Synthesis and pharmacological evaluation of novel arylpiperazine oxicams derivatives as potent analgesics without ulcerogenicity.

Gastrotoxicity continues to be a major issue in therapy with nonsteroidal anti-inflammatory drugs (NSAIDs). Medicine is yet to develop absolutely safe analgesics. Numerous strategies are employed to discover new, safer NSAIDs, for example selective inhibition of cyclooxygenase-2, new molecular targets (e.g. microsomal prostaglandin E2 synthase-1), incorporation of cytoprotective compounds in the drug molecule or modification of the classic NSAIDs currently available on the market. The research presented in this paper is indicative of a current worldwide trend in this area of science, and is an example of the fourth strategy noted above. Two series of new arylpiperazine derivatives of the classic NSAID - piroxicam, were developed by conventional synthesis. The full range of compounds obtained proved to be between two and five times analgesically more potent than the reference drug and, most importantly, they did not show any ulcerogenic activity.

Recognition of Pharmacological Bi-Heterocyclic Compounds by Using Terahertz Time Domain Spectroscopy and Chemometrics.

In this study, we presented the concept and implementation of a fully functional system for the recognition of bi-heterocyclic compounds. We have conducted research into the application of machine learning methods to correctly recognize compounds based on THz spectra, and we have described the process of selecting optimal parameters for the kernel support vector machine (KSVM) with an additional `unknown' class. The chemical compounds used in the study contain a target molecule, used in pharmacy to combat inflammatory states formed in living organisms. Ready-made medical products with similar properties are commonly referred to as non-steroidal anti-inflammatory drugs (NSAIDs) once authorised on the pharmaceutical market. It was crucial to clearly determine whether the tested sample is a chemical compound known to researchers or is a completely new structure which should be additionally tested using other spectrometric methods. Our approach allows us to achieve 100% accuracy of the classification of the tested chemical compounds in the time of several milliseconds counted for 30 samples of the test set. It fits perfectly into the concept of rapid recognition of bi-heterocyclic compounds without the need to analyse the percentage composition of compound components, assuming that the sample is classified in a known group. The method allows us to minimize testing costs and significant reduction of the time of analysis.

Synthesis, COX-1/2 inhibition activities and molecular docking study of isothiazolopyridine derivatives.

One of the main challenges for nowadays medicine is drugs selectivity. In COX-1 and COX-2, the active sites are composed of the same group of amino acids with the exception of the only one residue in position 523, in COX-1 is an isoleucine, while in COX-2 is a valine. Here, we presented a series of isothiazolopyridine/benzisothiazole derivatives substituted differently into an isothiazole ring, which were synthesized and investigated for their potencies to inhibit COX-1 and COX-2 enzymes by colorimetric inhibitor screening assay. All the tested compounds inhibited the activity of COX-1, the effect on COX-2 activity was differential. The mode of binding was characterized by a molecular docking study. Comparing biological activity of the investigated compounds, it was observed that compounds sharing the most similar position to flurbiprofen and meloxicam, representing the two main enzyme subdomains, achieved higher biological activity than others. It is directly related to the fit to the enzyme's active site, which prevents too early dissociation of the compounds.

New fluphenazine analogue with antimutagenic and anti-multidrug resistance activity-degradation profile and stability-indicating method.

Hydrochloride of 10-{2-hydroxy-3-[N,N-bis-(2-hydroxyethyl)amino]propyl}-2-trifluoromethylphenothiazine (Flu-A) is a analogue of neuroleptic fluphenazine. Flu-A exhibits anti-multidrug resistance, antimutagenic, proapoptopic, and cancer-chemopreventive activities in screening studies. To define identity, quality, and purity of new active substance it is necessary to develop a appropriate analytical method and to establish a degradation profile. Thus, a stability-indicating reversed-phase high-performance liquid chromatography method was developed and validated for quantitative determination of Flu-A in the presence of its degradation products generated under stress conditions. The compound was subjected to oxidation, photolysis, and degradation in aqueous solutions (neutral and acidic), and solid state according to the International Council for Harmonisation Guidelines. The method was also found to be suitable for intermediate and accelerated studies and for the evaluation of kinetic mechanism of Flu-A degradation in aqueous solutions (pH 5.1-7.5, 353 K). The structures of main potential degradation products were established using high-performance liquid chromatography-Electrospray Ionization-mass spectrometry method.

