Diarylthiazole and diarylimidazole selective COX-1 inhibitor analysis through pharmacophore modeling,virtual screening,and DFT-based approaches

Structural Chemistry - The current work is focused on in silico modeling of COX-1 inhibitors with enhanced safety gastric profile. A 5-point pharmacophore model, atom-based 3D quantitative...     

Wittig and Wittig-Horner reactions under phase transfer catalysis conditions

Wittig and Wittig-Horner reactions are favorite tools in preparative organic chemistry. These olefination methods enjoy widespread and recognition because of their simplicity, convenience, and effciency. Phase transfer catalysis (PTC) is a very important method in synthetic organic chemistry having many advantages over conventional, homogenous reaction procedures. In this paper, we attempt to summarize the aspects concerning Wittig and Wittig-Horner reactions that take place under phase transfer catalysis conditions.     

DFT plus PCM calculation for pairing specificity of Watson–Crick‐type bases in aqueous solutions

This study is aimed at explaining the preference for AT and CG pairings and the possible insertion of other tautomeric DNA base pairs such as G_enolT, that respect energetic and steric requirements including at least two hydrogen bonds and 11 ± 0.5Å distance between the 9‐CH₃ of purine and 5‐CH₃ of pyrimidine. The calculated free energy of formation ΔΔG at the DFT B3LYP/6‐31G*‐PCM/BEM level pointed out the CG and AT pairs as the most favored, followed closely by G_enolT, in good agreement with Michaelis–Menten first order kinetics (CG ≈ AT > G_enolT). Unusual DNA base pairs complexes such as AG (BEM) and CT (PCM) resulted to be stable, but it is very difficult to assume that they are likely to be included in the double strand DNA. The calculated enthalpy and dipole moments of isolated DNA bases agree well with experiment. The free energy of hydration, ΔG_hyd, was found to depend on the electrostatic term, while cavitation‐dispersion components are almost constant. The stability of DNA complexes in water resulted from PCM calculations is markedly influenced by the free energy of hydration. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Implementation of PLS discriminant analysis to rank indirubin derivatives against decoys

Partial Least Squares Discriminant Analysis (PLS-DA) is employed to obtain novel combinations of energetic terms present in classical scoring functions, which exceed and compensates the “traditional” consensus scheme. These novel scoring functions were involved to rank the database of indirubin inhibitors of glycogen synthase kinase-3β and cyclin dependent kinase-2 decoys from Directory of Useful Decoys. The ability of docking-scoring algorithm to prioritize the actives is assessed by means of several metrics. The best classification function includes donor component of Chemgauss2, steric contribution from Chemgauss3 and rotatable bond term of ScreenScore and provide significant improvement of enrichment factor at 5% of database.      

Intracellular Localization of an Osmocenyl‐Tamoxifen Derivative in Breast Cancer Cells Revealed by Synchrotron Radiation X‐ray Fluorescence Nanoimaging

A series of tamoxifen‐like metallocifens of the group‐8 metals (Fe, Ru, and Os) has strong antiproliferative activity on the triple‐negative breast cancer cells (MDA‐MB‐231). To shed light on the mechanism of action of these molecules, synchrotron radiation X‐ray fluorescence nanoimaging studies were performed on cells exposed to osmocenyl‐tamoxifen (Oc‐OH‐Tam) to disclose its intracellular distribution. High‐resolution mapping of the lipophilic Oc‐OH‐Tam in cells revealed its preferential accumulation in the endomembrane system. This is consistent with the ability of the amino nitrogen chain of the compounds to be protonated at physiological pH and responsible for electrostatic interactions between Oc‐OH‐Tam and membranes. A comprehensive scenario is proposed that provides new insight into the cellular behavior and activation of Oc‐OH‐Tam and advances the understanding of its mechanism of action.     

Aromatic λ<Superscript>3</Superscript> heterocycles XIV. Fosfinine-ether macrocyclesheterocycles XIV. Fosfinine-ether macrocycles

The geometry and electronic structure of several phosphinine-ether macrocycles were investigated at semiempirical level. The calculated geometries are in good agreement with experimental data. Compared to phosphinine, the coordinative abilities of phosphinineether macrocycles based on energy considerations suggest a little lowered π acceptor character, while π donor character is improved. The molecular environment causes a significant mixing of phosphinine and phenyl substituent π levels. The geometry and electronic properties of phosphinine-ether macrocycles can provide significant host coordination properties for guest species.