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.

Design, synthesis, and molecular docking of new phenothiazine incorporated N-Mannich bases as promising antimicrobial agents

The present work aims to synthesize four series of phenothiazine incorporation Mannich bases. Therefore, 10-methyl-10H-phenothiazine-3-sulfonamide (4) which was subjected to react with some secondary amines and formaldehyde to give the Mannich bases 5a-f, and 6-13. Compound 13 was then subjected to react with some secondary amines and formaldehyde to give the corresponding Mannich bases 14a-f. In total, twenty-two new compounds were synthesized and evaluated for in vitro growth inhibition activity against P. aeruginosa, E. coli, and S. aureus. Among the tested compounds, compounds 3, 5a, 5c, 6, 12, 13, 14d, and 14e exhibited good activity with a MIC value (12.5 μg/mL), compounds 5b, 10, 11, 14a, and 14c exhibited strong activity against the growth of S. aureus with a MIC value (6.25 μg/mL), and compound 14b superior against S. aureus with a MIC value (3.125 μg/mL) compared to drug reference ciprofloxacin with MIC value (2 μg/mL). The molecular docking investigation revealed the presence of many derivatives with high binding affinities and distinct interaction patterns with the target protein. Derivatives 14a-e emerged as the most promising possibilities, displaying the greatest binding energies and a varied variety of interaction types, including hydrogen bonding and pi interactions, over different distances, with derivative 14b exhibiting the highest binding energy at S = -8.3093 kcal/mol. These derivatives displayed superior binding affinities and various interaction mechanisms with the target protein, suggesting that they have great promise as lead compounds for future development into therapeutic medicines.

Formamidinium Lead Iodide-Based Inverted Perovskite Solar Cells with Efficiency over 25 % Enabled by An Amphiphilic Molecular Hole-Transporter

Formamidinium lead iodide (FAPbI3) represents an optimal absorber material in perovskite solar cells (PSCs), while the application of FAPbI3 in inverted-structured PSCs has yet to be successful, mainly owing to its inferior film-forming on hydrophobic or defective hole-transporting substrates. Herein, we report a substantial improvement of FAPbI3-based inverted PSCs, which is realized by a multifunctional amphiphilic molecular hole-transporter, (2-(4-(10H-phenothiazin-10-yl)phenyl)-1-cyanovinyl)phosphonic acid (PTZ-CPA). The phenothiazine (PTZ) based PTZ-CPA, carrying a cyanovinyl phosphonic acid (CPA) group, forms a superwetting hole-selective underlayer that enables facile deposition of high-quality FAPbI3 thin films. Compared to a previously established carbazole-based hole-selective material (2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid (MeO-2PACz), the crystallinity of FAPbI3 is enhanced and the electronic defects are passivated by the PTZ-CPA more effectively, resulting in remarkable increases in photoluminescence quantum yield (four-fold) and Shockley-Read-Hall lifetime (eight-fold). Moreover, the PTZ-CPA shows a larger molecular dipole moment and improved energy level alignment with FAPbI3, benefiting the interfacial hole-collection. Consequently, FAPbI3-based inverted PSCs achieve an unprecedented efficiency of 25.35 % under simulated air mass 1.5 (AM1.5) sunlight. The PTZ-CPA based device shows commendable long-term stability, maintaining over 90 % of its initial efficiency after continuous operation at 40 °C for 2000 hours.

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).

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.

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.

Targeting autophagy by antipsychotic phenothiazines: potential drug repurposing for cancer therapy

Cancer is recognized as the major cause of death worldwide and the most challenging public health issues. Tumor cells exhibit molecular adaptations and metabolic reprograming to sustain their high proliferative rate and autophagy plays a pivotal role to supply the high demand for metabolic substrates and for recycling cellular components, which has attracted the attention of the researchers. The modulation of the autophagic process sensitizes tumor cells to chemotherapy-induced cell death and reverts drug resistance. In this regard, many in vitro and in vivo studies having shown the anticancer activity of phenothiazine (PTZ) derivatives due to their potent cytotoxicity in tumor cells. Interestingly, PTZ have been used as antiemetics in antitumor chemotherapy-induced vomiting, maybe exerting a combined antitumor effect. Among the mechanisms of cytotoxicity, the modulation of autophagy by these drugs has been highlighted. Therefore, the use of PTZ derivatives can be considered as a repurposing strategy in antitumor chemotherapy. Here, we provided an overview of the effects of antipsychotic PTZ on autophagy in tumor cells, evidencing the molecular targets and discussing the underlying mechanisms. The modulation of autophagy by PTZ in tumor cells have been consistently related to their cytotoxic action. These effects depend on the derivative, their concentration, and also the type of cancer. Most data have shown the impairment of autophagic flux by PTZ, probably due to the blockade of lysosome-autophagosome fusion, but some studies have also suggested the induction of autophagy. These data highlight the therapeutic potential of targeting autophagy by PTZ in cancer chemotherapy.

Sedative and cardiorespiratory effects of dexmedetomidine alone or combined with acepromazine in healthy cats

The purpose of this study was to assess sedation, emesis and cardiovascular effects of dexmedetomidine alone or combined with acepromazine in healthy cats. Fourteen male cats aged 0.9 ± 0.5 years and weighing 3.7 ± 0.7 kg were randomly assigned to one of two experimental groups: GD, dexmedetomidine 5 µg/kg; and GDA, dexmedetomidine 5 µg/kg with acepromazine 0.03 mg/kg, all intramuscularly. Measurements were recorded at baseline, at 20 minutes and then at 10-minute intervals following sedation and included heart rate (HR), respiratory rate (FR), systolic arterial pressure (SAP), rectal temperature (RT), number of episodes of emesis and sedation score (0-4). Data were compared using ANOVA for repeated measures followed by Šídák and Dunnet test. Sedation scores were compared between groups at T20 using Mann-Whitney test. Significance was considered when P <0.05. At T20, HR was significantly lower in GDA (99 ± 14 beats/min) compared with GD (133 ± 19 beats/min) and SAP was significantly lower in both groups compared with baseline (126 ± 14 vs. 148 ± 26 and 111 ± 13 vs. 144 ± 17 mmHg in GD and GDA, respectively). Duration of sedation was similar between groups, although sedation scores differed significantly at T20, with 1 (0-4) in GD and 4 (4-4) in GDA. More episodes of emesis were recorded in GD compared with GDA. The combination of dexmedetomidine and acepromazine produced more profound sedation with faster onset and lower incidence of emesis compared with dexmedetomidine alone in healthy cats.

