Novel Tetracyclic Azaphenothiazines with the Quinoline Ring as New Anticancer and Antibacterial Derivatives of Chlorpromazine.

Phenothiazine derivatives are widely studied in various fields such as biology, chemistry, and medicine research because of their pharmaceutical effects. The first compound used successfully in the treatment of psychosis was a phenthiazine derivative, chlorpromazine. Apart from its activity in neurons, chlorpromazine has also been reported to display anticancer and antibacterial properties. In this study, we present the synthesis and research on the activity of A549, MDA, MiaPaCa, PC3, and HCT116 cancer cell lines and of S. aureus, S. epidermidis, E. coli, and P. aeruginosa bacterial strains against a series of new tetracyclic chlorpromazine analogues containing a quinoline scaffold in their structure instead of the benzene ring and various substituents at the thiazine nitrogen. The structure of these novel molecules has been determined by 1H NMR, 13C NMR, and HRMS spectral techniques. The seven most active of the twenty-four new chlorpromazine analogues tested were selected to study the mechanism of cytotoxic action. Their ability to induce apoptosis or necrosis in cancer cells was assessed by flow cytometry analysis. The results obtained confirmed the proapoptotic activity of selected compounds, especially in terms of inducing late apoptosis or necrosis in cancer cell lines A549, MiaPaCa-2, and HCT-116. Furthermore, studies on the induction of cell cycle arrest suggest that the new chlorpromazine analogues exert antiproliferative effects by inducing cell cycle arrest in the S phase and, consequently, apoptosis.

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 Lipinski, Veber, and Egan suggests that the tested pentacyclic phenothiazine analogs have a chance to become therapeutic drugs, especially orally active drugs.

Study of Lipophilicity and ADME Properties of 1,9-Diazaphenothiazines with Anticancer Action.

Lipophilicity is one of the key properties of a potential drug that determines the solubility, the ability to penetrate through cell barriers, and transport to the molecular target. It affects pharmacokinetic processes such as adsorption, distribution, metabolism, excretion (ADME). The 10-substituted 1,9-diazaphenothiazines show promising if not impressive in vitro anticancer potential, which is associated with the activation of the mitochondrial apoptosis pathway connected with to induction BAX, forming a channel in MOMP and releasing cytochrome c for the activation of caspases 9 and 3. In this publication, the lipophilicity of previously obtained 1,9-diazaphenothiazines was determined theoretically using various computer programs and experimentally using reverse-phase thin-layer chromatography (RP-TLC) and a standard curve. The study presents other physicochemical, pharmacokinetic, and toxicological properties affecting the bioavailability of the test compounds. ADME analysis was determined in silico using the SwissADME server. Molecular targets studies were identified in silico using the SwissTargetPrediction server. Lipinski's rule of five, Ghose's, and Veber's rules were checked for the tested compounds, confirming their bioavailability.

14-Substituted Diquinothiazines as a New Group of Anticancer Agents.

A series of novel double-angularly condensed diquinothiazines with aminoalkyl, amidoalkyl, sulfonamidoalkyl, and substituted phenyl groups was designed, synthesized, and evaluated for their anticancer activity against four selected human tumor cell lines (HTC116, SH-SY5Y, A549, and H1299). The cytotoxicity of the novel diquinothiazines was investigated against BEAS-2B cells. The activities of the compounds were compared to etoposide. Among them, compounds with aminoalkyl and phenyl groups showed excellent broad-spectrum anticancer activity. The most active 14-(methylthiophenyl)diquinothiazine, 3c, showed low cytotoxicity against BEAS-2B cells and high activity against tumor cell lines HTC116, SH-SY5Y, A549, and H1299, with IC50 values of 2.3 µM, 2.7 µM, 17.2 µM, and 2.7 µM, respectively (etopiside 8.6 µM, 3.9 µM, 44.8 µM, and 0.6, respectively). Live long-term microscopic observations of cell survival using the starting molecule M0 were also performed. Flow cytometry showed the proapoptotic effects of the studied diquinothiazines. Inhibition of the cell cycle in the S phase was observed, which is associated with damage to nucleic acids and connected to DNA replication arrest.

