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101.
102.
103.
Sáez-Ayala M Sánchez-del-Campo L Montenegro MF Chazarra S Tárraga A Cabezas-Herrera J Rodríguez-López JN 《ChemMedChem》2011,6(3):440-449
Despite bioavailability issues, tea catechins have emerged as promising chemopreventive agents because of their efficacy in various animal models. We synthesized two catechin-derived compounds, 3-O-(3,4,5-trimethoxybenzoyl)-(-)-catechin (TMCG) and 3-O-(3,4,5-trimethoxybenzoyl)-(-)-epicatechin (TMECG), in an attempt to improve the stability and cellular absorption of tea polyphenols. The antiproliferative and pro-apoptotic activities of both compounds were analyzed with various cancer cell systems, and TMCG, which was easily synthesized in excellent yield, was more active than TMECG in both melanoma and non-melanoma cell lines. TMCG was also a better inhibitor of dihydrofolate reductase and was more efficiently oxidized by tyrosinase, potentially explaining the difference in activity between these epimers. 相似文献
104.
Aulacoscelinae beetles have an ancient relationship with cycads (Cycadophyta: Zamiaceae), which contain highly toxic azoxyglycoside
(AZG) compounds. How these “primitive” leaf beetles deal with such host-derived compounds remains largely unknown. Collections
were made of adult Aulacoscelis appendiculata from Zamia cf. elegantissima in Panama, A. vogti from Dioon edule in Mexico, and Janbechynea paradoxa from Zamia boliviana in Bolivia. Total AZG levels were quantified in both cycad leaves and adult beetles by high performance liquid chromatography
(HPLC). On average, cycad leaves contained between 0.5–0.8% AZG (frozen weight, FW), while adult beetles feeding on the same
leaves contained even higher levels of the compounds (average 0.9–1.5% FW). High AZG levels were isolated from reflex bleeding
secreted at the leg joints when beetles were disturbed. Nuclear magnetic resonance and mass spectroscopy identified two AZGs,
cycasin and macrozamin, in the reflex bleeding; this is the first account of potentially plant-derived compounds in secretions
of the Aulacoscelinae. These data as well as the basal phylogenetic position of the Aulacoscelinae suggest that sequestration
of plant secondary metabolites appeared early in leaf beetle evolution. 相似文献
105.
The main focus of this research is the modelization of the ultraviolet protection factor of the fabrics in relation with the most significant structural parameters that are likely to be varied during the weaving process: yarn number and thread count. By statistical planning and data analysis, a model that correlates the ultraviolet protection factor with these parameters is formulated for three different types of cellulosic fibres. The composition and structure of the studied fabrics are appropriate for their use in summer garments. 相似文献
106.
María Jesús Cejudo‐Bastante Isidro Hermosín‐Gutiérrez María Soledad Pérez‐Coello 《Journal of food science》2013,78(4):C507-C513
The effects of time (storage period) and temperature (accelerated aging) on Chardonnay white wines have been evaluated. Attention was focused on a large extent of individual volatile compounds, scarcely previously reported in that kind of wines. On the one hand, several volatile compounds (mainly esters, benzenic compounds, C13‐norisoprenoids, acids, and terpenes) showed the same behavior when temperature and time were applied separately. Therefore, the effect of 1 y of storage could be predicted by temperature application during short time, just analyzing those volatile compounds. Moreover, the formation of some volatile compounds (such as dioxanes, dioxolanes, and 1,2‐dihydro‐1,1,6‐trimethylnaphtalene (TDN)) and the disappearance of some alcohols, terpenes, and furanic compounds occurred in both conventional stored and accelerated‐aged wines. On the other hand, wines submitted to high temperature differed from 1‐y stored wines on several volatile compounds, such as β‐damascenone, C6‐alcohols, dioxolanes, γ‐butyrolactone, and TDN. Therefore, it is possible to assert that the analysis of these compounds could allow checking the possible inadequate handling by employing an excessive temperature. 相似文献
107.
