In vitro antioxidant,antimicrobial and anti-proliferative activities of purple potato extracts (Solanum tuberosum cv Vitelotte noire) following simulated gastro-intestinal digestion

Analyses of antioxidant and in vitro antimicrobial and anti-proliferative activities of anthocyanin-rich extracts from purple potatoes, Solanum tuberosum L. cv Vitelotte noire (Solanaceae), were performed by simulating both a domestic cooking process and human digestion. Extracts of crude and cooked purple potato did not exhibit antimicrobial activity against the tester strains: Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa. The behaviour changed after the simulated gastrointestinal transit, when an inhibition halo was observed against all tester strains used, ranging from 0.53 cm against B. cereus to 0.82 cm against E. coli. In addition antioxidant activity exhibited, before and after the simulated gastrointestinal digestion (5.96 mg/mL ± 0.92; 28 mg/mL ± 0 .13, respectively) and the persistence of anti-proliferative activity against the colon cancer cells Caco-2, SW48 and MCF7, MDA-MB-231 breast cancer cells, after the simulated digestion, (EC₅₀ = 0.21; 1.13 μg/mL), suggest that vitelotte consumption might bring tangible benefits for human health.     

1-substituted beta-carbolines by a Pictet-Spengler cyclization with thioortho esters and carbon-carbon bond formation via N-sulfonyl iminium ions generated from N,S-sulfonyl acetals

The reaction of N-tosyltryptamines with thioortho esters, leading to 1-thiosubstituted tetrahydro-beta-carbolines under modified Pictet-Spengler conditions, is described. The 1-heterosubstituted beta-carbolines furnished 1-substituted beta-carbolines upon reaction with Grignard reagents and silyl derivatives under Lewis acid promotion. [reaction: see text]     

Equilibrium in Saturated Ca(OH)2 Solutions: Parameters and Dissociation Constants

A new computer program has been developed for the calculation of pH, pOH, hydroxide ion concentration m _OH, species distribution coefficients _i, ionic activity coefficients _i ionic strength I, buffer capacity , solubility product K _s0, and the two dissociation constants, K _b1 and K _b2, corresponding, respectively, to first and second dissociation steps of Ca(OH)₂ in aqueous solution. Previously developed methodology, for the calculation of pH, _i, _i I, and parameters of pH buffer solutions, starting from the corresponding acidity constants, has been adapted for the case of aqueous Ca(OH)₂ solutions, for which the pertinent stoichiometric relationships are different from those applicable to mixtures of acids and their salts. The results show that, contrary to what is currently assumed, the first dissociation is far from complete. Values are given for the concentrations and activities of species Ca(OH)₂(aq), Ca(OH)⁺(aq), and Ca²⁺ (aq) in saturated calcium hydroxide solutions at 25°C.     

The Effects of Cosolvents on the Complexation of α-Cyclodextrin with Alkylated Substances. Calorimetric Studies at 25 °C

The formation of complexes of -cyclodextrin with 1,2-alkanediols, ,-alkanediols and some cycloalkanols has been studied calorimetrically at 25 °C in water, in 7 mol kg^-1 aqueous urea and in 3 mol kg^-1 aqueous glucose. When a complex is formed, calorimetry enables the calculation of both the enthalpy and the association constant, from which the free energy and the entropy of the process can be obtained. The forces involved in the association process are discussed in the light of the signs and values of the thermodynamic parameters obtained. The effect of the variation of the aqueous medium on the hydration of the interacting substances and the consequent changes in the association parameters have been investigated. As respect to water, complexes are less stable in urea and more stable in glucose. The analysis of the data shows that this is the result of a different enthalpy-entropy balance in the two solvent media. Deaquation of the interacting substances plays a major role in determining the stability of the inclusion complexes.     

Phase behavior of C60 by computer simulation using ab‐initio interaction potential

A first‐principles intermolecular potential recently proposed by Pacheco and Ramalho [Phys Rev Lett 1997, 79, 3873–3876] has been used with the Gibbs ensemble and Gibbs–Duhem integration Monte Carlo methods to simulate the vapor–liquid and fluid–solid coexistence properties of C₆₀. The critical properties were calculated by fitting the results to the laws of rectilinear diameters and order parameter scaling. The triple‐point properties were determined from the limiting behavior of the Gibbs ensemble vapor–liquid simulations at the lowest temperature range. A stable liquid phase is predicted for temperatures between 1570±20 and 2006±27 K and densities between 0.444±0.003 and 1.05±0.01 nm^?3. The estimated critical and triple‐point pressures are, respectively, 35±6 and 5±16 bars. We show for the first time, to our knowledge, that it is possible, strictly by computer simulation, to estimate a triple point for C₆₀ in accordance with the predictions of theoretical methods and the basic concepts of thermodynamics. The liquid and fluid radial distribution functions indicate the presence of solid or glasslike features. This may support the suggestion of a more cooperative interaction of clusters in C₆₀. A comparison of our results with the data obtained by other authors is presented and discussed. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 375–387, 2001     

Symmetry of positive solutions of an almost-critical problem in an annulus

We consider the subcritical problem & 0 & \qquad\textrm{in} \; A\\ u & = & 0 & \qquad\textrm{on} \; \delta A\\ \end{array} \right.$$" align="middle" border="0"> where A is an annulus in , , is the critical Sobolev exponent and 0$" align="middle" border="0"> is a small parameter. We prove that solutions of (I) which concentrate at one or two points are axially symmetric.Received: 7 July 2003, Accepted: 10 May 2004, Published online: 16 July 2004Filomena Pacella: Research supported by MIUR, project Variational Methods and Nonlinear Differential Equations.     

On an eigenvalue problem related to the critical exponent

In this paper we study the eigenvalue problemwhere is a smooth bounded domain, and u is a positive solution of the problemsuch thatwhere S is the best Sobolev constant for the embedding of H¹₀() into L²*(), We prove several estimates for the eigenvalues _i, of (I), i=2,..,N+2 and some qualitative properties of the corresponding eigenfunctions.Supported by M.I.U.R., project Variational methods and nonlinear differential equations.     

Structure–Activity Relationship Study of a Potent α-Thrombin Binding Aptamer Incorporating Hexitol Nucleotides

The replacement of one or more nucleotide residues in the potent α-thrombin-binding aptamer NU172 with hexitol-based nucleotides has been devised to study the effect of these substitutions on the physicochemical and functional properties of the anticoagulant agent. The incorporation of single hexitol nucleotides at the T9 and G18 positions of NU172 substantially retained the physicochemical features of the parent oligonucleotide, as a result of the biomimetic properties of the hexitol backbone. Importantly, the NU172- T ^H9 mutant exhibited a higher binding affinity toward human α-thrombin than the native aptamer and an improved stability even after 24 h in 90 % human serum, with a significant increase in the estimated half-life. The anticoagulant activity of the modified oligonucleotide was also found to be slightly preferable to NU172. Overall, these results confirm the potential of hexitol nucleotides as biomimetic agents, while laying the foundations for the development of NU172-inspired α-thrombin-binding aptamers.