5-Aryl-1H-pyrazole-3-carboxylic acids as selective inhibitors of human carbonic anhydrases IX and XII.

Inhibitory activity of a congeneric set of 23 phenyl-substituted 5-phenyl-pyrazole-3-carboxylic acids toward human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms I, II, IX and XII was evaluated by a stopped-flow CO2 hydrase assay. These compounds exerted a clear, selective inhibition of hCA IX and XII over hCAI and II, with Ki in two to one digit micromolar concentrations (4-50 µM). Derivatives bearing bulkier substituents in para-position of the phenyl ring inhibited hCA XII at one-digit micromolar concentrations, while derivatives having alkyl substituents in both ortho- and meta-positions inhibited hCA IX with Kis ranging between 5 and 25 µM. Results of docking experiments offered a rational explanation on the selectivity of these compounds toward CA IX and XII, as well as on the substitution patterns leading to best CA IX or CA XII inhibitors. By examining the active sites of these four isoforms with GRID generated molecular-interaction fields, striking differences between hCA XII and the other three isoforms were observed. The field of hydrophobic probe (DRY) appeared significantly different in CA XII active site, comparing to other three isoforms studied. To the best of our knowledge such an observation was not reported in literature so far. Considering the selectivity of these carboxylates towards membrane-associated over cytosolic CA isoforms, the title compounds could be useful for the development of isoform-specific non-sulfonamide CA inhibitors.

Antiproliferative activity of the Michael adducts of aroylacrylic acids and cyclic amines.

Antiproliferative activity of twenty one Michael adducts of aroylacrylic acids and cyclic amines (N-Me-piperazine, imidazole, 2-Me-imidazole, and indole) was tested toward five human tumor cell lines (HeLa, LS174, K562, FemX, MDA-MB-361) in vitro. Compounds exerted antiproliferative activity in the high to the single-digit micromolar concentrations, causing increase of the cell population fraction in S phase and apoptosis. N-Me-piperazine and imidazole derivatives of aroylacrylic acids substituted with bulky alkyl substituents (2,4-di-i-Pr-Ph-, 2,4,6-tri-Et-Ph-, or ß-tetrahydronaphthyl-) showed the best potency, while indole adducts were proved as the inferior antiproliferative agents. Few compounds showed significant selectivity, tumor versus healthy cells, with selectivity index ~60 for the most selective congener. An unbiased in silico distinction between more and less potent compounds was obtained from 3D QSAR models derived by alignment-independent GRIND-2 descriptors.

Docking Studies and α-Substitution Effects on the Anti-Inflammatory Activity of ß-Hydroxy-ß-arylpropanoic Acids.

Six ß-hydroxy-ß-aryl propanoic acids were synthesised using a modification of Reformatsky reaction which has already been reported. These acids belong to the aryl propanoic acid class of compounds, structurally similar to the NSAIDs, such as ibuprofen, and an anti-inflammatory activity is thus expected. The aim of this work was to determine anti-inflammatory activity, examine gastric tolerability, and to carry out molecular docking experiments to identify potential COX-2 inhibitors among the ß-hydroxy-ß-aryl propanoic acids, and to elucidate the effect α-methyl substitution on the anti-inflammatory activity. Anti-inflammatory activity and gastric tolerability were determined on rats using carrageenan induced paw oedema method, and docking studies were carried out using Autodock v4.0.1. The range of ED50 values is between 127 µmol/kg and 15 µmol/kg, while the result for ibuprofen is 51.7 µmol/kg. Only slight hyperaemia or few petechiae were spotted on rat's stomach. The results indicate that all compounds possess significant anti-inflammatory activity after oral administration, and that 2-methyl-3-hydroxy-3,3-diphenyl-propanoic acid has greatest activity, surpassing that of ibuprofen, a standard NSAID. Another compound, 3-hydroxy-3,3-diphenylpropanoic acid, shows activity matching that of ibuprofen, and is non-chiral and is proven to be non-toxic. The most of investigated compounds have interactions with P3 anchor site like COX-2 selective inhibitors. No tested substances or ibuprofen produced any significant gastric lesions.

4-Aryl-4-oxo-N-phenyl-2-aminylbutyramides as acetyl- and butyrylcholinesterase inhibitors. Preparation, anticholinesterase activity, docking study, and 3D structure-activity relationship based on molecular interaction fields.

