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1.
J Environ Sci (China) ; 95: 210-216, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32653182

RESUMO

The reaction of alkenes with ozone has great effect on atmospheric oxidation, its transient species can produce OH radicals and contribute to the formation of secondary organic aerosols (SOA). In the present study, the reaction of tetramethylethene (TME) with ozone was investigated using self-assembled low temperature matrix isolation system. The TME and ozone were co-deposited on a salt plate at 15 K, and then slowly warmed up the plate. The first transient species primary ozonide (POZ) was detected, indicating that the reaction followed Criegee mechanism. Then POZ began to decompose at 180 K. However, secondary ozonide (SOZ) was not observed according to Criegee mechanism. Probably, Criegee Intermediate (CI) did not react with inert carbonyl of acetone, but with remaining TME formed tetra-methyl epoxide (EPO).


Assuntos
Ozônio , Acetona , Aerossóis , Alcenos , Oxirredução
2.
Science ; 368(6496): 1181-1182, 2020 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-32527815
3.
Nature ; 584(7819): 69-74, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32512577

RESUMO

Enzymes are increasingly explored for use in asymmetric synthesis1-3, but their applications are generally limited by the reactions available to naturally occurring enzymes. Recently, interest in photocatalysis4 has spurred the discovery of novel reactivity from known enzymes5. However, so far photoinduced enzymatic catalysis6 has not been used for the cross-coupling of two molecules. For example, the intermolecular coupling of alkenes with α-halo carbonyl compounds through a visible-light-induced radical hydroalkylation, which could provide access to important γ-chiral carbonyl compounds, has not yet been achieved by enzymes. The major challenges are the inherent poor photoreactivity of enzymes and the difficulty in achieving stereochemical control of the remote prochiral radical intermediate7. Here we report a visible-light-induced intermolecular radical hydroalkylation of terminal alkenes that does not occur naturally, catalysed by an 'ene' reductase using readily available α-halo carbonyl compounds as reactants. This method provides an efficient approach to the synthesis of various carbonyl compounds bearing a γ-stereocentre with excellent yields and enantioselectivities (up to 99 per cent yield with 99 per cent enantiomeric excess), which otherwise are difficult to access using chemocatalysis. Mechanistic studies suggest that the formation of the complex of the substrates (α-halo carbonyl compounds) and the 'ene' reductase triggers the enantioselective photoinduced radical reaction. Our work further expands the reactivity repertoire of biocatalytic, synthetically useful asymmetric transformations by the merger of photocatalysis and enzyme catalysis.


Assuntos
Alcenos/química , Alcenos/metabolismo , Hidrogênio/química , Hidrogênio/metabolismo , Luz , Oxirredutases/metabolismo , Processos Fotoquímicos/efeitos da radiação , Álcoois/química , Álcoois/metabolismo , Alquilação/efeitos da radiação , Biocatálise/efeitos da radiação , Biomassa , Carboxiliases/metabolismo , Flavinas/metabolismo , Modelos Químicos , Modelos Moleculares , Estereoisomerismo
4.
J Chromatogr A ; 1624: 461236, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32540076

RESUMO

On-line coupled high performance liquid chromatography-gas chromatography-flame ionization detection (HPLC-GC-FID) used for determining mineral oil aromatic hydrocarbons (MOAH) in foods, particularly in certain oils and fats, may be disturbed by interfering olefins present as natural food components or resulting from raffination of the oils and fats. While some interference can be coped with by disregarding their peaks, others overload GC to the extent of obscuring the MOAH or form humps which need to be distinguished from the hump formed by the MOAH. In the latter cases, it is necessary to remove these interferences prior to HPLC-GC analysis. So far, epoxidation of the olefins to increase their retention time beyond that of the MOAH in HPLC is the best method available, though imperfect by causing some loss of MOAH and sometimes incomplete removal of the interference. Two methods are re-evaluated; preference is given to a slightly modified version of that proposed by Nestola and Schmidt. The performances are comparable: the losses of MOAH are similar and with both methods not all interfering olefins may be removed from refined edible oils. However, the Nestola/Schmidt method has practical advantages, the main ones being that no cooling is necessary and no solvent needs to be evaporated, which facilitates automation. Potential residual interferences must be recognized and subtracted, which can be by the characteristics of the hump they form in HPLC-GC-FID, by GCxGC-FID or by GCxGC-MS using characteristic mass fragments.


