Allosteric Activators of Protein Phosphatase 2A Display Broad Antitumor Activity Mediated by Dephosphorylation of MYBL2.

Protein phosphatase 2A (PP2A) enzymes can suppress tumors, but they are often inactivated in human cancers overexpressing inhibitory proteins. Here, we identify a class of small-molecule iHAPs (improved heterocyclic activators of PP2A) that kill leukemia cells by allosterically assembling a specific heterotrimeric PP2A holoenzyme consisting of PPP2R1A (scaffold), PPP2R5E (B56ε, regulatory), and PPP2CA (catalytic) subunits. One compound, iHAP1, activates this complex but does not inhibit dopamine receptor D2, a mediator of neurologic toxicity induced by perphenazine and related neuroleptics. The PP2A complex activated by iHAP1 dephosphorylates the MYBL2 transcription factor on Ser241, causing irreversible arrest of leukemia and other cancer cells in prometaphase. In contrast, SMAPs, a separate class of compounds, activate PP2A holoenzymes containing a different regulatory subunit, do not dephosphorylate MYBL2, and arrest tumor cells in G1 phase. Our findings demonstrate that small molecules can serve as allosteric switches to activate distinct PP2A complexes with unique substrates.

Exploring the Theoretical Foundations of Thermally Activated Delayed Fluorescence (TADF) Emission: A Comprehensive TD-DFT Study on Phenothiazine Systems.

This study conducts a thorough theoretical investigation of Thermally Activated Delayed Fluorescence (TADF) in phenothiazine-based systems, examining ten molecular configurations recognized experimentally as TADF-active. Employing Time-Dependent Density Functional Theory (TD-DFT), our analysis spans the investigation of singlet-triplet energy gaps (ΔEST), spin-orbit coupling, and excitation characteristics using Multiwfn. This approach not only validates the adherence to El Sayed's rule across these systems but also provides a detailed understanding of charge transfer dynamics, as visualized through heat maps. A significant aspect of our study is the exploration of different oxidation states of sulfur and site substitutions on phenothiazine. This systematic variation aims to identify additional TADF-active compounds, drawing parallels with properties characterizing other known TADF emitters. Our investigation into Reverse Intersystem Crossing (rISC) rates and the analysis of dihedral angles in relation to ΔEST values offer nuanced insights into the TADF behaviours of these molecules. By integrating rigorous computational analysis with practical implications, we provide a foundational understanding that enhances the design and optimization of phenothiazine-based materials for optoelectronic applications. This work not only advances our theoretical understanding of TADF in phenothiazine derivatives but also serves as a guide for experimentalists and industry professionals in the strategic design of new TADF materials.

A New Phenothiazine-Based Fluorescent Probe for Rapid and Specific Detection of Fluoride.

Fluorescent probes with specific and rapid response to fluoride ions are important mediators for detecting fluoride ions in biological systems. In this study, a phenothiazine-based fluorescent probe, PTC, was designed and synthesized, which undergoes cleavage activation and cyclization induced by fluoride ions targeting Si-O bonds. The probe exhibits strong anti-interference properties and reaches peak fluorescence within 5 min, allowing for quantitative detection of fluoride ions content in the concentration range of 0 to 12.5µM, suitable for live cell fluorescence imaging. The research findings suggest its potential application value in biological systems.

Hemicyanine-Phenothiazine Based Highly Selective Ratiometric Fluorescent Probes for Detecting Hypochlorite Ion in Fruits, Vegetables and Beverages.

Hypochloric acid (HClO) is a reactive oxygen species (ROS) that functions as a bacteriostatic and disinfectant in food production. Excessive levels of ClO-, however, have been linked to various health issues, including cardiovascular diseases (Halliwell and Gutteridge in Oxford University press, USA, 2015), arthritis, and neurodegenerative diseases (Heinzelmann and Bauer in Biol Chem. 391(6):675-693, 2010). Therefore, synthesizing highly selective and sensitive probes for rapidly detecting endogenous ClO- in daily foods is currently a popular research topic (Kalyanaraman et al. in Redox Biol. 15:347-362, 2018; Winterbourn in Nat Chem Biol. 4(5):278-286, 2008; Turrens in J Physiol. 552(2):335-344, 2003). Thus, we have developed two highly selective ratiometric fluorescent probes (Probe1 and Probe2) based on indole-phenothiazine to detect ClO- in common vegetables, fruits and beverages qualitatively and quantitatively. Moreover, Both Probe1 and Probe2 have shown good specificity and stability, with high fluorescence intensity and long duration (Feng et al. in Adv Sci. 5:1800397, 2018; Wei et al. in Angew Chem. 131(14):4595-4599, 2019; Baruah et al. in J Mater Chem B, 2022).

