Kinetic and mechanism study of the spontaneous, solvent- and base-catalyzed degradation of the precursor of the ß-nitro alcohol metaraminol by combining HPLC/electronic circular dichroism/theoretical methods.

Chiral ß-nitro alcohols are key intermediates in the synthesis of a wide range of active pharmaceutical ingredients. Despite their massive use for pharmaceutical applications, in-depth kinetics studies concerning their stability during formation and transformation reactions are scarce in the literature. In this study, the (1R,2S)-1-(m-benzyloxy)-2-nitro-1-propanol) (BNA), the precursor of the metaraminol, was selected as a molecular model and the retro-Henry reaction was explored by a multidisciplinary approach involving HPLC, electronic circular dichroism and theoretical methods. The enantio-, diastereo-, and chemo-selective high-performance liquid chromatographic method for determining the purity of ß-nitro alcohol during its formation and degradation is based on the use of an amylose-derived chiral stationary phase under normal-phase eluent conditions. The influence of various factors (e.g. temperature, type of reaction solvent, basic and acid catalysts) on the degradation kinetics has been investigated. The retro-Henry reaction was found to be the major degradation of BNA, under spontaneous, solvent- and base-catalyzed conditions, resulting in the formation of its precursors 3-benzyloxybenzaldehyde and nitroethane.

ON/OFF receptor-like enantioseparation of planar chiral 1,2-ferrocenes on an amylose-based chiral stationary phase: The role played by 2-propanol.

A set of nine planar chiral 1,2-ferrocenes was analyzed by high-performance liquid chromatography (HPLC) on the amylose tris(3,5-dimethylphenylcarbamate) chiral stationary phase. The enantioseparations were carried out using neat methanol, ethanol, 1-propanol, and 2- propanol as well as mixtures of n-hexane-2-propanol as mobile phases. The differences in retention times between the second eluted (Rp)-enantiomers and the first eluted (Sp)-enantiomers were significantly influenced by elution modes and the steric hindrance of substituents at the aromatic rings of the ferrocene backbone. It has been demonstrated an ON/OFF switching of receptor-like chiral discrimination through the employment of different alcohols as mobile phases. In particular, the presence of pure 2-propanol triggers exceptional conditions of enantioselectivity that for some ferrocenes result in values of the enantioseparation factor higher than 80.

Anticancer Activity of (S)-5-Chloro-3-((3,5-dimethylphenyl)sulfonyl)-N-(1-oxo-1-((pyridin-4-ylmethyl)amino)propan-2-yl)-1H-indole-2-carboxamide (RS4690), a New Dishevelled 1 Inhibitor.

Wingless/integrase-11 (WNT)/ß-catenin pathway is a crucial upstream regulator of a huge array of cellular functions. Its dysregulation is correlated to neoplastic cellular transition and cancer proliferation. Members of the Dishevelled (DVL) family of proteins play an important role in the transduction of WNT signaling by contacting its cognate receptor, Frizzled, via a shared PDZ domain. Thus, negative modulators of DVL1 are able to impair the binding to Frizzled receptors, turning off the aberrant activation of the WNT pathway and leading to anti-cancer activity. Through structure-based virtual screening studies, we identified racemic compound RS4690 (1), which showed a promising selective DVL1 binding inhibition with an EC50 of 0.74 ± 0.08 µM. Molecular dynamic simulations suggested a different binding mode for the enantiomers. In the in vitro assays, enantiomer (S)-1 showed better inhibition of DVL1 with an EC50 of 0.49 ± 0.11 µM compared to the (R)-enantiomer. Compound (S)-1 inhibited the growth of HCT116 cells expressing wild-type APC with an EC50 of 7.1 ± 0.6 µM and caused a high level of ROS production. These results highlight (S)-1 as a lead compound for the development of new therapeutic agents against WNT-dependent colon cancer.

Enantioselective HPLC analysis of escitalopram oxalate and its impurities using a cellulose-based chiral stationary phase under normal- and green reversed-phase conditions.

Normal-phase and reversed-phase high-performance liquid chromatography methods for the separation of the active pharmaceutical ingredient escitalopram from its (R)-enantiomer impurity have been developed on the cellulose-based Chiralcel OJ-H chiral stationary phase. Both methods share two features: they use ethanol as a cosolvent and are able to give a complete enantioseparation without interference from other associated chiral impurities. With the green eluent mixture ethanol-water-diethylammine 70:30:0.1 (v/v/v), the resolution between escitalopram and (R)-enantiomer was 2.09 at 30°C. The limits of quantification for the (S) and (R) enantiomers were 4.5 and 3.8 µg mL-1 , respectively.