Assuntos
Compostos de Epóxi/química , Contaminação de Alimentos/análise , Alimentos , Hidrocarbonetos Aromáticos/análise , Óleo Mineral/análise , Alcenos/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Etanol/química , Azeite de Oliva/análise , Sistemas On-Line
5.
Medicine (Baltimore) ; 99(23): e20059, 2020 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-32501968

RESUMO

BACKGROUND: Salvianolic acids (SA) has been widely used for the treatment of acute cerebral infarction (ACI) combined with basic western medicine therapy in China. This study was aimed to evaluate the efficacy and safety of SA on ACI treatment and its influence on neurological functions, activity of daily living, and cognitive functions. METHODS: We retrieved related articles from PubMed, the Cochrane Center Controlled Trials Register, EMBASE, Medline, Ovid, Chinese National Knowledge Infrastructure, Chinese Biomedical Literature Database, and Wanfang Database without date and language restrictions. Finally, 58 randomized controlled trials were included from 239 retrieved records. Two researchers extracted the basic information and data from included articles and assessed the quality and analysis of data by using Review Manager 5.3. RESULTS: The administration of SA significantly increased the total clinical effective rate of ACI treatment (P < .001) and improved the National Institute of Health Stroke Scale scores, modified Rankin Scale scores, and Barthel Index scores after treatment and 3 months after ACI (P < .05). The activities of daily living scores in the SA group were significantly increased after treatment (P < .001), whereas they were remarkably decreased 3 months after ACI (P < .001) compared with that in the control group. Besides, SA profoundly promoted the recovery of Montreal Cognitive Assessment scores (P < .001). However, the use of SA increased the risk of adverse events occurrence (P = .007). CONCLUSION: SA combined with basic western medicine treatment could promote neurological functions, daily living activities, and cognitive functions recovery of ACI patients. Although SA increased the risk of adverse events occurrence, these adverse events were easily controlled or disappeared spontaneously.


Assuntos
Alcenos/uso terapêutico , Infarto Cerebral/tratamento farmacológico , Polifenóis/uso terapêutico , Atividades Cotidianas , Doença Aguda , Alcenos/administração & dosagem , Alcenos/efeitos adversos , Cognição , Terapia Combinada , Humanos , Polifenóis/administração & dosagem , Polifenóis/efeitos adversos , Ensaios Clínicos Controlados Aleatórios como Assunto , Projetos de Pesquisa
6.
Chemosphere ; 255: 126959, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32388263

RESUMO

The photolytic chlorination of n-alkanes in presence of sulfuryl chloride (SO2Cl2) was explored to produce new standard materials. Five mixtures of chlorinated tetradecanes were synthesized with chlorination degrees (mCl,EA) varying from 43.7% to 59.4% (m/m) based on elemental analysis. Chlorine-enhanced negative chemical ionization mass spectrometry (CE-NCI-MS) forcing the formation of chloride-adduct ions [M+Cl]- was applied to characterize these materials which all contained tetra-to deca-chlorinated paraffins. Deconvolution of respective mass spectra revealed the presence of chlorinated olefins (COs). CO levels were highest in materials, which were exposed longest. All synthesized materials also contained two classes of polar impurities, tentatively assigned as sulfite- and sulfate-diesters with molecular formulas of C14H28-xO3SClx (x = 1-4) and C14H28-xO4SClx (x = 3-6), respectively. MS data were in accordance with the proposed structures but further work is needed to deduce their constitutions. These compounds are thermolabile and were not detected with GC-MS methods. We could remove these sulfur-containing impurities from the CPs with normal-phase liquid chromatography. In conclusion, single-chain CP materials were synthesized via chlorination of n-alkanes with sulfuryl chloride, but these materials contained reactive side products which should be removed to gain non-reactive and stable CP materials suitable as standards and for fate and toxicity studies.