Phenothiazine-based fluorescent probes for the detection of hydrazine in environment and living cells

As an important chemical raw material, hydrazine brings convenience to people's lives and provides opportunities for human development. However, the misuse or leakage of hydrazine has brought pollution to the environment, including water, soil and living organisms. At the same time, hydrazine poses a potential threat to human health as a carcinogen. Despite the enormous challenges, it is crucial to develop an effective method to detect hydrazine in environmental samples. In this work, we have synthesized a series of probes based on phenothiazine fluorophore by the introduction of different substituents and developed a novel probe for the detection of hydrazine. The probe is capable of detecting hydrazine in aqueous solutions with high sensitivity and selectivity, and can be easily fabricated into paper test strips for use in in situ samples. In addition, the probe is effective in detecting hydrazine in water, soil, cells, and zebrafish, providing an excellent tool for detecting hydrazine in the environment.

Switching thermally activated delayed fluorescence to room temperature phosphorescence for oxygen sensing: Effect of donor substituents of trifluoromethylphenyl

Two compounds consisting of electron-accepting trifluoromethylphenyl moiety and electron-donating phenoxazine and phenothiazine moieties were designed and synthesized via Buchwald-Hartwig coupling reaction. Thermal, photophysical, and electrochemical properties of the compounds are discussed. Only compound with phenothiazine form molecular glass, with glass transition temperatures of 90 °C. The geometry and electronic characteristics of the compounds were substantiated within density functional theory (DFT). 10,10'-(2-(Trifluoromethyl)-1,4-phenylene)bis(10H-phenoxazine) shows efficient thermally activated delayed fluorescence with high spin-orbit coupling values. 10,10'-(2-(Trifluoromethyl)-1,4-phenylene)bis(10H-phenothiazine) as efficient room-temperature phosphor shows high oxygen sensitivity.

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.

Receptor-free phenothiazine derivative as fluorescent probe for picric acid: Investigation of the inner filter effect channel

In this study, a highly fluorescent and receptor-free phenothiazine derivative (PDAB) was developed to detect picric acid. A combination of steady-state and time-resolved fluorescence studies was conducted to examine the excited state behavior of PDAB with picric acid in solution. The PDAB probe displayed a significant degree of selectivity and was highly sensitive to picric acid, with an extremely low detection limit of 9.82 nM. Time-resolved fluorescence quenching studies exhibit direct evidence of an inner filter effect-based sensing mechanism. Using the Parker equation, a thorough analysis was done to correct the inner filter effect on the sensing of picric acid. Overall, these studies provide critical information on the sensing mechanism for picric acid detection.

A Dual Functional Fluorescent Probe Based on Phenothiazine for Detecting Hg2+ and ClO- and its Applications

For the efficient detection of Hg2+ and ClO-, a double-analyte-responsive fluorescent probe PTB was successfully synthesized by combining N-butyl-3-formyl phenothiazine with hydrazine benzothiazole, and designing a specific reaction site for recognizing two analytes (Hg2+ and ClO-) in a compound. It was shown that probe PTB successfully formed a stable complex with Hg2+ in the coordination ratio of 2:1 by using the strong sulfur affinity of Hg2+, which resulted in a remarkable "turn-off" effect, with a quenching efficiency of 92.5% and four reversible cycles of Hg2+ fluorescence detection. For the fluorescence detection of Hg2+, the response time is fast (≤ 2 min) and the detection limit is low (7.8 nM), showing extremely high sensitivity, and the performance is obviously better than that of the reported fluorescent probes for detecting Hg2+. In particular, probe PTB has low toxicity and good biocompatibility, and has been successfully used for imaging of Hg2+ in living cells. Moreover, probe PTB uses thioether bond and carbon-nitrogen double bond as reaction sites to detect ClO-, which has large Stokes Shift (149 nm), good selectivity, high quenching efficiency (96.5%) and fast time response (about 10 s), and successfully detects ClO- in actual water samples. The dual functional fluorescent probe PTB is sensitive for Hg2+ and ClO-. It has been successfully used for making pH fluorescent test paper and imaging detection of exogenous Hg2+ in VSMC cells with low toxicity.

Design, Synthesis, and Cellular Imaging Application of a Fluorescent Probe Based on Fluoride Ion-Induced Cyclization of Phenothiazine Derivatives

Fluoride is both necessary and potentially harmful in excessive amounts, making its detection crucial. Fluorescent probes provide a sensitive and selective means for this purpose. In this study, we developed and synthesized a fluorescent probe for LDT using phenothiazine derivatives and aryl vinyl nitrile. Initially non-fluorescent, the probe undergoes a Si-O bond breakage in the presence of fluoride ions, resulting in the formation of a larger conjugated system and subsequent fluorescence emission. The probe exhibits superior selectivity and sensitivity towards fluoride ions, with a detection limit of 0.35 µM. Moreover, cellular imaging experiments demonstrated the probe's effectiveness in recognizing fluoride ions within HepG2 cells.

A phenothiazine urea derivative broadly inhibits coronavirus replication via viral protease inhibition

Coronavirus (CoV) replication requires efficient cleavage of viral polyproteins into an array of non-structural proteins involved in viral replication, organelle formation, viral RNA synthesis, and host shutoff. Human CoVs (HCoVs) encode two viral cysteine proteases, main protease (Mpro) and papain-like protease (PLpro), that mediate polyprotein cleavage. Using a structure-guided approach, a phenothiazine urea derivative that inhibits both SARS-CoV-2 Mpro and PLpro protease activity was identified. In silico docking studies also predicted the binding of the phenothiazine urea to the active sites of structurally similar Mpro and PLpro proteases from distantly related alphacoronavirus, HCoV-229 E (229 E), and the betacoronavirus, HCoV-OC43 (OC43). The lead phenothiazine urea derivative displayed broad antiviral activity against all three HCoVs tested in cellulo. It was further demonstrated that the compound inhibited 229 E and OC43 at an early stage of viral replication, with diminished formation of viral replication organelles, and the RNAs that are made within them, as expected following viral protease inhibition. These observations suggest that the phenothiazine urea derivative readily inhibits viral replication and may broadly inhibit proteases of diverse coronaviruses.

Design of phenothiazine-based cationic amphiphilic derivatives incorporating arginine residues: Potential membrane-active broad-spectrum antimicrobials combating pathogenic bacteria in vitro and in vivo

Multidrug-resistant bacteria infections pose an increasingly serious threat to human health, and the development of antimicrobials is far from meeting the clinical demand. It is urgent to discover and develop novel antibiotics to combat bacterial resistance. Currently, the development of membrane active antimicrobial agents is an attractive strategy to cope with antimicrobial resistance issues. In this study, the synthesis and biological evaluation of cationic amphiphilic phenothiazine-based derivatives were reported. Among them, the most promising compound 30 bearing a n-heptyl group and two arginine residues displayed potent bactericidal activity against both Gram-positive (MICs = 1.56 μg/mL) and Gram-negative bacteria (MICs = 3.125-6.25 μg/mL). Compound 30 showed low hemolysis activity (HC50 = 281.4 ± 1.6 μg/mL) and low cytotoxicity (CC50 ＞ 50 μg/mL) toward mammalian cells, as well as excellent salt resistance. Compound 30 rapidly killed bacteria by acting on the bacterial cell membrane and appeared less prone to resistance. Importantly, compound 30 showed potent in vivo efficacy in a murine model of bacterial keratitis. Hence, the results suggested compound 30 has a promising prospect as a broad-spectrum antibacterial agent for the treatment of drug-resistant bacterial infections.

