Oximes: Novel Therapeutics with Anticancer and Anti-Inflammatory Potential

Antioxidant Effects of Tryptanthrin Oxime

We studied the radical-binding and antioxidant activities of the alkaloid tryptanthrin (TR) and its new synthetic derivative tryptanthrin oxime (TR-Ox), as well as the cytoprotective activity of TR-Ox under conditions of oxidative stress. The antiradical activity of TR-Ox was revealed in the test of binding with stable chromogen radical 2,2-diphenyl-1-picrylhydrazyl and in the superoxide radical generation test (riboflavin photoreduction reaction with detection by NBT reduction). TR-Ox was inferior to ionol and dihydroquercetin by the antiradical activity. In these tests, TR did not exhibit antiradical activity. TR-Ox did not show iron-chelating activity (in the test with the formation of the o-phenanthroline-Fe2+ complex and its destruction in the presence of chelating agents). In brain homogenate, TR-Ox significantly reduced the increase in spontaneous chemiluminescence. Under conditions of oxidative stress induced by 15 mM H2O2 in the SH-SY5Y neuroblastoma cell culture, TR-Ox exhibited cytoprotective activity and increased the number of viable cells.

Modulation of blood-tumor barrier transcriptional programs improves intra-tumoral drug delivery and potentiates chemotherapy in GBM

Glioblastoma (GBM) is the most common malignant primary brain tumor. GBM has an extremely poor prognosis and new treatments are badly needed. Efficient drug delivery to GBM is a major obstacle as the blood-brain barrier (BBB) prevents passage of the majority of cancer drugs into the brain. It is also recognized that the blood-brain tumor barrier (BTB) in the growing tumor represents a challenge. The BTB is heterogeneous and poorly characterized, but similar to the BBB it can prevent therapeutics from reaching effective intra-tumoral doses, dramatically hindering their potential. Here, we identified a 12-gene signature associated with the BTB, with functions related to vasculature development, morphogenesis and cell migration. We identified CDH5 as a core molecule in this set and confirmed its over-expression in GBM vasculature using spatial transcriptomics of GBM patient specimens. We found that the indirubin-derivative, 6-bromoindirubin acetoxime (BIA), could downregulate CDH5 and other BTB signature genes, causing endothelial barrier disruption in endothelial monolayers and BBB 3D spheroids in vitro. Treatment of tumor-bearing mice with BIA enabled increased intra-tumoral accumulation of the BBB non-penetrant chemotherapeutic drug cisplatin and potentiated cisplatin-mediated DNA damage by targeting DNA repair pathways. Finally, using an injectable BIA nanoparticle formulation, PPRX-1701, we significantly improved the efficacy of cisplatin in patient-derived GBM xenograms and prolonged their survival. Overall, our work reveals potential targets at the BTB for improved chemotherapy delivery and the bifunctional properties of BIA as a BTB modulator and potentiator of chemotherapy, supporting its further development.

Bromo-substituted indirubins for inhibition of protein kinase-mediated signalling involved in inflammatory mediator release in human monocytes

Targeting protein kinases that regulate signalling pathways in inflammation is an effective pharmacological approach to alleviate uncontrolled inflammatory diseases. In this context, the natural product indirubin and its 6-bromo-substituted analogue 6-bromoindirubin-3 -glycerol-oxime ether (6BIGOE; 1) were identified as potent inhibitors of glycogen synthase kinase-3β (GSK-3β). These inhibitors suppress the release of pro-inflammatory cytokines and prostaglandins (PG) from human monocytes. However, indirubin derivatives target several protein kinases such as cyclin-dependent kinases (CDKs) which has been a major concern for their application in inflammation therapy. Here, we report on a library of 13 5-bromo-substituted indirubin derivatives that have been designed to improve potency and target selectivity. Side-by-side comparison of reference compound 1 (6BIGOE) with 5-bromo derivatives revealed its isomer 2 (5BIGOE), as the most potent derivative able to supress pro-inflammatory cytokine and PG release in lipopolysaccharide-stimulated human monocytes. Analysis of protein kinase inhibition in intact monocytes, supported by our in silico findings, proposed higher selectivity of 1 for GSK-3β inhibition with lesser potency against CDKs 8 and 9. In contrast, 2 supressed the activity of these CDKs with higher effectiveness than GSK-3β, representing additional targets of indirubins within the inflammatory response. Encapsulation of 1 and 2 into polymer-based nanoparticles (NP) improved their pharmacological potential. In conclusion, the 5- and 6-brominated indirubins 1 and 2 as dual GSK-3β and CDK8/9 inhibitors represent a novel concept for intervention with inflammatory disorders.