Synthesis and Structural Characterization of Novel Dimers of Dipyridothiazine as Promising Antiproliferative Agents.

Many new isomeric dipyridothiazine dimers have been presented as molecules with anticancer potential. These compounds were obtained in efficient syntheses of 1,6-, 1,8-, 2,7- and 3,6-diazaphenothiazines with selected alkylaromatic linkers. The structures of these compounds has been proven with two-dimensional spectroscopic techniques (COSY, NOESY, HSQC and HMBC) and high-resolution mass spectrometry (HRMS). In silico analyses of probable molecular targets were performed using the Way2Drug server. All new dimers were tested for anticancer activity against breast cancer line MCF7 and colon cancer line SW480. Cytotoxicity was assessed on normal L6 muscle cells. The tested dimers had high anticancer potential expressed as IC50 and the selectivity index SI. The most active derivative, 4c, showed an IC50 activity of less than 1 µM and an SI selectivity index higher than 100. Moreover, the compounds were characterized by low toxicity towards normal cells, simultaneously indicating a high cytostatic potential.

Lipophilicity and Pharmacokinetic Properties of New Anticancer Dipyridothiazine with 1,2,3-Triazole Substituents.

The lipophilicity parameters (logPcalcd, RM0 and logPTLC) of 10 new active anticancer dipirydothiazines with a 1,2,3-triazole ring were determined theoretically using computational methods and experimentally by reversed-phase TLC. Experimental lipophilicity was assessed using mobile phases (a mixture of TRIS buffer and acetone) using a linear correlation between the RM retention parameter and the volume of acetone. The RM0 parameter was correlated with the specific hydrophobic surface b, revealing two congenerative subgroups: 1,2,3-triazole-1,6-diazaphenothiazines and 1,2,3-triazole-1,8-diazaphenothiazines hybrids. The RM0 parameter was converted into the logPTLC lipophilicity parameter using a calibration curve. The investigated compounds appeared to be moderately lipophilic. Lipophilicity has been compared with molecular descriptors and ADME properties. The new derivatives followed Lipinski's, Ghose's and Veber's rules.

Tri- and Pentacyclic Azaphenothiazine as Pro-Apoptotic Agents in Lung Carcinoma with a Protective Potential to Healthy Cell Lines.

The phenothiazine derivatives, tricyclic 10H-3,6-diazaphenothiazine (DPT-1) and pentacyclic 7-(3'-dimethylaminopropyl)diquinothiazine (DPT-2), have recently been shown to exhibit promising anticancer activities in vitro. In this report, we demonstrated that DPT-1 and DPT-2 could be pro-apoptotic agents in lung carcinoma, the human lung carcinoma A549 and non-small lung carcinoma H1299, in the range of IC50 = 1.52-12.89 µM, with a protective potential to healthy cell lines BEAS-2B and NHDF. The compounds showed higher activity in the range of the tested concentrations and low cytotoxicity in relation to normal healthy cells than doxorubicin, used as the reference drug. The cytostatic potential of DPT-1 and DPT-2 was demonstrated with the use of MTT assay. Cell cycle analysis via flow cytometry using Annexin-V assay showed the pro-apoptotic and pro-necrotic role of the studied diazaphenothiazines in the cell cycle. DPT-1 and DPT-2 initiated a biological response in the investigated cancer models with a different mechanism and at a different rate. Based on these findings, it can be concluded that DPT-1 and DPT-2 have potential as chemotherapeutic agents.

Dual Action of Dipyridothiazine and Quinobenzothiazine Derivatives-Anticancer and Cholinesterase-Inhibiting Activity.

