Electronic and Magnetic Interactions in 6-Oxoverdazyl Diradicals: Connection through N(1) vs C(3) Revisited.

Four isomeric di-6-oxoverdazyl diradicals connected at their N(1) or C(3) positions with either 1,3- or 1,4-phenylene linkers were obtained and characterized by spectroscopic, electrochemical, magnetic, and structural methods. These results were compared to those for the corresponding 6-oxoverdazyl monoradicals. UV-vis spectroscopy demonstrated that only the N(1)-connected para-through-benzene diradical has a distinct spectrum with significant bathochromic and hypsochromic shifts relative to the remaining species. Electrochemical analysis revealed two one-electron reduction processes in all diradiacals, while only the N(1)-connected para-through-benzene diradical exhibits two one-electron oxidation processes separated by 0.10 V. Variable temperature EPR measurements in polystyrene solid solutions gave negative mean exchange interaction energies J for all diradicals, suggesting the dominance of conformers with significant intramolecular antiferromagnetic interactions for the meta-through-benzene isomers. DFT calculations predict a small preference for the triplet state with the ΔES-T of about 0.25 kcal mol-1 for both meta-through-benzene connected diradicals.

[closo-B10H8-10-PhI-1-COOH]- Anion: An Intermediate for Functional Anionic Carboxylate Ligands.

A potentially general intermediate, [closo-B10H8-10-PhI-1-COOH]-, for a class of functional anionic carboxylic acids, [closo-B10H8-10-X-1-COOH]2-, was obtained in four steps and 26% overall yield from [closo-B10H10]2-. It was converted to the pyridinium derivative (X = C5H5N+) and subsequently to coordination complexes with (phen)2Cu2+ and (phen)2Zn2+ ions. Both the acid and Zn(II) complex exhibit a cage-to-pyridine charge-transfer band. The availability of such acids opens access to functional metal-ion complexes with compensated charges.

[closo-B10H8-1-CN-10-Azinium]- Anions: Photoactive Heteroditopic Ligands for Metal Complexes.

A new class of rigid, photoactive heteroditopic anionic ligands based on the 1,10-disubstituted [closo-B10H10]2- anion was designed and six of these compounds were obtained from [closo-B10H10]2- in three steps with yields in the range of 25-30%. The design includes two apical substituents, a metal coordinating cyano group and an azinium (4-cyanopyridinium, 4,4'-bipyridinium, pyrazinium, pyrimidinium, and pyridazinium), which provides a secondary binding site. The azinium substituent is involved in an efficient intramolecular charge transfer process and compensates one of the two delocalized negative charges of the boron cluster. The compounds exhibit intramolecular CT bands with maxima in the range of 340-410 nm (MeCN) and two are weakly fluorescent with significant Stokes shifts. A highly colored bis-zwitterionic byproduct with two clusters, [closo-1-CN-B10H8-10-(pyrazinium-1,4-diyl)-10'-B10H8-1'-CN-closo]2-, was also obtained in a low yield. The ligands were structurally characterized (XRD) and their geometrical and photophysical properties were compared to those of the analogues lacking the CN group and the parent pyridinium derivative. A comparative analysis of experimental data was augmented with DFT and TD-DFT results. Two of the ligands (with the 4,4'-bipyridinium and pyrazinium) were converted to (η5-Cp)(dppe)Fe complexes and one of them was used to obtain a heterodinuclear complex with Cu(pdc)(H2O)3 to demonstrate the ditopic function of the ligand. All three iron complexes were characterized by the XRD method.

Paramagnetic Liquid Crystals With Close π-π Packing: The Effect of Blatter Radical Planarization on Behavior of Bent-Core Mesogens.

