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The potential of 2‐(alkylsulfanyl)azine ligands for crystal engineering of functional Ag(I) complexes has been firstly demonstrated. The reaction of AgNO3, AgClO4 and AgOTf with 2‐(alkylsulfanyl)pyridines, ‐pyrimidines, and ‐quinolines gives a series of new Ag(I) compounds that range from mono‐ and dinuclear complexes to chain (1D), layered (2D) and framework (3D) coordination polymers (CPs). 2‐(Alkylsulfanyl)pyridines and ‐pyrimidines, depending on the reaction conditions, are assembled either into molecular complexes or CPs, while 2‐(alkylsulfanyl)quinolines afford dinuclear complexes exclusively. The most of compounds engineered feature site‐specific interactions such as Ag···Ag, Ag···O, and Ag···S ones. The 2‐(methylsulfanyl)quinoline (2‐MeSQn) complex, [Ag2(2‐MeSQn)2(NO3)2], displays room temperature intraligand (IL) phosphorescence, while the 2‐(methylsulfanyl)pyridine‐derived CPs emit dual luminescence expressed by IL fluorescence and phosphorescence. Moreover, cytotoxic activity of the compounds synthesized has been evaluated against hTERT lung fibroblasts, HeLa, MCF7, HepG2 and A549 cancer cells. [ABSTRACT FROM AUTHOR]

• Two epimers of ursolic acid labeled with FITC were synthesized for the first time. • It was shown that inclusion of a FITC enhances the cytotoxicity of the ursolic acid. • Akt1/protein kinase is the most likely target for binding with ursolic acid. Fluorescent labeling is a widely-used approach in the study of intracellular processes. This method is becoming increasingly popular for studying small bioactive molecules of natural origin; it allows us to estimate the vital intracellular changes which occur under their influence. We propose a new approach for visualization of the intracellular distribution of triterpene acids, based on fluorescent labeling by fluoresceine isothiocyanate. As a model compound we took the most widely-used and best-studied acid in the ursane series – ursolic acid, as this enabled us to compare the results obtained during our research with the available data, in order to evaluate the validity of the proposed method. Experimental tracing of the dynamics of penetration and distribution of the labeled ursolic acid has shown that when the acid enters the cell, it initially localizes on the inner membranes where the predicted target Akt1/protein kinase B – a protein that inhibits apoptosis – is located. [ABSTRACT FROM AUTHOR]

Here we explore the effect of the nature of organic ligands in rhenium cluster complexes [Re6Q8L6]4− (where Q=S or Se, and L=benzotriazole, 1,2,3‐triazole or 1,2,4‐triazole) on the biological properties of the complexes, in particular on the cellular toxicity, cellular internalization and localization. Specifically, the study describes the synthesis and detailed characterization of the structure, luminescence and electrochemical properties of the four new Re6 clusters with 1,2,3‐ and 1,2,4‐triazoles. Biological assays of these complexes are also discussed in addition to those with benzotriazole using cervical cancer (HeLa) and immortalized human fibroblasts (CRL‐4025) as model cell lines. Our study demonstrates that the presence of hydrophobic and π‐bonding rich units such as the benzene ring in benzotriazole significantly enhances cellular internalization of rhenium clusters. These ligands facilitate binding of the clusters to DNA, which results in increased cytotoxicity of the complexes. [ABSTRACT FROM AUTHOR]

Specific molecular recognition of γ‐cyclodextrin (γ‐CD) by the cationic hexanuclear niobium [Nb6Cl12(H2O)6]2+ cluster complex in aqueous solutions results in a 1:1 supramolecular assembly {[Nb6Cl12(H2O)6]@γ‐CD}2+. NMR spectroscopy, isothermal titration calorimetry (ITC), and ESI‐MS were used to study the interaction between the inorganic cluster and the organic macrocycle. Such molecular association affects the biological activity of [Nb6Cl12(H2O)6]2+, decreasing its cytotoxicity despite enhanced cellular uptake. The 1:1 stoichiometry is maintained in solution over a large window of the reagents' ratio, but crystallization by slow evaporation produces a 1:2 host–guest complex [Nb6Cl12(H2O)6@(γ‐CD)2]Cl2⋅20 H2O featuring the cluster encapsulated between two molecules of γ‐CD. The 1:2 complex was characterized by XRD, elemental analysis, IR spectroscopy, and thermogravimetric analysis (TGA). Quantum chemical calculations were performed to model host–guest interaction. [ABSTRACT FROM AUTHOR]

