Asymmetric Organocatalyzed Transfer Hydroxymethylation of Isoindolinones Using Formaldehyde Surrogates

The piperidine-based Takemoto catalyst has been successfully employed in a novel asymmetric transfer hydroxymethylation of activated isoindolinones, allowing us to prepare the enantioenriched hydroxymethylated adducts in good to excellent yields (48-96%) and enantiopurities (81:19-97:3 e.r.). To increase the reaction rate without compromising the selectivity, carefully optimized formaldehyde surrogates were employed, providing a convenient source of anhydrous formaldehyde with a base-triggered release. The substrate scope, including 34 entries, showed the considerable generality of the asymmetric transformation, and most entries exhibited complete conversions in 24-48 h. A scale-up experiment and multiple enantioselective downstream transformations were also carried out, suggesting the prospective synthetic utility of the products.

Triphenyltin isoselenocyanate: a novel nuclear retinoid X receptor ligand with antiproliferative and cytotoxic properties in cell lines derived from human breast cancer

Several commercially available triorganotin compounds were previously found to function as agonist ligands for nuclear retinoid X receptor (RXR) molecules. Triphenyltin isoselenocyanate (TPT-NCSe), a novel selenium atom containing a derivative of triorganotin origin, was found to represent a new cognate bioactive ligand for RXRs. TPT-NCSe displayed a concentration- and time-dependent decrease in the cell viability in both human breast carcinoma MCF-7 (estrogen receptor positive) and MDA‑MB‑231 (triple negative) cell lines. Reactive oxygen species levels generated in response to TPT-NCSe were significantly higher in both carcinoma cell lines treated with TPT-NCSe when compared to mock-treated samples. Treatment with 500 nM TPT-NCSe caused a decrease in SOD1 and increased SOD2 mRNA in MCF-7 cells. The levels of SOD2 mRNA were more increased following the treatment with TPT-NCSe along with 1 μM all-trans retinoic acid (AtRA) in MCF-7 cells. An increased superoxide dismutase SOD1 and SOD2 mRNA levels were also detected in combination treatment of 500 nM TPT-NCSe and 1 μM AtRA in TPT-NCSe-treated MDA-MB-231 cells. The data have also shown that TPT-NCSe induces apoptosis via a caspase cascade triggered by the mitochondrial apoptotic pathway. TPT-NCSe modulates the expression levels of apoptosis‑related proteins, Annexin A5, Bcl‑2 and BAX family proteins, and finally, it enhances the expression levels of its cognate nuclear receptor subtypes RXRalpha and RXRbeta.

Enantioselective Bifunctional Ammonium Salt-Catalyzed Syntheses of 3-CF3S-, 3-RS-, and 3-F-Substituted Isoindolinones

We herein report the ammonium salt-catalyzed synthesis of chiral 3,3-disubstituted isoindolinones bearing a heteroatom functionality in the 3-position. A broad variety of differently substituted CF3S- and RS-derivatives were obtained with often high enantioselectivities when using Maruoka's bifunctional chiral ammonium salt catalyst. In addition, a first proof-of-concept for the racemic synthesis of the analogous F-containing products was obtained as well, giving access to one of the rare examples of a fairly stable α-F-α-amino acid derivative.

One-pot method for the synthesis of 1-aryl-2-aminoalkanol derivatives from the corresponding amides or nitriles

We have identified a novel one-pot method for the synthesis of β-amino alcohols, which is based on C–H bond hydroxylation at the benzylic α-carbon atom with a subsequent nitrile or amide functional group reduction. This cascade process uses molecular oxygen as an oxidant and sodium bis(2-methoxyethoxy)aluminum hydride as a reductant. The substrate scope was examined on 30 entries and, although the respective products were provided in moderate yields only, the above simple protocol may serve as a direct and powerful entry to the sterically congested 1,2-amino alcohols that are difficult to prepare by other routes. The plausible mechanistic rationale for the observed results is given and the reaction was applied to a synthesis of a potentially bioactive target.

A one-pot method for β-amino alcohol synthesis based on α-hydroxylation and subsequent amide or nitrile functional group reduction has been identified and examined.

Down-regulation of vimentin by triorganotin isothiocyanates-nuclear retinoid X receptor agonists: A proteomic approach

An attempt has been made to delineate the role of natural and synthetic retinoid receptor ligands on vimentin expression in the human triple-negative breast cancer cells. The effects of currently synthesized triorganotin derivatives of the general formula R₃SnX (R is butyl or phenyl, X is isothiocyanate), which are considered RXR ligands, were investigated in the human MDA-MB-231 breast cancer cell line. Studies were evaluated in the presence and absence of all-trans retinoic acid (ATRA), a natural RAR ligand. Vimentin represents the major protein associated with epithelial-mesenchymal transition (EMT), an essential process when the primary tumour transforms into a malignant one. mRNA and proteomic data obtained in this study, based on the PDQuest software protein evaluation and further quantification of proteins by iTRAQ analysis, suggest that vimentin was significantly reduced in the combination of RAR ligand and RXR ligand treatment. Both tested triorganotin compounds showed similarly reduced expression of vimentin, but tributyltin isothiocyanate (TBT-ITC) proved to be more effective than triphenyltin isothiocyanate (TPT-ITC). Furthermore, the effect of natural (9cRA) and synthetic RXR ligands, both chloride and isothiocyanate derivatives, on vimentin expression was compared.