New Butterfly-Shaped Naphthalimide-Based AIE Gens: Synthesis and Photophysical Properties.

Two novel naphthalimide derivatives PTZNI-Cz and PTZNI-TPA were successfully designed and synthesized, in which phenothiazine, triphenylamine and carbazole were used as electron donors and naphthalimide was used as the electron acceptor. Their photophysical, electrochemical, and thermal properties were investigated. These derivatives showed remarkable aggregation-induced emission (AIE) effect. Furthermore, the maximum emission peaks of PTZNI-Cz and PTZNI-TPA in the thin film state are at 610 nm and 623 nm respectively, which is typical of red fluorescent materials.

Synthesis of New D-π-A Phenothiazine-Based Fluorescent Dyes: Aggregation Induced Emission and Antibacterial Activity.

Highly solid-state fluorescent dyes based on phenothiazine bearing sulfa-drug derivatives were successfully prepared and fully characterized by NMR, mass spectra, and elemental analysis. The prepared phenothiazine dyes bearing sulfadiazine and sulfathiazole 4-(((10-hexyl-10 H-phenothiazin-3-yl)methylene)amino)-N-(pyrimidin-2yl) benzenesulfonamide (PTZ-1) and 4-(((10-hexyl-10 H-phenothiazin-3-yl) methylene) amino)-N-(thiazol-2-yl)benzenesulfonamide (PTZ-2), showed strong emission in polycrystalline form, and significant emission in solution was observed. The quantum yield of the prepared dyes varied and decreased by increasing the solvent polarity, with the maximum recorded value being 0.63 and 0.6 in dioxane. Aggregation-induced emission (AIE) and the effect of the solvent polarity on absorption and emission spectra were investigated. The dyeing application of polyester fabrics using the prepared phenothiazine-based dyes was studied, showing very good affinity to dyed fabrics. The antibacterial affinity against gram-positive and gram-negative bacteria for the dye powder as well as the dyed PET fabric was investigated, with PTZ-2 showing better affinity against bacteria compared to PTZ-1. This multifunctional property highlights the potential uses of PTZ-1 and PTZ-2 for advanced applications in biomedicine and optoelectronics.

Phenothiazines: Nrf2 activation and antioxidant effects.

Phenothiazines (PTZs) are an emerging group of molecules showing effectiveness toward redox signaling and reduction of oxidative injury to cells, via the activation on Kelch-like ECH-associated protein 1/nuclear factor erythroid 2-related factor 2 (Nrf2). Although several electrophilic and indirect Nrf2 activators have been reported, the risk of "off-target" effect due to the complexity of their molecular mechanisms of action, has aroused research interest toward non-electrophilic and direct modulators of Nrf2 pathway, such as PTZs. This review represents the first overview on the roles of PTZs as non-electrophilic Nrf2 activator and free radical scavengers, as well as on their potential therapeutic effects in oxidative stress-mediated diseases. Here, we provide a collective and comprehensive information on the PTZs ability to scavenge free radicals and activate the Nrf2 signaling pathway, with the aim to broaden the knowledge of their therapeutic potentials and to stimulate innovative research ideas.

Design and synthesis of sulfonamide phenothiazine derivatives as novel ferroptosis inhibitors and their therapeutic effects in spinal cord injury.