Polypharmacy-Related Shock Symptoms and Complications Associated with Phenothiazine: A Case Report

This report describes a case of shock symptoms in a 72-year-old woman with epilepsy who had been in a state of polypharmacy, taking multiple antipsychotic drugs. After receiving a normal dose of periciazine, she exhibited impaired consciousness, hypothermia, and hypotension and was admitted to hospital. Despite poor response to vasopressors, conservative treatment led to gradual improvement. Subsequent pharmacokinetic analysis showed non-toxic blood concentrations of periciazine, suggesting that even small doses of phenothiazines could result in toxic symptoms. This case highlights the importance of monitoring for adverse reactions when prescribing multiple antipsychotic drugs, particularly in older polypharmacy patients.

A "Turn-on" Fluorescent Probe Based on Phenothiazine for Selectively Recognizing ClO- and its Practical Applications

Hypochlorous acid (HClO), a highly reactive oxygen species, has important effects on human health. High selectivity and sensitivity remain challenges of fluorescent probes for detection of ClO- with a large Stokes shift. This work designed and synthesized a novel phenothiazine-based fluorescent probe TF which can detect ClO- by colorimetric and fluorescent dual signals. TF displayed turn-on fluorescence effect toward ClO- with high selectivity (≥ 28-folds) and sensitivity (LOD = 0.472 μM), fast response time (< 1 min) and large Stokes shift (150 nm) in PBS (pH = 7.4, 40% DMSO). Meanwhile, TF can visualize ClO- on the mung bean sprouts model and apply as testing strips for portable and rapid detecting ClO- by the naked eyes. A phenothiazine-based fluorescent probe with large Stokes shift was synthesized and its responding rapidly ability to detect ClO- was studied.

Biological and Sensing Applications of a Few 1,3,4-Oxadiazole Based Donor-Acceptor Systems

1,3,4-Oxadiazole pharmacophore is still considered a viable biologically active scaffold for the synthesis of more effectual and broad-spectrum antimicrobial agents. Therefore, the present study is based on five 1,3,4-oxadiazole target structures, viz., CAROT, CAROP, CARON (D-A-D-A systems) and NOPON and BOPOB (D-A-D-A-D systems) bearing various bioactive heterocyclic moieties relevant to potential biological activities. Three of the compounds, CARON, NOPON and BOPOB were assessed in-vitro for their efficacy as antimicrobial agents against gram positive (Staphylococcus aureus and Bacillus cereus) and gram negative (Escherichia coli and Klebsiella pneumonia) bacteria; and two fungi, Aspergillus niger and Candida albicans; also, as an anti-tuberculosis agent against Mycobacterium tuberculosis. Most of the tested compounds displayed promising antimicrobial activity, especially CARON which was then analyzed for the minimum inhibitory concentration (MIC) studies. Similarly, NOPON portrayed the highest anti-TB activity among the studied compounds. Consequently, to justify the detected anti-TB activity of these compounds and to recognize the binding mode and important interactions between the compounds and the ligand binding site of the potential target, these compounds were docked into the active binding site of cytochrome P450 CYP121 enzyme of Mycobacterium tuberculosis, 3G5H. The docking results were in good agreement with the result of in-vitro studies. In addition, all the five compounds were tested for their cell viability and have been investigated for cell labeling applications. To conclude, one of the target compounds, CAROT was used for the selective recognition of cyanide ion by 'turn-off' fluorescent sensing technique. The entire sensing activity was examined by spectrofluorometric method and MALDI spectral studies. The limit of detection obtained was 0.14 µM.

Synthesis, structure and mechanofluorochromic properties of phenothiazine-S-oxide and phenothiazine-S,S-dioxide derivatives

In this work, two novel luminescent molecules containing distorted phenothiazine-S-oxide and phenothiazine-S,S dioxide skeletons were synthesized by oxidation reactions using different oxidants (m-chloroperoxybenzoic acid, acetic acid /hydrogen peroxide). The target compounds were all confirmed by ¹H NMR, ¹³C NMR and EI-MS. Combined with the results of UV-vis absorption spectra and fluorescence emission spectra, we found that the different oxidation states of S-atom, from sulfide (+2) to sulfoxide (+4) and sulfone (+6), led to the blue, yellow-green and yellowish fluorescence of these compounds in the solid states. Subsequent studies showed that the molecule containing the phenothiazine-S-oxide skeleton exhibited obvious solvatochromism, and the increase of solvent polarity induced a red-shift in the emission wavelength. Moreover, this molecule also exhibited a rare self-recovery mechanochromatic behavior. In addition, these properties were further confirmed by theoretical calculations and X-ray single-crystal diffraction analysis.

Phenothiazines as anti-cancer agents: SAR overview and synthetic strategies

Cancer is a leading cause of death worldwide and there are still limited options for cure. Chemotherapy is the most significant treatment for cancer which increased survival rates, despite this, it is associated with numerous side effects, as well as cancer relapsing due to drug resistance insurgence; consequently, it is still a challenging task to develop new potent and less toxic anti-cancer agents for patients' care. Phenothiazine moiety, which leads a class of well-known antipsychotic drugs, possesses a wide range of biological activities and has been also introduced in cancer chemotherapy. This review aims in disclosing the use of phenothiazines during the last five years for the development of different anti-cancer drug candidates. The design and the synthetic strategies adopted, the SAR investigations and the role of reviewed phenothiazine derivatives as anti-cancer agents and multi-drug resistance (MDR) reversals are here fully described and discussed.

Phenothiazine functionalized fulleropyrrolidines: synthesis, charge transport and applications to organic solar cells

