single cell resolution. However, most of the resonance Raman profiles of carotenoids have very minute differences, thereby making it extremely difficult to confirm if these differences are attributed to the presence of different carotenoids or if it is a consequence of their interaction with other cellular components. In this study, we devised a method to overcome this problem by monitoring also the photodegradation of the carotenoids in question by UVA radiation wherein a differential photodegradation response will confirm the presence of different carotenoids irrespective of the proximities in their resonance Raman profiles. Using this method, the detection and characterization of carotenoids in pure cultures of five species of pigmented coccoid soil bacteria is achieved. We also shed light on the influence of the structure of the carotenoid on its photodegradation which can be exploited for use in the characterization of carotenoids via resonance Raman spectroscopy. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
26. Selective etherification of β-citronellene catalyzed by zeolite beta.
- Author
-
Radhakrishnan, Sambhu, Purino, Martin, Alexopoulos, Konstantinos, Taulelle, Francis, Reyniers, Marie-Françoise, Marin, Guy B., and Martens, Johan A.
- Subjects
ETHERIFICATION ,ZEOLITE catalysts ,ALCOHOL ,CONTINUOUS flow reactors ,CHEMOSELECTIVITY ,TERPENES ,HOMOGENEOUS catalysis - Abstract
The etherification of β-citronellene with bioalcohols over zeolite beta was performed in a continuous flow liquid phase reactor. At 80 °C, the catalyst exhibits 50% β-citronellene conversion with a high selectivity for the etherification reaction. High chemoselectivity (90%) at the β-double bond of β-citronellene was observed, while β-citronellene isomers were formed as minor products. In order to rationalize the observed chemoselectivity, the relative stabilities of the protonated reaction intermediates were estimated using theoretical calculations. The zeolite beta catalyst exhibits high stability as well as low coke formation. Considering the industrial importance of terpene ethers as sophisticated solvents, fragrance or flavor additives, a novel and environmentally friendly synthesis is presented as an alternative to homogeneous catalysis using strong Brønsted or Lewis acids in solution. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
27. Tuning the aggregation mode to induce different chiralities in organogels of mono- and bis-triterpenoid derivatives and the preparation of gold nanoparticles for use as a template.
- Author
-
Lu, Jinrong, Wu, Jindan, and Ju, Yong
- Subjects
DIMETHYL sulfoxide ,TRITERPENOIDS ,TERPENES ,LANOSTEROL ,ENANTIOSELECTIVE catalysis - Abstract
New gelators, based on chiral triterpenoids linked with aromatic rings and amide structures, were designed and synthesized. Different chiral properties of assembly of the organogels were observed and these were expressed by different close degrees of molecular packing, which were attributed to the formation of H-type aggregates in the monotriterpenoid and of J-type aggregates in the bis-triterpenoid derivatives. The nanofibers of the organogel in dimethylsulfoxide were used to engineer gold nanoparticles and generate gel–nanoparticle hybrid materials. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
28. Microwave assisted extraction as an important technology for valorising orange waste.
- Author
-
Attard, Thomas M., Watterson, Baillie, Budarin, Vitaliy L., Clark, James H., and Hunt, Andrew J.
- Subjects
MICROWAVES ,HEATING ,IRRADIATION ,LIMONENE ,TERPENES - Abstract
Microwave assisted extraction has been demonstrated as an efficient green technology for the recovery of d-limonene from orange waste. Microwave irradiation was shown to be a more efficient method when compared to conventional heating due to its high selectivity for d-limonene, significantly shortened extraction durations and d-limonene yields twice that of conventional heating. Kinetic analysis of the extraction process indicated a typical two-step diffusion process, an initial stage of extraction from the exterior of the cells (1st stage) and diffusion of solute across the membrane (2nd stage). Diffusion coefficients for the initial stage of extraction from the exterior of cells (1st stage) for both conventional and microwave extraction demonstrated similar trends and activation energies. Interestingly, trans-membrane diffusion coefficient for the microwave assisted extraction at 110 °C was significantly high. Crucially, this was not observed with conventional heating suggesting that microwave radiation favourably interacts with the sample during extraction, causing simultaneous cell rupture and diffusion, resulting in greater yield. This provides an important insight into the development of extraction processes for orange peel. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
