1,720,975 research outputs found
Alcohol and 1,2-diol dehydrogenases : synthetic use as oxidants
No full textThe redox equilibrium between alcohol - carbonyl groups is greatly used by enzymes and chemists to prepare useful compounds. Carbonyls are often intermediate groups whose reactivity can be used to synthesize complex Structures: in contrast, alcohols are more easily found in the products of interest because their coordinative ability is used both in biology and in chemistry. Dehydrogenase activities are an interesting alternative to chemical redox reactants because they are often chemo-. regio-. and stereo-selective. These enzymes allow for two different uses: direct, as racemates resolving agents-, inverse. as enantioselective reducing agents. We will focus on their use as oxidative agents. considering both the well-known alcohol dehydrogenases and the less known and less used 1,2-diol dehydrogenases. An account of both classes will be presented
Quantitative aquatic toxicity prediction: using group contribution and classification methods on polar and non-polar narcotics
No full textA model based on a Group Contribution Method (GCM) approach developed to correlate aquatic toxicity to fathead minnow (Pimephales promelas) has been applied to an external set containing 190 organic chemicals. This set was also previously partitioned into polar and non-polar toxicants using a different classification model. The application of the GCM approach to develop specific models both of the entire set and of its partitions permits to discuss the importance of the subclassification in order to improve the result
Application of a Fragment–based Model to the Prediction of the Genotoxicity of Aromatic Amines
No full textAnalysis of a Theoretical Model Based on Similarity for Studying RNA Base Pairings
No full textA theoretical model for studying RNA base pairing is presented, based on similarity measures of the bases and corresponding indexes. Similarity calculations are made by evaluating atomic importance in molecules, a method that uses an original method for the calculation of electronic energy. The application of the model to both Watson-Crick and non-Watson-Crick pairings is commented on. Some theoretical considerations concerning the capability of the genetic code to repair dangerous mutations contribute to the ongoing debate
Cathode and medium effects on the electroreductive glucosidation of phenols
No full textThe electroreductive pathway to phenol glucosidation, recently introduced by the authors' research group, is analyzed here in detail for both mechanism elucidation and choice of operating conditions. Preparative electrosyntheses were carried out on model substrates, varying either the cathode material, the supporting electrolyte, and/or the potential/current electrolysis conditions, to study their effects on the glucosidation yields and stereochem. Special care was devoted to the anal. of the reaction mixts., leading to the identification and characterization of several new products
Electrocatalytic potentialities of silver as a cathode for organic halide reductions
No full textThe peculiar halide affinity for silver results in an extraordinary electrocatalytic activity for the redn. of halides (either glycosyl halides or, more generally, aryl and alkyl halides). The most striking features are: (a) a redn. potential shift in the pos. direction of ∼1000 mV with respect to glassy carbon and 500 mV with respect to mercury; (b) a cage effect, evidenced in previous synthetic work concerning bromosugars, promoted by the halide acting as a bridge between the electrode surface and the reacting substrate, which mainly results in dimerization and/or addn. products. The above electrocatalytic effect is here studied by a systematic reactivity study on Ag, Hg and glassy carbon cathodes, with a variety of substrates. The effect of the supporting electrolyte is also analyzed in detail, providing a 1st inspection on specific halide/silver interactions in acetonitrile media
Bibenzyls and Stilbenes: Compounds with Potential Biological Activity; Synthesis and Structure Modifications
No full textBibenzyls and stilbenes (Figure 1) are widely distributed in the plant kingdom where they mostly act as phytoalexins. Some of them have been reported to show remarkable biological activities as anticancer and chemopreventive agents. Since many years we are interested in the synthesis of both natural and modified bibenzyls and stilbenes with the objective to investigate their biological targets. [1-3] In this communication we will present our recent results in the field, also in the perspective of the most recent achievements concerning their biological activities. We will describe the synthesis of some derivatives that present modifications of the ring substituent pattern and of the alkyl chain interconnecting the two phenyl rings. The syntheses can be roughly divided into two main parts: the construction of the skeleton through Wittig-type condensations, and the modification of the ring substituents and/or of the interconnecting alkyl chain. Finally, we will present new results concerning the structure-activity relationships of these derivatives towards different biological end points.
Refs.1. Orsini, F.; Verotta, L.; Lecchi, M.; Restano, R.; Curia, G.; Redaelli, E.; Wanke, E. J. Nat. Prod., 67, 421-426, (2004)
2. Orsini, F.; Verotta, L. “Stilbenes and bibenzyls with potential anticancer or chemopreventive activity” in: Advances in Nutrition and Cancer II, Zappia, V. Della Ragione, F., Barbarisi, A., Russo, G. L. eds, Plenum Press, London, UK, p. 169-186, 1999.
3. Orsini, F.; Pelizzoni, F.; Verotta, L.; Aburjai, T.; Rogers C.B. J. Nat. Prod., 60, 1082-1087, (1997)
Determination of ergothioneine in red blood cells by high-performance liquid chromatography
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