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21.
The catalytic activity of cucurbituril in 1,3-dipolar cycloadditions has been applied to the synthesis of oligotriazoles. 相似文献
22.
de Boer JW Browne WR Harutyunyan SR Bini L Tiemersma-Wegman TD Alsters PL Hage R Feringa BL 《Chemical communications (Cambridge, England)》2008,(32):3747-3749
High turnover enantioselective alkene cis-dihydroxylation is achieved with H(2)O(2) catalysed by manganese based complexes containing chiral carboxylato ligands. 相似文献
23.
Sofianos ZD Katsila T Kostomitsopoulos N Balafas V Matsoukas J Tselios T Tamvakopoulos C 《Journal of mass spectrometry : JMS》2008,43(10):1381-1392
The study of pharmacologically active peptides is central for the understanding of cancer and the development of novel therapeutic approaches. In this context, both qualitative and quantitative determination of bioactive peptides in biological fluids/tissues and their effect on endogenous factors (e.g. hormones) are of great importance. A mass spectrometry-based approach was developed and applied towards the measurement of leuprolide, a peptide drug for the treatment of prostate cancer, in mouse plasma. High-pressure liquid chromatography coupled to a hybrid quadrupole linear ion trap (QqLIT) mass spectrometer, a platform that combines the benefits of triple QqLIT instruments, was employed for the study. Using the described methodology, we established that picomolar concentrations of leuprolide could be measured in mouse plasma (limit of quantification of 0.1 ng/ml). In order to optimize pharmacokinetic properties of analogs of leuprolide, a facile in vivo mouse model was developed and leuprolide concentrations were determined in mouse plasma following intraperitoneal administration. In the same animal model, we demonstrated the versatility of the described MS-based approach by the determination of plasma concentrations of testosterone, an established biomarker for the treatment of prostate cancer. Following dosing with leuprolide, circulating testosterone was increased significantly in comparison to vehicle-treated mice. Finally, in vitro metabolism of leuprolide was evaluated by incubation of leuprolide with mouse kidney membranes, followed by identification of major metabolites by MS. Such studies provide the framework for future evaluation of novel leuprolide analogs with potential therapeutic advantages. 相似文献
24.
25.
Andreadou I Tsantili-Kakoulidou A Spyropoulou E Siatra T 《Chemical & pharmaceutical bulletin》2003,51(10):1128-1131
We have previously reported on the synthesis of novel indole derivatives containing an amine-triazole moiety (1a-d, 2a-c), and their antioxidant activity on in vitro non-enzymatic rat hepatic microsomal lipid peroxidation. Some of the compounds showed protective activity against oxidative injury of ischemic myocardium. In the present paper we investigated the interactions of these derivatives with reactive oxygen species, in order to find a mechanism of their antioxidant capacity and to identify structural characteristics responsible for these properties. These interactions were compared with melatonin, which is also an indole derivative. The antioxidant profiles of the compounds were established by different in vitro protocols as follows: 1) by the interaction of the compounds with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable free radical, 2) their scavenging effects on superoxide anions using an enzymic system of xanthine-xanthine oxidase, 3) their inhibitory effects on xanthine oxidase and 4) their ability to scavenge hydroxyl radicals by comparison with dimethyl sulfoxide (DMSO) for *OH. All compounds were found to interact with DPPH, most of them to be superoxide anion scavengers and to be strong hydroxyl radical scavengers. Derivatives 1a and 1d substituted on the nitrogen of the indolic nucleus were found to have better antioxidant properties than the reference compounds used and melatonin. 相似文献
26.