Ferroptosis is a novel style of cell death, and studies have shown that ferroptosis is strongly associated with spinal cord injury (SCI). A large number of ferroptosis inhibitors have been reported, but so far no ferroptosis inhibitor has been used clinically. Therefore there is an urgent need to discover a better inhibitor of ferroptosis. In this study, 24 novel sulfonamide phenothiazine ferroptosis inhibitors were designed and synthesized, followed by structure-activity relationship studies on these compounds. Among them, compound 23b exhibited the best activity in Erastin-induced PC12 cells (EC50 = 0.001 µM) and demonstrated a low hERG inhibition activity (IC50 > 30 µM). Additionally, compound 23b was identified as a ROS scavenger and showed promising therapeutic effects in an SD rat model of SCI. Importantly, 23b did not display significant toxicity in both in vivo and in vitro experiments and show good pharmacokinetic properties. These findings suggest that compound 23b, a novel ferroptosis inhibitor, holds potential as a therapeutic agent for spinal cord injury and warrants further investigation.

A novel approach to investigate the combinatorial effects of TLK1 (Tousled-Like Kinase1) inhibitors with Temozolomide for glioblastoma therapy.

Glioblastoma multiforme (GBM) is an aggressive, incurable brain tumor with poor prognosis and limited treatment options. Temozolomide (TMZ) is the standard chemotherapeutic treatment for GBM, but its efficacy has drawn strong criticism from clinicians due to short survival gains and frequent relapses. One critical limitation of TMZ therapy is the hyperactivation of DNA repair pathways, which over time neutralizes the cytotoxic effects of TMZ, thus highlighting the urgent need for new treatment approaches. Addressing this, our study explores the therapeutic potential of in-house-designed phenothiazine-based Tousled-like kinase-1 (TLK1) inhibitors for GBM treatment. TLK1, overexpressed in GBM, plays a role in DNA repair. Phenothiazines are known to cross the blood-brain barrier (BBB). Among all molecules, J54 was identified as a potential lead molecule with improved cytotoxicity. In the context of O6-methylguanine-DNA methyltransferase (MGMT)-deficient GBM cells, the combined administration of phenothiazines and TMZ exhibited a collective reduction in clonogenic growth, coupled with anti-migratory and anti-invasion effects. Conversely, in MGMT-proficient cells, phenothiazine monotherapy alone showed reduced clonogenic growth, along with anti-migratory and anti-invasion effects. Notably, a synergistic increase in γH2AX levels and concurrent attenuation of DNA repair upon combinatorial exposure to TMZ and J54 were observed, implying increased cytotoxicity due to sustained DNA strand breaks. Overall, this study provides new insights into TLK1 inhibition for GBM therapy. Collectively, these findings indicate that TLK1 is one of the upregulated kinases in GBM and phenothiazine-based TLK1 inhibitors could be a promising treatment option for GBM patients.

A PEGylated liposomal formulation of prochlorperazine that limits brain exposure but retains dynamin II activity: A potential adjuvant therapy for cancer patients receiving chemotherapeutic mAbs.

Anti-cancer monoclonal antibodies often fail to provide therapeutic benefit in receptor-positive patients due to rapid endocytosis of antibody-bound cell surface receptors. High dose co-administration of prochlorperazine (PCZ) inhibits endocytosis and sensitises tumours to mAbs by inhibiting dynamin II but can also introduce neurological side effects. We examined the potential to use PEGylated liposomal formulations of PCZ (LPCZ) to retain the anti-cancer effects of PCZ, but limit brain uptake. Uncharged liposomes showed complete drug encapsulation and pH-dependent drug release, but cationic liposomes showed limited drug encapsulation and lacked pH-dependent drug release. Uncharged LPCZ showed comparable inhibition of EGFR internalisation to free PCZ in KJD cells. After IV administration to rats, LPCZ reduced the plasma clearance and brain uptake of PCZ compared to IV PCZ. The results suggest that LPCZ may offer some benefit over PCZ as an adjunct therapy in cancer patients receiving mAb treatment.

Design, synthesis, structure elucidation, antimicrobial, molecular docking, and SAR studies of novel urea derivatives bearing tricyclic aromatic hydrocarbon rings.