29. Continuous catalyst-free aromatization of γ-terpinene using air as an oxidant.
- Author
-
Asikainen, Martta, Jauhiainen, Olli, Aaltonen, Olli, and Harlin, Ali
- Subjects
CONTINUOUS flow reactors ,AROMATIZATION ,DEHYDROGENATION ,OXIDIZING agents ,TERPENES - Abstract
The dehydrogenation of γ-terpinene was studied under catalyst- and solvent-free reaction conditions using air as an oxidant. The dehydrogenation affords p-cymene in good yields in a continuous flow reaction setup. The initial optimization of the reaction parameters showed that the dehydrogenation is highly dependent on the vapour/liquid phase equilibrium and the availability of oxygen in the vapour phase. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
30. Structure, synthesis, biosynthesis, and activity of the characteristic compounds from Ginkgo biloba L.
- Author
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Liu, Xin-Guang, Lu, Xu, Gao, Wen, Li, Ping, and Yang, Hua
- Subjects
GINKGO ,FLAVONOL glycosides ,BIOSYNTHESIS ,HERBAL medicine ,ALKYLPHENOLS ,TERPENES - Abstract
Covering: 1928–2021 Ginkgo biloba L. is one of the most distinctive plants to have emerged on earth and has no close living relatives. Owing to its phylogenetic divergence from other plants, G. biloba contains many compounds with unique structures that have served to broaden the chemical diversity of herbal medicine. Examples of such compounds include terpene trilactones (ginkgolides), acylated flavonol glycosides (ginkgoghrelins), biflavones (ginkgetin), ginkgotides and ginkgolic acids. The extract of G. biloba leaf is used to prevent and/or treat cardiovascular diseases, while many ginkgo-derived compounds are currently at various stages of preclinical and clinical trials worldwide. The global annual sales of G. biloba products are estimated to total US$10 billion. However, the content and purity of the active compounds isolated by traditional methods are usually low and subject to varying environmental factors, making it difficult to meet the huge demand of the international market. This highlights the need to develop new strategies for the preparation of these characteristic compounds from G. biloba. In this review, we provide a detailed description of the structures and bioactivities of these compounds and summarize the recent research on the development of strategies for the synthesis, biosynthesis, and biotechnological production of the characteristic terpenoids, flavonoids, and alkylphenols/alkylphenolic acids of G. biloba. Our aim is to provide an important point of reference for all scientists who research ginkgo-related compounds for medicinal or other purposes. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
31. Analysis of fresh Mentha haplocalyxvolatile components by comprehensive two-dimensional gas chromatography and high-resolution time-of-flight mass spectrometry.
- Author
-
Gang Cao, Qiyuan Shan, Xiaomeng Li, Xiaodong Cong, Yun Zhang, Hao Cai, and Baochang Cai
- Subjects
- *
CHINESE medicine , *GAS chromatography , *MASS spectrometry , *KETONES , *TERPENES , *ENANTIOMERS - Abstract
Fresh Mentha haplocalyxis a well known traditional Chinese medicinal material (CMM) used in both China and America. This paper reports analysis of the volatile components of fresh Mentha haplocalyxby comprehensive two-dimensional gas chromatography (GCxGC) and high-resolution time-of-flight mass spectrometry (HR-TOF-MS), a combination that provides almost complete chemical separation with elemental composition determination of analytes. 163 ketones and terpenes, including menthol and menthone, were tentatively identified, including enantiomers. This study suggests that GCxGCxHR-TOF-MS is suitable for routine identification of target compounds and enantiomers in CMM. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
32. Hot off the press.
- Author
-
Robert A. Hill and Andrew Sutherland
- Subjects
- *
BIOORGANIC chemistry , *IRIDACEAE , *ORNAMENTAL plants , *TERPENES , *NATURAL products , *CHEMICAL biology - Abstract
A personal selection of 27 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as dibelamcandal A from Belamcanda chinensis. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
33. Sustainable catalytic epoxidation of biorenewable terpene feedstocks using H2O2 as an oxidant in flow microreactors.
- Author
-
Tibbetts, Joshua D., Cunningham, William B., Vezzoli, Massimiliano, Plucinski, Pawel, and Bull, Steven D.