The inverse correlation observed between Alzheimer's disease (AD) and cancer has prompted us to look for cholinesterase-inhibiting activity in phenothiazine derivatives that possess anticancer properties. With the use of in silico and in vitro screening methods, our study found a new biological activity in anticancer polycyclic, tricyclic, and tetracyclic compounds. The virtual screening of a library of 120 ligands, which are the derivatives of azaphenothiazine, led to the identification of 25 compounds that can act as potential inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Biological assays revealed the presence of selective inhibitors of eeAChE (electric eel AChE) or eqBuChE (equine serum BuChE) and nonselective inhibitors of both enzymes among the tested compounds. Their potencies against eeAChE were in a submicromolar-to-micromolar range with IC50 values from 0.78 to 19.32 µM, while their IC50 values against eqBuChE ranged from 0.46 to 10.38 µM. The most potent among the compounds tested was the tetracyclic derivative, 6-(4-diethylaminobut-2-ynyl)-9-methylthioquinobenzothiazine 24, which was capable of inhibiting both enzymes. 9-Fluoro-6-(1-piperidylethyl)quinobenzothiazine 23 was found to act as a selective inhibitor of eqBuChE with an IC50 value of 0.46 µM. Compounds with such a dual antitumor and cholinesterase-inhibitory activity can be considered as a valuable combination for the treatment of both cancer and AD prevention. The results presented in this study might open new directions of research on the group of tricyclic phenothiazine derivatives.

Evaluation of angularly condensed diquinothiazines as potential anticancer agents.

We present efficient synthesis of isomeric types of angularly fused diquinothiazines in the reactions of 2,2'-dichloro-3,3'-diquinolinyl disulfide and diquinodithiin with 3-, 5-, 6- and 8-aminoquinolines. The pentacyclic diquinothiazine ring systems were identified as diquino[3,2-b;3',4'-e][1,4]thiazine, diquino[3,2-b;5',6'-e][1,4]thiazine, diquino[3,2-b;6',5'-e][1,4]thiazine and diquino[3,2-b;8',7'-e][1,4]thiazine with advanced two-dimensional 1H and 13C NMR techniques (COSY, ROESY, HSQC and HMBC) of N-methyl derivatives. The identification of pentacyclic ring system was confirmed by X-ray diffraction analysis of selected N-alkyl derivatives. The X-ray analysis revealed different spatial structures of the ring system (planar and folded). NH-diquinothiazines were further transformed into N-alkyl and N-dialkylaminoalkyl derivatives. Most of diquinothiazines exhibited significant cancer cell growth inhibition against the human glioblastoma SNB-19, colorectal carcinoma Caco-2, breast cancer MDA-MB-231 and lung cancer A549 cell lines with the IC50 values < 3 µM. This anti-proliferative activity was found to be more than for cisplatin. The most promising compound, 7-dimethylaminopropyldiquino[3,2-b;6',5'-e]thiazine, was used for gene expression analysis by reverse transcription-quantitative real-time PCR (RT-QPCR) method. The expression of H3, TP53, CDKN1A, BCL-2 and BAX genes revealed that this compound inhibited the proliferation in all cells (H3) and activated mitochondrial events of apoptosis (BAX/BCL-2) in two cancer cell lines (SNB-19 and Caco-2).

10H-1,9-diazaphenothiazine and its 10-derivatives: synthesis, characterisation and biological evaluation as potential anticancer agents.

10H-1,9-diazaphenothiazine was obtained in the sulphurisation reaction of diphenylamine with elemental sulphur and transformed into new 10-substituted derivatives, containing alkyl and dialkylaminoalkyl groups at the thiazine nitrogen atom. The 1,9-diazaphenothiazine ring system was identified with advanced 1H and 13C NMR techniques (COSY, NOESY, HSQC and HMBC) and confirmed by X-ray diffraction analysis of the methyl derivative. The compounds exhibited significant anticancer activities against the human glioblastoma SNB-19, melanoma C-32 and breast cancer MDA-MB-231 cell lines. The most active 1,9-diazaphenothiazines were the derivatives with the propynyl and N, N-diethylaminoethyl groups being more potent than cisplatin. For those two compounds, the expression of H3, TP53, CDKN1A, BCL-2 and BAX genes was detected by the RT-QPCR method. The proteome profiling study showed the most probable compound action on SNB-19 cells through the intrinsic mitochondrial pathway of apoptosis. The 1,9-diazaphenotiazine system seems to be more potent than known isomeric ones (1,6-diaza-, 1,8-diaza-, 2,7-diaza- and 3,6-diazaphenothiazine).