A series of phenothiazine-C_60/70 dyads containing fulleropyrrolidine tethered to C-3 position (C₆₀-PTZ and C₇₀-PTZ) or to the heteroatom N-position via either phenyl (C₆₀-Ph-PTZ and C₇₀-Ph-PTZ) or phenoxyethyl linkers (C₆₀-PhOEt-PTZ and C₇₀-PhOEt-PTZ) of the phenothiazine were synthesized and light-induced electron transfer events were explored. Optimized studies suggested that the highest molecular orbital (HOMO) resides on donor phenothiazine moiety while lowest molecular orbital (LUMO) on the acceptor fulleropyrrolidine moiety of the dyads. Optical and electrochemical properties suggested no electronic communication between the donor and acceptor moieties in the ground state. However, steady-state emission studies in solvents of varied polarity, involving selective excitation of C₆₀/C₇₀, disclosed that the emission intensity of C₆₀/C₇₀ was quenched in the dyads in the increasing order, C_60/70-PTZ > C_60/70-Ph-PTZ > C_60/70-PhOEt-PTZ as a consequence of the donor-acceptor distance resulted due to spacer lengths. Also, the emission quenching is more pronounced in polar solvents such as DMF compared to a non-polar solvent, toluene. With the support of parallel electrochemical studies, the emission quenching is attributed to intramolecular photo-induced electron transfer occurring from PTZ to (C₆₀/C₇₀)* generating a radical ion pair, PTZ^+⋅-C₆₀^-⋅/PTZ^+⋅-C₇₀^-⋅. Finally, bulk heterojunction (BHJ) solar cells devices inverted fashion prepared by employing the dyads as acceptors, and PTB7 as donor, suggested that the devices prepared from C₇₀ derivatives i.e., PTB7:C₇₀-PTZ and PTB7:C₇₀-PhOEt-PTZ exhibited better power conversion efficiency of 2.66% and 2.15%, respectively over C₆₀ derivatives i.e., PTB7:C₆₀-PTZ and PTB7:C₆₀-PhOEt-PTZ with the efficiencies of 1.80 and 1.72%, respectively. AFM studies revealed that the poor performance of PTB7:C₆₀-PTZ- and PTB7:C₆₀-PhOEt-PTZ-based devices can be ascribed to the lower solubility of the dyads in 1,2-DCB solvent leading to rough morphology.

Phenothiazines inhibit SARS-CoV-2 cell entry via a blockade of spike protein binding to neuropilin-1

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters cells using angiotensin-converting enzyme 2 (ACE2) and neuropilin-1 (NRP-1) as the primary receptor and entry co-factor, respectively. Cell entry is the first and major step in initiation of the viral life cycle, representing an ideal target for antiviral interventions. In this study, we used a recombinant replication-deficient vesicular stomatitis virus-based pseudovirus bearing the spike protein of SARS-CoV-2 (SARS2-S) to screen a US Food and Drug Administration-approved drug library and identify inhibitors of SARS-CoV-2 cell entry. The screen identified 24 compounds as primary hits, and the largest therapeutic target group formed by these primary hits was composed of seven dopamine receptor D2 (DRD2) antagonists. Cell-based and biochemical assays revealed that the DRD2 antagonists inhibited both fusion activity and the binding of SARS2-S to NRP-1, but not its binding to ACE2. On the basis of structural similarity to the seven identified DRD2 antagonists, which included six phenothiazines, we examined the anti-SARS-CoV-2 activity of an additional 15 phenothiazines and found that all the tested phenothiazines shared an ability to inhibit SARS2-S-mediated cell entry. One of the phenothiazines, alimemazine, which had the lowest 50% effective concentration of the tested phenothiazines, exhibited a clear inhibitory effect on SARS2-S-NRP-1 binding and SARS-CoV-2 multiplication in cultured cells but not in a mouse infection model. Our findings provide a basis for the development of novel anti-SARS-CoV-2 therapeutics that interfere with SARS2-S binding to NRP-1.

Observation of HOCl generation associated with diabetic cataract using a highly sensitive fluorescent probe

Diagnosis of diabetic cataract (DC) in the early stage is of great significance for drug intervention and surgery circumvention for DC patients. However, the lack of reliable imaging tools greatly limits the diagnosis of early DC. In this context, a fluorescent probe BBPy for hypochlorous acid (HOCl) is presented based on the oxidation of phenothiazine. The probe displays apparent emission enhancement at 562 nm toward HOCl with high selectivity, superb sensitivity (detection limit: 12.6 nM), and rapid response (within seconds). Using the probe, the HOCl generation in diabetic human lens epithelial cells was monitored, as well as the HOCl down-regulation during antioxidant treatment. Therefore, it is proposed that HOCl can be a promising biomarker for DC and fluorescence imaging technique can be regarded as a candidate tool for DC diagnosis.

Recent development of small-molecule fluorescent probes based on phenothiazine and its derivates

Fluorescence probes, as analytical tools with the ability to perform rapid and sensitive detection of target analytes, have made outstanding contributions to environmental analysis and bioassays. Considering the expanding developments in these areas, fluorophores play a key role in the de-sign of fluorescence probes. Compared to classical fluorophores, phenothiazines with elec-tron-rich characteristics have been widely applied to construct electron donor-acceptor dyes, which exhibit outstanding performance in both fluorimetric and colorimetric analysis. In addition, these probes also exhibit the pronounced ability in both solution and solid-state, achieving portable detection for environmental analysis. In this review, we summarize recent advances in the performance of phenothiazine-based fluorescent probes for detecting various analytes, especially in cations, anions, ROS/RSS, enzyme and other small molecules. The general design rules, response mechanisms and practical applications of the probes are analyzed, followed by a discussion of exiting challenges and future research perspectives. It is hoped that this review will provide a few strategies for the development of phenothiazine-based fluorescent probes.

Synthesis and Luminescent Properties of 1,4,5-Triphenylimidazole‒Phenothiazine Fluorophores

Two blue donor-acceptor fluorophores with 1,4,5-triphenylimidazole as the electron-transporting unit and phenothiazine as the hole-transporting unit were synthesized by grafting 1,4,5-triphenylimidazole moieties onto 3- and 3,7-position of the phenothiazine core and characterized by spectroscopic methods. Their thermal stability, photophysical, electrochemical and electroluminescence properties were systematically investigated. These compounds exhibit good thermal stability and show blue emission in dichloromethane solution and thin solid films. The solution-processed doped devices were fabricated by using these fluorophores as the emitting dopant in 1,3-bis(N-carbazolyl)benzene host, in which the device fabricated from the fluorophore containing two 1,4,5-triphenylimidazole moieties exhibited blue emission with a luminance of 648 cd/m² and external quantum efficiency of 1.48%.

Phenothiazine, anthraquinone and related tricyclic derivatives as inhibitors of monoamine oxidase

Inhibitors of the monoamine oxidase (MAO) enzymes are important agents for the treatment of central nervous system disorders and have established roles in the therapy of neuropsychiatric diseases such as depression and in the neurodegenerative disorder, Parkinson's disease. A number of good potency MAO inhibitors consist of tricyclic ring systems as exemplified by the structures of harmine and the phenothiazine compound methylene blue. In an attempt to discover novel MAO inhibitors, 30 phenothiazine, anthraquinone and related tricyclic derivatives were selected and evaluated as potential inhibitors of human MAO-A and MAO-B. The results show that, in general, the tricyclic compounds are specific inhibitors of MAO-A over the MAO-B isoform. Quinizarin (IC₅₀ = 0.065 µM), 2-chloro-7-methoxy-10H-phenothiazine (IC₅₀ = 0.576 µM) and xanthone (IC₅₀ = 0.623 µM) proved to be the most potent MAO-A inhibitors, while the most potent MAO-B inhibition was recorded with 2-chloro-7-methoxy-10H-phenothiazine (IC₅₀ = 1.34 µM), 1,2-diaminoanthraquinone (IC₅₀ = 2.41 µM) and emodin (IC₅₀ = 3.24 µM). These compounds may undergo further preclinical evaluation and development, and may also serve as potential lead compounds for the future design of MAO inhibitors.