Assuntos
Hidrocarbonetos Clorados/química , Alcanos , Alcenos , Cloro/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Halogenação , Hidrocarbonetos Clorados/análise , Espectrometria de Massas/métodos , Parafina/análise
7.
Phytochemistry ; 176: 112398, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32450381

RESUMO

This work presents the study of the roots of the Macaronesian paleoendemism Persea indica (L.) Spreng. The root biomass of this protected tree species has been produced by soil-less aeroponic culture under controlled environment. This system has important advantages over traditional plant production techniques because it provides opportunities to optimize the yield of metabolite production under well-controlled conditions, thereby facilitating commercial-scale production of bioactive compounds. Thus, for the first time a study of this type has permitted the isolation from the roots of seven undescribed dextrorotatory lactones: the alkane-γ-lactones (+)-majoranolide and (+)-dihydromajorenolide, the alkene-γ-lactones (+)-majorenolide and (+)-majorenolide acetate, and the alkyne-γ-lactones, (+)-majorynolide, (+)-majorynolide acetate and (+)-isomajorynolide. In addition, thirteen known compounds were also isolated including two possible avocadofurane precursors, avocadynone acetate and avocadenone acetate, the monoterpene esters cis- and trans-p-coumarate of (-)-borneol, and the ryanoid diterpenes cinnzeylanone, anhidrocinnzeylanine, cinnzeylanine, cinnzeylanol, epiryanodol, perseanol, cinncassiol E, perseaindicol and secoperseanol. The configuration at C-14 de two ryanodane diterpenes has also been revised in this work. Furthermore, (-)-borneol cis-p-coumarate has showed to be insecticidal to S. littoralis and cytotoxic to insect (Sf9) cells, (+)-majorenolide antifeedant to aphids and cytotoxic to Sf9, cinnceylanol antifeedant and insecticidal to S. littoralis, and (+)-majorynolide (2), insecticidal against S. littoralis, cytotoxic to Sf9 and nematicidal, suggesting a defensive role for these compounds.


Assuntos
Diterpenos , Persea , Alcanos , Alcenos , Alquinos , Animais , Lactonas , Raízes de Plantas
8.
Chemosphere ; 256: 126985, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32445994

RESUMO

Biodegradable mulch films are an alternative to polyethylene films used in agriculture for weed control, improving crop productivity. This change could minimize the residue production and costs related to the final disposal. Nevertheless, the environmental safety of these biodegradable products is scarcely investigated. In this work, samples of poly(butylene adipate-co-terephthalate)-PBAT mulch films, with and without UV stabilizer additives, were prepared. Aqueous extracts of soil samples, where mulch films were disposed, were investigated using bioassays with Lactuca sativa, Allium cepa, and cell culture HepG2/C3A. As PBAT is expected to suffer photodegradation and biodegradation, soil samples mixed with films before and after these processes were evaluated. Soil aqueous extracts promoted root grown (mainly hypocotyl) of L. sativa, probably due to presence of nutrients. So, to evaluate toxicity potential, in this case it was necessary to use aqueous extract prepared with soil instead of ultrapure water as the control. After doing this analysis it was observed that no adverse impacts due to PBAT films occurred. No chromosomal abnormalities were observed in A. cepa bioassay for any of tested samples. The absence of genotoxic potential was confirmed by comet assay and micronucleus test using human hepatocarcinoma cell line HepG2/C3A. These results showed that the soil did not induce damage to the tested organisms, before and after degradation of PBAT films.


Assuntos
Biodegradação Ambiental , Alface/efeitos dos fármacos , Cebolas/efeitos dos fármacos , Adipatos , Agricultura , Alcenos , Ecotoxicologia , Humanos , Alface/fisiologia , Cebolas/fisiologia , Ácidos Ftálicos , Poliésteres/química , Poluentes do Solo
9.
J Chromatogr A ; 1621: 461081, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32349863

RESUMO

The chemical composition distribution (CCD) of three single site made ethylene/1-octene copolymers was investigated through offline-hyphenation of solvent gradient interaction chromatography (SGIC) with 1H NMR. Thus, a clear, non-linear correlation between SGIC elution time and chemical composition was found under the specific measurement conditions applied here. The application of 1H NMR as detection allowed to determine the CCD with unprecedented accuracy. 2D-LC of the copolymers revealed the correlation between CCD and molar mass distribution (MMD) in a quantitative manner. Furthermore, this approach allowed a comparison between the response behavior of an evaporative light scattering detector (ELSD, semi-quantitative, commonly applied in SGIC) and that of an infrared (IR) detector (quantitative, commonly applied in SEC). As a result, it could be shown that ELSD results are close to IR results for the system investigated here, in other words, the often-criticized semi-quantitative response behavior of the ELSD is affecting results in an acceptable manner.