- Subjects
EPOXIDATION ,TERPENES ,MICROREACTORS ,OXIDIZING agents ,CATALYSTS ,HYDROGEN peroxide ,ALKENES ,MONOTERPENES ,EPOXY compounds - Abstract
Solvent-free continuous flow epoxidation of the alkene bonds of a range of biorenewable terpene substrates have been carried out using a recyclable tungsten-based polyoxometalate phase transfer catalyst and aqueous H
2 O2 as a benign oxidant. These sustainable flow epoxidation reactions are carried out in commercial microreactors containing static mixing channels that enable common monoterpenes (e.g. untreated crude sulfate turpentine, limonene, etc.) to be safely epoxidized in short reaction times and in good yields. These flow procedures are applicable for the flow epoxidation of trisubstituted and disubstituted alkenes for the safe production of multigram quantities of a wide range of epoxides. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
34. Making natural products from renewable feedstocks: back to the roots?
- Author
-
Kühlborn, Jonas, Groß, Jonathan, and Opatz, Till
- Subjects
NATURAL products ,FATS & oils ,LIGNINS ,TERPENES ,CELLULOSE - Abstract
Covering: up to mid-2019 This review highlights the utilization of biomass-derived building blocks in the total synthesis of natural products. An overview over several renewable feedstock classes, namely wood/lignin, cellulose, chitin and chitosan, fats and oils, as well as terpenes, is given, covering the time span from the initial beginning of natural product synthesis until today. The focus is put on the origin of the employed carbon atoms and on the nature of the complex structures that were assembled therefrom. The emerging trend of turning away from petrochemically derived starting materials back to bio-based resources, just as seen in the early days of total synthesis, shall be demonstrated. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
35. Bacterial terpene cyclases.
- Author
-
Dickschat, Jeroen S.
- Subjects
CYCLASES ,ENZYMES ,TERPENES ,CATALYSTS ,MANUFACTURED products - Abstract
Covering: up to 2015 This review summarises the accumulated knowledge about characterised bacterial terpene cyclases. The structures of identified products and of crystallised enzymes are included, and the obtained insights into enzyme mechanisms are discussed. After a summary of mono-, sesqui- and diterpene cyclases the special cases of the geosmin and 2-methylisoborneol synthases that are both particularly widespread in bacteria will be presented. A total number of 63 enzymes that have been characterised so far is presented, with 132 cited references. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
36. Engineered biosynthesis of natural products in heterologous hosts.
- Author
-
LuoEqual contribution., Yunzi, Li, Bing-Zhi, Liu, Duo, Zhang, Lu, Chen, Yan, Jia, Bin, Zeng, Bo-Xuan, Zhao, Huimin, and Yuan, Ying-Jin
- Subjects
BIOSYNTHESIS ,NATURAL products ,ANTIBACTERIAL agents ,ANTINEOPLASTIC agents ,TERPENES ,FLAVONOIDS ,ALKALOIDS ,POLYKETIDES - Abstract
Natural products produced by microorganisms and plants are a major resource of antibacterial and anticancer drugs as well as industrially useful compounds. However, the native producers often suffer from low productivity and titers. Here we summarize the recent applications of heterologous biosynthesis for the production of several important classes of natural products such as terpenoids, flavonoids, alkaloids, and polyketides. In addition, we will discuss the new tools and strategies at multi-scale levels including gene, pathway, genome and community levels for highly efficient heterologous biosynthesis of natural products. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