Patricia Cid María Jesús Doldán María Soledad Rodríguez Benjamin Prego Encarnación de Miguel 《Microscopy research and technique》2013,76(6):588-597
The morphogenesis and cell proliferation in the retina of turbot (Psetta maxima, Pleuronectiformes: Teleostei) from embryo through metamorphosis have been examined by using proliferating cell nuclear antigen (PCNA)‐immunohistochemistry and general histological procedures. In the embryonic retina, cell proliferation and spatial cell reorganization form the anlage of the pigment epithelium and neural retina. Neurogenesis begins around hatching in the temporal retina, dorsal to the optic nerve exit, and then a wave of cell differentiation spreads to the nasal retina to yield a laminated retina by the end of the prolarval turbot stage. Germinal zones in the differentiated retina persist as a rim at the retinal margin, as well as surrounding the optic fissure in premetamorphic and metamorphic turbot larvae. In these zones, progenitor cells with different morphologies show a similar spatial arrangement, which suggests that they have a similar retinogenic potential. During metamorphosis, asymmetric proliferative activity in turbot germinal zones is associated with a marked expansion of the retinal tissue. Scattered stem cells in the laminated retina, related to the lineage of rod photoreceptors, were also observed both in large premetamorphic larvae and metamorphic turbots. The proliferative activity of these cells increases considerably during metamorphosis, when rod photoreceptors become morphologically differentiated. Microsc. Res. Tech. 76:588–597, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
108.
This note shows how the transmission system can enhance competition in price-regulated power industries, thus extending earlier findings reported in the literature for deregulated industries. In the context of a two-technology, price-regulated power industry, we show that the interconnection of two markets initially supplied by a different monopoly reduces market power and raises welfare. We also show that the capacity of the transmission line plays a key role in determining whether market equilibrium lies closer to competition or monopoly. 相似文献
109.
Mercedes Jimenez Josefa Escribano Manuela Pérez-Gilabert Soledad Chazarra Juana Cabanes Francisco García-Carmona 《Lipids》2001,36(10):1169-1174
Patatin was extracted from potato tubers (Solanum tuberosum L. cv. Spunta) and purified to homogeneity by ammonium sulfate salt fractionation and one sole chromatographic step. A spectrophotometric
mixed micellar assay for patatin lipid acyl hydrolase (LAH) activity was designed with the detergent octaethylene glycol monododecyl
ether (C12E8). Patatin LAH used p-nitrophenyl butyrate (PNP-butyrate) as substrate when solubilized in (C12E8) micelles. In the mixed micellar system, patatin LAH responds to the PNP-butyrate surface concentration expressed as mol%
(=[PNP-butyrate]·100/([detergent]-critical micellar concentration)) and not to the molarity of PNP-butyrate. The kinetic parameters
were determinined; V
max was independent of the mixed micelle concentration, as was K
m, when expressed as mol%. However, K
m was dependent on C12E8 concentration when expressed in molar concentration. C12E8/PNP-butyrate proved to be a reliable system for assaying patatin LAH activity and is superior to the commonly used Triton
X-100 and SDS methods. It permits investigation of the substrate requirements of patatin LAH activity because the concentration-independent
K
m can be determined both in mol% and as the absolute number of substrate molecules per micelle. In addition, the detergent
did not affect the enzyme activity. 相似文献
110.
We presentthe results of a research work targeted to understanding thedomains and consequences of CASE tools usage in Nokia. We aimto evaluate the importance of the various CASE tools features,as rated by our developers, and how well such features are implementedin currently available CASE tools. A structured questionnairewas sent to our most experienced developers and CASE users. Fromthis survey, it emerged that CASE tools support is reputed mostuseful for the following functions: graphical drawing, automaticdocumentation generation and storage of diagrams. The resultshint to a mismatch between the features required by the developersand those offered by CASE products. Further research is neededbefore more definite conclusions can be drawn. 相似文献