Phenothiazine Analogues Research Articles

Evaluation of the Lipophilicity of Angularly Condensed Diquino- and Quinonaphthothiazines as Potential Candidates for New Drugs.

Lipophilicity is one of the most important properties of compounds required to estimate the absorption, distribution, and transport in biological systems, in addition to solubility, stability, and acid-base nature. It is crucial in predicting the ADME profile of bioactive compounds. The study assessed the usefulness of computational and chromatographic methods (thin-layer chromatography in a reversed-phase system, RP-TLC) for estimating the lipophilicity of 21 newly synthesized compounds belonging to diquinothiazines and quinonaphthiazines. In order to obtain reliable values of the relative lipophilicities of diquinothiazines and quinonaphthiazines, the partition coefficients obtained using different algorithms such as AlogPs, AClogP, AlogP, MLOGP, XLOGP2, XLOGP3, logP, and ClogP were compared with the chromatographic RM0 values of all the tested compounds measured by the experimental RP-TLC method (logPTLC). Additionally, logPTLC values were also correlated with other descriptors, as well as the predicted ADME and drug safety profiling parameters. The linear correlations of logPTLC values of the tested compounds with other calculated molecular descriptors such as molar refractivity, as well as ADME parameters (Caco-2 substrates, P-gp inhibitors, CYP2C19, and CYP3A4) generally show poor predictive power. Therefore, in silico ADME profiling can only be helpful at the initial step of designing these new candidates for drugs. The compliance of all discussed diquinothiazines and naphthoquinothiazines with the rules of Lipiński, Veber, and Egan suggests that the tested pentacyclic phenothiazine analogs have a chance to become therapeutic drugs, especially orally active drugs.

Synthesis, kinetics and cellular studies of new phenothiazine analogs as potent human-TLK inhibitors.

The alterations in the expression patterns of protein kinases often implicate human cancer initiation and progression. Human tousled-like kinases (TLKs), both TLK1/1B and TLK2, are evolutionary kinases found in cell signaling pathways and are involved in DNA repair, replication, and chromosomal integrity. Several reports have demonstrated the numerous roles of TLK1B in the development and progression of cancer via its interactions with different partners, and this direct association has made them viable molecular targets for cancer therapy. Previous studies have shown phenothiazines to be potent TLK1B inhibitors. Herein, we report the design and synthesis of a class of phenothiazine molecules and their biological inhibitory effect on hTLK1B/KD through in vitro kinase assays, cellular assays, and in silico studies. We identified a few inhibitors with better inhibition and physio-chemical properties than the reported TLK1B inhibitors using a recombinant human tousled-like kinase 1B-kinase domain (hTLK1B-KD). Very interestingly, inhibitory activity with LNCap cells was found to be on the sub-nanomolar level. Our attempts to study the newly designed phenothiazine analogs, as well as generate a stable catalytically active hTLK1B-KD in high yield, represent a fundamental step towards the structure-based design of future TLK-specific inhibitors.

Adsorption of Phenothiazine Derivatives on Graphene – DFT, Docking and MD Simulation

Impurity-related detection and certification cycle assumes significance in drug production and this study provides theoretical structural and spectral characterization of phenothiazine analogues, acepromazine (P1), amitriptyline (P2) and chlorpromazine HCl (P3) and their adsorption with graphene. Reactivity scores suggest these molecule’s properties are adequate, leading to the consideration of potential drug agents. MD simulations could identify P1, P2, P3 and complex with graphene has better binding energy and is more stable in simulation. Enhancement for different wavenumbers are seen in the graphene complex-molecules assembly.

Antiferroptotic Activity of Phenothiazine Analogues: A Novel Therapeutic Strategy for Oxidative Stress Related Disease.

Ferroptosis is an iron-catalyzed, nonapoptotic form of regulated necrosis that has been implicated in the pathological cell death associated with various disorders including neurodegenerative diseases (e.g., Friedreich's ataxia (FRDA), Alzheimer's disease, and Parkinson's disease), stroke, and traumatic brain injury. Recently, we showed that lipophilic methylene blue (MB) and methylene violet (MV) analogues both promoted increased frataxin levels and mitochondrial biogenesis, in addition to their antioxidant activity in cultured FRDA cells. Presently, we report the synthesis of series of lipophilic phenothiazine analogues that potently inhibit ferroptosis. The most promising compounds (1b-5b) exhibited an improved protection compared to the parent phenothiazine against erastin- and RSL3-induced ferroptotic cell death. These analogues have equivalent or better potency than ferrostatin-1 (Fer-1) and liproxstatin-1 (Lip-1), that are among the most potent inhibitors of this regulated cell death described so far. They represent novel lead compounds with therapeutic potential in relevant ferroptosis-driven disease models such as FRDA.

