C-Terminal-Modified Oligourea Foldamers as a Result of Terminal Methyl Ester Reactions under Alkaline Conditions.

Hybrids of short oligourea foldamers with residues of α, ß and γ-amino acids esters at the C-terminus were obtained and subjected to a reaction with LiOH. There are two possible transformations under such conditions, one of which is ester hydrolysis and the formation of a carboxylic group and the other is the cyclization reaction after abstraction of a proton from urea by a base. We have investigated this reaction with difference C-terminal residue structures, as well as under different work-up conditions, especially for oligourea hybrids with α-amino acid esters. For these compounds, an oligourea-hydantoin combination is the product of cyclization. The stability of the hydantoin ring under alkaline conditions has been alsotested. Furthermore, this work reports data related to the structure of C-terminal-modified oligourea foldamers in solution and, for one compound, in the solid state. Helical folding is preserved both for cyclized and linear modifications, with oligourea-acid hybrids appearing to be more conformationally stable, as they are stabilized by an additional intramolecular hydrogen bond in comparison to cyclic derivatives.

Dimeric Benzodiazepines as Peptide Mimetics to Overcome p53-Dependent Drug Resistance of Tumors.

Benzodiazepines that consist of one α- and one ß-amino acid residues linked together in a seven-membered heterocyclic ring could be treated as small, rigid, cyclic dipeptides capable of exhibiting a wide range of biological activities. During our research on novel analogues of anthramycin, a tricyclic antibiotic benzodiazepine, we developed the synthesis of two benzodiazepine dimers, obtained through the cyclization of appropriate linear tripeptides. The synthesized compounds were tested on a panel of seven cancer and normal cell lines. The developed molecules exhibited promising cytotoxic activity against the lung cancer cell lines A549 and NCI-H1299 and the epidermoid carcinoma cell line A-431. Moreover, they showed significant selectivity compared to the reference cell lines (BJ-human normal skin fibroblasts and MRC-5-human normal lung cell line). When tested on two isogenic cell lines, HCT116 and HCT116p53-/- (colon cancer), contrary to cisplatin being used as a positive control, the obtained compounds showed a cytotoxic effect independent of the p53 protein status. For the above reasons, the obtained compounds can be considered a new group of promising anticancer agents, useful in the fight against p53-dependent drug resistance in cancers. They can also be treated as convenient, leading structures suitable for further optimization and searching for more active and selective molecules.

Structural Consequences of N-Methylation of N-Terminus in Oligourea Foldamers.

Oligourea foldamers fold into 2.5-helices. Most of the known modifications of the backbone, such as NH or CO group substitutions or incorporations of non-canonical residues, do not change the conformational properties of the resulting oligourea oligomers. In this study, we examined the structural influence of the methyl group, substituting NH protons in one or two residues at the N-terminus of the foldamer. Such N-methylated oligoureas appear to be helically folded with helix parameters determined from the crystal structure being almost the same as for non-methylated oligomers. Solution studies (CD, NMR) reveal that the backbone with N-Me urea groups is more flexible, but the urea group is still predominantly in trans,trans conformation. N-Methylation does not change the structural properties of oligourea foldamers, and thus may be a useful modification for modulating the strength of hydrogen bonds and intermolecular interactions.

Tripodal, Squaramide-Based Ion Pair Receptor for Effective Extraction of Sulfate Salt.

Combining three features-the high affinity of squaramides toward anions, cooperation in ion pair binding and preorganization of the binding domains in the tripodal platform-led to the effective receptor 2. The lack of at least one of these key elements in the structures of reference receptors 3 and 4 caused a lower affinity towards ion pairs. Receptor 2 was found to form an intramolecular network in wet chloroform, which changed into inorganic-organic associates after contact with ions and allowed salts to be extracted from an aqueous to an organic phase. The disparity in the binding mode of 2 with sulfates and with other monovalent anions led to the selective extraction of extremely hydrated sulfate anions in the presence of more lipophilic salts, thus overcoming the Hofmeister series.

Design and in Vitro Characterization of Tricyclic Benzodiazepine Derivatives as Potent and Selective Antileukemic Agents.

