N-Acyl phenothiazines as mycobacterial ATP synthase inhibitors: Rational design, synthesis and in vitro evaluation against drug sensitive, RR and MDR-TB.

The mycobacterial F-ATP synthase is responsible for the optimal growth, metabolism and viability of Mycobacteria, establishing it as a validated target for the development of anti-TB therapeutics. Herein, we report the discovery of an N-acyl phenothiazine derivative, termed PT6, targeting the mycobacterial F-ATP synthase. PT6 is bactericidal and active against the drug sensitive, Rifampicin-resistant as well as Multidrug-resistant tuberculosis strains. Compound PT6 showed noteworthy inhibition of F-ATP synthesis, exhibiting an IC50 of 0.788 µM in M. smegmatis IMVs and was observed that it could deplete intracellular ATP levels, exhibiting an IC50 of 30 µM. PT6 displayed a high selectivity towards mycobacterial ATP synthase compared to mitochondrial ATP synthase. Compound PT6 showed a minor synergistic effect in combination with Rifampicin and Isoniazid. PT6 demonstrated null cytotoxicity as confirmed by assessing its toxicity against VERO cell lines. Further, the binding mechanism and the activity profile of PT6 were validated by employing in silico techniques such as molecular docking, Prime MM/GBSA, DFT and ADMET analysis. These results suggest that PT6 presents an attractive lead for the discovery of a novel class of mycobacterial F-ATP synthase inhibitors.

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.

Protein coupled thionine acetate probed silica nanoparticles: An integrated laser-assisted therapeutic approach for treating cancer.

Herein, we report a multifaceted nanoformulation, developed by binding thionine acetate (TA) in silica matrix to form TA loaded silica nanoparticles (STA Nps), which were characterized using various physicochemical techniques. STA NPs were spherical shaped having size 40-50 nm and exhibited good heating efficiency, improved photostability and singlet oxygen production rate than TA alone. In PDT experiment, the rate of degradation for ABDMA was enhanced from 0.1367 min-1 for TA alone to 0.1774 min-1 for STA Nps, depicting an increase in the reactive oxygen species (ROS) generation ability of STA Nps. Further, the cytotoxicity of STA Nps was investigated by carrying out the biophysical studies with Calf thymus DNA (Ct-DNA) and Human Serum Albumin (HSA). The results indicated that the binding of STA Nps to Ct-DNA causes alterations in the double helix structure of DNA and as a result, STA Nps can impart chemotherapeutic effects via targeting DNA. STA Nps showed good binding affinity with HSA without compromising the structure of HSA, which is important for STA Nps sustainable biodistribution and pharmacokinetics. Based on this study, it is suggested that because of the synergistic effect of chemo and phototherapy, STA Nps can be extensively utilized as potential candidates for treating cancer.

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.

Synthesis and biological evaluation of ortho-phenyl phenylhydroxamic acids containing phenothiazine with improved selectivity for class IIa histone deacetylases.

Class IIa histone deacetylases (HDACs) have been linked to tumorigenesis in various cancers. Previously, we designed phenylhydroxamic acid LH4f as a potent class IIa HDAC inhibitor. However, it also unselectively inhibited class I and class IIb HDACs. To enhance the compound's selectivity towards class IIa HDACs, the ortho-phenyl group from the selective HDAC7 inhibitor 1 is incorporated into ortho position of the phenylhydroxamic acid in LH4f. Compared to LH4f, most resulting compounds displayed substantially improved selectivity towards the class IIa HDACs. Notably, compound 7 g exhibited the strongest HDAC9 inhibition with an IC50 value of 40 nM. Molecular modelling further identified the key interactions of compound 7 g bound to HDAC9. Compound 7 g significantly inhibited several human cancer cells, induced apoptosis, modulated caspase-related proteins as well as p38, and caused DNA damage. These findings suggest the potential of class IIa HDAC inhibitors as lead compounds for the development of cancer therapeutics.

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.

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

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

Synthesis, Electronic, and Antibacterial Properties of 3,7-Di(hetero)aryl-substituted Phenothiazinyl N-Propyl Trimethylammonium Salts.

In this study, a library of 3,7-di(hetero)aryl-substituted 10-(3-trimethylammoniumpropyl)10H-phenothiazine salts is prepared. These title compounds and their precursors are reversible redox systems with tunable potentials. The Hammett correlation gives a very good correlation of the first oxidation potentials with σp parameters. Furthermore, the title compounds and their precursors are blue to green-blue emissive. Screening of the salts reveals for some derivatives a distinct inhibition of several pathogenic bacterial strains (Mycobacterium tuberculosis, Staphylococcus aureus, Escherichia coli, Aconetobacter baumannii, and Klebsiella pneumoniae) in the lower micromolar range.

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.

Development of Phenothiazine Hybrids with Potential Medicinal Interest: A Review.