Cavalcante TT Anderson Matias da Rocha B Alves Carneiro V Vassiliepe Sousa Arruda F Fernandes do Nascimento AS Cardoso Sá N do Nascimento KS Sousa Cavada B Holanda Teixeira E 《Molecules (Basel, Switzerland)》2011,16(5):3530-3543
Surface colonization is an essential step in biofilm development. The ability of oral pathogens to adhere to tooth surfaces is directly linked with the presence of specific molecules at the bacterial surface that can interact with enamel acquired pellicle ligands. In light of this, the aim of this study was to verify inhibitory and antibiofilm action of lectins from the Diocleinaesubtribe against Streptococcus mutans and Streptococcus oralis. The inhibitory action against planctonic cells was assessed using lectins from Canavaliaensi formis (ConA), Canavalia brasiliensis (ConBr), Canavalia maritima (ConM), Canavalia gladiata (CGL) and Canavalia boliviana (ConBol). ConBol, ConBr and ConM showed inhibitory activity on S. mutans growth. All lectins, except ConA, stimulated significantly the growth of S. oralis. To evaluate the effect on biofilm formation, clarified saliva was added to 96-well, flat-bottomed polystyrene plates, followed by the addition of solutions containing 100 or 200 μg/mL of the selected lectins. ConBol, ConM and ConA inhibited the S. mutans biofilms. No effects were found on S. oralis biofilms. Structure/function analysis were carried out using bioinformatics tools. The aperture and deepness of the CRD (Carbohydrate Recognition Domain) permit us to distinguish the two groups of Canavalia lectins in accordance to their actions against S. mutans and S. oralis. The results found provide a basis for encouraging the use of plant lectins as biotechnological tools in ecological control and prevention of caries disease. 相似文献
27.
Kyriakos C. Prousis Andromachi Tzani Nicolaos Avlonitis Theodora Calogeropoulou Anastasia Detsi 《Journal of heterocyclic chemistry》2013,50(6):1313-1321
The reactivity of variably substituted 2‐methyl‐4H‐3,1‐benzoxazin‐4‐ones and 2‐methyl‐4H‐pyrido[2,3‐d][1,3]oxazin‐4‐one towards carbon and oxygen nucleophiles under microwave irradiation conditions was investigated. Optimization of the reaction conditions of oxazinones with carbon nucleophiles led to the synthesis of a series of 4‐hydroxy‐quinolin‐2‐ones and 4‐hydroxy‐1,8‐naphthyridin‐2‐ones in high yields, whereas reaction with a variety of alcohols proceeded smoothly to the formation of the corresponding N‐acetyl‐anthranilates and nicotinates. 相似文献
28.
Karanikolopoulos N Pitsikalis M Hadjichristidis N Georgikopoulou K Calogeropoulou T Dunlap JR 《Langmuir : the ACS journal of surfaces and colloids》2007,23(8):4214-4224
A series of well-defined poly[(ethylene oxide)-b-2-(dimethylamino)ethyl methacrylate] (PEO-b-PDMAEMA) diblock copolymers were synthesized by atom transfer radical polymerization (ATRP) techniques. Post-polymerization reactions were performed to transform a portion of the tertiary amine groups of the PDMAEpsilonMA into phosphorozwitterions. The aggregation behavior of the prepared zwitterionic block copolymers was investigated by static and dynamic light scattering techniques at 25 and 37 degrees C, in weakly basic and acidic aqueous solutions. Antiparasitic drugs used for the treatment of Leishmania were incorporated into the copolymer aggregates. The effect of the solution pH, the zwitterion content, temperature, and the quantity of the incorporated drug on the aggregation behavior of the copolymers was tested. 相似文献
29.
We used Fourier transform infrared spectromicroscopy in the attenuated total reflection configuration to study biochemical
events associated with the response to light of an intact retina. We show that the technique is suitable for the detection
in real time of molecular processes occurring in rod outer segments induced by light absorption. Two-dimensional correlation
analysis was applied to the identification and interpretation of specific spectral changes associated to the evolution of
the system. The technique allows us to observe an extensive protein translocation, which we interpret as arising from the
release of transducin from the disk membrane and its redistribution from the outer segment towards the inner segment of rod
cells. These results are in full agreement with our current understanding of retinal physiology and validate the technique
as a useful tool for the study of complex molecular processes in intact tissue.
Figure Spectral changes in the mid infrared region following exposure of an intact retina to light 相似文献
30.
Emmanuel N. Zevgolis Charalabos Zografidis Theodora Perraki Eamonn Devlin 《Journal of Thermal Analysis and Calorimetry》2010,100(1):133-139
This article refers to the mineralogical composition and phase transformations of Greek nickeliferous laterites and to their
metallurgical behaviour, during preheating and reduction with carbon monoxide. Transformation of goethite to hematite and
decomposition of chlorite and serpentine, were identified during preheating. Higher iron metallization was achieved for the
ore in which goethite is the main iron mineral and reduction goes up to 95%, whereas it goes up to 50% for the ore in which
hematite is the main iron mineral. The higher reducibility, however, seems to be due to the higher specific surface area of
the goethitic type of ore. 相似文献