A Tri-state Fluorescent Switch with "Gated" Solid-state Photochromism Induced by an External Force

Mr. Chen Qian, Dr. Zhimin Ma, Mr. Jianwei Liu, Mrs. Xue Zhang, Prof. Shitao Wang and Prof. Zhiyong Ma. In this article, we report a newly designed molecule composed of a dihydroazulene (DHA) group and a phenothiazine (PTZ) moiety, which achieves aggregation-induced emission enhancement (AIEE), mechanochromism and "gated" solid-state photochromism upon stimulation by an external force. Grinding loosens intermolecular interactions in the crystal and causes a red-shift of fluorescence from 570 nm to 600 nm. Meanwhile, the ring-opening reaction of DHA unit is activated by grinding and a remarkable photochromism could be observed from the grinded powder. The reddish emission of the grinded powder peaked at 600 nm weakened gradually and finally became dark, and a new absorption band at 470 nm emerged in the absorption spectra. Time-dependent density functional theory (TD-DFT) calculation results reveal that the intramolecular intramolecular charge-transfer (ICT) process is replaced by a locally excited (LE) emission on the DHA group, which leads to the quenching of fluorescence. Its impressive photochromic property inspired us to a simple but effective way to develop an encryption system which can let the correct information be displayed upon external stimulation.

Efficient decolorization of recalcitrant dyes at neutral/alkaline pH by a new bacterial laccase-mediator system

Laccases and laccase-mediator systems (LMS) are versatile catalysts that can oxidize a broad range of substrates coupled to the sole reduction of dioxygen to water. They possess many biotechnological applications in paper, textile, and food industries, bioethanol production, organic synthesis, detection and degradation of pollutants, and biofuel cell development. In particular, bacterial laccases are getting relevance due to their activity in a wide range of pH and temperature and their robustness under harsh conditions. However, the enzyme and the redox mediator's availability and costs limit their large-scale commercial use. Here we demonstrate that β-(10-phenothiazyl)-propionic acid can be used as an efficient and low-cost redox mediator for decolorizing synthetic dyes by the recombinant laccase SilA from Streptomyces ipomoeae produced in E. coli. This new LMS can decolorize more than 80% indigo carmine and malachite green in 1 h at pH = 8.0 and 2 h in tap water (pH = 6.8). Furthermore, it decolorized more than 40% of anthraquinone dye remazol brilliant blue R and 80% of azo dye xylidine ponceau in 5 h at 50 °C, pH 8.0. It supported at least 3 decolorization cycles without losing activity, representing an attractive candidate for a cost-effective and environmentally friendly LMS functional at neutral to alkaline pH.

Synthesis and biological evaluation of phenothiazine derivative-containing hydroxamic acids as potent class II histone deacetylase inhibitors

The pathogenesis of Alzheimer's disease (AD) has been associated with dysregulation of histone deacetylases (HDACs). Previously, acridine-based HDAC inhibitors have shown potential in ameliorating HDAC activity and enhancing neurite outgrowth. In this study, the acridine ring was modified using various phenothiazine derivatives. Several resulting compounds exhibited potent enzyme-inhibiting activity towards class II HDACs when compared to the clinically approved HDAC inhibitor SAHA. Compound 4f demonstrated the highest class II HDAC inhibition (IC₅₀ = 4.6-600 nM), as well as promotion of neurite outgrowth. Importantly, compound 4f displayed no cytotoxicity against neuron cells. Compound 4f was further evaluated for cellular effects. Altogether, these findings show a potential strategy in HDAC inhibition for treatment of the neurological disease.

Phenothiazine-Thiophene Hydrazide Dyad: An Efficient "On-Off" Chemosensor for Highly Selective and Sensitive Detection of Hg2+ Ions

A new phenothiazine-thiophene hydrazone based ((10-ethyl-10H-phenothiazine-3,7-diyl)bis(methanylylidene))bis(thiophene-2-carbohydrazide) (PHT) chemosensor was synthesized via a single-step reaction and utilized as fluorescence "On-Off" sensor towards Hg²⁺ ion. The PHT was fully characterized by FT-IR, ¹H-NMR, and ESI-Mass spectral analysis. The PHT probe was efficiently used for the selective detection of Hg²⁺ ion in the presence of other metal ions. Further, the stoichiometry of the PHT with Hg²⁺ complex was confirmed by Job's plot analysis. The limit of detection (LOD) value of the probe PHT was found to be 0.44 × 10^-8 M.

The effect of levomepromazine on the healthy and injured developing mouse brain - An in vitro and in vivo study

Levomepromazine (LMP) is a phenothiazine neuroleptic drug with strong analgesic and sedative properties that is increasingly used off-label in pediatrics and is being discussed as an adjunct therapy in neonatal intensive care. Basic research points towards neuroprotective potential of phenothiazines, but LMP's effect on the developing brain is currently unknown. The aim of the present study was to assess LMP as a pharmacologic strategy in established neonatal in vitro and in vivo models of the healthy and injured developing mouse brain. In vitro, HT-22 cells kept exposure-naïve or injured by glutamate were pre-treated with vehicle or increasing doses of LMP and cell viability was determined. In vivo, LMP's effects were first assessed in 5-day-old healthy, uninjured CD-1 mouse pups receiving a single intraperitoneal injection of vehicle or different dosages of LMP. In a second step, mouse pups were subjected to excitotoxic brain injury and subsequently treated with vehicle or LMP. Endpoints included somatometric data as well as histological and immunohistochemical analyses. In vitro, cell viability in exposure-naïve cells was significantly reduced by high doses of LMP, but remained unaffected in glutamate-injured cells. In vivo, no specific toxic effects of LMP were observed neither in healthy mouse pups nor in experimental animals subjected to excitotoxic injury, but body weight gain was significantly lower following higher-dose LMP treatment. Also, LMP failed to produce a neuroprotective effect in the injured developing brain. Additional studies are required prior to a routine clinical use of LMP in neonatal intensive care units.

Water soluble PEGylated phenothiazines as valuable building blocks for bio-materials

The paper reports a series of three new PEGylated phenothiazine derivatives which keep the potential of valuable building blocks for preparing eco-materials addressed to a large realm of fields, from bio-medicine to opto-electronics. They were synthetized by connecting the hydrophilic poly(ethylene glycol) to the hydrophobic phenothiazine via an ether, ester, or amide linking group. The successful synthesis of the targeted polymers and their purity were demonstrated by NMR and FTIR spectroscopy methods. Their capacity to self-assembly in water was studied by DLS and UV-vis techniques and the particularities of the formed aggregates were investigated by fluorescence spectroscopy, SEM, AFM, POM and UV light microscopy. The biocompatibility was assessed on normal human dermal fibroblasts and human cervical cancer cells. The synthetized compounds showed the formation of luminescent aggregates and proved excellent biocompatibility on normal cells. In addition, a concentration dependent cytotoxicity against HeLa cancer cells was noticed for the PEGylated phenothiazine containing an ester unit.