The molecular hybridization approach has been used to develop compounds with improved efficacy by combining two or more pharmacophores of bioactive scaffolds. In this context, hybridization of various relevant pharmacophores with phenothiazine derivatives has resulted in pertinent compounds with diverse biological activities, interacting with specific or multiple targets. In fact, the development of new drugs or drug candidates based on phenothiazine system has been a promising approach due to the diverse activities associated with this tricyclic system, traditionally present in compounds with antipsychotic, antihistaminic and antimuscarinic effects. Actually, the pharmacological actions of phenothiazine hybrids include promising antibacterial, antifungal, anticancer, anti-inflammatory, antimalarial, analgesic and multi-drug resistance reversal properties. The present review summarizes the progress in the development of phenothiazine hybrids and their biological activity.

Unimolecular Photodynamic O2-Economizer To Overcome Hypoxia Resistance in Phototherapeutics.

Tumor hypoxia has proven to be the major bottleneck of photodynamic therapy (PDT) to clinical transformation. Different from traditional O2 delivery approaches, here we describe an innovative binary photodynamic O2-economizer (PDOE) tactic to reverse hypoxia-driven resistance by designing a superoxide radical (O2•-) generator targeting mitochondria respiration, termed SORgenTAM. This PDOE system is able to block intracellular O2 consumption and down-regulate HIF-1α expression, which successfully rescues cancer cells from becoming hypoxic and relieves the intrinsic hypoxia burden of tumors in vivo, thereby sparing sufficient endogenous O2 for the PDT process. Photosensitization mechanism studies demonstrate that SORgenTAM has an ideal intersystem crossing rate and triplet excited state lifetime for generating O2•- through type-I photochemistry, and the generated O2•- can further trigger a biocascade to reduce the PDT's demand for O2 in an O2-recycble manner. Furthermore, SORgenTAM also serves to activate the AMPK metabolism signaling pathway to inhibit cell repair and promote cell death. Consequently, using this two-step O2-economical strategy, under relatively low light dose irradiation, excellent therapeutic responses toward hypoxic tumors are achieved. This study offers a conceptual while practical paradigm for overcoming the pitfalls of phototherapeutics.

Indolizine-phenothiazine hybrids as the first dual inhibitors of tubulin polymerization and farnesyltransferase with synergistic antitumor activity.

In the incessant search for innovative cancer control strategies, this study was devoted to the design, synthesis and pharmacological evaluation of dual inhibitors of farnesyltransferase and tubulin polymerization (FTI/MTIs). A series of indolizine-phenothiazine hybrids 16 (amides) and 17 (ketones) has been obtained in a 4-step procedure. The combination of the two heterocycles provided potent tubulin polymerization inhibitors with similar efficiency as the reference phenstatin and (-)-desoxypodophyllotoxin. Ketones 17 were also able to inhibit human farnesyltransferase (FTase) in vitro. Interestingly, three molecules 17c, 17d and 17f were very effective against both considered biological targets. Next, nine indolizine-phenothiazine hybrids 16c, 16f, 17a-f and 22b were evaluated for their cell growth inhibition potential on the NCI-60 cancer cell lines panel. Ketones 17a-f were the most active and displayed promising cellular activities. Not only they arrested the cell growth of almost all tested cancer cells, but they displayed cytotoxicity potential with GI50 values in the low nanomolar range. The most sensitive cell lines upon treatment with indolizine-phenothiazine hybrids were NCI-H522 (lung cancer), COLO-205 and HT29 (colon cancer), SF-539 (human glioblastoma), OVCAR-3 (ovarian cancer), A498 (renal cancer) and especially MDA-MB-435 (melanoma). Demonstrating the preclinical effectiveness of these dual inhibitors can be crucial. A single dual molecule could induce a synergy of antitumor activity, while increasing the effectiveness and reducing the toxicity of the classical combo treatments currently used in chemotherapy.

Synthesis, modelling, and solvatochromic properties of a phenothiazine derivative.

A new A-π-D-π-A phenothiazine derivative, 2,2'-((10-octyl-10H-phenothiazine-3,7-diyl)bis (ethene-2,1-diyl))bis(1-ethyl-3,3-dimethyl-3H-indol-1-ium)iodide (PTZ-BEI) was prepared and fully characterized using infra-red (IR), 1 H nuclear magnetic resonance (NMR), 13 C NMR, ultraviolet-visible light and mass spectra. Electronic spectra of PTZ-BEI solutions in solvents with different polarities displayed absorption bands (λmax ) related to intramolecular charge transfer. In addition, the emission spectra of PTZ-BEI solutions were strongly solvent dependent for both wavelength and intensity. Stokes' shift ( Δ ν ¯ ) increased with increasing solvent polarity up to 4105 cm-1 in the most polar solvent, dimethylformamide. The linear solvation-energy relationship was utilized to investigate solvent dependency of the Stokes' shifts. Relative quantum yield (φ) of PTZ-BEI was calculated. Finally, density functional theory was employed at the B3LYP level for geometrical optimization and simulation of electron spectra for the PTZ derivative in gaseous and solvated states to explore the solvent effect.

Synthesis and photophysical studies on a new fluorescent phenothiazine-based derivative.