A new, 19 π-delocalized electrons planar Blatter radical building block was developed and used to obtain paramagnetic bent-core liquid crystals. The mesogens were investigated by optical, thermal, powder XRD and DFT methods in the pure form and as binary mixtures. Comparison of their properties with those of the classical Blatter radical analogues revealed that planarization of the central angular element results in a significantly higher stability of the mesophases and increased molecular organization suitable for the formation of ordered banana and columnar mesophases with tighter π-π interactions. These results indicate access to a new, potentially rich class of functional paramagnetic soft materials.

Photophysical Behavior of Self-Organizing Derivatives of 10- and 12-Vertex p-Carboranes, and their Bicyclo[2.2.2]octane and Benzene Analogues.

Four series of isostructural derivatives of 3-ring liquid crystalline derivatives containing p-carboranes (12-vertex A, and 10-vertex B), bicyclo[2.2.2]octane (C), or benzene (D) as the variable structural element were investigated for their mesogenic behavior and electronic interactions. Comparative studies demonstrated that the effectiveness of elements A-D in stabilization of the mesophase typically increases in the order: B

C(1)-Phenethyl Derivatives of [closo-1-CB11 H12 ]- and [closo-1-CB9 H10 ]- Anions: Difunctional Building Blocks for Molecular Materials.

C(1)-vinylation of [closo-1-CB9 H10 ]- (A) and [closo-1-CB11 H12 ]- (B) with 4-benzyloxystyryl iodide followed by hydrogenation of the double bond and reductive deprotection of the phenol functionality led to C(1)-(4-hydroxyphenethyl) derivatives. The phenol functionality was protected as the acetate. The esters were then treated with PhI(OAc)2 and the resulting isomers were separated kinetically (for derivatives of anion A) or by chromatography (for derivatives of anion B) giving the difunctionalized building blocks in overall yields of 9 % and 50 %, respectively. A similar series of reactions was performed starting with anions A and B and 4-methoxystyryl bromide and iodide. Significant differences in the reactivity of derivatives of the two carborane anions were rationalized with DFT computational results. Application of the difunctionalized carboranes as building blocks was demonstrated through preparation of two ionic liquid crystals. The extensive synthetic work is accompanied by single crystal XRD analysis of six derivatives.

A New Hybrid δ-Lactone Induces Apoptosis and Potentiates Anticancer Activity of Taxol in HL-60 Human Leukemia Cells.

In the search for new drug candidates, researchers turn to natural substances isolated from plants which may be either used directly or may serve as a source for chemical modifications. An interesting strategy in the design of novel anticancer agents is based on the conjugation of two or more biologically active structural motifs into one hybrid compound. In this study, we investigated the anticancer potential of 4-benzyl-5,7-dimethoxy-4-methyl-3-methylidene-3,4-dihydro-2H-chroman-2-one (DL-247), a new hybrid molecule combining a chroman-2-one skeleton with an exo-methylidene bond conjugated with a carbonyl group, in human myeloid leukemia HL-60 cell line. The cytotoxicity of the new compound was tested using MTT assay. The effect of DL-247 on cell proliferation and apoptosis induction were studied by flow cytometry, fluorometric assay and ELISA analysis. DL-247 displayed high cytotoxic activity (IC50 = 1.15 µM, after 24 h incubation), significantly inhibited cell proliferation and induced apoptosis by both, the intrinsic and extrinsic pathways. A combination of DL-247 with taxol exhibited a strong synergistic effect on DNA damage generation, apoptosis induction and inhibition of cell growth.

A novel de novo mutation p.Ala428Asp in KRT5 gene as a cause of localized epidermolysis bullosa simplex.

Epidermolysis bullosa is a group of inherited blistering skin diseases resulting in most cases from missense mutations in KRT5 and KRT14 genes encoding the basal epidermal keratins 5 and 14. Here, we present a patient diagnosed with a localized subtype of epidermolysis bullosa simplex caused by a heterozygous mutation p.Ala428Asp in the KRT5 gene, that has not been previously identified. Moreover, a bioinformatic analysis of the novel mutation was performed, showing changes in the interaction network between the proteins. Identification of novel mutations and genotype-phenotype correlations allow to better understanding of underlying pathophysiologic bases and is important for genetic counselling, patients' management, and disease course prediction.