Male Breast Carcinoma after Irradiation and Long-Term Phenothiazine Exposure: A Case Report

We present a young male patient with breast cancer having several risk factors likely acting in consort: irradiation of the breast for gynecomastia in adolescence and a life-long administration of phenothiazine for schizophrenia from the age of 16 years, with elevated serum prolactin level resulting in breast cancer development 24 years after irradiation.

Phenothiazine-chitosan based eco-adsorbents: A special design for mercury removal and fast naked eye detection

The aim of the paper was to investigate the ability of an eco-friendly luminescent xerogel prepared by chitosan crosslinking with a phenothiazine luminogen to detect and remove heavy metals. Its ability to give a divergent morphological and optical response towards fifteen environmental relevant metals was investigated by naked eye and UV lamp, fluorescence spectroscopy and scanning electron microscopy. A distinct response was noted for mercury, consisting in the transformation of the xerogel into a rubber-like material accompanied by the red shifting of the color of emitted light from yellow-green to greenish-yellow domain. The particularities of the metals anchoring into the xerogel were analyzed by FTIR spectroscopy and X-ray diffraction. The morphological changes and the metal uptake were analyzed by SEM-EDAX, swelling and gravimetric methods. It was concluded that mercury has a superior affinity towards this heteroatoms rich system, leading to a secondary crosslinking. This directed a great absorption capacity of 1673 mg/g and a specific morphological response for mercury ion concentrations up to 0.001 ppm.

Functional polymers in photoelectrochemical biosensing

Photoelectrochemical (PEC) analysis is a detection technique that has gained a wide attention in sensing applications. PEC presents the advantages of high sensitivity, low background signal, simple equipment and easy miniaturization. In PEC detection, light is used as an excitation source while current or voltage is measured as the output detection signal. The ability to couple the PEC process with specific bioreceptors gives PEC biosensing a unique advantage of being both selective and sensitive. The growing interest in PEC bioanalysis has resulted in essential progress in its analytical performance and biodetection applications. Functional polymers have different applications in the development of novel PEC biosensing platforms. Recently, the interest in polymer-based photoactive materials has emerged as they are efficient and less toxic alternatives to certain kinds of inorganic semiconductors and sensitizers. Moreover, molecularly imprinted polymers are a class of synthetic bioreceptors that are increasingly used in PEC bioanalytics. In this review, we will provide an overview on functional polymer-based PEC biosensing approaches. Novel classes of polymers as photoactive materials are reviewed and selected applications are described. Furthermore, molecularly imprinted polymers in the development of smart and sensitive PEC bioanalytical strategies are discussed.

Theoretical study of T shaped phenothiazine/carbazole based organic dyes with naphthalimide as π-spacer for DSSCs

Eight novel T shaped phenothiazine/carbazole based organic dyes with naphthalimide as π-spacer were designed, and the geometries, electronic structures, and optical features of these isolated dyes and dye-(TiO₂)₉ systems were investigated with density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculations. Some quantify factors influencing the energy conversion efficiency (PCE) such as the light harvesting efficiency (LHE), electron injection driving force (ΔG_inject) and dye regeneration driving force (ΔG_reg) were also calculated for dye-sensitized solar cells (DSSCs) applications. It is found that these dyes show a good performance of electron injection and dye regeneration owing to the proper value of ΔG_inject and ΔG_reg. The optimized geometries of the non-planar molecular configuration of donor and the planar structure of the naphthalimide conjugated bridge are beneficial to efficient intramolecular charge transfer and the suppression of molecular aggregation. The properties about the electronic structure and absorption spectra indicate that replacement of benzene with thiophene unit near to cyanoacetic acid acceptor can generate more efficient conjugation effect and achieve red shift of absorption spectra, resulting a higher J_sc and V_oc in DSSCs device. The theoretical results reveal that DTPH2, DTPH4, DTCA2 and DTCA4 would be used as potential sensitizers for DSSCs applications.

Chiral separation of four phenothiazines by nonaqueous capillary electrophoresis and quality by design-based method development for quantification of dextromepromazine as chiral impurity of levomepromazine

The separation of the enantiomers of mepromazine, promethazine, thioridazine and alimemazine was studied by nonaqueous capillary electrophoresis in the presence of cyclodextrins using 1 M acetic acid and 50 mM ammonium acetate in methanol as background electrolyte. Heptakis(2,3-di-O-acetyl-6-O-sulfo)-β-cyclodextrin, heptakis(2,3-di-O-methyl-6-O-sulfo)-β-cyclodextrin (HDMS-β-CD) and octakis(2,3-di-O-methyl-6-O-sulfo)-γ-cyclodextrin were the most effective chiral selectors for mepromazine, promethazine and alimemazine. Subsequently, a method for the determination of dextromepromazine as chiral impurity of levomepromazine was developed employing quality by design principles. Using HDMS-β-CD as selector, a fractional factorial resolution V+ design was employed for evaluating the knowledge space, while a central composite face centered design provided further method optimization and the basis for the computation of the design space by Monte Carlo simulations. The final experimental conditions included a 30/40.2 cm fused-silica capillary with 75 µm inner diameter and a background electrolyte composed of 0.75 M acetic acid and 55 mM ammonium acetate in methanol containing 27.5 mg/mL HDMS-β-CD. The applied voltage was 22 kV and the capillary temperature was 15°C. Following method robustness testing via a Plackett-Burman design, the method was validated for dextromepromazine in the range of 0.01 to 3.0 % relative to a concentration of 0.74 mg/mL levomepromazine and applied to the analysis of reference standards of the European Pharmacopoeia and commercial tablets. The assay also allowed the detection of levomepromazine sulfoxide although the quantitation of the compound was hampered by the poor peak shape of the late migrating diastereomer.

Mediated electrochemical oxidation of glucose via poly(methylene green) grafted on the carbon surface catalyzed by flavin adenine dinucleotide-dependent glucose dehydrogenase

Electrochemically polymerized phenothiazines (thionine, methylene green, methylene blue, and toluidine blue) on carbon electrodes were investigated as electron transfer mediators of glucose oxidation by flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) for biosensor and biofuel cell applications. Among the tested polyphenothiazines grafted on a glassy carbon electrode, clear redox-mediating activity was observed for poly(methylene green), and the catalytic oxidation current depended on the concentrations of glucose and enzymes and the amount of polymer deposited on the electrode surface. The poly(methylene green)-grafted porous carbon electrodes showed 3 mA cm-2 of glucose oxidation current catalyzed by FAD-GDH.