The targeted compounds were prepared using both (9H-fluoren-9-ylidene)hydrazine (1) and 10H-phenothiazine (2) as starting materials. The treatment of 1 or 2 with different isocyanates afforded the title compounds 7a-d, 8a, and 8b in excellent yield. All compounds were characterized and ascertained by infrared, nuclear magnetic resonance, and elemental analyses as well as single-crystal X-ray diffraction. The antimicrobial efficiency of all was tested in vitro, and a noticeable inhibition activity against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans was obtained by compounds 7a, 7b, 8a, and 8b. Moreover, the biofilm mechanism activity was strongly inhibited by compounds 7b and 8b for all bacterial pathogens, with a percentage ratio of more than 55%. The findings from the molecular docking simulation revealed that compounds 7a, 7b, 8a, and 8b exhibited favorable binding energies and interacted effectively with the active sites of sterol 14-demethylase, dihydropteroate synthase, gyrase B, LasR (major transcriptional activator of P. aeruginosa), and carbapenemase for C. albicans, S. aureus, B. subtills, K. pneumoniae, and P. aeruginosa, respectively. These results suggest that the compounds have the potential to inhibit the activity of these enzymes and demonstrate promising antimicrobial properties. Moreover, the in silico evaluation of drug likeness and absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiles for compounds 7a, 7b, 8a, and 8b demonstrated their compatibility with Lipinski's, Ghose's, Veber's, Muegge's, and Egan's rules. These findings suggest that these compounds possess favorable physicochemical properties, making them promising candidates for continued drug development efforts.

Synthesis of new phenothiazine derivatives: Molecular docking, assessment of cytotoxic activity and oxidant-antioxidant properties on PCS-201-012, HT-29, and SH-SY5Y cell lines.

Phenothiazine (PTZ) derivatives have been acknowledged as versatile compounds with significant implications across various areas of medicine, particularly, in cancer research. The cytotoxic effects of synthesized compounds on both normal and cancerous cells, along with their oxidant-antioxidant properties, are pivotal factors in cancer treatment strategies. In the current study, eight new PTZ derivatives were synthesized and the compounds' cytotoxic activities were assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay while the oxidant-antioxidant properties were evaluated by oxidative stress index (OSI) calculation in SH-SY5Y (a human neuroblastoma cell line), HT-29 (a human colorectal adenocarcinoma cell line), and PCS-201-012 (a human primary dermal fibroblast cell line) cells. Consequently, the half-maximal inhibitory concentration (IC50) values of compound 3a were determined to be 218.72, 202.85, and 227.86 µM while the IC50 values of compound 3b were defined to be 227.42, 199.27, and 250.11 µM in PCS-201-012, HT-29, and SH-SY5Y cells, respectively. Additionally, it was determined that the synthesized compounds demonstrated the lowest OSI in PCS-201-012 cells as compared to the other cell lines.

Electrochemical Synthesis of the In Human S-oxide Metabolites of Phenothiazine-Containing Antipsychotic Medications.

The tractable preparation of Phase I drug metabolites is a critical step to understand the first-pass behaviour of novel chemical entities (NCEs) in drug discovery. In this study, we have developed a structure-electroactivity relationship (SeAR)-informed electrochemical reaction of the parent 2-chlorophenothiazine and the antipsychotic medication, chlorpromazine. With the ability to dial-in under current controlled conditions, the formation of S-oxide and novel S,S-dioxide metabolites has been achieved for the first time on a multi-milligram scale using a direct batch electrode platform. A potential rationale for the electrochemical formation of these metabolites in situ is proposed using molecular docking to a cytochrome P450 enzyme.

Chlorpromazine-Polypyrrole Drug Delivery System Tailored for Neurological Application.

Nowadays, drug delivery systems (DDSs) are gaining more and more attention. Conducting polymers (CPs) are efficiently used for DDS construction as such systems can be used in therapy. In this research, a well-known CP, polypyrrole (PPy), was synthesized in the presence of the polysaccharide heparin (HEP) and chlorpromazine (CPZ) using sodium dodecyl sulfate (SDS) as electrolyte on a steel substrate. The obtained results demonstrate the successful incorporation of CPZ and HEP into the polymer matrix, with the deposited films maintaining stable electrochemical parameters across multiple doping/dedoping cycles. Surface roughness, estimated via AFM analysis, revealed a correlation with layer thickness-decreasing for thinner layers and increasing for thicker ones. Moreover, SEM images revealed a change in the morphology of PPy films when PPy is electropolymerized in the presence of CPZ and HEP, while FTIR confirmed the presence of CPZ and HEP within PPy. Due to its lower molecular mass compared to HEP, CPZ was readily integrated into the thin polymer matrix during deposition, with diffusion being unimpeded, as opposed to films with greater thickness. Finally, the resulting system exhibited the ability to release CPZ, enabling a dosing range of 10 mg to 20 mg per day, effectively covering the therapeutic concentration range.