Synthesis and fluorescence properties of new ester derivatives of isothiazolo [4,5-b] pyridine.

A two new compounds with potential biologically active were synthesized: ethyl 4-(2H-4,6-dimethyl-3-oxo-2,3-dihydroisothiazolo [5,4-b] pyridin-2-yl) butanoate and ethyl 4-(2H-4,6-dimethyl-2,3-dihydroisothiazolo [5,4-b] pyridin-3-yloxy) butanoate. The structures of all of the newly formed compounds were identified by elemental analysis, FTIR and (1)H NMR. Their optical properties were studied in ethanol and n-hexane by UV-Vis absorption and fluorescence spectroscopy. The ground-state and excited-state properties were investigated using the density functional theory (DFT) and the time-dependent density functional theory (TDDFT) methods. The results showed differences between emission spectra in ethanol and n-hexane solution (solvatochromism) for both new compounds.

Forced Degradation and Photodegradation Studies of Pyrrolo[3,4-c]pyridine-1,3-dione Derivatives as Analgesic Active Compounds Using HPLC, UV and IR Spectrometry, and HPLC/MS Methods.

The stress and accelerated tests as well as photostability analysis in solutions and the solid phase of three selected derivatives of pyrrolo[3,4-c]pyridine-1,3-dione were carried out according the International Conference on Harmonization guidelines. For observation of the degradation of tested compounds, the RP-HPLC method was used. The study included the effect of temperature, relative humidity, water, H+ and OH- ions, hydrogen peroxide, and light (6.0×10(6), 1.2×10(6) lux·h) on the stability of pyrrolo[3,4-c]pyridine-1,3-dione derivatives. Studies have shown that these derivatives are photolabile, extremely unstable in an alkaline medium, labile in an acidic medium, and stable in a neutral medium. Their sensitivity to oxidizing agents depends on the chemical structure. The shortening of the aliphatic chain leads to an increase in the sensitivity to hydrolytic and oxidizing factors. The presence of the 1,3,4-tetraisoquinoline group promotes an increase in the susceptibility to photodegradation. The introduction of a carbonyl group to the aliphatic chain and the tetrafluoromethyl group to the phenyl ring stabilizes the molecule in the case of hydrolysis and oxidation and also increases sensitivity to light. The analysis of observed photodegradation products using the HPLC-diode array detector, HPLC/MS, and UV and IR spectrometry techniques showed degradation targeted at the breaking of the pyrrolo[3,4-c]pyridine-1,3-dione, piperazine, and/or tetrahydroisoquinoline rings.

The Cu²âº binding properties of branched peptides based on L-2,3-diaminopropionic acid.

Three new branched peptides, namely, H-Gly-Dap(H-Gly)-Gly-NH2 (3G), H-His-Dap(H-His)-Gly-NH2 (2HG), and H-Gly-Dap(H-Gly)-His-NH2 (2GH), where Dap stands for the 2,3-diaminopropionic acid residue, were synthesized by solid phase procedures. Because of the junction at Dap these peptides have three available pending arms for metal chelation. The complex formation between these peptides and 1 equiv of Cu(2+) was investigated as a function of pH by potentiometry ultraviolet-visible absorption, circular dichroism, and X-band electron paramagnetic resonance spectroscopy in aqueous medium. Our results clearly demonstrate that cooperation between all three peptide arms essentially contributes to the stability of copper(II) complexes.

Synthesis, pro-apoptotic activity and 2D-QSAR studies of new analogues of fluphenazine.

