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51.
Celeste de Jesus Pereira Franco Oberdan Oliveira Ferreira ngelo Antnio Barbosa de Moraes Everton Luiz Pompeu Varela Lidiane Diniz do Nascimento Sandro Percrio Mozaniel Santana de Oliveira Eloisa Helena de Aguiar Andrade 《Molecules (Basel, Switzerland)》2021,26(11)
Essential oils (EOs) were extracted from Eugenia patrisii, E. punicifolia, and Myrcia tomentosa, specimens A and B, using hydrodistillation. Gas chromatography coupled with mass spectrometry (GC/MS) was used to identify the volatile constituents present, and the antioxidant capacity of EOs was determined using diphenylpicryl-hydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays. For E. patrisii, germacrene D (20.03%), bicyclogermacrene (11.82%), and (E)-caryophyllene (11.04%) were identified as the major constituents of the EOs extracted from specimen A, whereas specimen B primarily comprised γ-elemene (25.89%), germacrene B (8.11%), and (E)-caryophyllene (10.76%). The EOs of E. punicifolia specimen A contained β-Elemene (25.12%), (E)-caryophyllene (13.11%), and bicyclogermacrene (9.88%), while specimen B was composed of (E)-caryophyllene (11.47%), bicyclogermacrene (5.86%), β-pinene (5.86%), and γ-muurolene (5.55%). The specimen A of M. tomentosa was characterized by γ-elemene (12.52%), germacrene D (11.45%), and (E)-caryophyllene (10.22%), while specimen B contained spathulenol (40.70%), α-zingiberene (9.58%), and γ-elemene (6.89%). Additionally, the chemical composition of the EOs was qualitatively and quantitatively affected by the collection period. Furthermore, the EOs of the studied specimens, especially specimen A of E. punicifolia, showed a greater antioxidant activity in DPPH rather than TEAC, as represented by a significantly high inhibition percentage (408.0%). 相似文献
52.
Silvie Rimpelov Michal Kol Hynek Strnad Tom Ruml Libor Vítek Helena Gbelcov 《Molecules (Basel, Switzerland)》2021,26(12)
Statins have been widely used for the treatment of hypercholesterolemia due to their ability to inhibit HMG-CoA reductase, the rate-limiting enzyme of de novo cholesterol synthesis, via the so-called mevalonate pathway. However, their inhibitory action also causes depletion of downstream intermediates of the pathway, resulting in the pleiotropic effects of statins, including the beneficial impact in the treatment of cancer. In our study, we compared the effect of all eight existing statins on the expression of genes, the products of which are implicated in cancer inhibition and suggested the molecular mechanisms of their action in epigenetic and posttranslational regulation, and in cell-cycle arrest, death, migration, or invasion of the cancer cells. 相似文献
53.
Mozaniel Santana de Oliveira Jorddy Neves Cruz Oberdan Oliveira Ferreira Daniel Santiago Pereira Natanael Santiago Pereira Marcos Enê Chaves Oliveira Giorgio Cristino Venturieri Giselle Maria Skelding Pinheiro Guilhon Antnio Pedro da Silva Souza Filho Eloisa Helena de Aguiar Andrade 《Molecules (Basel, Switzerland)》2021,26(11)
Propolis is a balsamic product obtained from vegetable resins by exotic Africanized bees Apis mellifera L., transported and processed by them, originating from the activity that explores and maintains these individuals. Because of its vegetable and natural origins, propolis is a complex mixture of different compound classes; among them are the volatile compounds present in the aroma. In this sense, in the present study we evaluated the volatile fraction of propolis present in the aroma obtained by distillation and simultaneous extraction, and its chemical composition was determined using coupled gas chromatography, mass spectrometry, and flame ionization detection. The majority of compounds were sesquiterpene and hydrocarbons, comprising 8.2–22.19% α-copaene and 6.2–21.7% β-caryophyllene, with additional compounds identified in greater concentrations. Multivariate analysis showed that samples collected from one region may have different chemical compositions, which may be related to the location of the resin’s production. This may be related to other bee products. 相似文献
54.
Lidiane Diniz do Nascimento Sebastio Gomes Silva Mrcia Moraes Cascaes Kauê Santana da Costa Pablo Luis Baia Figueiredo Cristiane Maria Leal Costa Eloisa Helena de Aguiar Andrade Lênio Jos Guerreiro de Faria 《Molecules (Basel, Switzerland)》2021,26(9)
Leaves of Lippia thymoides (Verbenaceae) were dried in an oven at 40, 50 and 60 °C and the kinetic of drying and the influence of the drying process on the chemical composition, yield, and DPPH radical scavenging activity of the obtained essential oils were evaluated. The composition of the essential oils was determined with gas chromatography-mass spectrometry and gas chromatography-flame ionization detection analyses. The influence of drying on the chemical composition of the essential oils of L. thymoides was evaluated by multivariate analysis, and their antioxidant activity was investigated via the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The Midilli model was the most appropriate to describe the behavior of drying kinetic data of L. thymoides leaves. Thymol was the major compound for all analyzed conditions; the maximum content was obtained from fresh leaves (62.78 ± 0.63%). The essential oils showed DPPH radical scavenging activity with an average of 73.10 ± 12.08%, and the fresh leaves showed higher inhibition (89.97 ± 0.31%). This is the first study to evaluate the influence of drying on the chemical composition and antioxidant activity of L. thymoides essential oils rich in thymol. 相似文献
55.