Assuntos
Alcenos/análise , Cromatografia Líquida de Alta Pressão/métodos , Elastômeros/análise , Etilenos/análise , Polienos/análise , Calibragem , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Elastômeros/química , Peso Molecular , Espectroscopia de Prótons por Ressonância Magnética , Solventes/química , Temperatura , Fatores de Tempo
10.
Pestic Biochem Physiol ; 166: 104561, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32448416

RESUMO

The harlequin ladybird, Harmonia axyridis (H. axyridis), possesses a strong chemical defence that has contributed to its invasive success. Ladybird beetle defensive chemicals, secreted in response to stress and also found on the coating of laid eggs, are rich in alkaloids that are thought to be responsible for this beetle's toxicity to other species. Recent studies have shown that alkaloids from several species of ladybird beetle can target nicotinic acetylcholine receptors (nAChRs) acting as receptor antagonists, hence we have explored the actions of alkaloids of the ladybird H. axyridis on both mammalian and insect nAChRs. Electrophysiological studies on native and functionally expressed recombinant nAChRs were used to establish whether an alkaloid extract from H. axyridis (HAE) targeted nAChRs and whether any selectivity exists for insect over mammalian receptors of this type. HAE was found to be an inhibitor of all nAChRs tested with the voltage-dependence of inhibition and the effect on ACh EC50 differing between nAChR subtypes. Our finding that an HAE fraction consisting almost entirely of harmonine had a strong inhibitory effect points to this alkaloid as a key component of nAChR inhibitory actions. Comparison of HAE inhibition between the mammalian and insect nAChRs investigated indicates some preference for the insect nAChR supporting the view that investigation of ladybird alkaloids shows promise as a method for identifying natural product leads for future insecticide development.


Assuntos
Alcaloides , Besouros , Receptores Nicotínicos , Alcenos , Animais , Extratos Vegetais
11.
Zhongguo Zhong Yao Za Zhi ; 45(3): 548-554, 2020 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-32237512

RESUMO

Study the suitability of organic film for salvianolic acid in the ultrafiltration process of Danshen Dizhuye. UPLC was used to analyze the migration of nine phenolic active ingredients in Danshen Dizhuye during ultrafiltration of PES hollow fiber membrane and PS hollow fiber membrane. The structural composition of multi-components was analyzed by three different batches of Danshen Dizhuye before and after ultrafiltration of the two membranes. The results showed that 9 phenolic active ingredients in Danshen Dizhuye did not change significantly after ultrafiltration through PES membrane. However, after ultrafiltration through PS membrane, the content of sodium danshensu, protocatechualdehyde, caffeic acid, 3-hydroxy-4-methoxycinnamic acid and rosmarinic acid in Danshen Dizhuye did not change significantly, while salvianolic acid D, salvianolic acid B and lithospermic acid decreased by about 20%, and the content of salvianolic acid A decreased significantly. The final content in equilibrium was only about 20% of the original solution. Therefore, an in-depth study on the migration particularity of salvianolic acid A in ultrafiltration membrane was the focuse. The results showed that the loss of salvianolic acid A was caused by both membranes during ultrafiltration, and salvianolic acid A was lost more in PS membrane. When the membrane was washed and regenerated, it was found that salvianolic acid A was detected in the ethanol washing solution, but not in the washing liquid, indicating that the loss of salvianolic acid A during the ultrafiltration was mainly adsorptive action. The results suggested that the migration of phenolic active ingredients in Danshen Dizhuye during the membrane ultrafiltration process did not completely follow the molecular weight passing rule of the membrane pore size. At the same time, it may be affected by factors, such as the structure of the membrane material, and the interaction between the membrane structure and the structure of components, and exhibit different migration behaviors during the ultrafiltration of the membrane.


Assuntos
Alcenos/química , Medicamentos de Ervas Chinesas/química , Polifenóis/química , Salvia miltiorrhiza/química , Ultrafiltração , Cromatografia Líquida de Alta Pressão
12.
Environ Sci Pollut Res Int ; 27(19): 23575-23585, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32297111