Dominant ELOVL1 mutation causes neurological disorder with ichthyotic keratoderma, spasticity, hypomyelination and dysmorphic features.

BACKGROUND: Ichthyosis and neurological involvement occur in relatively few known Mendelian disorders caused by mutations in genes relevant both for epidermis and neural function. OBJECTIVES: To identify the cause of a similar phenotype of ichthyotic keratoderma, spasticity, mild hypomyelination (on MRI) and dysmorphic features (IKSHD) observed in two unrelated paediatric probands without family history of disease. METHODS: Whole exome sequencing was performed in both patients. The functional effect of prioritised variant in ELOVL1 (very-long-chain fatty acids (VLCFAs) elongase) was analysed by VLCFA profiling by gas chromatography-mass spectrometry in stably transfected HEK2932 cells and in cultured patient's fibroblasts. RESULTS: Probands shared novel heterozygous ELOVL1 p.Ser165Phe mutation (de novo in one family, while in the other family, father could not be tested). In transfected cells p.Ser165Phe: (1) reduced levels of FAs C24:0-C28:0 and C26:1 with the most pronounced effect for C26:0 (P=7.8×10-6 vs HEK293 cells with wild type (wt) construct, no difference vs naïve HEK293) and (2) increased levels of C20:0 and C22:0 (P=6.3×10-7, P=1.2×10-5, for C20:0 and C22:0, respectively, comparison vs HEK293 cells with wt construct; P=2.2×10-7, P=1.9×10-4, respectively, comparison vs naïve HEK293). In skin fibroblasts, there was decrease of C26:1 (P=0.014), C28:0 (P=0.001) and increase of C20:0 (P=0.033) in the patient versus controls. There was a strong correlation (r=0.92, P=0.008) between the FAs profile of patient's fibroblasts and that of p.Ser165Phe transfected HEK293 cells. Serum levels of C20:0-C26:0 FAs were normal, but the C24:0/C22:0 ratio was decreased. CONCLUSION: The ELOVL1 p.Ser165Phe mutation is a likely cause of IKSHD.

Towards A New Approach for the Description of Cyclo⁻2,4-Dihydroxybenzoate, A Substance Which Effectively Mimics Zearalenone in Imprinted Polymers Designed for Analyzing Selected Mycotoxins in Urine.

A method of purifying cyclododecyl 2,4-dihydroxybenzoate as a potential replacement template molecule for preparation of molecularly-imprinted polymers for isolation of zearalenone in urine was developed. Full physicochemical characteristics of cyclododecyl 2,4-dihydroxybenzoate for the first time included crystallographic analysis and molecular modelling, which made possible the determination of the similarity between the cyclododecyl 2,4-dihydroxybenzoate and zearalenone molecules. The obtained molecularly-imprinted polymers show very high in vitro selectivity towards zearalenone due to specific interactions (e.g., hydrogen bonding, molecular recognition interaction). The achieved extraction recovery exceeds 94% at the tested concentration levels (20⁻500 ng·mL-1) with a relative standard deviation below 2%. Immunosorbents were found to have lower recoveries (below 92.5%) and RSD value between 2 and 4% for higher concentrations of the studied substance (400 ng·mL-1).

Regioselective Functionalization of the [ closo-1-CB9H10]- Anion through Iodonium Zwitterions.