Kažoka Helena Turovska Baiba Upmanis Toms Orlova Natalja Vorona Maksims 《Chromatographia》2021,84(7):663-675
Chromatographia - Our previous studies concerning the enantioseparation of 4C-substituted pyrrolidin-2-one derivatives on coated polysaccharide-based chiral stationary phases have shown that... 相似文献
56.
57.
Pia Hellström Anette Heijnesson-Hultén Magnus Paulsson Helena Håkansson Ulf Germgård 《Cellulose (London, England)》2014,21(3):1489-1503
A fully bleached birch kraft pulp was treated with acidic hydrogen peroxide in the presence of ferrous ions (Fenton’s reagent) and thereafter treated mechanically in a colloid mill to produce a product containing microfibrillated cellulose (MFC). The produced MFC products were chemically and morphologically characterized and compared with MFC products produced without pretreatment as well as with enzymatic hydrolysis. Fenton treatment resulted in an increase in total charge and number of carbonyl groups while the intrinsic viscosity decreased. The Fenton treated pulps were easier to process mechanically i.e. they reached a higher specific surface area at a given mechanical treatment time and the MFC produced had a stable water-fibre suspension for at least 8 weeks compared to enzymatic pretreated pulps and pulps not subjected to any pretreatment. 相似文献
58.
Dr. Helena Isla Dr. Emilio M. Pérez Prof. Dr. Nazario Martín 《Angewandte Chemie (International ed. in English)》2014,53(22):5629-5633
Supramolecular polymers based on dispersion forces typically show lower molecular weights (MW) than those based on hydrogen bonding or metal–ligand coordination. We present the synthesis and self‐assembling properties of a monomer featuring two complementary units, a C60 derivative and an exTTF‐based macrocycle, that interact mainly through π–π, charge‐transfer, and van der Waals interactions. Thanks to the preorganization in the host part, a remarkable log Ka=5.1±0.5 in CHCl3 at room temperature is determined for the host–guest couple. In accordance with the large binding constant, the monomer self‐assembles in the gas phase, in solution, and in the solid state to form linear supramolecular polymers with a very high degree of polymerization. A MW above 150 kDa has been found experimentally in solution, while in the solid state the monomer forms extraordinarily long, straight, and uniform fibers with lengths reaching several microns. 相似文献
59.
Mirosław Dors Helena Nowakowska Mariusz Jasiński Jerzy Mizeraczyk 《Plasma Chemistry and Plasma Processing》2014,34(2):313-326
Results of chemical kinetics modeling in methane subjected to the microwave plasma at atmospheric pressure are presented in this paper. The reaction mechanism is based on the methane oxidation model without reactions involving nitrogen and oxygen. For the numerical calculations 0D and 1D models were created. 0D model uses Calorimetric Bomb Reactor whereas 1D model is constructed either as Plug Flow Reactor or as a chain of Plug Flow Reactor and Calorimetric Bomb Reactor. Both models explain experimental results and show the most important reactions responsible for the methane conversion and production of H2, C2H2, C2H4 and C2H6 detected in the experiment. Main conclusion is that the chemical reactions in our experiment proceed by a thermal process and the products can be defined by considering thermodynamic equilibrium. Temperature characterizing the methane pyrolysis is 1,500–2,000 K, but plasma temperature is in the range of 4,000–5,700 K, which means that methane pyrolysis process is occurring outside the plasma region in the swirl gas flowing around the plasma. 相似文献
60.
Gonzalo Abellán Jose A. Carrasco Eugenio Coronado Helena Prima-García 《Journal of Sol-Gel Science and Technology》2014,70(2):292-299
Pure and highly crystalline FeNi3 alloy nanoparticles (NPs) were synthesized via sol–gel route with benzyl alcohol, using hydrazine as a reduction reagent without the usage of additional surfactant molecules nor further annealing processes. The structural studies revealed that the particle size is of ca. 200 nm, whose structure consisted on aggregation of small crystallites of about 13 nm. The magnetic properties of the as-synthesized NPs were similar to the bulk with a saturation magnetization of 95 emu g?1. Moreover, the coercive field was ca. 50 G, exhibiting a M r /M s ratio of 0.03, indicative of soft ferromagnetism. The electrical transport in the temperature range 2–300 K exhibits a typical ferromagnetic metallic behaviour. Finally, similar FeNi3 NPs were synthesized in EtOH/H2O mixtures in the presence of sodium dodecyl sulphate molecules as surfactant for comparative purposes, exhibiting a typical half hard magnetic behaviour, highlighting the interest of the reported benzylic route. 相似文献