RESUMO

Dengue is the most important infectious disease in the world and is a severe public health problem. The chikungunya is an arbovirus, in many cases, increased, which is transmitted by the same transmitter dengue vector, Aedes aegypti. The symptoms of both diseases are similar, and infections can be lethal. Although there is no preventive vaccine against any of the two diseases, therefore, it is extremely important to control the mosquito. The eggs of A. aegypti are very resistant and hatch into larvae, which later give rise to mosquitoes in any container with water. Natural plant extracts have come from active substances with larvicidal activity against A. aegypti. However, they tend to be highly hydrophobic and need some strategy to improve its affinity for water. Because of these factors, this research aims to synthesize and characterize polymeric materials with properties suitable for the release of hydrophobic principles with larvicidal action. The synthesized polymers are poly (butylene succinate) (PBS) and PBS block copolymer with polyethylene glycol (PEG). The synthesized polymers were characterized by nuclear magnetic resonance, thermal analysis simultaneous, differential scanning calorimetry, Fourier transform infrared spectroscopy, and diffraction of X-rays analysis. The analysis results showed that the synthesized materials have chemical composition and properties suitable for use in the controlled release of actives substances. Systems were prepared using the Dendranthema grandiflora extract, which has larvicidal activity was incorporated via fusion to polymers, to evaluate its release in aqueous media. The results proved that higher amounts of PEG in the copolymer chain speed up the delivery of the larvicidal extract. Besides that, the larvicidal extract concentration required to cause death larvae of A. aegypti was achieved from the first minutes of dissolution tests, indicating that the materials developed are promising tool to fight dengue and chikungunya. This new system is a vital tool for eliminating vectors, potentially contributing to saving millions of lives worldwide.


Assuntos
Aedes , Inseticidas , Nanopartículas Metálicas , Alcenos , Animais , Larva , Mosquitos Vetores , Extratos Vegetais , Folhas de Planta , Polímeros , Succinatos
13.
Nat Commun ; 11(1): 1956, 2020 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-32327665

RESUMO

The dehydrogenative alkenylation of C-H bonds with alkenes represents an atom- and step-economical approach for olefin synthesis and molecular editing. Site-selective alkenylation of alkanes and aldehydes with the C-H substrate as the limiting reagent holds significant synthetic value. We herein report a photocatalytic method for the direct alkenylation of alkanes and aldehydes with aryl alkenes in the absence of any external oxidant. A diverse range of commodity feedstocks and pharmaceutical compounds are smoothly alkenylated in useful yields with the C-H partner as the limiting reagent. The late-stage alkenylation of complex molecules occurs with high levels of site selectivity for sterically accessible and electron-rich C-H bonds. This strategy relies on the synergistic combination of direct hydrogen atom transfer photocatalysis with cobaloxime-mediated hydrogen-evolution cross-coupling, which promises to inspire additional perspectives for selective C-H functionalizations in a green manner.


Assuntos
Aldeídos/química , Alcanos/química , Alcenos/química , Alcenos/síntese química , Catálise , Técnicas de Química Sintética , Química Verde , Estrutura Molecular , Compostos Organometálicos/química , Processos Fotoquímicos , Estereoisomerismo
14.
Phytother Res ; 34(7): 1704-1720, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32185841

RESUMO

Microcirculation, which connects macrocirculation and cells between arterioles and venules, plays a major role in the early onset of a variety of diseases. In this article, a dextran-induced microcirculation dysfunction (MCDF) model rats were adopted to evaluate the effects and mechanism of Salvia miltiorrhiza stem-leaf extracts based on plasma and urine metabonomics. The results showed the effective components of S. miltiorrhiza stem-leaf could significantly improve the hemorheology and coagulation index of MCDF rats and callback the expression of endothelin-1 (ET-1), induciblenitric oxide synthase (iNOS), vascularendothelial growth factor (VEGF), P-Selectin, thromboxane A2, 6-keto-PGF1α , TNF-α, and interleukin-1ß to control group in MCDF rats. The decrease of microvessel density (MVD) in lung and thymus caused by MCDF was upgraded by Salvia miltiorrhiza stem-leaf. Based on the plasma and urine metabolic data, 20 potential biomarkers were identified. These biomarkers are mainly related to linoleic acid metabolism, glutathione metabolism, pantothenate and coenzyme A biosynthesis, pentose and glucuronate interconversions, pyruvate metabolism, glyoxylate and dicarboxylate metabolism, beta-alanine metabolism, and citrate cycle. The results indicated that the effective components of S. miltiorrhiza stem-leaf can improve the hemorheological disorder and vascular endothelial function. Meanwhile, the effective components can regulate potential biomarkers and correlated metabolic pathway, which can provide guidance for the research and development of new drugs for MCDF.


