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21.
The formal asymmetric and stereodivergent enzymatic reduction of α-angelica lactone to both enantiomers of γ-valerolactone was achieved in a one-pot cascade by uniting the promiscuous stereoselective isomerization activity of Old Yellow Enzymes with their native reductase activity. In addition to running the cascade with one enzyme for each catalytic step, a bifunctional isomerase-reductase biocatalyst was designed by fusing two Old Yellow Enzymes, thereby generating an unprecedented case of an artificial enzyme catalyzing the reduction of nonactivated C=C bonds to access (R)-valerolactone in overall 41 % conversion and up to 91 % ee. The enzyme BfOYE4 could be used as single biocatalyst for both steps and delivered (S)-valerolactone in up to 84 % ee and 41 % overall conversion. The reducing equivalents were provided by a nicotinamide recycling system based on formate and formate dehydrogenase, added in a second step. This enzymatic system provides an asymmetric route to valuable chiral building blocks from an abundant bio-based chemical.  相似文献   
22.
Although human cytomegalovirus (HCMV) infection is mostly asymptomatic for immunocompetent individuals, it remains a serious threat for those who are immunocompromised, in whom it is associated with various clinical manifestations. The therapeutic utility of the few available anti‐HCMV drugs is limited by several drawbacks, including cross‐resistance due to their common mechanism of action, i.e., inhibition of viral DNA polymerase. Therefore, compounds that target other essential viral events could overcome this problem. One example of this is the 6‐aminoquinolone WC5 , which acts by directly blocking the transactivation of essential viral Early genes by the Immediate‐Early 2 (IE2) protein. In this study, the quinolone scaffold of the lead compound WC5 was investigated in depth, defining more suitable substituents for each of the scaffold positions explored and identifying novel, potent and nontoxic compounds. Some compounds showed potent anti‐HCMV activity by interfering with IE2‐dependent viral E gene expression. Among them, naphthyridone 1 was also endowed with potent anti‐HIV activity in latently infected cells. Their antiviral profile along with their innovative mechanism of action make these anti‐HCMV quinolones a very promising class of compounds to be exploited for more effective antiviral therapeutic treatment.  相似文献   
23.
The preparation of highly aromatic elastomers from a bisphenol A-based divinyl-terminated resin and polymerization with various aromatic silane containing compounds utilizing a room temperature hydrosilylation reaction is demonstrated. The polymers exhibit high thermal and oxidative stability with 5% weight losses around 430 and 350°C and char yields ranging from 35% to 40%. The thermosets maintained their elastomeric properties with good hardness and mechanical properties as measured by elongation measurements. The toughness of the thermosets was not improved with the inclusion of aromatic moieties but the hardness did appear to increase with the addition of more aromatic groups.  相似文献   
24.
Poly(ADP-ribose) polymerases (PARP) are proteins responsible for DNA damage detection and signal transduction. PARP inhibitors (PARPi) are able to interact with the binding site for PARP cofactor (NAD+) and trapping PARP on the DNA. In this way, they inhibit single-strand DNA damage repair. These drugs have been approved in recent years for the treatment of ovarian cancer. Although they share some similarities, from the point of view of the chemical structure and pharmacodynamic, pharmacokinetic properties, these drugs also have some substantial differences. These differences may underlie the different safety profiles and activity of PARPi.  相似文献   
25.
Resveratrol (RSV) is a natural compound that displays several pharmacological properties, including anti-cancer actions. However, its clinical application is limited because of its low solubility and bioavailability. Here, the antiproliferative and anti-inflammatory activity of a series of phenylacetamide RSV derivatives has been evaluated in several cancer cell lines. These derivatives contain a monosubstituted aromatic ring that could mimic the RSV phenolic nucleus and a longer flexible chain that could confer a better stability and bioavailability than RSV. Using MTT assay, we demonstrated that most derivatives exerted antiproliferative effects in almost all of the cancer cell lines tested. Among them, derivative 2, that showed greater bioavailability than RSV, was the most active, particularly against estrogen receptor positive (ER+) MCF7 and estrogen receptor negative (ER-) MDA-MB231 breast cancer cell lines. Moreover, we demonstrated that these derivatives, particularly derivative 2, were able to inhibit NO and ROS synthesis and PGE2 secretion in lipopolysaccharide (LPS)-activated U937 human monocytic cells (derived from a histiocytoma). In order to define the molecular mechanisms underlying the antiproliferative effects of derivative 2, we found that it determined cell cycle arrest at the G1 phase, modified the expression of cell cycle regulatory proteins, and ultimately triggered apoptotic cell death in both breast cancer cell lines. Taken together, these results highlight the studied RSV derivatives, particularly derivative 2, as promising tools for the development of new and more bioavailable derivatives useful in the treatment of breast cancer.  相似文献   
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27.
