1,665 research outputs found
Ti-MCM-41 materials synthesised at room temperature as catalysts for cyclisation of (±)-citronellal”
In the present work we extend the applicability of those Ti-MCM-41 materials, as heterogeneous catalysts, to produce an important intermediate, isopulegol, from the cyclisation of citronellal. The use of this kind of materials appears to be a good option over homogeneous catalysts, because they offer the advantage of recovery and, consequently, contribute to environmentally friendly processes
In vitroandin vivoassessment of the effect ofLaurus novocanariensisoil and essential oil in human skin
Laurus novocanariensis is an endemic plant from the Madeira Island forest that derives a fatty oil, with a strong spicy odour, from its berries that has been used for centuries in traditional medicine to treat skin ailments. This work aimed to investigate the effect of the application of both the oil and its essential oil on normal skin, to assess their safety and potential benefits. Diffusion studies with Franz cells using human epidermal membranes were conducted. The steady-state fluxes of two model molecules through untreated skin were compared with those obtained after a 2-h pre-treatment with either the oil or the essential oil. Additionally, eleven volunteers participated in the in vivo study that was conducted on the forearm and involved daily application of the oil for 5 days. Measurements were performed every day in the treated site with bioengineering methods that measure erythema, irritation and loss of barrier function. Slightly higher steady-state fluxes were observed for both the lipophilic and the hydrophilic molecule when the epidermal membranes were pre-treated. Nevertheless, such differences had no statistical significance, which seems to confirm that neither the oil nor the essential oil impaired the epidermal barrier. Results collected with the Chromameter, the Laser Doppler Flowmeter and the visual scoring are in agreement with those established in the in vitro study. They indicate that the repeated application of the oil did not cause erythema, because the results observed in the first day of the study were maintained throughout the week. Application of the oil did not affect the skin barrier function, because the transepidermal water loss remained constant throughout the study. The stratum corneum hydration was slightly reduced on days 4 and 5. This work shows that both the oil and the essential oil were well tolerated by the skin and did not cause significant barrier impairment or irritation.info:eu-repo/semantics/publishedVersio
Compostos bioativos e atividade antioxidante em cálices de hibísco (Hibiscus sabdariffa L.).
bitstream/item/31489/1/comunicado-213.pd
Effects of hydroxycinnamic acids on the glycolysis pathway
Glycolysis is a metabolic pathway vital to the production of energy and some organisms rely on it solely to meet
their energy requirements. It is also a central pathway in the metabolism of carbohydrates and a source of
therapeutic targets against diabetes and cancer. Caffeoylquinic acids (CQAs) have been extensively studied for
their role in the treatment and prevention of diabetes (and cancer) but their mechanisms of action remain mostly
unknown. As such, molecular docking was used to find possible targets of CQAs in the glycolysis pathway. The
molecular docking assays showed that CQAs were docked preferably to the Rossman fold (nicotinamide adenine
dinucleotide — NAD(H) binding site) of oxidoreductases, that use NAD(H) as a cofactor, than to any other site.
In-vitro assays were then performed using two NAD(H) dependent oxidoreductases from glycolysis (alcohol
dehydrogenase and L-lactate dehydrogenase) in order confirm if CQAs would compete with the cofactor to
inhibit the reaction. The results from these assays indicate that CQAs can act as both inhibitors and activators
of NAD(H) dependent oxidoreductases of the glycolysis pathway.info:eu-repo/semantics/publishedVersio
Restoring observed classical behavior of the carbon nanotube field emission enhancement factor from the electronic structure
Experimental Fowler-Nordheim plots taken from orthodoxly behaving carbon
nanotube (CNT) field electron emitters are known to be linear. This shows that,
for such emitters, there exists a characteristic field enhancement factor (FEF)
that is constant for a range of applied voltages and applied macroscopic fields
. A constant FEF of this kind can be evaluated for classical CNT
emitter models by finite-element and other methods, but (apparently contrary to
experiment) several past quantum-mechanical (QM) CNT calculations find
FEF-values that vary with . A common feature of most such
calculations is that they focus only on deriving the CNT real-charge
distributions. Here we report on calculations that use density functional
theory (DFT) to derive real-charge distributions, and then use these to
generate the related induced-charge distributions and related fields and FEFs.