Synthesis and anticholinesterase activity of 4-aryl-4-oxo-N-phenyl-2-aminylbutyramides, novel class of reversible, moderately potent cholinesterase inhibitors, are reported. Simple substituent variation on aroyl moiety changes anti-AChE activity for two orders of magnitude; also substitution and type of hetero(ali)cycle in position 2 of butanoic moiety govern AChE/BChE selectivity. The most potent compounds showed mixed-type inhibition, indicating their binding to free enzyme and enzyme-substrate complex. Alignment-independent 3D QSAR study on reported compounds, and compounds having similar potencies obtained from the literature, confirmed that alkyl substitution on aroyl moiety of molecules is requisite for inhibition activity. The presence of hydrophobic moiety at close distance from hydrogen bond acceptor has favorable influence on inhibition potency. Docking studies show that compounds probably bind in the middle of the AChE active site gorge, but are buried deeper inside BChE active site gorge, as a consequence of larger BChE gorge void.

Role of complexes formation between drugs and penetration enhancers in transdermal delivery.

The use of chemical penetration enhancers (CPE) is growing due to their ability to improve drug delivery through the skin. A possible mechanism of penetration enhancement could involve the complex formation between drug and components in the pharmaceutical formulation, thus altering the physicochemical properties of the active substance. Here, modelling studies indicate that hydrocarbon and oxygen-containing terpenes (penetration enhancers) could form complexes with drugs. Satisfactory correlations have been obtained between the predicted molecular properties of enhancers and their enhancement effects.

Docking studies and anti-inflammatory activity of beta-hydroxy-beta-arylpropanoic acids.

The article describes a two-step synthesis of diastereomeric 3-hydroxy-2-methyl-3-(4-biphenylyl)butanoic acids. In the first step an intermediate alpha-bromo propanoic acid 1-ethoxyethyl ester was synthesized. The second step is a new modified Reformatsky reaction in presence of Zn in tetrahydrofuran (THF) at -5 to 10 degrees C between the previously synthesized intermediate and 4-acetylbiphenyl. Synthesis of the other studied beta-hydroxy-beta-arylpropanoic acids has already been reported. These beta-hydroxy-beta-arylpropanoic acids belong to the arylpropanoic acid class of compounds, structurally similar to the NSAIDs such as ibuprofen. The anti-inflammatory activity and gastric tolerability of the synthesized compounds were evaluated. Molecular docking experiments were carried out to identify potential COX-2 inhibitors among the beta-hydroxy-beta-aryl-alkanoic acids class. The results indicate that all compounds possess significant anti-inflammatory activity after oral administration and that the compounds 2-(9-(9-hydroxy-fluorenyl))-2-methylpropanoic acid (5) and 3-hydroxy-3,3-diphenyl-propanoic acid (3) possess the strongest anti-inflammatory activity, comparable to that of ibuprofen, a standard NSAID,and that none of tested substances or ibuprofen produced any significant gastric lesions.

Design, synthesis and biological evaluation of novel aryldiketo acids with enhanced antibacterial activity against multidrug resistant bacterial strains.

Antimicrobial resistance (AMR) is a major health problem worldwide, because of ability of bacteria, fungi and viruses to evade known therapeutic agents used in treatment of infections. Aryldiketo acids (ADK) have shown antimicrobial activity against several resistant strains including Gram-positive Staphylococcus aureus bacteria. Our previous studies revealed that ADK analogues having bulky alkyl group in ortho position on a phenyl ring have up to ten times better activity than norfloxacin against the same strains. Rational modifications of analogues by introduction of hydrophobic substituents on the aromatic ring has led to more than tenfold increase in antibacterial activity against multidrug resistant Gram positive strains. To elucidate a potential mechanism of action for this potentially novel class of antimicrobials, several bacterial enzymes were identified as putative targets according to literature data and pharmacophoric similarity searches for potent ADK analogues. Among the seven bacterial targets chosen, the strongest favorable binding interactions were observed between most active analogue and S. aureus dehydrosqualene synthase and DNA gyrase. Furthermore, the docking results in combination with literature data suggest that these novel molecules could also target several other bacterial enzymes, including prenyl-transferases and methionine aminopeptidase. These results and our statistically significant 3D QSAR model could be used to guide the further design of more potent derivatives as well as in virtual screening for novel antibacterial agents.

A QSAR study of acute toxicity of N-substituted fluoroacetamides to rats.

Acute toxicity in vivo toward rats, of nineteen N-alkyl and N-cycloalkyl fluorocetamides [F-CH(2)-C(O)-NH-R] was correlated with their structure-dependent properties. Used descriptors are: molecular weights (M(w)) and heat of formation (DeltaH(f)) of compounds; molar refractivity (CMR), lipophilicity (ClogP), Broto lipol values, virtual logP, molecular lipophilic potential (MLP), Van der Waals surfaces (VdW SAS) and hydropathicity surface (ILM) of whole molecules; Taft steric parameters (E(s)); E(s) values with Hancock corrections (E(s)(CH)) and Verloop sterimol (B(5)) and (L) parameters of alkyl and cycloalkyl residues; superdelocalizabilities and electron densities on the [NH-C(O)-CH(2)-F] fragment. Strong quantitative structure-activity relationships were assessed. Obtained correlation suggested that lipophilicity, shape and bulkiness of the alkyl and cycloalkyl substituents, particular nearest vicinity of the amide nitrogen, as well charges on the amide moiety are the main factors that influence on the acute toxicity of studied compounds toward rats. Mechanism of toxic action was proposed.