Synthesis, Anticancer Activity, and Apoptosis Induction of Novel 3,6-Diazaphenothiazines.

New 10-substituted derivatives of 3,6-diazaphenothiazine, containing the triple bond linker terminated with tertiary cyclic and acyclic amine groups, were synthesized and screened for their anticancer action. The compounds exhibited varied anticancer activities against human glioblastoma SNB-19, melanoma C-32, and breast cancer MDA-MB231 cell lines, depending on the nature of the substituents. The most active 3,6-diazaphenothiazine, 4, was the derivative with the N,N-diethylamino-2-butynyl substituent against glioblastoma SNB-19, and was ten times more potent than cisplatin. For this compound, the expression of H3, TP53, CDKN1A, BCL-2, and BAX genes was detected by the RT-qPCR method. The gene expression ratio BAX/BCL-2 indicated the induction of mitochondrial apoptosis in cancer cell lines. The transformation of the propynyl substituent into amino-2-butynyl can be a method applicable to the search for more anticancer-active azaphenothiazines.

Design, Synthesis, and Structural Characterization of Novel Diazaphenothiazines with 1,2,3-Triazole Substituents as Promising Antiproliferative Agents.

A series of novel 1,2,3-triazole-diazphenothiazine hybrids was designed, synthesized, and evaluated for anticancer activity against four selected human tumor cell lines (SNB-19, Caco-2, A549, and MDA-MB231). The majority of the synthesized compounds exhibited significant potent activity against the investigated cell lines. Among them, compounds 1d and 4c showed excellent broad spectrum anticancer activity, with IC50 values ranging from 0.25 to 4.66 µM and 0.25 to 6.25 µM, respectively. The most promising compound 1d, possessing low cytotoxicity against normal human fibroblasts NHFF, was used for gene expression analysis using reverse transcription-quantitative real-time PCR (RT-qPCR). The expression of H3, TP53, CDKN1A, BCL-2, and BAX genes revealed that these compounds inhibited the proliferation in all cells (H3) and activated mitochondrial events of apoptosis (BAX/BCL-2).

An Anti-Inflammatory Azaphenothiazine Inhibits Interferon ß Expression and CXCL10 Production in KERTr Cells.

An azaphenothiazine derivative, 6-chloroethylureidoethyldiquino[3,2-b;2',3'-e][1,4]thiazine (DQT), has recently been shown to exhibit immunosuppressive activities in mouse models. It also inhibited the expression of CXCL10 at the protein level, at non-toxic concentrations, in the culture of KERTr cells treated with double-stranded RNA, poly(I:C). In this report, we demonstrated that DQT inhibits the transcription of the CXCL10 gene. Although CXCL10 is an IFNγ-inducible protein, we found that the CXCL10 protein was induced without the detectable release of IFNγ or IκB degradation. Hence, we concluded that IFNγ or NFκB was not involved in the regulation of the CXCL10 gene in KERTr cells transfected with poly(I:C), nor in the inhibitory activity of DQT. On the other hand, we found that IFNß was induced under the same conditions and that its expression was inhibited by DQT. Kinetic analysis showed that an increase in IFNß concentrations occurred 4⁻8 h after poly(I:C) treatment, while the concentration of CXCL10 was undetectable at that time and started to increase later, when IFNß reached high levels. Therefore, DQT may be regarded as a new promising inhibitor of IFNß expression and IFNß-dependent downstream genes and proteins, e.g., CXCL10 chemokine, which is implicated in the pathogenesis of autoimmune diseases.