Triorganotin Isothiocyanates Affect Migration and Immune Check-point Receptors in Human Triple-negative Breast Carcinoma MDA-MB-231 Cells

BACKGROUND/AIM

Triple-negative breast cancer (TNBC) constitutes 15-20% of all breast carcinomas, affecting younger women more often and has a worse prognosis than other types of breast cancer, due to the combination of more aggressive clinical behavior and lack of molecular targets for therapy. This study assessed the effects of non-genotoxic concentrations of tributyltin isothiocyanate (TBT-ITC) and triphenyltin isothiocyanate (TPT-ITC) on MDA-MB-231 cells.

MATERIALS AND METHODS

MTT assay, comet assay, kinetic imaging and flow cytometry were used for analysis of MDA-MB-231 cells.

RESULTS

The results showed that 100 nM concentration of TBT-ITC and TPT-ITC, that did not affect viability or DNA integrity, slowed-down migration by CD44 down-regulation. Moreover, both compounds demonstrated immunomodulatory properties, attenuating PD-L1 expression in MDA-MB-231 cells.

CONCLUSION

TPT-ITC was more effective in down-regulating CD44 expression and reducing migration than TBT-ITC, while TBT-ITC was more potent in lowering PD-L1 expression in comparison with TPT-ITC.

Bianthryl-based organocatalysts for the asymmetric Henry reaction of fluoroketones

We have developed a catalytic system based on bianthrylbis(thiourea) for the asymmetric Henry reaction of fluoroketones and nitroalkanes that resulted from the screening of a library containing 31 chiral non-racemic organocatalysts. The corresponding adducts were isolated in up to 6 times shorter reaction time in comparison with the previously published organocatalysts. High levels of stereocontrol have been generally observed, with measured product enantiomeric excesses up to 97% and diastereomeric ratio 3 : 2 (anti/syn). The above-mentioned catalysts have been successfully applied to the total asymmetric synthesis of CF₃-tethered (S)-halostachines, which has proved that this method constitutes an easy entry to similar enantiopure compounds.

An integrative study to identify novel scaffolds for sphingosine kinase 1 inhibitors

Sphingosine kinase 1 (SphK1), the enzyme that produces the bioactive sphingolipid metabolite, sphingosine-1-phosphate, is a promising new molecular target for therapeutic intervention in cancer and inflammatory diseases. In view of its importance, the main objective of this work was to find new and more potent inhibitors for this enzyme possessing different structural scaffolds than those of the known inhibitors. Our theoretical and experimental study has allowed us to identify two new structural scaffolds (three new compounds), which could be used as starting structures for the design and then the development of new inhibitors of SphK1. Our study was carried out in different steps: virtual screening, synthesis, bioassays and molecular modelling. From our results, we propose a new dihydrobenzo[b]pyrimido[5,4-f]azepine and two alkyl{3-/4-[1-hydroxy-2-(4-arylpiperazin-1-yl)ethyl]phenyl}carbamates as initial structures for the development of new inhibitors. In addition, our molecular modelling study using QTAIM calculations, allowed us to describe in detail the molecular interactions that stabilize the different Ligand-Receptor complexes. Such analyses indicate that the cationic head of the different compounds must be refined in order to obtain an increase in the binding affinity of these ligands.

Application of BY-2 cell model in evaluating an effect of newly prepared potential calcium channel blockers

Calcium channel blockers represent a group of therapeutically important compounds that have found an application in treatment of systemic vascular resistance and arterial pressure, eventually angina pectoris. We studied possibility of application of a BY-2 cell model to evaluate the potential of newly prepared potential calcium channel blockers. In the preliminary experiment, toxicity of studied compounds was determined. In the next experiment, we evaluated possible protective effect of studied compounds on programmed cell death induced by hydrogen peroxide on the BY-2 cells. Calcium channel blocker lanthanum ions and imidazole, inhibitor of NAD(P)H oxidase (EC 1.6.3.1) that prevents reactive oxygen species formation and programmed cell death, were used as reference compounds to compare the effect of studied compounds. We studied changes in the cell viability and growth as well as markers of cell proliferation, levels of intracellular free calcium ions, reactive oxygen species, lipid peroxidation, and markers of programmed cell death, mitochondrial membrane potential and caspase-like activity. Late signs of programmed cell death (changes in nuclear architecture) were also evaluated. Our experiments revealed protective potential of studied compounds against programmed cell death induced by hydrogen peroxide and possibility of application of the BY-2 cell culture to evaluate pharmacological effects of studied compounds in preliminary tests.

Investigating the spectrum of biological activity of ring-substituted salicylanilides and carbamoylphenylcarbamates

In this study, a series of twelve ring-substituted salicylanilides and carbamoylphenylcarbamates were prepared and characterized. The compounds were analyzed using RP-HPLC to determine lipophilicity. They were tested for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Moreover, their site of action in the photosynthetic apparatus was determined. Primary in vitro screening of the synthesized compounds was also performed against mycobacterial, bacterial and fungal strains. Several compounds showed biological activity comparable with or higher than the standards 3-(3,4-dichlorophenyl)-1,1-dimethylurea, isoniazid, penicillin G, ciprofloxacin or fluconazole. The most active compounds showed minimal anti-proliferative activity against human cells in culture, indicating they would have low cytotoxicity. For all compounds, the relationships between lipophilicity and the chemical structure are discussed.