New highly fluorinated aromatic polyimide based on 4-chloro-2,5,6-trifluoro-1,3-phenylenediamine and 2,2-bis(3′,4′-dicarboxyphenyl)hexafluoropropane dianhydride was prepared by the two methods condensation in a solution followed by a high-temperature solid-state chain extension and one-pot high temperature polycondensation in a benzoic acid melt. The polyimide is soluble in polar amide- and ketone-type solvents, has good thermal stability and a high glass transition temperature. The polyimide films exhibit a low cut-off wavelength and excellent transparency in the UV-vis-near IR range. Low molecular weight prepolymer, formed by the solution condensation, was used to obtain the guest-host electro-optic polymer having a high glass transition temperature. The prepolymer layer doped with azochromophore DR1 (25 wt%) was subjected to a combined poling+curing procedure upon a two-stepped heating in a corona discharge field. Nonlinear optical coefficient d 33 of the prepared chromophore-doped highly halogenated polyimide film measured by the Maker fringes method is 70 pm/V at the fundamental wavelength of 1064 nm and remains stable up to 85 °C. [ABSTRACT FROM AUTHOR]

• Reactions of ursane- and lupane- type alkyns with azole-type azides. • Triterpenoid hybrids with 1,2,3-triazoles and 1,3,4- or 1,2,5- oxadiazoles. • MTT test on MCF-7, U-87, A549, HepG2 cells. • The in silico evaluation of conjugates affinity to MDM2. Ursane and lupane type (1-((5-aryl-1,3,4-oxadiazol-2-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl and (1-((4-methyl-2-oxido-1,2,5-oxadiazol-3-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl hybrids were prepared by 1,3-cycloaddition reactions of azole-derived azides with alkyne esters connected to positions C-3 and C-28 of triterpene core and tested for cytotoxicity. Hybrid compounds of 1,3,4-oxadiazoles attached at positions 3- and 28- of triterpenoid frame via triazole spacer and combinations of 1,2,5-oxadiazole or 1,3,4-oxadiazole, tethered with succinate linker and 1,2,3-triazole at the position 3- of the ursane backbone, were inactive in relation to all the cancer cells tested. Eventually, combinations of furoxan fragment and 1,2,3-triazole linked to C-28 position of triterpene backbone demonstrated marked cytotoxic activity towards MCF-7 and HepG2 cells. The most active ester of ursolic acid with (1-((4-methyl-2-oxido-1,2,5-oxadiazol-3-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl substituent and 3-O-acetyl group was superior in activity and selectivity over doxorubicin and ursolic acid on MCF-7 cells. The length of the carbon spacer group may be of crucial importance for cytotoxicity. The introduction of the additional ester linker between the C-28 of triterpenoid and triazole or changing triazole spacer between furoxan moiety and triterpenoid core resulted in activity decrease against all the tested cells. In accordance with molecular modeling results, the activity of new derivatives may be explained in terms of the interaction of the new hybrid molecules and Mdm2 binding sites. [ABSTRACT FROM AUTHOR]

• Synthesis of hydrazides tethered by different linkers from ursane core. • Synthesis of ursane hybrids with 1,3,4-oxadiazoles and 1,2,4-triazoles. • In-vitro antioxidant studies by DPPH method. • In-vitro cytotoxicity tests on MCF7, U-87, A549, HepG2 cells. • In silico evaluation of conjugates affinity to MDM2 molecular target. A small library of 2-mercapto-1,3,4-oxadiazoles, 2-amino-1,3,4-oxadiazoles, and 3-mercapto-1,2,4-triazoles attached to the urs-12-ene- and 28-nor-urs-12-ene skeleton has been obtained. Ursolic acid derived hydrazides have been identified as useful starting materials for the developed synthesis. Ursolic acid hydrazide provided access to oxadiazoles attached directly to C-17 of the ursane core, but synthesis of structurally related 3-mercapto-1,2,4-triazoles was not possible in this way due to steric hindrance of the triterpenoid. Ester- and amide-linked hydrazides arising from ethoxycarbonylmethyl ursolate and ursolic acid amide with methyl β-alaninate served as key starting materials for the remotely connected mercapto-and amino-azoles. Antioxidant activities (DPPH method) of the newly obtained compounds are mediocre. However, excellent cytotoxicity and selectivity against MCF7 cell line were found for 28-nor-urs-12-ene 2-amino-1,3,4-oxadiazole conjugate. Also some other library members exceeded the cytotoxicity values of natural ursolic acid. The novel hybrid heterocycles with amino and mercapto substituents possess a great potential for further derivatization and are prospective scaffolds for the synthesis of triterpenoid analogs with chemopreventive and cytotoxic properties. [ABSTRACT FROM AUTHOR]