Green Public Procurement (GPP) is a significant policy tool for reducing the environmental impacts of services and products throughout their whole life cycle. Scientific and easily verifiable environmental criteria, based on a life cycle approach, should be developed and used within procurement procedures. In this paper, Life Cycle Assessment (LCA) is applied to wood windows showing how it can support the criteria definition. After a foreword on GPP development in Italy, the evaluation features of the environmental performances of building materials and components are outlined. The LCA case study is then presented, describing the use of the analysis results to define the environmental criteria. LCA allowed to identify the main impacts and the critical processes of the window life cycle, giving a scientific framework to discuss GPP criteria with manufacturers associations and stakeholders. Nevertheless, it couldn’t help neither in identifying detailed criteria for GPP nor to define numerical thresholds to be used as reference in procurement procedures. The appropriate strategies should be selected taking into account the technical status of the market, the standard development and the voluntary industry commitments, involving manufacturers associations. Finally, some elements to develop a structured approach for GPP of construction materials are presented.  相似文献   
28.
This paper describes the development and validation of an analytical method to determine 15 polybrominated diphenyl ethers (PBDEs) in fish and shellfish tissues with gas chromatography coupled to triple quadrupole mass spectrometry using electron impact source (GC-EI-MS/MS). A QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe)-like procedure was applied; the extract was cleaned up on an acidic Extrelut-NT3 column connected on top of a silica cartridge and further purified with gel permeation chromatography (GPC). The SIM acquisition proved to yield better results than traditional MRM approach for octa-, nona-, and deca-brominated congeners. The validation study was carried out in inter-laboratory conditions. The average recoveries were in the range 66–118%, with relative standard deviations generally lower than or equal to 22%. Quality assurance and quality control practices were thoroughly described and highlighted. These long and tedious practices are fundamental to obtain reliable quantitative data during food monitoring programs and, therefore, to support daily intake assessments. Finally, the procedure was applied to the analysis of marine fish samples collected in local markets. Mackerel and mullet were the most contaminated species.  相似文献   
29.
This study was carried out to determine the current levels of total mercury in the muscle tissue of swordfish (Xiphias gladius) and bluefin tuna (Thunnus thynnus) caught in the Mediterranean Sea with the purpose of ascertaining whether the concentrations exceeded the maximum level fixed by the European Commission Decision. In addition, specimens of each species were divided into different ranges of weight to investigate the influence of size on mercury accumulation in order to provide data upon which commercial fishing strategies and marketing of swordfish and bluefin tuna may be based. Higher mean levels of total mercury were found in bluefin tuna (1.02 microg g(-1) wet wt) than in swordfish (0.49 microg g(-1) wet wt). In 4.3% of swordfish and in 44.3% of bluefin tuna analyzed, total mercury concentrations exceeded the maximum level fixed by the European Commission Decision (Hg = 1 microg g(-1) wet wt). Besides, for bluefin tuna the total mercury level variability observed, due to size, suggests that there should be greater regulatory control by the authorities.  相似文献   
30.
This paper illustrates a bio-inspired approach to effective, smooth and safe navigation in the human body and, in particular, in the gastrointestinal tract. This idea originates from the medical need to develop more powerful tools for microendoscopy, which is one of the most challenging frontiers of modern medicine. Understanding motion and perception systems of lower animal forms, such as parasites, worms, insects and snakes, can help to design and fabricate bio-inspired robots able to navigate in tortuous, slippery and difficult-to-access cavities of the human body. A preliminary study of a biomimetic adhesion system for the human tissues is presented in this work and some technological implementations are illustrated and discussed. Finally, some issues concerning the goals of smart and reactive locomotion are considered and the most promising and relevant enabling technologies are discussed.  相似文献   
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