A lysosome-targeted ratiometric fluorescent probe with a large blue shift for monitoring hypochlorous acid in living cells and zebrafish

A new phenothiazine derivative as lysosome-targeted fluorescent probe with a large blue-shift (128 nm) for ClO^- detection in a fine ratiometric manner has been designed and synthesized. Probe Lyso-PTB has remarkable fluorescence ratiometric variations (98-fold), low cytotoxicity, rapid response time (50 s) and a low detection limit (23 nM). In particular, the application of Lyso-PTB for ClO^- detection was successfully demonstrated in lysosome and in zebrafish.

Phenothiazine-based fluorescence probe for ratiometric imaging of hydrazine in living cells with remarkable Stokes shift

By modifying the 10-butyl-2-methoxy-10H-phenothiazine-3-carbaldehyde with malonontrile group, a new fluorescent sensor PBM for selective detection of hydrazine in ratiometric mode has been developed. Probe PBM owned the advantages of quick response (10 min), remarkable Stokes shift (168 nm for PBM, 161 nm for PBM-NH₂), excellent selectivity, high sensitivity (detection limit of 63.2 nM was obtained from in vitro experiment), profound ratiometric change (82-fold) and low cytotoxicity in response to hydrazine. Additionally, it could be utilized to monitor hydrazine in gas state with various concentrations through vivid color changes and imaged hydrazine in living MCF-7 cells with excellent performance.

A new phenothiazine-based selective visual and fluorescent sensor for cyanide

A new donor-π-acceptor derived from phenothiazine, namely 2-(2-((10-hexyl-10H-phenothiazin-3-yl)methylene)-3-oxo-2,3-dihydroinden-1-ylidene) malononitrile (PTZON) was synthesized and fully characterized, and its potential as a fluorescent sensor for cyanide anion was investigated. The PTZON showed a visible absorption band at 564 nm corresponds to an intramolecular charge transfer (ICT) and an emission band at 589 nm in CH₃CN/H₂O. The results of cyanide anion titration revealed ratiometric changes in both absorption and fluorescence spectra as a result of the nucleophilic addition of cyanide anion via Michael addition. The optical studies, FT-IR spectra, NMR, high-resolution mass, and DFT calculations confirmed the sensing mechanism. The selectivity of PTZON as a cyanide anion fluorescent sensor was proved in mixed solvent solutions, and the sensitivity was as low as 0.011 µM, which is far lower than the value allowed by the United States Environmental Protection Agency for drinking water (1.9 µM). Also, the detection limit of PTZON was assessed to be 3.39 μM by the spectrophotometric method. The binding stoichiometry between PTZON and cyanide anion was found to be 1:1 as evidenced by mass spectra. TLC silica-coated plates test strips demonstrated the fluorescent detection of cyanide anion.

A comparative study of the cardiopulmonary and sedative effects of a single intramuscular dose of ketamine anesthetic combinations in rabbits

The aim of this prospective, randomized, blinded crossover study was compare the cardiopulmonary and sedative effects of ketamine in combination with acepromazine, diazepam, dexmedetomidine, midazolam or xylazine, injected intramuscularly in rabbits, using eight one-year-old male New Zealand rabbits (4.1 ± 0.40 kg). All treatments included ketamine (K; 30 mg/kg) in combination with one of the following: acepromazine 0.5 mg/kg (treatment KA); diazepam 1 mg/kg (KD); dexmedetomidine 0.025 mg/kg (KDex); midazolam 1 mg/kg (KM); or xylazine 3 mg/kg (KX) mixed in the same syringe and injected intramuscularly. Cardiopulmonary variables, blood gases and sedative scores were measured before injection (T0 or baseline) and every 10 min thereafter, over a 60-min period. There were reductions in heart rate, compared with the baseline, at all evaluation times in treatment KX. Treatments KDex, KM and KX presented reductions in respiratory rate at all evaluation times, in comparison with the baseline. There were reductions in mean arterial pressure in KA and KX at times T10-T60 and in PaO2 in KDex, KM and KX at T10-T50. The sedation scores were similar in KA, KDex, KM and KX at T10-T20. Ketamine in combination with acepromazine, dexmedetomidine, midazolam or xylazine promoted similar sedative effects for twenty minutes, but the α2-agonists can promote hypoxemia.

AMPK activation induced by promethazine increases NOXA expression and Beclin-1 phosphorylation and drives autophagy-associated apoptosis in chronic myeloid leukemia

Relapse and drug resistance is still major challenges in the treatment of leukemia. Promethazine, an antihistaminic phenothiazine derivative, has been used to prevent chemotherapy-induced emesis, although there is no report about its antitumor potential. Thus, we evaluated the promethazine cytotoxicity against several leukemia cells and the underlying mechanisms were investigated. Promethazine exhibited potent and selective cytotoxicity against all leukemia cell types in vitro at clinically relevant concentrations. Philadelphia positive chronic myeloid leukemia (CML) K562 cells were the most sensitive cell line. The cytotoxicity of promethazine in these cells was triggered by the activation of AMPK and inhibition of PI3K/AKT/mTOR pathway. The subsequent downstream effects were NOXA increase, MCL-1 decrease, and Beclin-1 activation, resulting in autophagy-associated apoptosis. These data highlight targeting autophagy may represent an interesting strategy in CML therapy, and also the antitumor potential of promethazine by acting in AMPK and PI3K/AKT/mTOR signaling pathways. Since this drug is currently used with relative low side effects, its repurposing may represent a new therapeutic opportunity for leukemia treatment.

aPDT using nanoconcentration of 1,9-dimethylmethylene blue associated to red light is efficacious in killing Enterococcus faecalis ATCC 29212 in vitro

The Enterococcus faecalis is a microorganism that causes multiple forms of resistance to a wide range of drugs used clinically. aPDT is a technique in which a visible light activates photosensitizer (PS), resulting in generation of reactive oxygen species that kill bacteria unselectively via an oxidative burst. aPDT is an alternative to antibiotics with the advantage of not causing resistance. The search for an alternative treatment of infections caused by E. faecalis, without using antibiotics, is off great clinical importance. The aim of present investigation was to assess the efficacy of using 3.32 ηg/mL of 1,9-dimethylmethylene blue (DMMB) as photosensitizer associated with the use of either Laser (λ660 nm) or LED (λ632 ± 2 nm) using different energy densities (6, 12 and 18 J/cm²) to kill E. faecalis in vitro. Under different experimental conditions, 14 study groups, in triplicate, were used to compare the efficacy of the aPDT carried out with either the laser or LED lights using different energy densities associated to DMMB. The most probable number method (MPN) was used for quantitative analysis. Photodynamic antimicrobial effectiveness was directly proportional to the energy density used, reaching at 18 J/cm², 99.999998% reduction of the counts of E. faecalis using both light sources. The results of this study showed that the use of 3.32 ηg/mL of DMMB associated with the use 18 J/cm² of LED light (λ632 ± 2 nm) reduced >7-log counts of planktonic culture of E. faecalis.