Synthesis and Structure of 5-Methyl-9-(trifluoromethyl)-12H-quino[3,4-b][1,4]benzothiazinium Chloride as Anticancer Agent.

In this work, the synthesis, structural analysis and anticancer properties of 5-methyl-9-trifluoromethyl-12H-quino[3,4-b][1,4]benzothiazinium chloride (3) are described. Compound 3 was synthesized by reacting 1-methyl-4-butylthio-3-(benzoylthio)quinolinium chloride with 4-(trifluoromethyl)aniline, respectively. The structure of the resulting product was determined using 1H-NMR and 13C-NMR spectroscopy as well as HR-MS spectrometry. The spatial geometry of agent 3 and the arrangement of molecules in the crystal (unit cell) were also confirmed using X-ray diffraction. The tetracyclic quinobenzothiazinium system is fairly planar because the dihedral angle between the planes formed by the benzene ring and the quinoline system is 173.47°. In order to obtain insight into the electronic charge distribution of the investigated molecule, electronic structure calculations employing the Density Functional Theory (DFT) were performed. Moreover, antiproliferative activity against a set of pancreatic cancer cell lines was tested, with compound 3 showing IC50 values against human primary pancreatic adenocarcinoma BxPC-3 and human epithelioid pancreatic carcinoma Panc-1 of 0.051 µM and 0.066 µM, respectively. The IC50 value of cytotoxicity/cell viability of the investigated compound assessed on normal human lung fibroblasts WI38 was 0.36 µM.

A Photoelectrochemical Sensor for the Detection of Hypochlorous Acid with a Phenothiazine-Based Photosensitizer.

This paper presents the development of a photoelectrochemical sensor for hypochlorous acid (HOCl) detection, employing a phenothiazine-based organic photosensitizer (Dye-PZ). The designed probe, Dye-PZ, follows a D-π-A structure with phenothiazine as the electron-donating group and a cyano-substituted pyridine unit as the electron-accepting group. A specific reaction of the phenothiazine sulfur atom with HOCl enables selective recognition. The covalent immobilization of Dye-PZ onto a titanium dioxide nanorod-coated fluorine-doped tin oxide electrode (FTO/TiO2) using bromo-silane coupling agent (BrPTMS) resulted in the fabrication of the photoanode FTO/TiO2/BrPTMS/Dye-PZ. The photoanode exhibited a significant photoresponse under visible-light irradiation, with a subsequent reduction in photocurrent upon reaction with HOCl. The oxidation of the phenothiazine sulfur atom to a sulfoxide diminished the internal charge transfer (ICT) effect. Leveraging this principle, the successful photoelectrochemical sensing of HOCl was achieved. The sensor showed high stability, excellent reproducibility, and selective sensitivity for HOCl detection. Our study provides a novel approach for the development of efficient photoelectrochemical sensors based on organic photosensitizers, with promising applications in water quality monitoring and biosensing.

Synthesis and Dynamic Behavior of Ce(IV) Double-Decker Complexes of Sterically Hindered Phthalocyanines.

Phthalocyanines and their double-decker complexes are interesting in designing rotative molecular machines, which are crucial for the development of molecular motors and gears. This study explores the design and synthesis of three bulky phthalocyanine ligands functionalized at the α-positions with phenothiazine or carbazole fragments, aiming to investigate dynamic rotational motions in these sterically hindered molecular complexes. Homoleptic and heteroleptic double-decker complexes were synthesized through the complexation of these ligands with Ce(IV). Notably, CeIV(Pc2)2 and CeIV(Pc3)2, both homoleptic complexes, exhibited blocked rotational motions even at high temperatures. The heteroleptic CeIV(Pc)(Pc3) complex, designed to lower symmetry, demonstrated switchable rotation along the pseudo-C4 symmetry axis upon heating the solution. Variable-temperature 1H-NMR studies revealed distinct dynamic behaviors in these complexes. This study provides insights into the rotational dynamics of sterically hindered double-decker complexes, paving the way for their use in the field of rotative molecular machines.