A series of 10 novel analogues of fluphenazine (FPh) were synthesized. Influence of the synthesized analogues of FPh on frequency of apoptosis and necrosis in cultures of human lymphocytes genotoxically damaged in vitro with benzo[a]pyrene (B[a]P; 7,5 microM, 48 h) was compared with the effect of FPh. Activity of the tested compounds was expressed by ED50 (pro-apoptotic activity) and TD50 (pro-necrotic effect, cytotoxicity). It was noticed that compounds 3-9 and 12 exerted a pro-apoptotic effect markedly stronger than that of FPh. Additionally, compounds 3, 9 and 10 exhibited the weakest influence on frequency of necrotic lymphocyte in cultures. 2D-QSAR analysis was done in order to find quantitative relationship between structures of the tested analogues and their pro-apoptotic activity or pro-necrotic effect in B[a]P-damaged cell cultures. Several statistically significant QSAR models were generated. Information obtained from 2D-QSAR study will be used in further design of analogues of FPh more active in cancer chemoprevention.

The interaction of new piroxicam analogues with lipid bilayers--a calorimetric and fluorescence spectroscopic study.

The purpose of the present paper was to assess the ability of new piroxicam analogues to interact with the lipid bilayers. The results of calorimetric and fluorescence spectroscopic experiments of two new synthesized analogues of piroxicam, named PR17 and PR18 on the phase behavior of phospholipid bilayers and fluorescence quenching of fluorescent probes (Laurdan and Prodan), which molecular location within membranes is known with certainty, are shown in present work. The presented results revealed that, depending on the details of chemical structure, the studied compounds penetrated the lipid bilayers.

Synthesis of new piroxicam derivatives and their influence on lipid bilayers.

A novel series of potentially biologically active 1,2-benzothiazine 1,1-dioxides--analogs of piroxicam (a recognized non-steroidal anti-inflammatory drug) were synthesized from commercially available saccharin. All of the synthesized compounds were subjected to preliminary evaluation for their ability to interact with lipid bilayers. The influence of the new derivatives of piroxicam on liposomes made of EYPC was investigated by fluorescence spectroscopy with two fluorescent probes--Laurdan and Prodan. All the studied compounds showed an interaction with model membranes.

Synthesis of novel isothiazolopyridines and their in vitro evaluation against Mycobacterium and Propionibacterium acnes.

In this paper we describe synthesis, structures and some physicochemical properties of 20 isothiazolopyridines 8-13 substituted differently into an isothiazole ring as well as their in vitro antibacterial assays against Mycobacterium tuberculosis H37Rv, Mycobacterium fortuitum PCM 672 and Propionibacterium acnes PCM 2400. Compound 13a was found to be the most active derivative against M. tuberculosis H37Rv, demonstrating 100% growth inhibition of microorganisms in the primary screen (minimum inhibitory concentration [MIC] 6.25µg/mL). Nineteen of the prepared compounds were evaluated against M. fortuitum PCM 672 and P. acnes PCM 2400 and only compounds 9 and 12d exhibited excellent activity against individual strains of microorganisms with MIC90 <1µg/mL. The inhibitory action of the remaining isothiazolopyridines towards the tested strains of the microorganism was low, absent, or a non-linear correlation prohibited accurate determination of MIC values. Unexpectedly, seven of the remaining isothiazolopyridines tested against M. fortuitum and P. acnes stimulated growth of the microorganisms in the range 10-50% or even more (10b) under experimental conditions.

New fluphenazine analogues as inhibitors of P-glycoprotein in human lymphocyte cultures.

AIM OF THE STUDY: To evaluate the inhibitory effect of 17 new analogues of FPh on the Pgp transport function, by estimation of the rhodamine 123 (Rod-123) accumulation inside cultured lymphocytes. MATERIAL AND METHODS: Lymphocyte were cultured in the presence of a lectin (PHA; 2%, v/v), incubated with benzo[α]pyrene (B[α]P; 7.5 µM, 48 h) to induce genotoxic damage and to increase Pgp expression in the cells. Lymphocytes cultured without the tested compounds were considered as controls. RESULTS: It was established that 10 analogues of FPh, among 17 tested, significantly increased Rod-123 accumulation in lymphocytes at the concentration of 10 µM. As compared to the control cultures the Pgp transport function was the most strongly inhibited by 1a, 1b, 1d, 3f, 3h and 3i analogues (approximately by 25%). CONCLUSIONS: FPh analogues 1a, 1b, 1d, 3f, 3h and 3i should be further studied as promising candidates for adjuvant cancer chemotherapeutics.