2-[(Carboxymethyl)sulfanyl]-4-oxo-4-arylbutanoic acids selectively suppressed proliferation of neoplastic human HeLa cells. A SAR/QSAR study.

A series of twenty alkyl-, halo-, and methoxy-aryl-substituted 2-[(carboxymethyl)sulfanyl]-4-oxo-4-arylbutanoic acids were synthesized. The new compounds, called CSAB, suppressed proliferation of human cervix carcinoma, HeLa cells, in vitro in a concentration range of 0.644 to 29.48 microM/L. Two compounds exhibit antiproliferative activity in sub-micromolar concentrations. Five compounds act in low micromolar concentrations (<2 microM/L). The most active compounds exert lower cytotoxicity toward healthy human peripheral blood mononuclear cells (PBMC and PBMC+PHA) (selectivity indexes > 10). A strong structure-activity relationship, using estimated log P values and BCUT descriptors, was observed.

Solvatochromism of symmetrical 2,6-distyrylpyridines. An experimental and theoretical study.

Seven symmetrical 2,6-distyrylpyridines, phenyl-substituted with hydrogen-bond donors, hydrogen-bond acceptors, halogens and hydrophobic moieties were synthesized and their spectroscopic characterization was done. Solvent effects on the absorption and fluorescence spectra were analyzed and quantified using the Kamlet-Taft and Catalán approach. The obtained results were rationalized by comparison of electrostatic potentials of the molecules in the ground and in excited state and by comparison of the frontier molecular orbitals (HOMO and LUMO), derived from quantum-mechanical calculations (HF, DFT, MP2). Analysis of the results revealed an important influence of non-specific (dispersive) interactions on the solvatochromic behavior of the compounds. 1D and 2D NMR data, in silico obtained conformational assembly of the compound, and the NMR analysis of molecular flexibility in solution (NAMFIS), were used to estimate population of conformers and to deconvolute the UV-Vis spectrum of representative derivative; inferring that the conformational assembly is more complex than was assumed in so far published literature data for this class of compounds. Along with this, the emission spectra of the representative compounds were decomposed by the Multivariate Curve Resolution analysis.

Structural modifications of 4-aryl-4-oxo-2-aminylbutanamides and their acetyl- and butyrylcholinesterase inhibitory activity. Investigation of AChE-ligand interactions by docking calculations and molecular dynamics simulations.

Congeneric set of thirty-eight 4-aryl-4-oxo-2-(N-aryl/cycloalkyl)butanamides has been designed, synthesized and evaluated for acetyl- and butyrylcholinesterase inhibitory activity. Structural variations included cycloalkylamino group attached to C2 position of butanoyl moiety, and variation of amido moiety of molecules. Twelve compounds, mostly piperidino and imidazolo derivatives, inhibited AChE in low micromolar range, and were inactive toward BChE. Several N-methylpiperazino derivatives showed inhibition of BChE in low micromolar or submicromolar concentrations, and were inactive toward AChE. Therefore, the nature of the cycloalkylamino moiety governs the AChE/BChE selectivity profile of compounds. The most active AChE inhibitor showed mixed-type inhibition modality, indicating its binding to free enzyme and to enzyme-substrate complex. Thorough docking calculations of the seven most potent AChE inhibitors from the set, showed that the hydrogen bond can be formed between amide -NH- moiety of compounds and -OH group of Tyr 124. The 10 ns unconstrained molecular dynamic simulation of the AChE-compound 18 complex shows that this interaction is the most persistent. This is, probably, the major anchoring point for the binding.

Quantum mechanical and spectroscopic (FT-IR, 13C, 1H NMR and UV) investigations of potent antiepileptic drug 1-(4-chloro-phenyl)-3-phenyl-succinimide.

This study represents an integrated approach towards understanding the vibrational, electronic, NMR, and structural aspects, and reactivity of 1-(4-chloro-phenyl)-3-phenyl-succinimide (CPPS). A detailed interpretation of the FT-IR, UV and NMR spectra were reported. The equilibrium geometry, bonding features, and harmonic vibrational frequencies have been investigated with the help of density functional theory (DFT) B3LYP method using 6-31G(d,p) and 6-311++G(d,p) basis set. The scaled theoretical wavenumber showed very good agreement with the experimental values. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge-Invariant Atomic Orbital (GIAO) method. Stability of the molecule, arising from hyperconjugative interactions and charge delocalization, has been analyzed using Natural Bond Orbital (NBO) analysis. The results show that ED in the σ(*) and π(*) antibonding orbitals and second order delocalization energies E(2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. UV-Vis spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies, were calculated by Time-Dependent DFT (TD-DFT) approach. To estimate chemical reactivity of the molecule, the molecular electrostatic potential (MEP) surface map is calculated for the optimized geometry of the molecule.