Tuning Electron-Withdrawing Strength on Phenothiazine Derivatives: Achieving 100 % Photoluminescence Quantum Yield by NO2 Substitution.

The weak fluorescence (quantum yield <1 % in cyclohexane) of phenothiazine (PTZ) impedes its further application. In addition, the nitro group (NO2 ) is a well-known fluorescence quencher. Interestingly, we obtained a highly fluorescent chromophore by combining these two moieties, forming 3-nitrophenothiazine (PTZ-NO2 ). For comparison, a series of PTZ derivatives bearing electron-withdrawing groups (EWGs; CN and CHO) or electron-donating groups (EDGs; OMe) at the 3-position have been designed and synthesized. The phenothiazines bearing EWGs exhibited enhanced emission compared with the parent PTZ or EDG derivatives. Computational approaches unveiled that for PTZ and PTZ-OMe, the transitions are from HOMOs dominated by π orbitals to LUMOs of mixed sulfur nonbonding-π* orbitals, and hence are partially forbidden. In contrast, the EWGs lower the energy level of the lone-pair electrons on the sulfur atom, thereby suppressing the mixing of the nonbonding orbital with the π* orbital in the LUMO, such that the allowed ππ* transition becomes dominant. This work thus demonstrates a judicious chemical design to fine-tune the transition character in PTZ analogues, with PTZ-NO2 attaining 100 % emission quantum yields in nonpolar solvent.

Tubulin Inhibitors Binding to Colchicine-Site: A Review from 2015 to 2019.

Due to the three domains of the colchicine-site which is conducive to the combination with small molecule compounds, colchicine-site on the tubulin has become a common target for antitumor drug development, and accordingly, a large number of tubulin inhibitors binding to the colchicine-site have been reported and evaluated over the past years. In this study, tubulin inhibitors targeting the colchicine-site and their application as antitumor agents were reviewed based on the literature from 2015 to 2019. Tubulin inhibitors were classified into ten categories according to the structural features, including colchicine derivatives, CA-4 analogs, chalcone analogs, coumarin analogs, indole hybrids, quinoline and quinazoline analogs, lignan and podophyllotoxin derivatives, phenothiazine analogs, N-heterocycle hybrids and others. Most of them displayed potent antitumor activity, including antiproliferative effects against Multi-Drug-Resistant (MDR) cell lines and antivascular properties, both in vitro and in vivo. In this review, the design, synthesis and the analysis of the structure-activity relationship of tubulin inhibitors targeting the colchicine-site were described in detail. In addition, multi-target inhibitors, anti-MDR compounds, and inhibitors bearing antitumor activity in vivo are further listed in tables to present a clear picture of potent tubulin inhibitors, which could be beneficial for medicinal chemistry researchers.

Bond Rotations and Heteroatom Effects in Donor-Acceptor-Donor Molecules: Implications for Thermally Activated Delayed Fluorescence and Room Temperature Phosphorescence.

The synthesis of 1-methylphenoxazine via CO2-directed lithiation chemistry is reported. This electron donor was coupled with 2,8-dibromodibenzothiophene- S, S-dioxide with Buchwald-Hartwig chemistry to give a new donor-acceptor-donor charge-transfer fluorescent molecule 1b. X-ray crystal structures and calculations show that the phenoxazinyl groups are coplanar and equatorial (eq) to the acceptor plane in nonmethylated 1a but are pyramidal and axial (ax) in 1b. The bond rotation energy barriers between donor and acceptor groups for 1a and 1b are only 0.13 and 0.19 eV, respectively, from hybrid-DFT computations at the CAM-B3LYP/6-31G(d) level. Many possible conformers are present in solutions and in zeonex. In zeonex, the methyl groups in 1b shift the emission band 0.13 eV higher in energy compared to 1a. Excited state eq-eq and ax-ax geometries were identified with DFT calculations with charge transfer (CT) emission assigned as 1CT(eq) and 1CT(ax) dominating. The lower energy 1CT(eq) contributes to thermally activated delayed fluorescence, whereas the higher energy 1CT(ax) does not. Phenothiazine analogues 2a and 2b also have major fluorescence emissions assigned as 1CT(eq) and 1CT(ax), respectively. 2a and 2b have substantial room temperature phosphorescence (RTP), whereas 1a and 1b do not, highlighting the importance of the sulfur atom in 2a and 2b to obtain RTP emission.