Mechanism of solvolysis of N-[2-(4-o-fluorophenylpiperazin-1-yl)ethyl]-2,5-dimethyl-1-phenylpyrrole-3,4-dicarboximide (PDI).

The stability of N-[2-(4-o-fluorophenylpiperazin-1-yl)ethyl]-2,5-dimethyl-1-phenylpyrrole-3,4-dicarboximide (PDI; a derivative with an analgesic activity) was studied in order to investigate its degradation mechanism and identify its degradation products in aqueous-organic solutions. The stability of PDI and its two degradation products (A and B) was performed with an HPLC method: (LiChrospher C18 column (250 x 4 mm LD., dp = 5 microm), mobile phase: 3.5 g/L solution of sodium lauryl sulfate and 1.6 mL of phosphoric acid(V)-acetonitrile (40:60, v/v), UV detector: 240 nm, flow rate: 1 ml/min). The identification of products A and B was conducted using HPLC-ES-MS and 1H- and 13C-NMR methods.

The stability of N-[2-(4-o-fluorophenylpiperazin-1-yl)ethyl]-2,5-dimethyl-1 -phenylpyrrole-3,4-dicarboximide in aqueous-organic solutions.

The first-order reaction of solvolysis of N-[2-(4-o-fluorophenylpiperazin-1-yl)ethyl]-2,5-dimethyl-1-phenylpyrrole-3,4-dicarboximide (PDI) was investigated as a function of pH at 333, 328, 323, 318 and 308 K in the pH range 1.11 - 12.78. The decomposition of PDI was followed by the HPLC method (Nucleosil 10-C8 column (250 x 4 mm I.D., dp = 10 microm), mobile phase: 0.018 mol/L ammonia acetate - acetonitrile (40: 60 v/v), UV detector: 240 nm, flow rate: 1 mL/min. Specific acid-base catalysis involves solvolysis of the undissociated molecules of PDI catalyzed by hydroxide ions and spontaneous solvolysis of the undissociated and monoprotonated forms of PDI under the influence of solvents. The thermodynamic parameters of the reactions--activation energy (E(a)), enthalpy (DH(#)), entropy (DS(#))--were calculated.

Synthesis and studies on antibacterial activity of pyrido[3,2-e]-1,2-thiazines and related derivatives.

Twenty of the known and newly synthesized derivatives of pyrido-1,2-thiazine derivatives 3-7, which represent a novel class of potential antibacterial agents, were evaluated against strains of Mycobacterium fortuitum (PCM 672) and Staphylococcus aureus (PCM 2602). The pilot experiments showed that the compounds in an initial in vitro microbiological evaluation were not efficient antibacterial agents, whereas some of them unexpectedly promoted replication of the microorganisms in the range of 10-50% even at sub-mg/mL concentrations.

Pyrido-1,2-thiazines and their in vitro antibacterial evaluation.

A series of known and newly synthesized pyrido-1,2-thiazine derivatives of type 3-6 were evaluated against strains of Mycobacterium fortuitum (PCM 672) and Staphylococcus aureus (PCM 2602) The pilot experiments showed that most of the compounds in initial in vitro microbiological evaluation were not efficient antibacterial agents, but unexpectedly promoted replication of the microorganisms in the range of 10-50%.

Chemometric Evaluation of THz Spectral Similarity for the Selection of Early Drug Candidates.

In this paper we discuss the link between the domain of physical parameters - molecular descriptors of a drug, and terahertz (THz) spectra. We measured the derivatives of the well-known anti-inflammatory drug Piroxicam using THz spectroscopy and employed Principal Component Analysis to build similarity maps in the molecular descriptor and spectral domains. We observed, that the spatial neighborhood on the molecular descriptors map is highly correlated with the spectral neighbourhood within a group of structurally-similar molecules. We built a Partial Least Squares (PLS) predictive model to quantify the relationship between the spectra and the melting point, which can guide the selection of early drug candidates.