37. Biological activity of natural sesquiterpenoids containing a gem-dimethylcyclopropane unit.
- Author
-
Durán-Peña, María Jesás, Botubol Ares, José Manuel, Hanson, James R., Collado, Isidro G., and Hernández-Galán, Rosario
- Subjects
SESQUITERPENES ,TERPENES ,PROPANE ,ANTIVIRAL agents ,ANTI-infective agents ,PHARMACEUTICAL chemistry - Abstract
Covering: 1963 up to the end of 2014 The biological activities of aristolane, aromadendrane, ent-1,10-secoaromadendrane, 2,3-secoaromadendrane, ent-5,10-cycloaromadendrane, bicyclogermacrene, lepidozane, and maaliane terpenoids which contain the gem-dimethylcyclopropyl unit are described. Particular attention is given to their anti-viral, anti-microbial and cytotoxic activities. In the main text there are 119 references covering the literature from 1963–2014. The ESI contains tables listing 332 of these terpenoids, their occurrence and biological activity together with the related references. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
38. Application of an indenyl molybdenum dicarbonyl complex in the isomerisation of α-pinene oxide to campholenic aldehyde.
- Author
-
Bruno, Sofia M., Gomes, Ana C., Gamelas, Carla A., Abrantes, Marta, Oliveira, M. Conceição, Valente, Anabela A., Almeida Paz, Filipe A., Pillinger, Martyn, Romão, Carlos C., and Gonçalves, Isabel S.
- Subjects
PINENE ,CHROMIUM group ,MOLYBDENUM ,ISOMERIZATION ,TERPENES - Abstract
The complex [{(η
5 -Ind)Mo(CO)2 (μ-Cl)}2 ] (1) has been tested for the industrially relevant catalytic isomerisation of α-pinene oxide (PinOx) to campholenic aldehyde (CPA) in the liquid phase. PinOx conversion and CPA selectivity are strongly influenced by the solvent employed. Complete conversion of PinOx was achieved within 1 min at 55 °C or 30 min at 35 °C using 1,2-dichloroethane as solvent, giving CPA in 68% yield. Other products included trans-carveol, iso-pinocamphone and trans-pinocarveol. The stability of 1 under the reaction conditions used was investigated by using FT-IR spectroscopy and electrospray ionisation mass spectrometry (ESI-MS) to characterise recovered solids. In the presence of air/moisture 1 undergoes oxidative decarbonylation upon dissolution to give oxomolybdenum species that are proposed to include a tetranuclear oxomolybdenum(v) complex. Conversely, ESI-MS studies of 1 dissolved in dry acetonitrile show mononuclear species of the type [IndMo(CO)2 (CH3 CN)n ]+ . The crystal structure of the ring-slipped dicarbonyl complex [(η3 -Ind)Mo(CO)2 Cl(CH3 CN)2 ] (2) (obtained after dissolution of 1 in acetonitrile) is reported. [ABSTRACT FROM AUTHOR]- Published