3,6-Diazaphenothiazines as potential lead molecules - synthesis, characterization and anticancer activity.

3,6-Diazaphenothiazines were obtained in cyclization of 3-amino-3'-nitro-2,4'-dipyridinyl sulfide and the reaction of sodium 3-amino-2-pyridinethiolate with 4-chloro-3-nitropyridine followed by alkylation and heteroarylation. The thiazine ring formation ran via the Smiles rearrangement. The structure elucidation was based on 2D NMR and X-ray analysis of N-methylated product. 3,6-Diazaphenothiazines were investigated for antitumor activity using glioblastoma SNB-19, melanoma C-32 and breast cancer MCF-7 cells. 10H-3,6-diazaphenothiazine was 10 times more active (IC50 < 0.72 µg/mL) than cisplatin. Two diazaphenothiazines with the 2-pyrimidinyl and dimethylaminopropyl substituents were selectively active against MCF-7 and C-32 cells. The expressions of H3 (proliferation marker), TP53, CDKN1A (cell cycle regulators), BAX and BCL-2 (proapoptopic and antiapoptopic genes) were detected by RT-QPCR method. The expression analysis suggests the cell cycle arrest and the mitochondrial apoptosis pathway activation in MCF-7 and SNB-19 cells.

Synthesis and anticancer and lipophilic properties of 10-dialkylaminobutynyl derivatives of 1,8- and 2,7-diazaphenothiazines.

New derivatives of two isomeric types of azaphenothiazines, 1,8- and 2,7-diazaphenothiazine, containing the triple bond substituents and additionally tertiary cyclic and acyclic amine groups, were synthesized and tested for their anticancer activity. The compounds exhibited differential inhibitory activities. Better results were obtained when the acetylenic group was transformed via the Mannich reaction to the dialkylaminobutynyl groups. The most active was 2,7-diazaphenothiazine with the N-methylpiperazine-2-butynyl substituent against the human ductal breast epithelial tumor cell line T47D, more potent than cisplatin. The 2,7-diazaphenothiazine system turned out to be more active than isomeric 1,8-diaza one. For the most active compound, the expression of TP53, CDKN1A, BCL-2 and BAX genes was detected by the RT-QPCR method. The gene expression ratio BACL-2/BAX suggests the mitochondrial apoptosis in T47D cells. The synthesis makes possible to obtain many new bioactive phenothiazines with the dialkylaminoalkynyl substituents inserting various tertiary cyclic and acyclic amine moieties to the substituents.

Synthesis and biological evaluation of novel propargylquinobenzothiazines and their derivatives as potential antiproliferative, anti-inflammatory, and anticancer agents.

Azaphenothiazines containing the quinoline ring, 8-10-substituted 6H-quinobenzothiazines and 6H-diquinothiazine were transformed into new 6-propargyl and 6-dialkylaminobutynyl derivatives containing the triple bond. Most of them displayed strong antiproliferative actions against human peripheral blood mononuclear cells (PBMC) stimulated with phytohemagglutinin A (PHA), strongly suppressed lipopolysaccharide (LPS)-induced TNF-α production by whole blood human cell cultures, and exhibited low cytotoxicity. Three propargylquinobenzothiazines with the bromine, trifluoromethyl, and methylthio groups at position 9 and propargyldiquinothiazine exhibited comparable actions to cisplatin against the L-1210 and SW-948 tumor lines. 6-Propargyl-9-trifluoromethylquinobenzothiazine was shown to block caspase 3 expression and inhibit expression of caspase 8 and 9 in Jurkat cells indicating its possible mechanism of action. These derivatives could be promising, potential therapeutics for treatment of neoplastic diseases and autoimmune disorders.

Synthesis, spectroscopic characterization, and anticancer activity of new 10-substituted 1,6-diazaphenothiazines.