Self-assembled, nanostructured coatings for water oxidation by alternating deposition of Cu-branched peptide electrocatalysts and polyelectrolytes.

This work demonstrates the heterogenization of homogeneous water oxidation electrocatalysts in surface coatings produced by combining the substances with a suitable polyelectrolyte. The electrocatalysts i.e. Cu(ii)-branched peptide complexes involving a 2,3-l-diaminopropionic acid junction unit are heterogenized by building composite layers on indium-tin-oxide (ITO) electrode surface. Alternating deposition of the peptide complexes and poly(l-lysine) or poly(allylamine hydrochloride) were carried out in the presence of phosphate in a pH range of 7.5-10.5. Discussion of the results is divided to (1) characteristics of composite layer buildup and (2) electrocatalytic water oxidation and accompanying changes of these layers. For (1), optical waveguide lightmode spectroscopy (OWLS) has been applied to reveal the layer-by-layer formation of a Cu-ligand/polyelectrolyte/phosphate coating. The fabricated structures had a nanoporous topography (atomic force microscopy). As for (2), electrochemistry employing coated ITO substrates indicated improved water oxidation electrocatalysis vs. neat ITO and dependence of this improvement on the presence or absence of a histidine ligand in the deposited Cu(ii)-complexes equally, as observed in homogeneous systems. Electrochemical OWLS revealed changes in the coatings in operando, upon alternating positive-zero-positive etc. polarization: after some initial loss of the coating mass steady-state electrolysis was sustained by a compact and stable layer. According to X-ray photoelectron spectroscopy Cu remains in an N-donor ligand environment after electrolysis.

Antinociceptive, anti-inflammatory and smooth muscle relaxant activities of the pyrrolo[3,4-d]pyridazinone derivatives: Possible mechanisms of action.

The aim of this study was to evaluate the analgesic as well as anti-inflammatory activities of the new pyrrolo[3,4-d]pyridazinone derivatives. Moreover, the present study attempted to assess some of the mechanisms involved in the pharmacological activity of these compounds. In the previous studies it was shown that these compounds were highly active in the phenylbenzoquinone-induced 'writhing syndrome' test and had much lower activity in the hot plate, which indicates that mainly peripheral mechanisms of analgesia are involved in their effects. In these extended studies the analgesic activity of two tested compounds (4c, 4f) was confirmed in some animal models of pain. The studied compounds showed a significant and dose-related antinociceptive effect in the models of pain induced by formalin, capsaicin and glutamic acid. Both compounds decreased the edema formation and one of them (4c) attenuated mechanical hyperalgesia in carrageenan-induced paw inflammation in rats. Furthermore, both compounds inhibited cell migration, plasma exudation and nociceptive reaction in zymosan A-induced mouse peritonitis. In the subsequent studies, including experiments on isolated organs (ileum, trachea, aorta), radioligand assays and biochemical tests, it was demonstrated that analgesic and anti-inflammatory effects of the investigated structures are largely due to their competitive antagonism for histamine H1 receptor. The influence on the level of cAMP in inflammatory cells (shown in RAW 264.7 macrophages) and subsequent inhibition of cytokine (TNFα, IL-1ß) release can also be one of the important mechanisms of their action. Moreover some additional mechanisms may also be involved in the eventual analgesic effect of tested pyrrolo[3,4-d]pyridazinone derivatives.

Electrocatalytic water oxidation by Cu(II) complexes with branched peptides.

Two mononuclear Cu(II) complexes with tetrapeptides incorporating a L-2,3-diaminopropionic acid (dap) branching unit are reported to undergo PCET and catalyse water oxidation. C-terminal His extension of dap (L = 2GH) instead of Gly (L = 3G) lowers the pKa for Cu(III)H-2L (9.36 vs. 9.98) and improves the TOF at pH 11 (53 vs. 24 s(-1)).