Lipophilic methylene violet analogues as modulators of mitochondrial function and dysfunction

In an effort to identify methylene blue analogues having improved antioxidant activity, a series of new methylene violet analogues have been designed and synthesized. The analogues were prepared following a synthetic route that is more efficient than the previously reported methods, both in terms of yield and purity of the final products. The route involves the Smiles rearrangement as one of the crucial steps. Smiles rearrangement of suitably substituted diphenyl sulfide intermediates afforded the corresponding phenothiazine analogues in high yields, which were subsequently converted to the final products. The methylene violet analogues were evaluated for their ability to preserve mitochondrial function in Friedreich’s ataxia (FRDA) lymphocytes. The analogues were shown to be efficient ROS scavengers, and able to protect cultured FRDA lymphocytes from oxidative stress resulting from inhibition of complex I. The analogues also preserved mitochondrial membrane potential and augmented ATP production. The analogues were found to be better antioxidants than the parent compounds methylene blue and methylene violet.

Microwave‐Assisted Catalytic Amination of Phenothiazine; Reliable Access to Phenothiazine Analogues of Tröger's Base

AbstractEfficient protocols for microwave‐assisted catalyzed amination of halogeno‐phenothiazines are described. Phenothiazine analogues of Tröger's base (PTB) were obtained by condensation of amino‐phenothiazines with formaldehyde in HCl/EtOH/H2O and structurally characterized by NMR and XRD analyses. The formation of PTB isomers was predicted by computational analysis based on theoretical methods (DFT and HF). Electronic properties of the parent amino‐phenothiazines and PTB were assessed on the basis of cyclic voltammetry and UV/Vis absorption/emission spectroscopy data. The compounds exhibit blue fluorescence emission characterized by extremely large Stokes shifts (8900–10300 cm–1) in both dilute solutions and aggregated states. Interactions with different types of biomolecules show the capacity of binding to proteins and DNA, with effects on prooxidant reactivity including lipid peroxidation.

Thioridazine: resurrection as an antimicrobial agent?

The emergence of multiresistant bacterial strains and the continuing burden of infectious disease globally point to the urgent need for novel affordable antimicrobial drugs. Thioridazine is a phenothiazine antipsychotic drug with well-recognized antimicrobial activity, but this property has not been harnessed for clinical use as a result of its central nervous system and cardiac side-effects. The cardiotoxicity of thioridazine has recently been shown to be structurally specific at a molecular level, whereas its antimicrobial properties are shared by a number of phenothiazine analogues. This raises the possibility that its enantiomers or its inactive metabolite, the ring sulphoxide, may act as a lead compound in the future development of antimicrobial drugs to face the new challenges in infectious disease.

Functional activity of the mouse flavin‐containing monooxygenase forms 1, 3, and 5

Three functional mouse flavin-containing monooxygenases (mFMOs) (i.e., mFMO1, mFMO3, and mFMO5) have been reported to be the major FMOs present in mouse liver. To examine the biochemical features of these enzymes, recombinant enzymes were expressed as maltose-binding protein fusion proteins (i.e., MBP-mFMO1, MBP-mFMO3, and MBP-mFMO5) in Escherichia coli and isolated and purified with affinity chromatography. The substrate specificity of these three mouse hepatic FMO enzymes were examined using a variety of substrates, including mercaptoimidazole, trimethylamine, S-methyl esonarimod, and an analog thereof, and a series of 10-(N,N-dimethylaminoalkyl)-2-(trifluoromethyl)phenothiazine analogs. The kinetic parameters of the three mouse FMOs for these substrates were compared in an attempt to explore substrate structure--function relationships specific for each mFMO. Utilizing a common phenothiazine substrate for all three enzymes, we compared the pH dependence for the recombinant enzymes under similar conditions. In addition, thermal stability for mFMO1, mFMO3, and mFMO5 enzymes was examined in the presence and absence of NADPH. The results revealed unique features for mFMO5, suggesting possible impact on the functional significance of this abundantly expressed FMO5 isoform in both human and mouse liver.