Currently available chemotherapeutic treatments for blood cancers (leukemia) usually have strong side effects. More selective, efficient, and less toxic anticancer agents are needed. We synthesized seven, new, optically pure (12aS)-1,3,4,12a-tetrahydropyrazino[2,1-c][1,4],12(2H,11H)-dione derivatives and examined their cytotoxicity towards eight cancer cell lines, including urinary bladder (TCC-SUP, UM-UC-3, KU-19-9), colon (LoVo), and breast (MCF-7, MDA-MB-231) cancer representatives, as well as two leukemic cell lines (MV-4-11, CCRF-CEM) and normal murine fibroblasts (Balb/3T3) as reference cell line. Three of the seven newly-obtained compounds ((12aS)-8-bromo-2-(3-phenylbenzoyl)-1,3,4,12a-tetrahydropyrazino[2,1-c][1,4],12(2H,11H)-dione, (12aS)-8,9-dimethoxy-2-(4-phenylbenzoyl)-1,3,4,12a-tetrahydropyrazino[2,1-c][1,4],12(2H,11H)-dione and (12aS)-8-nitro-2-(4-phenylbenzoyl)-1,3,4,12a-tetrahydropyrazino[2,1-c][1,4],12(2H,11H)-dione, showed enhanced activity and selectivity toward the leukemic MV-4-11 cell lines when compared to our previously reported compounds, with IC50 values in the range of 2.9-5.6 µM. Additionally, (12aS)-9-nitro-2-(4-phenylbenzoyl)-1,3,4,12a-tetrahydropyrazino[2,1-c][1,4],12(2H,11H)-dione exhibited a strong cytotoxic effect against the leukemic CCRF-CEM (IC50 =6.1 µM) and MV-4-11 (IC50 =11.0 µM) cell lines, a moderate cytotoxic effect toward other tumor lines (IC50 =31.8-55.0 µM) and very weak cytotoxic effect toward the Balb/3T3 reference cell lines. Selected compounds were further evaluated for their potential to induce apoptotic cell death in MV-4-11 cells by measuring caspase-3 activity. We also established the crystal structure of three products and investigated the effect of 22 derivatives of 1,3,4,12a-tetrahydropyrazino[2,1-c][1,4],12(2H,11H)-dione on the activity of the cancer-associated enzyme autotaxin. All compounds proved to be weak inhibitors of autotaxin, although some (R) and (S) enantiomers had Ki values of 10-19 µM. The obtained results showed that the tested compounds exhibited a selective antileukemic effect, which appeared not to be related directly to autotaxin. Molecular targets responsible for this effect remain to be identified. The newly obtained compounds can be used in the search for new, selective anticancer therapies.

Cooperative Transport and Selective Extraction of Sulfates by a Squaramide-Based Ion Pair Receptor: A Case of Adaptable Selectivity.

The use of a squaramide-based ion pair receptor offers a solution to the very challenging problem of extraction and transport of extremely hydrated sulfate salt. Herein we demonstrate for the first time that a neutral receptor is able not only to selectively extract but also to transport sulfates in the form of an alkali metal salt across membranes and to do so in a cooperative manner while overcoming the Hofmeister bias. This was made possible by an enhancement in anion binding promoted by cation assistance and by diversifying the stoichiometry of receptor complexes with sulfates and other ions. The existence of a peculiar 4:1 complex of receptor 2 with sulfates in solution was confirmed by UV-vis and 1H NMR titration experiments, DOSY and DLS measurements, and supported by solid-state X-ray measurements. By varying the separation technique and experimental conditions, it was possible to switch the depletion of the aqueous layer into extremely hydrophilic or less lipophilic salts, thus obtaining the desired selectivity.

Synthesis, crystal structure and biological activity of novel analogues of tricyclic drugs.