Assuntos
Alcenos/química , Células Endoteliais/efeitos dos fármacos , Flavonoides/química , Hemorreologia/efeitos dos fármacos , Microcirculação/efeitos dos fármacos , Folhas de Planta/química , Caules de Planta/química , Polifenóis/química , Salvia miltiorrhiza/química , Animais , Masculino , Ratos , Ratos Wistar
15.
Chemosphere ; 252: 126413, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32197171

RESUMO

O3 and alkenes are important reactants in the formation of SOA in the atmosphere. The intermediates and reaction mechanism of ozonation of alkene is an important topic in atmospheric chemistry. In this study, the low-temperature matrix isolation was used to capture the intermediates such as Primary ozonides (POZs), Criegee Intermediates (CIs), and Secondary ozonides (SOZs) generated from ozonation of 2-methyl-1-butene (2M1B) and 2-methyl-2-butene (2M2B). The results have been identified by the vacuum infrared spectroscopy and theoretical calculation. Our results show that during the ozonation of asymmetric alkenes, two kinds of CIs and more than two kinds of SOZs were generated due to the different decomposition modes of POZs. The infrared absorption peaks of (CH3)2COO and CH3CH2C(CH3)OO for O-O telescopic vibration was determined to be 889 cm-1 and 913 cm-1, respectively. Using the merged jet method, it was found that a large amount of HCHO was produced during the ozonation of 2M1B, and glyoxal and methylglyoxal were produced in the ozonation of 2M2B. Our findings highlight the importance of asymmetric alkene ozonolysis reactions in producing CIs, further improving the understanding of the generation of CIs from ozonation of alkenes.


Assuntos
Alcenos/química , Modelos Químicos , Ozônio/química , Atmosfera , Compostos Heterocíclicos , Espectrofotometria Infravermelho , Espectroscopia de Infravermelho com Transformada de Fourier
16.
J Vis Exp ; (156)2020 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-32150174

RESUMO

Lewis acid-activation of carbonyl-containing substrates is a fundamental basis for facilitating transformations in organic chemistry. Historically, characterization of these interactions has been limited to models equivalent to stoichiometric reactions. Here, we report a method utilizing in situ infrared spectroscopy to probe the solution interactions between Lewis acids and carbonyls under synthetically relevant conditions. Using this method, we were able to identify 1:1 complexation between GaCl3 and acetone and a highly ligated complex for FeCl3 and acetone. The impact of this technique on mechanistic understanding is illustrated by application to the mechanism of Lewis acid-mediated carbonyl-olefin metathesis in which we were able to observe competitive binding interactions between substrate carbonyl and product carbonyl with the catalyst.


Assuntos
Alcenos/química , Ácidos de Lewis/química , Espectrofotometria Infravermelho/métodos , Catálise
17.
Proc Biol Sci ; 287(1921): 20192466, 2020 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-32097587

RESUMO

Once emitted, semiochemicals are exposed to reactive environmental factors that may alter them, thus disrupting chemical communication. Some species, however, might have adapted to detect environmentally mediated breakdown products of their natural chemicals as semiochemicals. We demonstrate that air, water vapour and ultraviolet (UV) radiation break down unsaturated cuticular hydrocarbons (CHCs) of Periplaneta americana (American cockroach), resulting in the emission of volatile organic compounds (VOCs). In behavioural assays, nymphs strongly avoided aggregating in shelters exposed to the breakdown VOCs from cuticular alkenes. The three treatments (air, water vapour, UV) produced the same VOCs, but at different time-courses and ratios. Fourteen VOCs from UV-exposed CHCs elicited electrophysiological responses in nymph antennae; 10 were identified as 2-nonanone, 1-pentanol, 1-octanol, 1-nonanol, tetradecanal, acetic acid, propanoic acid, butanoic acid, pentanoic acid and hexanoic acid. When short-chain fatty acids were tested as a mix and a blend of the alcohols and aldehyde was tested as a second mix, nymphs exhibited no preference for control or treated shelters. However, nymphs avoided shelters that were exposed to VOCs from the complete 10-compound mix. Conditioned shelters (occupied by cockroaches with faeces and CHCs deposited on the shelters), which are normally highly attractive to nymphs, were also avoided after UV exposure, confirming that breakdown products from deposited metabolites, including CHCs, mediate this behaviour. Our results demonstrate that common environmental agents degrade CHCs into behaviourally active volatile compounds that potentially may serve as necromones or epideictic pheromones, mediating group dissolution.