Synthesis and antitubercular activity of phenothiazines with reduced binding to dopamine and serotonin receptors

Analogs of the psychotropic phenothiazines were synthesized and examined as antitubercular agents against Mycobacterium tuberculosis H37Rv. The compounds were subsequently counter-screened for binding to the dopaminergic-receptor subtypes D1, D2, D3 and the serotonergic-receptor subtypes 5-HT 1A, 5-HT 2A, and 5-HT 2C. The most active compounds showed MICs from 2 to 4 μg/mL and had overall reduced binding to the dopamine and serotonin receptors compared to chlorpromazine and trifluoperazine.

Steady-state Kinetics and Inhibitory Action of Antitubercular Phenothiazines on Mycobacterium tuberculosis Type-II NADH-Menaquinone Oxidoreductase (NDH-2)

Type-II NADH-menaquinone oxidoreductase (NDH-2) is an essential respiratory enzyme of the pathogenic bacterium Mycobacterium tuberculosis (Mtb) that plays a pivotal role in its growth. In the present study, we expressed and purified highly active Mtb NDH-2 using a Mycobacterium smegmatis expression system, and the steady-state kinetics and inhibitory actions of phenothiazines were characterized. Purified NDH-2 contains a non-covalently bound flavin adenine dinucleotide cofactor and oxidizes NADH with quinones but does not react with either NADPH or oxygen. Ubiquinone-2 (Q2) and decylubiquinone showed high electron-accepting activity, and the steady-state kinetics and the NADH-Q2 oxidoreductase reaction were found to operate by a ping-pong reaction mechanism. Phenothiazine analogues, trifluoperazine, Compound 1, and Compound 2 inhibit the NADH-Q2 reductase activity with IC50 = 12, 11, and 13 microm, respectively. Trifluoperazine inhibition is non-competitive for NADH, whereas the inhibition kinetics is found to be uncompetitive in terms of Q2.

Inhibitors of type II NADH:menaquinone oxidoreductase represent a class of antitubercular drugs

Mycobacterium tuberculosis (Mtb) is an obligate aerobe that is capable of long-term persistence under conditions of low oxygen tension. Analysis of the Mtb genome predicts the existence of a branched aerobic respiratory chain terminating in a cytochrome bd system and a cytochrome aa(3) system. Both chains can be initiated with type II NADH:menaquinone oxidoreductase. We present a detailed biochemical characterization of the aerobic respiratory chains from Mtb and show that phenothiazine analogs specifically inhibit NADH:menaquinone oxidoreductase activity. The emergence of drug-resistant strains of Mtb has prompted a search for antimycobacterial agents. Several phenothiazines analogs are highly tuberculocidal in vitro, suppress Mtb growth in a mouse model of acute infection, and represent lead compounds that may give rise to a class of selective antibiotics.

In vitroscreening for inhibitors of the human mitotic kinesin Eg5 with antimitotic and antitumor activities

AbstractHuman Eg5, a member of the kinesin superfamily, plays a key role in mitosis, as it is required for the formation of a bipolar spindle. We describe here the first in vitro microtubule-activated ATPase-based assay for the identification of small-molecule inhibitors of Eg5. We screened preselected libraries obtained from the National Cancer Institute and identified S-trityl-l-cysteine as the most effective Eg5 inhibitor with an IC50 of 1.0 μmol/L for the inhibition of basal ATPase activity and 140 nmol/L for the microtubule-activated ATPase activity. Subsequent cell-based assays revealed that S-trityl-l-cysteine induced mitotic arrest in HeLa cells (IC50, 700 nmol/L) with characteristic monoastral spindles. S-trityl-l-cysteine is 36 times more potent for inducing mitotic arrest than the well-studied inhibitor, monastrol. Gossypol, flexeril, and two phenothiazine analogues were also identified as Eg5 inhibitors, and we found that they all result in monoastral spindles in HeLa cells. It is notable that all the Eg5 inhibitors identified here have been shown previously to inhibit tumor cell line growth in the NCI 60 tumor cell line screen, and we conclude that their antitumor activity may at least in part be explained by their ability to inhibit Eg5 activity.

Lead identification for modulators of multidrug resistance based on in silico screening with a pharmacophoric feature model.