Reactions of [ closo-1-CB9H9-1-R]- (2, R = H, COOH, C5H11) with PhI(OAc)2 lead to mixtures of regioisomers [ closo-1-CB9H8-1-R-6-IPh] (5[6]) and [ closo-1-CB9H8-1-R-10-IPh] (5[10]) in ratios of ∼3:1 to 1:1, of which the former isomer undergoes selective reactions with nucleophiles (MeCN, pyridine, MeC(═NH)NH2, CN-). The products and the unreacted 10-isomers 5[10] are separated achieving kinetic resolution of the isomeric iodonium zwitterions. Pure 5[10] is reacted with nucleophiles (pyridine, 4-C7H15OPyridine, Me2NCHS, PhCO2-, CN-, N3-, I-, MeC(═NH)NH2, and MeCN), giving substitution products. The mechanism of the substitution is investigated with density functional theory (DFT) methods. Some of the nucleophilic substitution products are transformed further, expanding the scope of available functional groups for the [ closo-1-CB9H10]- anion. Four derivatives are characterized with single-crystal XRD methods: [ closo-1-CB9H9-10-N2] (4[10]a), [ closo-1-CB9H9-6-NC5H5] (9[6]a), [ closo-1-CB9H9-10-NC5H5] (9[10]a), and [ closo-1-CB9H9-10-NHC(NH2)Me] (10[10]a). Spectroscopic data for selected derivatives are interpreted in terms of transmission of electronic effects through the { closo-1-CB9} cluster (NMR) and interaction with substituents (IR, UV). The latter results are compared to those of TD-DFT computational methods.

Introduction of steered molecular dynamics into UNRES coarse-grained simulations package.

In this article, an implementation of steered molecular dynamics (SMD) in coarse-grain UNited RESidue (UNRES) simulations package is presented. Two variants of SMD have been implemented: with a constant force and a constant velocity. The huge advantage of SMD implementation in the UNRES force field is that it allows to pull with the speed significantly lower than the accessible pulling speed in simulations with all-atom representation of a system, with respect to a reasonable computational time. Therefore, obtaining pulling speed closer to those which appear in the atomic force spectroscopy is possible. The newly implemented method has been tested for behavior in a microcanonical run to verify the influence of introduction of artificial constrains on keeping total energy of the system. Moreover, as time dependent artificial force was introduced, the thermostat behavior was tested. The new method was also tested via unfolding of the Fn3 domain of human contactin 1 protein and the I27 titin domain. Obtained results were compared with Gø-like force field, all-atom force field, and experimental results. © 2017 Wiley Periodicals, Inc.

Novel KRT14 mutation causing epidermolysis bullosa simplex with variable phenotype.

About 75% of cases of epidermolysis bullosa simplex result from mutations in KRT5 and KRT14 genes. Here, we report a family with a novel heterozygous missense mutation p.Leu418Gln in the KRT14 gene causing EBS of phenotype varying from EBS-loc to EBS-gen intermed. To the best of our knowledge, the family reported by us is the largest one in which two different phenotypes can be distinguished. The molecular dynamics simulations show that p.Leu418Gln mutation results in clear disruption of intermolecular π-stacking between KRT14:Tyr415 and KRT5:Tyr470, which in turn may affect putative phosphorylation site at KRT14:Thr414. This study further supports the importance of the EIATYR/KLLEGE motif in maintaining structural stability of KRT14:KRT5 heterodimer and indicates that physical properties of introduced amino acid can modulate the disease severity. The results obtained indicate further need of genotype-phenotype studies in EBS. In conclusion, genotype-based prognosis should be given to patients with caution.

Lithium salt of a pro-mesogenic [closo-CB11H12]- derivative: anisotropic Li+ ion transport in liquid crystalline electrolytes.

Li+ ion conduction in two aligned liquid crystalline electrolytes consisting of 10 mol% Li+ salt of a pro-mesogenic anion derived from [closo-1-CB11H12]- in non-ionic hosts was investigated. Using electrochemical impedance spectroscopy (EIS), the ionic conductivity in the parallel (σ‖) and perpendicular (σ⊥) directions of the electrolyte samples was determined using two types of cells: an interdigitated gold electrode and a nylon 6-coated ITO cell. The ratio of ionic conductivities σ⊥/σ‖ in the electrolyte with a nona(ethylene oxide) spacer was about 3 in the entire SmA phase, while in the shorter homologue, the ratio monotonically increases from about 0.4 to 2.9. The liquid crystalline behavior of the hosts and the electrolytes was investigated by optical, thermal, and powder XRD methods.