A series of fourteen novel, eight-membered lactam- and dilactam-based analogues of tricyclic drugs were obtained in a simple one-pot procedure. Crystal structures of two compounds were determined by single-crystal X-ray diffraction analysis and their selected structural features were discussed and compared with those of imipramine and dibenzepine. Affinity of developed molecules for histamine receptor H1, serotonin receptors 5-HT1A, 5-HT2A, 5-HT6, 5-HT7, serotonin transporter (SERT) and dopamine receptor D2 was determined. The commercial drug dibenzepine was also checked on these molecular targets, as its mechanism of action is largely unknown. Two derivatives of 11,12-dihydrodibenzo[b,f]azocin-6(5H)-one (7,8) and two of dibenzo[b,f]azocin-6(5H)-one (9,10) were found to be active toward the H1 receptor in sub-micromolar concentrations.

17O and 1H NMR spectral parameters in isolated water molecules.

Small amounts of water enriched in oxygen-17 were studied by 17O and 1H NMR in binary gaseous mixtures with Xe, Kr, CHF3 and CH3F and CO2. The distinct linear dependences of 17O and 1H chemical shifts and 1J(17O,1H) spin-spin coupling on the density of every gas solvent were measured. After the extrapolation of experimental results to zero density the relevant parameters in the isolated H217O molecule were determined. The same procedure was applied for H216O when its proton chemical shift was analyzed but the secondary isotope effect in the 1H shielding of H217O and H216O molecules was too small for detection. As shown, all the intermolecular effects in nuclear magnetic shielding are negative and these effects are more significant for 17O nuclei than for protons. It is consistent with the appropriate gas-to-liquid shifts of water which also indicate deshielding effects for both the investigated nuclei. On the other hand, the 1J0(17O,1H) coupling constant in H217O, which is completely free from intermolecular interactions, considerably differs from the 1J(17O,1H) experimental values obtained for water in liquid solutions. The present experimental data of the isolated H217O molecule are compared with selected results of shielding and spin-spin coupling calculations available from the literature and with the recent experimental data for a water molecule encapsulated in the C60 fullerene. Additionally, on the basis of actual results the magnetic dipole moment of the 17O nucleus is revalued for greater accuracy.

Anti-inflammatory Potential of Flavonoids from the Aerial Parts of Corispermum marschallii.

The isolation of phenolics from aerial parts of Corispermum marschallii yielded a total of 13 compounds including nine previously undescribed patuletin and spinacetin glycosides. These were identified as patuletin 3- O-ß-d-galactopyranosyl-7- O-ß-d-glucopyranoside (1), spinacetin 3- O-ß-d-galactopyranosyl-7- O-ß-d-glucopyranoside (2), patuletin 3- O-(6″- O-ß-d-glucopyranosyl)-ß-d-galactopyranoside (3), patuletin 3- O-(6″- O-α-l-arabinopyranosyl)-ß-d-galactopyranoside (4), patuletin 3- O-(2″- O-(5‴- O-α-l-arabinopyranosyl)-ß-d-apiofuranosyl)-ß-d-galactopyranoside (5), patuletin 3- O-(2″- O-ß-d-apiofuranosyl)-ß-d-galactopyranoside (6), spinacetin 3- O-ß-d-galactopyranoside (7), patuletin 3- O-ß-d-galactopyranosyl-7- O-(6‴- O-feruloyl)-ß-d-glucopyranoside (8), and spinacetin 3- O-ß-d-galactopyranosyl-7- O-(6‴- O-feruloyl)-ß-d-glucopyranoside (9). Structure elucidation was based on UV-visible, multistage MS, and 1D and 2D NMR spectroscopy and chemical derivatization, which allowed the identification on the glycosides with two different hexose moieties occurring at different positions of the aglycones. Most of the compounds tested inhibited the production of pro-inflammatory factors such as ROS, IL-8, and TNF-α in stimulated neutrophils.

Novel (S)-1,3,4,12a-tetrahydropyrazino[2,1-c][1,4]benzodiazepine-6,12(2H,11H)-dione derivatives: Selective inhibition of MV-4-11 biphenotypic B myelomonocytic leukemia cells' growth is accompanied by reactive oxygen species overproduction and apoptosis.