We have analysed three carbon nanostructures involving CNT-like nanoprotrusions
of various lengths, and have also simulated geometrically equivalent classical
emitter models, using finite-element methods. We find that when the
DFT-generated local induced FEFs (LIFEFs) are used, the resulting values are
effectively independent of macroscopic field, and behave in the same
qualitative manner as the classical FEF-values. Further, there is fair to good
quantitative agreement between a characteristic FEF determined classically and
the equivalent characteristic LIFEF generated via DFT approaches. Although many
issues of detail remain to be explored, this appears to be a significant step
forwards in linking classical and QM theories of CNT electrostatics. It also
shows clearly that, for ideal CNTs, the known experimental constancy of the FEF
value for a range of macroscopic fields can also be found in appropriately
developed QM theory.Comment: A slightly revised version has been published - citation below -
under a title different from that originally used. The new title is:
"Restoring observed classical behavior of the carbon nanotube field emission
enhancement factor from the electronic structure
When epigenetics meets bioengineering—A material characteristics and surface topography perspective
The field of tissue engineering and regenerative medicine (TE/RM) involves regeneration of tissues and organs using implantable biomaterials. The term epigenetics refers to changes in gene expression that are not encoded in the DNA sequence, leading to remodeling of the chromatin and activation or inactivation of gene expression. Recently, studies have demonstrated that these modifications are influenced not only by biological cues but also by mechanical and topographical signals. This review highlights the current knowledge on emerging approaches in TE/RM with a focus on the effect of materials and topography on the epigenetic expression pattern in cells with potential impacts on modulating regenerative biology. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2065–2071, 2018.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144628/1/jbmb33953.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144628/2/jbmb33953_am.pd
Descriptor-and fragment-based QSAR models for a series of Schistosoma mansoni purine nucleoside inhibitors
The enzyme purine nucleoside phosphorylase from Schistosoma mansoni (SmPNP) is an attractive molecular target for the treatment of major parasitic infectious diseases, with special emphasis on its role in the discovery of new drugs against schistosomiasis, a tropical disease that affects millions of people worldwide. In the present work, we have determined the inhibitory potency and developed descriptor- and fragment-based quantitative structure-activity relationships (QSAR) for a series of 9-deazaguanine analogs as inhibitors of SmPNP. Significant statistical parameters (descriptor-based model: r² = 0.79, q² = 0.62, r²pred = 0.52; and fragment-based model: r² = 0.95, q² = 0.81, r²pred = 0.80) were obtained, indicating the potential of the models for untested compounds. The fragment-based model was then used to predict the inhibitory potency of a test set of compounds, and the predicted values are in good agreement with the experimental resultsA enzima purina nucleosídeo fosforilase de Schistosoma mansoni (SmPNP) é um alvo molecular atrativo para o tratamento de importantes doenças infecciosas parasitárias, com especial ênfase para o seu papel na descoberta de novos fármacos contra a esquistossomose, uma doença tropical que afeta cerca de 200 milhões de pessoas em 74 áreas endêmicas no mundo todo. No presente trabalho, a potência inibitória foi determinada e estudos das relações quantitativas entre a estrutura e atividade (QSAR), baseados em descritores e fragmentos, foram desenvolvidos para uma série de 9-deazaguaninas que atuam como inibidores da SmPNP. Parâmetros estatísticos significantes (modelo baseado em descritor: r² = 0,79; q² = 0,62, r²pred = 0,52; e modelo baseado em fragmento: r² = 0,95; q² = 0,81; r²pred = 0,80) foram obtidos, indicando o potencial dos modelos para compostos ainda não testados. O modelo baseado em fragmento foi então usado para predizer a potência inibitória de um conjunto teste de compostos, e os valores preditos estão em boa concordância com os resultados experimentais.Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB)(FAPESP) São Paulo Research Foundation(CNPq) National Council for Scientific and Technological Developmen
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