New phenothiazine derivatives as 10-substituted dipyridothiazines of the 1,6-diazaphenothiazine structure were obtained in the cyclization reaction of 3-amino-3'-nitro-2,2'-dipyridinyl sulfide and 3,3'-dinitro-2,2'-dipyridinyl disulfide, and in the reaction of 2-chloro-3-ntropyridine with sodium 3-amino-2-pyridinethiolate followed by various alkylation and arylation reactions. The reaction of the thiazine ring formation ran via the Smiles rearrangement of the S-N type. As the alkylation reactions could proceed at the thiazine, azine or both nitrogen atoms, the product structure elucidation was based on the 2D NMR (Rotating-frame Overhauser Effect Spectroscopy, Correlated Spectroscopy, Heteronuclear Single Quantum Coherence, and Heteronuclear Multiple Bond Correlation) spectra of the N-methylated product. Some 10-substituted 1,6-diazaphenothizines (5, 10, 12, 13) were at least anticancer active against melanoma C-32 and breast cancer MCF-7 cell lines as a reference drug - cisplatin. The monoazaphenothiazine drug, prothipendyl, turned out to be less active than least 6 derivatives of the 1,6-diazaphenothiazine structure.

Discovery of butyrylcholinesterase inhibitors among derivatives of azaphenothiazines.

The study presents the discovery of novel butyrylcholinesterase (BuChE) inhibitors among derivatives of azaphenothiazines by application of in silico and in vitro screening methods. From an in-house library of compounds, 143 heterocyclic molecules derived from the azaphenothiazine scaffold were chosen for virtual screening. Based on results of the docking procedure, 15 compounds were identified as exhibiting the best fit for the two screening complexes (ligand - AChE and ligand - BuChE). Five compounds displayed moderate AChE and good BuChE inhibitory activity at screening concentrations of 10 µM. The IC50 values for active BuChE inhibitors were in the 11.8-122.2 nM range. Three of the most active inhibitors are tetra- or pentacyclic derivatives of azaphenothiazines with the same N-methyl-2-piperidinethyl substituent.

Synthesis and selected immunological properties of 10-substituted 1,8-diazaphenothiazines.

A new type of tricyclic azaphenothiazines-1,8-diazaphenothiazines-was obtained in the reaction of 2,3- and 3,4-disubstituted pyridines. The reaction ran as the Smiles rearrangement. The 1,8-diazaphenothiazine system was determined using NOE experiment and 2D NMR spectra (COSY, HSQC, HMBC). 10H-1,8-diazaphenothiazine was transformed into 10-derivatives with alkyl, aminoalkyl, amidoalkyl, sulfonamidoalkyl, and nitrogen half-mustard groups. The compounds were tested for their effects on phytohemagglutinin A-induced proliferative response of human peripheral blood mononuclear cells (PBMC) and lipopolysaccharide-induced tumor necrosis factor alpha production by human whole blood cultures. The compounds exhibited differential, dose-dependent inhibitory activities in these tests. All the compounds were low toxic against PBMC. The compounds showing the highest antiproliferative activity strongly inhibited the growth of leukemia L-1210 and colon cancer SW-948 cell lines, similarly as cisplatin, a reference drug.

Synthesis of quinoline/naphthalene-containing azaphenothiazines and their potent in vitro antioxidant properties.

New tetracyclic and pentacyclic azaphenothiazines containing one or two quinoline rings instead of benzene rings were obtained in the original reactions of isomeric diquinodithiins, dichlorodiquinolinyl sulfides, and disulfide with aromatic amines. The type of ring fusion in the azaphenothiazine system was concluded from the 1H NMR spectra. The obtained azaphenothiazines were evaluated in vitro for their antioxidant activity on rat hepatic microsomal membranes for protection of non-enzymatic lipid peroxidation promoted by the Fe2+/ascorbic acid redox system. Most compounds exhibited a very significant antioxidant activity with IC50 values between 1 and 23 µM. The degree of antioxidant activity depends on the lipophilicity and molecular size as well as the (non)substitution of the thiazine nitrogen atom and type of ring system fusion. It is the first time to our knowledge that azaphenothiazines are shown to exhibit such potent antioxidant activity.