Phenothiazine Derivatives: The Importance of Stereoisomerism in the Tolerance and Efficacy of Antimicrobials.

Stereoisomers are molecules that are identical in atomic constitution and bonding. The biological properties may, however, differ significantly between two enantiomers (individual stereoisomers). JBC 1847, a phenothiazine derivative with strong antimicrobial activity against Gram-positive bacteria, exists in two enantiomers, S and R. Under standard chemical synthesis (S)-and (R)-JBC 1847 will be present in 50/50 amount (racemic). In this study, we have investigated the antimicrobial activity, the in vivo tolerance and therapeutic efficacy of purified (S)-JBC 1847. Compared to JBC 1847 racemic, the antimicrobial activity of (S)-JBC 1847 in vitro was in the same range or slightly increased, while the maximum tolerable concentration in vivo was five times higher for (S)-JBC 1847 (5 mg/kg versus 20 mg/kg bodyweight). Furthermore, the in vivo efficacy of (S)-JBC 1847 in a mouse peritonitis MRSA model was comparable to the activity of vancomycin. In conclusion, the antimicrobial activity and tolerance of a medical stereoisomeric compound may be significantly different using purified enantiomers compared with the racemic state. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-024-01309-3.

Bis-Ortho-Donor-Modification of Boracyclic π-Electron Systems beyond Steric Protection to Produce Thermally Activated Delayed Fluorescence Materials.

Polycyclic π-conjugated compounds that contain tricoordinate boron atoms at their periphery represent an attractive class of materials with electron-accepting character. Their molecular design generally requires the introduction of a bulky aryl group onto the boron atom, where it provides predominantly kinetic stabilization. The addition of extra functionality to the aryl group on the boron atom can be expected to further expand the potential utility of this class of materials. Herein, we report the synthesis of a series of boracyclic π-conjugated molecules with firm ortho B⋅⋅⋅N nonbonding interactions by introducing N-containing electron-donors at the ortho-positions of the aryl group on the boron atom. X-ray crystallographic analysis revealed that the combination of a planar boracyclic π-skeleton with only sp2 carbons and a strong electron-donating phenothiazine moiety results in a particularly short B⋅⋅⋅N distance. Theoretical study provided insights into the inherent nature of the B⋅⋅⋅N interaction. Owing to their donor-acceptor (D-A) structures, these molecules exhibit substantially red-shifted fluorescence in solution, albeit that the fluorescence quantum yields (ΦF) are low. In contrast, when incorporated into films, these compounds exhibit thermally activated delayed fluorescence (TADF) with improved ΦF values. Organic light-emitting diodes (OLEDs) fabricated using the ortho-donor-substituted derivatives exhibit orange-red electroluminescence.

Sequential C-F Bond Transformation of the Difluoromethylene Unit in Perfluoroalkyl Groups: A Combination of Fine-Tuned Phenothiazine Photoredox Catalyst and Lewis Acid.

A sequential process via photoredox catalysis and Lewis acid mediation for C-F bond transformation of the CF2 unit in perfluoroalkyl groups has been achieved to transform perfluoroalkylarenes into complex fluoroalkylated compounds. A phenothiazine-based photocatalyst promotes the defluoroaminoxylation of perfluoroalkylarenes with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) under visible light irradiation, affording the corresponding aminoxylated products. These products undergo a further defluorinative transformation with various organosilicon reagents mediated by AlCl3 to provide highly functionalized perfluoroalkyl alcohols. Our novel phenothiazine catalyst works efficiently in the defluoroaminoxylation. Transient absorption spectroscopy revealed that the catalyst regeneration step is crucial for the photocatalytic aminoxylation.