Design, synthesis and evaluation of novel phenothiazine derivatives as inhibitors of breast cancer stem cells

A novel series of phenothiazine derivatives containing diethanolamine, methoxyethylamine, flavonoids, and a nitric oxide (NO) donor was designed and synthesized for the treatment of breast cancer. Phenothiazine derivatives (l) did not noticeably inhibit the growth of SUM159, MDA-MB-231, MCF-7, and SKBR-3 cells, whereas phenothiazine derivatives (ll) containing the NO donor were more potent or had comparable inhibitory activity to trifluoperazine (TFP) and thioridazine against SUM159, MDA-MB-231, MCF-7, and SKBR-3 cells. Compounds 20a-c and 21a-c showed the strongest activity in SUM159, MDA-MB-231, MCF-7, and SKBR-3 cells, and more potent inhibitory activity than TFP against KG1a cells (IC₅₀ = 1.63, 2.93, 1.14, 1.78, 2.20, and 1.20 vs. 4.58 μM). Compounds 20a and 21a had lower toxicity than compounds 20b-c and 21b-c, and inhibited colony formation in MCF-7 cells, decreased the formation of mammospheres in SUM159 cells, and inhibited the migration of MDA-MB-231 cells. Compounds 20a and 21a could inhibited pNF-κB-p65 as shown by dual-luciferase reporter assays and western blotting in MDA-MB-231 cells.

Phenothiazine-rhodamine-based colorimetric and fluorogenic 'turn-on' sensor for Zn2+ and bioimaging studies in live cells

A phenothiazine-rhodamine (PTRH) fluorescent dyad was synthesized and its ability to selectively sense Zn²⁺ ions in solution and in in vitro cell lines was tested using various techniques. When compared with other competing metal ions, the PTRH probe showed the high selectivity for Zn²⁺ ions that was supported by electronic and emission spectral analyses. The emission band at 528 nm for the PTRH probe indicated the ring closed form of PTRH, as for Zn²⁺ ion binding to PTRH, the λ_em get shift to 608 nm was accompanied by a pale yellow to pink colour (under visible light) and green to pinkish red fluorescence emission (under UV light) due to ring opening of the spirolactam moiety in the PTRH ligand. Spectral overlap of the donor emission band and the absorption band of the ring opened form of the acceptor moiety contributed towards the fluorescence resonance energy transfer ON mechanism for Zn²⁺ ion detection. The PTRH sensor had the lowest detection limit for Zn²⁺ , found to be 2.89 × 10^-8  M. The sensor also demonstrated good sensing application with minimum toxicity for in vitro analyses using HeLa cells.

Oral microbiological control by photodynamic action in orthodontic patients

BACKGROUND

Orthodontics involves diagnosis and treatment of dental and skeletal malocclusions. Orthodontic apparatus may repair these malocclusions but may also impair oral hygiene making patients prone to develop both periodontal diseases and caries. Antimicrobial agents may be used to prevent this.To avoid increased antimicrobial resistance to available drugs, A-PDT (Antimicrobial Photodynamic Therapy) appears as a viable alternative.

OBJECTIVE

This work aimed to evaluate the efficacy of A-PDT on reducing the number of colony forming units (CFU) through the use of phenothiazine compound (methylene blue+ toluidine blue) as a photosensitizer, associated with red LED (λ640±5ηm) irradiation in orthodontic patients.

METHODOLOGY

Twenty-one patients consented to participate in the study. Three biofilm collections were performed around the brackets and gums of the inferior central incisors; first before any intervention (Control); second after 5min of pre-irradiation and the last one immediately after AmPDT. Subsequently, a microbiological routine for microorganism growth period were performed and CFU counting after a 24h done.

RESULTS

The data showed that the AmPDT was able to reduce CFU count around 90% when compared to Control group (p=0.007) and also between the A-PDT and Photosensitizer groups (p=0.010). However, there were no differences between the Control and Photosensitizer groups.

CONCLUSION

A-PDT associated with the use of phenothiazine compounds and red LED was able to significantly reduce the number of CFUs in orthodontic patients.

DFT/TD-DFT study of novel T shaped phenothiazine-based organic dyes for dye-sensitized solar cells applications

Five novel T shaped phenothiazine-based organic dyes DTTP1~5 with different spacers at N (10) position were designed. The geometries, electronic structures, absorption spectra, electron transfer and injection properties of these isolated dyes and dye/(TiO₂)₉ systems were investigated via density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculation. The optimized geometries indicate that these T shaped dyes show non-planar conformations, which are helpful in suppressing the close intermolecular π-π aggregation in device and enhancing thermal stability. The calculated results indicate that type of π-conjugated spacers can affect the molecular absorption spectra. Introduction of thiophene-benzothiadizole-thiophene unit as π-conjugated spacer can most effectively shift the light absorption to near infrared region and enhance the light harvesting efficiency (LHE). Moreover, it is found that these dyes show a good performance of electron injection and dye regeneration owing to the proper electron injection driving force (ΔG_inject) and dye regeneration driving force (ΔG_reg). The theoretical results reveal that these dyes could be used as potential sensitizers for DSSCs, and DTTP4 would be the most plausible sensitizer for high-efficiency DSSCs due to the narrow HOMO-LUMO energy gap (Δ_H-L), broad absorption spectrum, high LHE value, and large dipole moment (μ_normal).

Phenothiazine normalizes the NADH/NAD+ ratio, maintains mitochondrial integrity and protects the nigrostriatal dopamine system in a chronic rotenone model of Parkinson's disease

Impaired mitochondrial function has been associated with the etiopathogenesis of Parkinson's disease (PD). Sustained inhibition of complex I produces mitochondrial dysfunction, which is related to oxidative injury and nigrostriatal dopamine (DA) neurodegeneration. This study aimed to identify disease-modifying treatments for PD. Unsubstituted phenothiazine (PTZ) is a small and uncharged aromatic imine that readily crosses the blood-brain barrier. PTZ lacks significant DA receptor-binding activity and, in the nanomolar range, exhibits protective effects via its potent free radical scavenging and anti-inflammatory activities. Given that DAergic neurons are highly vulnerable to oxidative damage and inflammation, we hypothesized that administration of PTZ might confer neuroprotection in different experimental models of PD. Our findings showed that PTZ rescues rotenone (ROT) toxicity in primary ventral midbrain neuronal cultures by preserving neuronal integrity and reducing protein thiol oxidation. Long-term treatment with PTZ improved animal weight, survival rate, and behavioral deficits in ROT-lesioned rats. PTZ protected DA content and fiber density in the striatum and DA neurons in the SN against the deleterious effects of ROT. Mitochondrial dysfunction, axonal impairment, oxidative insult, and inflammatory response were attenuated with PTZ therapy. Furthermore, we have provided a new insight into the molecular mechanism underlying the neuroprotective effects of PTZ.