Considerable effort has been devoted to the characterization of P-glycoprotein - drug interaction in the past. Systematic quantitative structure-activity relationship (QSAR) studies identified both predictive physicochemical parameters and pharmacophoric substructures within homologous series of compounds. Comparative molecular field analysis (CoMFA) led to distinct 3D-QSAR models for propafenone and phenothiazine analogs. Recently, several pharmacophore models have been generated for diverse sets of ligands. Starting from a training set of 15 propafenone-type MDR-modulators, we established a chemical function-based pharmacophore model. The pharmacophoric features identified by this model were (i) one hydrogen bond acceptor, (ii) one hydrophobic area, (iii) two aromatic hydrophobic areas, and (iv) one positive ionizable group. In silico screening of the Derwent World Drug Index using the model led to identification of 28 compounds. Substances retrieved by database screening are diverse in structure and include dihydropyridines, chloroquine analogs, phenothiazines, and terfenadine. On the basis of its general applicability, the presented 3DQSAR model allows in silico screening of virtual compound libraries to identify new potential lead compounds.

The 50th Anniversary of Chlorpromazine.

In 1891, Paul Ehrlich began investigating the possible antimalarial effects of methylene blue. His studies prompted other such studies with antimalarials, including pheno-thiazine analogues of the dye. One of these analogues, fenethazine, was found to be a potent antihistamine, and was well received by clinicians as an antiallergic drug. Homologues of fenethazine, although found to be weak antihistamines, had pronounced anticholinergic effects and were used successfully in the treatment of Parkinson's disease. Henri Laborit's search to find a drug that would be of value in preventing the traumatic consequences of shock caused by circulatory collapse during surgery led him to discover the important effects that antihistamines, particularly promethazine, had on the central nervous system. Investigations of centrally acting phenothiazines suitable to Laborit's requirements, with more sedating properties, eventually led to the development of chlorpromazine and its use as an antipsychotic drug. (c) 2002 Prous Science. All rights reserved.

Horseradish Peroxidase Immobilized Electrode for Phenothiazine Analysis

A horseradish peroxidase (HRP) immobilized carbon composite electrode has been developed for the amperometric study of phenothiazine analogues. Flow injection analysis and batch experiments have been realized in acetate buffer in the presence of hydrogen peroxide. Cyclic voltammetry and amperometry using a thin-layer flow cell (dual configuration, serial mode) have permitted one to suggest the mechanisms governing the biosensor signal at −0.1 V (vs. Ag/Ag+), in the presence of hydrogen peroxide, by addition of a phenothiazine derivative. It was inferred that electron transfer mediation by the phenothiazine occcurred at HRP/graphite adsorbed sites, in addition to peroxidation by dispersed HRP with substrate recycling at the graphite array-like structure of the biosensor. Thanks to these processes, high sensitivities were achieved especially in batch configurations, with amperometric detection capabilities down to 10−8 M in acetate buffer pH 4.7. Application of the biosensor to the determination of phenothiazines in drug formulations were realized.

Horseradish Peroxidase Immobilized Electrode for Phenothiazine Analysis

A horseradish peroxidase (HRP) immobilized carbon composite electrode has been developed for the amperometric study of phenothiazine analogues. Flow injection analysis and batch experiments have been realized in acetate buffer in the presence of hydrogen peroxide. Cyclic voltammetry and amperometry using a thin-layer flow cell (dual configuration, serial mode) have permitted one to suggest the mechanisms governing the biosensor signal at −0.1 V (vs. Ag/Ag+), in the presence of hydrogen peroxide, by addition of a phenothiazine derivative. It was inferred that electron transfer mediation by the phenothiazine occcurred at HRP/graphite adsorbed sites, in addition to peroxidation by dispersed HRP with substrate recycling at the graphite array-like structure of the biosensor. Thanks to these processes, high sensitivities were achieved especially in batch configurations, with amperometric detection capabilities down to 10−8 M in acetate buffer pH 4.7. Application of the biosensor to the determination of phenothiazines in drug formulations were realized.

Generation of electronically excited species during enzymatic oxidation of chlorpromazine and related compound

Chemiluminescence in visible region was detected, during peroxidase-catalyzed oxidation of chlorpromazine at pH7.5 (but not at pH4.25) or of propericiazine, both at pH7.5 and at pH4.25. Red colored intermediates, cation radicals, were produced and decayed in all enzymatic systems used. Chemiluminescence was also detected at pH7.5, but not at pH4.25, when synthesized cation radical of chlorpromazine in water was mixed with concentrated buffer. Protonation of alkyl nitrogen in the cation radical of chlorpromazine was highly related to the appearance of luminescence. Possible mechanisms of the generation of the excited phenothiazine analogs were discussed.