A new typical phenothiazine compound functionalized with thienyl-indandione derivative (PTZTID) was synthesized and characterized using spectral analysis (ultraviolet-visible (UV-vis) light, infrared (IR), 1 H nuclear magnetic resonance (NMR) and 13 C NMR tools). The UV-vis absorption spectra of the PTZTID solution in 1,4-dioxane showed two absorption bands attributed to localized aromatic π-π* transitions of conjugated aromatic moieties and intramolecular charge transfer with the characteristics of a π-π* transition. The fluorescence spectra exhibited a maximum emission wavelength at 580 nm. The effect of concentration on photophysical properties took the form of a minor hypsochromic shift, which was attributed to some extent to the occurrence of H-type aggregation of the PTZTID derivative. Binary solvent effects on the spectroscopic behaviour of PTZTID were measured at different H2 O/1,4-dioxane ratios. Similarly, when increasing the water content, a hypsochromic shift was observed that resulted from H-type aggregation. Furthermore, geometry and electronic configurations of PTZTID were studied at density functional theory /B3LYP level and indicated that the compound had a nonplanar (butterfly structure).

Synthesis, In Silico and In Vitro Evaluation for Acetylcholinesterase and BACE-1 Inhibitory Activity of Some N-Substituted-4-Phenothiazine-Chalcones.

Acetylcholinesterase (AChE) and beta-secretase (BACE-1) are two attractive targets in the discovery of novel substances that could control multiple aspects of Alzheimer's disease (AD). Chalcones are the flavonoid derivatives with diverse bioactivities, including AChE and BACE-1 inhibition. In this study, a series of N-substituted-4-phenothiazine-chalcones was synthesized and tested for AChE and BACE-1 inhibitory activities. In silico models, including two-dimensional quantitative structure-activity relationship (2D-QSAR) for AChE and BACE-1 inhibitors, and molecular docking investigation, were developed to elucidate the experimental process. The results indicated that 13 chalcone derivatives were synthesized with relatively high yields (39-81%). The bioactivities of these substances were examined with pIC50 3.73-5.96 (AChE) and 5.20-6.81 (BACE-1). Eleven of synthesized chalcones had completely new structures. Two substances AC4 and AC12 exhibited the highest biological activities on both AChE and BACE-1. These substances could be employed for further researches. In addition to this, the present study results suggested that, by using a combination of two types of predictive models, 2D-QSAR and molecular docking, it was possible to estimate the biological activities of the prepared compounds with relatively high accuracy.

From aggregation-induced to solution emission: a new strategy for designing ratiometric fluorescent probes and its application for in vivo HClO detection.

In this paper, we introduced a new strategy for converting aggregation-induced emission (AIE) to fluorescence emission in solution into the rational design of new fluorescent probes. Two fluorescent probes based on this strategy, namely, PDAM-Lyso and PDAM-Me, have been synthesized and tested both in vitro and in vivo. The fluorophores of the two probes are both phenothiazine molecules, which link to the diaminomaleonitrile (DAMN) moiety through imine bonds. In the presence of imine bonds, the probes emit red fluorescence in an aqueous solution caused by the AIE effect. As the imine bonds are selectively cut-off by HClO, the DAMN moiety gets removed, inducing blue fluorescence of the reaction product. In this way, the selectivity of the DAMN-based probes toward HClO against metal ions and other reactive oxygen species (ROS) was successfully improved. The imaging of endogenous and exogenous HClO with these two probes reveals that lysosome-targeting probes are of great advantage in the detection of natively generated HClO. Furthermore, the imaging of endogenous HClO in zebrafish suggests that PDAM-Lyso is capable of monitoring the generation of HClO in vivo, illustrating that this strategy is of great significance in designing new probes.

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

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

Effect of Auxiliary Donors on 3,8-Phenothiazine Dyes for Dye-Sensitized Solar Cells.

Phenothiazines are one of the more common dye scaffolds for dye-sensitized solar cells. However, these sensitizers are exclusively based on a 3,7-substitution pattern. Herein, we have synthesized and characterized novel 3,8-substituted phenothiazine dyes in order to evaluate the effect of auxiliary donor groups on the performance of this new dye class. The power conversion efficiency increased by 7%-10% upon insertion of an auxiliary donor in position 8 of the phenothiazine, but the structure of the auxiliary donor (phenyl, naphthyl, pyrene) had a low impact when electrodes were stained with chenodeoxycholic acid (CDCA) additive. In the absence of CDCA, the highest power conversion efficiency was seen for the phenyl-based sensitizer attributed to a higher quality dye-monolayer. By comparing the novel dyes to their previously reported 3,7- analogues, only subtle differences were seen in photophysical, electrochemical, and performance measurements. The most notable difference between the two geometries is a lowering of the oxidation potentials of the 3,8-dyes by 40-50 mV compared to the 3,7-analogues. The best auxiliary donor for the 3,8-phenothiazine dyes was found to be pyrenyl, with the best device delivering a power conversion efficiency of 6.23% (99 mW cm-2, 10 eq. CDCA, JSC = 10.20 mA cm-2, VOC = 791 mV, and FF = 0.765).

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

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

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

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