A series of optically pure (R)- and (S)-1,3,4,12a-tetrahydropyrazino[2,1-c][1,4]benzodiazepine-6,12(2H,11H)-dione derivatives was designed and synthesized as novel anthramycin analogues in a three-step, one-pot procedure, and tested for their antiproliferative activity on nine following cell lines: MV-4-11, UMUC-3, MDA-MB-231, MCF7, LoVo, HT-29, A-549, A2780 and BALB/3T3. The key structural features responsible for exhibition of cytotoxic effect were determined: the (S)-configuration of chiral center and the presence of hydrophobic 4-biphenyl substituent in the side chain. Introduction of bromine atom into the 8 position (8g) or substitution of dilactam ring with benzyl group (8m) further improved the activity and selectivity of investigated compounds. Among others, compound 8g exhibited selective cytotoxic effect against MV-4-11 (IC50 = 8.7 µM) and HT-29 (IC50 = 17.8 µM) cell lines, while 8m showed noticeable anticancer activity against MV-4-11 (IC50 = 10.8 µM) and LoVo (IC50 = 11.0 µM) cell lines. The cell cycle arrest in G1/S checkpoint and apoptosis associated with overproduction of reactive oxygen species was also observed for 8e and 8m.

Magnetic polymer microcapsules loaded with Nile Red fluorescent dye.

Fabrication of multifunctional smart vehicles for drug delivery is a fascinating challenge of multidisciplinary research at the crossroads of materials science, physics and biology. We demonstrate a prototypical microcapsule system that is capable of encapsulating hydrophobic molecules and at the same time reveals magnetic properties. The microcapsules are prepared using a templated synthesis approach where the molecules to be encapsulated (Nile Red) are present in the organic droplets that are suspended in the polymerization solution which also contains magnetic nanoparticles. The polymer (polypyrrole) grows on the surface of organic droplets encapsulating the fluorescent dye in the core of the formed microcapsule which incorporates the nanoparticles into its wall. For characterization of the resulting structures a range of complementary physicochemical methodology is used including optical and electron microscopy, magnetometry, 1H NMR and spectroscopy in the visible and X-ray spectral ranges. Moreover, the microcapsules have been examined in biological environment in in vitro and in vivo studies.

REmote SUpervision to Decrease HospitaLization RaTe. Unified and integrated platform for data collected from devices manufactured by different companies: Design and rationale of the RESULT study.

The number of patients with heart failure implantable cardiac electronic devices (CIEDs) is growing. Hospitalization rate in this group is very high and generates enormous costs. To avoid the need for hospital treatment, optimized monitoring and follow-up is crucial. Remote monitoring (RM) has been widely put into practice in the management of CIEDs but it may be difficult due to the presence of differences in systems provided by device manufacturers and loss of gathered data in case of device reimplantation. Additionally, conclusions derived from studies about usefulness of RM in clinical practice apply to devices coming only from a single company. An integrated monitoring platform allows for more comprehensive data analysis and interpretation. Therefore, the primary objective of Remote Supervision to Decrease Hospitalization Rate (RESULT) study is to evaluate the impact of RM on the clinical status of patients with ICDs or CRT-Ds using an integrated platform. Six hundred consecutive patients with ICDs or CRT-Ds implanted will be prospectively randomized to either a traditional or RM-based follow-up model. The primary clinical endpoint will be a composite of all-cause mortality or hospitalization for cardiovascular reasons within 12 months after randomization. The primary technical endpoint will be to construct and evaluate a unified and integrated platform for the data collected from RM devices manufactured by different companies. This manuscript describes the design and methodology of the prospective, randomized trial designed to determine whether remote monitoring using an integrated platform for different companies is safe, feasible, and efficacious (ClinicalTrials.gov Identifier: NCT02409225).

Expanding the substrate scope of Ugi five-center, four-component reaction U-5C-4CR): ketones as coupling partners for secondary amino acids.

Various symmetrical and unsymmetrical ketones were successfully coupled with secondary amino acids in the course of Ugi five-center, four-component reaction (U-5C-4CR), thus expanding the molecular diversity possible to be achieved by the reaction. The chemical yields depended on the degree of hindrance of the components employed and were satisfactory in view of possible steric interactions in the U-5C-4CR zwitterionic intermediate. The sense of diastereoinduction for reactions employing unsymmetrical ketones was examined by converting the resulting Ugi adducts into the corresponding rigid 2,6-diketopiperazine derivatives.