(E)-4-aryl-4-oxo-2-butenoic acid amides, chalcone-aroylacrylic acid chimeras: design, antiproliferative activity and inhibition of tubulin polymerization.

Antiproliferative activity of twenty-nine (E)-4-aryl-4-oxo-2-butenoic acid amides against three human tumor cell lines (HeLa, FemX, and K562) is reported. Compounds showed antiproliferative activity in one-digit micromolar to submicromolar concentrations. The most active derivatives toward all the cell lines tested bear alkyl substituents on the aroyl moiety of the molecules. Fourteen compounds showed tubulin assembly inhibition at concentrations <20 µM. The most potent inhibitor of tubulin assembly was unsubstituted compound 1, with IC50 = 2.9 µM. Compound 23 had an oral LD50in vivo of 45 mg/kg in mice. Cell cycle analysis on K562 cells showed that compounds 1, 2 and 23 caused accumulation of cells in the G2/M phase, but inhibition of microtubule polymerization is not the principal mode of action of the compounds. Nevertheless, they may be useful leads for the design of a new class of antitubulin agents.

Carbenic vs. ionic mechanistic pathway in reaction of cyclohexanone with bromoform.

The extensive computation study was done to elucidate the mechanism of formation dibromoepoxide from cyclohexanone and bromoform. In this reaction, the formation of dihaloepoxide 2 is postulated as a key step that determines the distribution and stereochemistry of products. Two mechanistic paths of reaction were investigated: the addition of dibromocarbene to carbonyl group of ketone, and the addition of tribromomethyl carbanion to the same (C=O) group. The mechanisms for the addition reactions of dibromocarbenes and tribromomethyl carbanions with cyclohexanone have been investigated using ab initio HF/6-311++G** and MP2/6-311+G* level of theory. Solvent effects on these reactions have been explored by calculations which included a continuum polarizable conductor model (CPCM) for the solvent (H2O). The calculations showed that both mechanisms are possible and are exothermic, but have markedly different activation energies.

The 3D-QSAR study of 110 diverse, dual binding, acetylcholinesterase inhibitors based on alignment independent descriptors (GRIND-2). The effects of conformation on predictive power and interpretability of the models.

The 3D-QSAR analysis based on alignment independent descriptors (GRIND-2) was performed on the set of 110 structurally diverse, dual binding AChE reversible inhibitors. Three separate models were built, based on different conformations, generated following next criteria: (i) minimum energy conformations, (ii) conformation most similar to the co-crystalized ligand conformation, and (iii) docked conformation. We found that regardless on conformation used, all the three models had good statistic and predictivity. The models revealed the importance of protonated pyridine nitrogen of tacrine moiety for anti AChE activity, and recognized HBA and HBD interactions as highly important for the potency. This was revealed by the variables associated with protonated pyridinium nitrogen, and the two amino groups of the linker. MIFs calculated with the N1 (pyridinium nitrogen) and the DRY GRID probes in the AChE active site enabled us to establish the relationship between amino acid residues within AChE active site and the variables having high impact on models. External predictive power of the models was tested on the set of 40 AChE reversible inhibitors, most of them structurally different from the training set. Some of those compounds were tested on the different enzyme source. We found that external predictivity was highly sensitive on conformations used. Model based on docked conformations had superior predictive ability, emphasizing the need for the employment of conformations built by taking into account geometrical restrictions of AChE active site gorge.

An alignment independent 3D QSAR study of the antiproliferative activity of 1,2,4,5-tetraoxanes.

An alignment-free 3D QSAR study on antiproliferative activity of the thirty-three 1,2,4,5-tetraoxane derivatives toward two human dedifferentiated cell lines was reported. GRIND methodology, where descriptors are derived from GRID molecular interaction fields (MIF), were used. It was found that pharmacophoric pattern attributed to the most potent derivatives include amido NH of the primary or secondary amide, and the acetoxy fragments at positions 7 and 12 of steroid core which are, along with the tetraoxane ring, common for all studied compounds. Independently, simple multiple regression model obtained by using the whole-molecular properties, confirmed that the hydrophobicity and the H-bond donor properties are the main parameters influencing potency of compounds toward human cervix carcinoma (HeLa) and human malignant melanoma (FemX) cell lines. Corollary, similar structural motifs are found to be important for the potency toward both examined cell lines.