Synthesis and biological evaluation of α-methylidene-δ-lactones with 3,4-dihydrocoumarin skeleton.

A series of new 3-methylidenechroman-2-ones bearing various aromatic moieties and various substituents at position 4 were synthesized in a three step reaction sequence. Friedel-Crafts alkylation of phenols or naphthols using ethyl 3-methoxy-2-diethoxyphosphorylacrylate in the presence of trifluoromethanesulphonic acid gave 3-diethoxyphosphorylchromen-2-ones. These compounds were employed as Michael acceptors in the reaction with Grignard reagents to give adducts which were finally used as Horner-Wadsworth-Emmons reagents for the olefination of formaldehyde. All obtained 3-methylidenechroman-2-ones were tested against two human leukemia cell lines NALM-6 and HL-60 as well as MCF-7 breast cancer and HT-29 colon cancer adenocarcinomas. Several obtained methylidenechromanones displayed high cytotoxic activity with IC(50) values below 1 µM, mainly against leukemia and MCF-7 cell lines. Investigation of structure-activity relationships revealed that the presence of additional, ortho-fused benzene ring and n-butyl or i-propyl group in position 4 enhances the activity. Selected methylidenechromanones were also tested on normal human umbilical vein endothelial cells (HUVEC) and chromanone 14o was found to be eightfold more toxic against MCF-7 than normal cells. Furthermore, antimicrobial assays revealed that chromanone 14n is highly active and bactericidal at concentration equal to MIC or 2MIC against nosocomial and community-associated staphylococci (MRSA) which are resistant to most or all available therapeutic classes of antimicrobial drugs.

Polar derivatives of [closo-1-CB9H10]- and [closo-1-CB11H12]- anions as high Δε additives to a nematic host: a comparison of the CH2CH2 and COO linking groups.

A series of liquid crystalline pyridinium and sulfonium derivatives of the [closo-1-CB9H10]- and [closo-1-CB11H12]- anions containing the CH2CH2 linking group was prepared and their molecular and crystal structures were determined by single crystal XRD methods. Thermal and dielectric properties of the series were evaluated in a weakly polar nematic host. The highest extrapolated dielectric anisotropy, Δε, was observed for pyridinium zwitterions (up to 56.0). The dielectric data were analyzed with the Maier-Meier formalism augmented with density functional theory calculations, and the results were compared to those obtained for the analogous ester derivatives (COO linking group). The effect of the linking group on thermal and electrooptical properties is discussed.

Conformational Sampling of a Biomolecular Rugged Energy Landscape.

The protein structure refinement using conformational sampling is important in hitherto protein studies. In this paper, we examined the protein structure refinement by means of potential energy minimization using immune computing as a method of sampling conformations. The method was tested on the x-ray structure and 30 decoys of the mutant of [Leu]Enkephalin, a paradigmatic example of the biomolecular multiple-minima problem. In order to score the refined conformations, we used a standard potential energy function with the OPLSAA force field. The effectiveness of the search was assessed using a variety of methods. The robustness of sampling was checked by the energy yield function which measures quantitatively the number of the peptide decoys residing in an energetic funnel. Furthermore, the potential energy-dependent Pareto fronts were calculated to elucidate dissimilarities between peptide conformations and the native state as observed by x-ray crystallography. Our results showed that the probed potential energy landscape of [Leu]Enkephalin is self-similar on different metric scales and that the local potential energy minima of the peptide decoys are metastable, thus they can be refined to conformations whose potential energy is decreased by approximately 250 kJ/mol.

Synthesis of 4,4-Disubstituted 3-Methylidenechroman-2-ones as Potent Anticancer Agents.