Assuntos
Alcenos/metabolismo , Comportamento Animal/fisiologia , Periplaneta/fisiologia , Feromônios/metabolismo , Animais , Hidrocarbonetos/metabolismo , Comportamento Social , Compostos Orgânicos Voláteis
18.
Adv Pharmacol ; 87: 1-41, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32089230

RESUMO

Danshen, the dried root of Salvia miltiorrhiza Bge, is a common medicinal herb in Traditional Chinese Medicine, which has been used for the treatment of a number of diseases for thousands of years. More than 2000 years ago, the Chinese early pharmacy monograph "Shennong Materia Medica" recorded that Danshen could be used for the treatment of gastrointestinal diseases, cardiovascular diseases, certain gynecological diseases, etc. Since then, Danshen has been widely used clinically in many different prescriptions for many different diseases, especially for the treatment of cardiovascular diseases. Nowadays, many pharmacological studies about the water-soluble components from Danshen have been reported, especially salvianolic acids. It turned out that salvianolic acids showed strong anti-lipid peroxidation and anti-thrombic activities, and among them, SalAA and SalAB were the most potent. This review focused on the achievements in research of salvianolic acids regarding their bioactivities and pharmacological effects. These studies not only shed light on the water-soluble active components of Danshen and their mechanisms at the molecular level, but also provided theoretical information for the development of new medicines from Danshen for the treatment of cardiovascular and cerebrovascular diseases, inflammatory diseases, metabolic diseases, etc.


Assuntos
Alcenos/análise , Alcenos/farmacologia , Medicamentos de Ervas Chinesas/química , Polifenóis/isolamento & purificação , Alcenos/química , Alcenos/farmacocinética , Animais , Apoptose/efeitos dos fármacos , Humanos , Medicina Tradicional Chinesa , Polifenóis/análise , Polifenóis/química , Polifenóis/farmacocinética , Polifenóis/farmacologia , Salvia miltiorrhiza/química
19.
J Environ Sci (China) ; 90: 352-363, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32081331

RESUMO

Coal-based olefin (CTO) industry as a complement of traditional petrochemical industry plays vital role in China's national economic development. However, high CO2 emission in CTO industry is one of the fatal problems to hinder its development. In this work, the carbon emission and mitigation potentials by different reduction pathways are evaluated. The economic cost is analyzed and compared as well. According to the industry development plan, the carbon emissions from China's CTO industry will attain 189.43 million ton CO2 (MtCO2) and 314.11 MtCO2 in 2020 and 2030, respectively. With the advanced technology level, the maximal carbon mitigation potential could be attained to 15.3% and 21.9% in 2020 and 2030. If the other optional mitigation ways are combined together, the carbon emission could further reduce to some extent. In general, the order of mitigation potential is followed as: feedstock alteration by natural gas > CO2 hydrogenation with renewable electricity applied > CCS technology. The mitigation cost analysis indicates that on the basis of 2015 situation, the economic penalty for feedstock alteration is the lowest, ranged between 186 and 451 CNY/tCO2, and the cost from CCS technology is ranged between 404 and 562 CNY/tCO2, which is acceptable if the CO2 enhanced oil recovery and carbon tax are considered. However, for the CO2 hydrogenation technology, the cost is extremely high and there is almost no application possibility at present.


Assuntos
Alcenos/química , Dióxido de Carbono , Carbono , Carvão Mineral , Poluição Ambiental/prevenção & controle , Indústria Química , China , Poluição Ambiental/economia
20.
Chem Commun (Camb) ; 56(20): 3039-3042, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-32048637

RESUMO

We report synthesis and enzymatic assays on human histone lysine methyltransferase catalysed methylation of histones that possess lysine and its geometrically constrained analogues containing rigid (E)-alkene (KE), (Z)-alkene (KZ) and alkyne (Kyne) moieties. Methyltransferases G9a and GLP do have a capacity to catalyse methylation in the order K ≫ KE > KZ ∼ Kyne, whereas monomethyltransferase SETD8 catalyses only methylation of K and KE.


Assuntos
Histona-Lisina N-Metiltransferase/metabolismo , Lisina/metabolismo , Alcenos/química , Alcenos/metabolismo , Alquinos/química , Alquinos/metabolismo , Biocatálise , Humanos , Lisina/análogos & derivados , Lisina/química , Metilação , Conformação Molecular
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