- 2014
- Full Text
- View/download PDF
39. Cyclic limonene dicarbonate as a new monomer for non-isocyanate oligo- and polyurethanes (NIPU) based upon terpenes.
- Author
-
Bähr, Moritz, Bitto, Alexandro, and Mülhaupt, Rolf
- Subjects
LIMONENE ,MONOMERS ,POLYURETHANES ,TERPENES ,CARBONATION (Chemistry) ,CATALYSTS ,MOLECULAR weights ,POLYOLS - Abstract
Herein we report a very versatile new route to linear as well as cross-linked terpene-based non-isocyanate poly(hydroxyurethanes) (NIPUs) and prepolymers derived from the novel cyclic limonene dicarbonate (CL). The catalytic carbonation of epoxidized limonene with CO
2 was monitored in the presence of both homogeneous tetrabutylammonium bromide (TBAB) and heterogeneous silica supported 4-pyrrolidinopyridinium iodide (SiO2 -(I)) catalysts. The systematic variation of catalyst type, CO2 pressure and temperature enabled quantitative carbonation in bulk and incorporation of 34.4 wt% CO2 into CL. In contrast to conventional plant-oil-based cyclic carbonates, such terpene-based cyclic carbonates afford much higher CO2 fixation and do not contain ester groups. The absence of ester groups is essential to prevent side reactions during amine curing, such as ester cleavage and amide formation, impairing network formation and causing emission of low molecular weight polyols which can plastify NIPUs. Novel linear NIPUs and prepolymers were obtained by means of CL advancement with diamines such as 1,4-butane diamine (BDA), 1,6-hexamethylene diamine (HMDA), 1,12-dodecane diamine (DADO) and isophorone diamine (IPDA). Molar mass and formation of amine–amine and carbonate end groups were controlled by varying the CL/diamine molar ratio. Curing CL with tri- and polyfunctional amines such as citric acid aminoamides, tris(N-2-aminoethyl)amine, and amine-terminated hyperbranched polyethylenimines (Lupasol® ) afforded novel NIPU thermoset resins. With increasing amine functionality of the curing agent, it was possible to increase both stiffness (Young's modulus of 4100 MPa) and glass transition temperatures (62 °C). [ABSTRACT FROM AUTHOR]- Published
- 2012
- Full Text
- View/download PDF
40. Regioselective catalytic hydrogenation of citral with ionic liquids as reaction modifiers.
- Author
-
Arras, Jürgen, Steffan, Martin, Shayeghi, Yalda, Ruppert, Dominik, and Claus, Peter
- Subjects
CATALYSIS ,HYDROGENATION ,TERPENES ,IONIC liquids ,CHEMICAL reactions ,PALLADIUM catalysts ,CATALYST supports - Abstract
Silica and polyaniline supported palladium catalysts prepared by different techniques (incipient-wetness impregnation, deposition precipitation) using Pd(OAc)2or H2PdCl4as precursors were studied in the liquid-phase hydrogenation of citral under addition of several ionic liquids ([BMIM][NTf2], [BMIM][PF6], [BMPL][NTf2], [BMIM][DCA], [BMPL][DCA], [B3MPYR][DCA]) either as catalyst coating or as additive. By an incipient-wetness technique, the catalysts were coated with a mixture of IL in acetone. The catalysts were characterized by nitrogen physisorption, whereby a decrease of surface area and pore volume was detected by the IL coated catalysts. Furthermore, ICP-OES, TEM and IR spectroscopy were performed to analyze metal content, particle size and coverage of the catalyst with ionic liquid. Citral hydrogenation was performed at 323 K and under 2.0 MPa H2in an autoclave with off-line GC analysis of the product mixtures. Beside stirrer speed, catalyst mass and citral concentration, the type and quantity of ionic liquid were also varied to elucidate their influence on activity and selectivity of the Pd/SiO2catalysed citral hydrogenation. The results show that treatment of the catalyst with ionic liquids—independent of catalyst coating or additive—leads to a selectivity enhancement of the desired product, citronellal. With [PF6]−or [NTf2]−as the IL anion, maximum selectivities were (60 ± 2)% at 70% conversion. In particular, dicyanamide (DCA) containing ionic liquids allow, under optimised conditions, the quantitative one-pot synthesis of citronellal, at least if the Pd/SiO2catalyst was coated with 29 wt% [B3MPYR][DCA]. By using polyaniline supported Pd catalysts and [BMIM][DCA] as additive, the consecutive hydrogenation towards dihydrocitronellal was less pronounced and the influence of metal precursor, support material and preparation technique of the catalyst could be excluded. Hydrogenation of pure citral on [BMIM][DCA] coated palladium catalysts offers a solvent-free, green route to citronellal in reasonable selectivities (S= 86%). [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
41. Indium tribromide-promoted arene-terminated epoxy olefin cyclization.
- Author
-
Jun-Feng Zhao, Yu-Jun Zhao, and Teck-Peng Loh
- Subjects
AROMATIC compounds ,ALKENES ,LEWIS acids ,TERPENES - Abstract
An arene-terminated epoxy olefin cyclization was promoted by a water-tolerant Lewis acid to give tri- and tetracyclic 3β-hydroxy terpenoids and steroid derivatives in 57 and 37% yields, respectively, per new formed ring up to 75%. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
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