The synthesis of a new library of 4,4-disubstituted 3-methylidene-3,4-dihydro-2H-chroman-2-ones applying Horner-Wadsworth-Emmons methodology for the construction of an exo-methylidene moiety is reported. Corresponding 3-diethoxyphosphorylchroman-2-ones were synthesized in a three-step reaction sequence consisting of O-methylation of ethyl 2-diethoxyphosphoryl-3-oxoalkanoates, followed by reaction of the obtained 2-diethoxyphosphoryl-3-methoxy-2-alkenoates with phenols or 1-naphthol. The resulting 3-diethoxyphosphorylochromen-2-ones proved to be effective Michael acceptors in reactions with various Grignard reagents. Preliminary biological evaluations showed that many of the synthesized 3-methylidenechroman-2-ones possess very high cytotoxic activity against NALM-6 and HL-60 cancer cell lines (IC50 <1.0 µm) as well as high activity against the MCF-7 cancer cell line (IC50 <10 µm). Furthermore, two of the highly active 3-methylidenechroman-2-ones with geminal methyl and ethyl substituents at position 4 showed promising therapeutic indexes of 10 and 13 in tests against human umbilical vein endothelial cells (HUVECs).

Design, synthesis and cytotoxic evaluation of 4-methylidenepyrazolidin-3-ones.

Three series of new 4-methylidenepyrazolidin-3-ones with various substitution patterns were synthesized and tested for the cytotoxic activity against two human leukemia cell lines NALM-6 and HL-60 as well as MCF-7 breast cancer cell line. Several obtained methylidenepyrazolidinones exhibited high cytotoxic activity with IC50 values below 10 µM, mainly against HL-60 leukemia cell line and two of them, 18d,e, displayed IC50 ≤ 5 µM, against all tested cell lines. Structure-activity relationship studies revealed that the presence of phenyl substituents on both ring nitrogen atoms and vinyl or phenyl substituents in position 5 are crucial for high activity. Selected methylidenepyrazolidinones were also tested on normal human umbilical vein endothelial cells (HUVEC) and pyrazolidinone 18a was found to be 5-fold more toxic against HL-60 than normal cells.

Anticancer Activity of New Synthetic α-Methylene-δ-Lactones on Two Breast Cancer Cell Lines.

Natural products are important leads in drug discovery. The search for effective plant-derived anticancer agents or their synthetic analogues has continued to be of interest to biologists and chemists for a long time. In this report, cytotoxicity and anticancer activity of new synthetic α-methylene-δ-lactones was tested against two breast cancer cell lines, invasive, hormone-independent MDA-MB-231 and hormone-dependent MCF-7. Cytotoxicity was examined using MTT assay. The ability to induce apoptosis and changes in mitochondrial membrane potential was studied by flow cytometry. The expression levels of pro- and anti-apoptotic genes were determined by quantitative real-time PCR. Cancer cell migration and invasion were assessed by wound healing and Matrigel assays. Additionally, secretion of proteins associated with invasiveness, metalloproteinase-9 (MMP-9) and urokinase plasminogen activator (uPA) was investigated using commercial ELISA kits and MMP-9 activity by gelatin zymography. A natural sesquiterpene lactone, parthenolide, was used as a positive control. Screening results showed all four analogues to be highly cytotoxic. The most potent compound of the series, 1-isopropyl-2-methylene-1,2-dihydrobenzochromen-3-one, designated DL-3, which reduced the number of viable MDA-MB-231 and MCF-7 cells with the IC50 values of 5.3 µM and 3.54 µM, respectively, was selected for further research. DL-3 activated the intrinsic pathway of apoptosis, associated with the loss of mitochondrial membrane potential and changes in Bax/Bcl-2 ratio. DL-3 also inhibited the movement of both types of breast cancer cells. Suppression of cell migration and invasion was the result of the decreased secretion of enzymes responsible for the degradation of the extracellular matrix, MMP-9 and uPA. These findings show that the synthetic α-methylene-δ-lactone, DL-3, displays potential to be further explored in the development of new anticancer agents.