Structure-activity relationships of the aromatic site in novel anticonvulsant pyrrolo[1,2-a]pyrazine derivatives.

Novel, chiral derivatives of pyrrolo[1,2-a]pyrazine with aromatic substituents at carbon C-4 were synthesized by a short synthetic sequence involving Ugi multicomponent reaction. The compounds were evaluated for their in vivo efficacy in animal models of epilepsy within the Anticonvulsant Screening Program (ASP). High activity in 'classical' maximal electroshock seizure (MES) and subcutaneous Metrazol (scMET) tests was characteristic for meta-substituted analogs. On the other hand, efficacy of compounds in the 6 Hz model of pharmacoresistant limbic seizures was only marginally affected by the orientation of substituents in the phenyl moiety. The most active derivative, 5a, displayed an ED50 value of 32.24 mg/kg and a protective index of 6.6 (PI) in the 6 Hz test. It was also active in a pilocarpine-induced status prevention model of pharmacoresistant status epilepticus.

Peptides and peptidoaldehydes as substrates for the Pictet-Spengler reaction.

The Pictet-Spengler (PS) reaction was performed with various types of substrates: H-Trp-OMe and dipeptides with N-terminal Trp as arylethylamine components and Z-protected amino aldehydes and peptidoaldehydes as carbonyl components. We found that the C-terminal part of Trp derivatives did not have any influence on the stereoselectivity of the reaction and the results are the same for simple esters of Trp and dipeptides. On the contrary, the selectivity of the PS reaction with peptidoaldehydes with L configuration of the C-terminus residue is totally different from that obtained with simple L-amino aldehydes. It allows us to obtain cis stereoisomers, which cannot be isolated from the reaction with amino aldehydes. But the utility of the peptidoaldehydes as substrates for the PS reaction is reduced by the side formation of enamides which decrease the yield of cyclization.

Synthesis and anticonvulsant activity of novel 2,6-diketopiperazine derivatives. Part 1: perhydropyrrole[1,2-a]pyrazines.

A number of novel pyrrole[1,2-a]pyrazine derivatives were synthesized and evaluated in in vivo animal models of epilepsy. Among them, several compounds displayed promising seizure protection in the maximal electroshock seizure (MES), subcutaneous metrazol seizure (scMET), 6 Hz and pilocarpine-induced status prevention (PISP) tests, with ED(50) values comparable to the reference anticonvulsant drugs (AEDs). A critical influence of the stereochemistry and conformational preferences of the pyrrole[1,2-a]pyrazine core on in vivo pharmacological activity was observed. The mechanism of the anticonvulsant action of the agents synthesized is most probably not via inhibition of the voltage-dependent sodium (Na(+)) currents.

Alternative approach to the standardization of NMR spectra. Direct measurement of nuclear magnetic shielding in molecules.

Exploring the relation between shielding constants, resonance frequencies and magnetic moments of the nuclei we demonstrate that nuclear magnetic shielding can be directly observed from NMR spectra. In this approach, the absolute shielding constants of all the nuclei can be related to a single reference scale, with atomic (3)He as the primary standard. The accuracy of the data obtained using our method is confirmed comparing the (1)H and (13)C shielding constants for a series of deuterated compounds with those determined analyzing the traditional chemical shifts. Since the use of helium-3 is not in general a practical alternative, we next transfer the reference standard to the (2)H signals of external lock solvents, in this way making the method easy and ready for application with most NMR spectrometers. Finally, we illustrate our new method with the measurements of the (2/1)H primary isotope effects in several liquid deuterated solvents.

NMR frequency and magnetic dipole moment of (3)He nucleus.

We present new gas-phase NMR spectra which relate the resonance frequency of (3)He nucleus to the resonance frequency of the proton in tetramethylsilane (TMS). We discuss the dependence of (3)He resonance frequency on the density of the solvent gas, and we consider in detail the absolute shielding scales of both nuclei. Finally, we analyse the accuracy of the results, using the relationship between the resonance frequencies, absolute shielding constants and magnetic dipole moments of (1)H and (3)He nuclei.