Thymoquinone oxime synthesis and its effects on melanoma cells: cytotoxic, genotoxic, and apoptotic evaluation

Strong evidence supports the anticancer properties of natural plant product isolates. The cytotoxic, genotoxic, and apoptotic properties of an oxime derivative of thymoquinone (TQ) in melanoma cancer cells were investigated. The structure of TQ-Oxime was elucidated through nuclear magnetic resonance, and its effect on B16F10 and L929 cell lines was assessed using a luminometric adenosine triphosphate assay. Intracellular reactive oxygen species (iROS) were quantified via fluorometry, mitochondrial membrane potential (MMP) was assessed using flow cytometry, glutathione (GSH) levels were measured using a luminometric GSH/oxidized glutathione assay, DNA damage via comet assay, and apoptosis was detected using acridine orange/ethidium bromide staining. Concentrations (0.5-20 μM) of TQ-Oxime significantly increased cytotoxicity, DNA damage, apoptosis, and iROS, in a concentration-dependent manner compared (p < 0.001). In addition, MMP and GSH levels decreased significantly with increasing concentrations compared with the control (p < 0.001). Overall, these findings contribute to our understanding of the therapeutic potential of TQ and its derivatives in cancer treatment.

Synthesised thymoquinone-oxime induces cytotoxicity, genotoxicity and apoptosis in hepatocellular cancer cells: in vitro study

Hepatocellular carcinoma is the most common primary malignant tumor of the liver, and its incidence is increasing worldwide. There is a need to develop new therapeutic strategies to treat the disease. In this study, we synthesised the oxime derivative of thymoquinone and investigated cytotoxicity, genotoxicity, and apoptosis in hepatocellular cancer cells. The synthesised thymoquinone-oxime structure was confirmed by NMR. After incubating the hepatocellular cancer cell line for 24 h, the cytotoxicity ATP by luminometric, intracellular reactive oxygen species, and intracellular calcium by fluorometric. The mitochondrial membrane potential was determined by flow cytometry. DNA damage by alkaline single-cell gel electrophoresis, and apoptosis damage by acridine orange/ethidium bromide double dye method. Concentrations of thymoquinone-oxime statistically increased cytotoxicity, intracellular reactive oxygen species, intracellular calcium, apoptosis, and DNA damage in a concentration-dependent manner. Mitochondrial membrane potential and glutathione levels are also decreased. These findings show that thymoquinone-oxime has an anti-tumor effect on hepatocellular carcinoma cells.

Novel Pyrazole-4-Carboxamide Derivatives Containing Oxime Ether Group as Potential SDHIs to Control Rhizoctonia solani

In the search for novel succinate dehydrogenase inhibitor (SDHI) fungicides to control Rhizoctonia solani, thirty-five novel pyrazole-4-carboxamides bearing either an oxime ether or an oxime ester group were designed and prepared based on the strategy of molecular hybridization, and their antifungal activities against five plant pathogenic fungi were also investigated. The results indicated that the majority of the compounds containing oxime ether demonstrated outstanding in vitro antifungal activity against R. solani, and some compounds also displayed pronounced antifungal activities against Sclerotinia sclerotiorum and Botrytis cinerea. Particularly, compound 5e exhibited the most promising antifungal activity against R. solani with an EC50 value of 0.039 μg/mL, which was about 20-fold better than that of boscalid (EC50 = 0.799 μg/mL) and 4-fold more potent than fluxapyroxad (EC50 = 0.131 μg/mL). Moreover, the results of the detached leaf assay showed that compound 5e could suppress the growth of R. solani in rice leaves with significant protective efficacies (86.8%) at 100 μg/mL, superior to boscalid (68.1%) and fluxapyroxad (80.6%), indicating promising application prospects. In addition, the succinate dehydrogenase (SDH) enzymatic inhibition assay revealed that compound 5e generated remarkable SDH inhibition (IC50 = 2.04 μM), which was obviously more potent than those of boscalid (IC50 = 7.92 μM) and fluxapyroxad (IC50 = 6.15 μM). Furthermore, SEM analysis showed that compound 5e caused a remarkable disruption to the characteristic structure and morphology of R. solani hyphae, resulting in significant damage. The molecular docking analysis demonstrated that compound 5e could fit into the identical binding pocket of SDH through hydrogen bond interactions as well as fluxapyroxad, indicating that they had a similar antifungal mechanism. The density functional theory and electrostatic potential calculations provided useful information regarding electron distribution and electron transfer, which contributed to understanding the structural features and antifungal mechanism of the lead compound. These findings suggested that compound 5e could be a promising candidate for SDHI fungicides to control R. solani, warranting further investigation.

Schiff bases and their metal complexes to target and overcome (multidrug) resistance in cancer

Overcoming multidrug resistance (MDR) is one of the major challenges in cancer therapy. In this respect, Schiff base-related compounds (bearing a R1R2CNR3 bond) gained high interest during the past decades. Schiff bases are considered privileged ligands for various reasons, including the easiness of their preparation and the possibility to form complexes with almost all transition metal ions. Schiff bases and their metal complexes exhibit many types of biological activities and are used for the treatment and diagnosis of various diseases. Until now, 13 Schiff bases have been investigated in clinical trials for cancer treatment and hypoxia imaging. This review represents the first collection of Schiff bases and their complexes which demonstrated MDR-reversal activity. The areas of drug resistance covered in this article involve: 1) Modulation of ABC transporter function, 2) Targeting lysosomal ABCB1 overexpression, 3) Circumvention of ABC transporter-mediated drug efflux by alternative routes of drug uptake, 4) Selective activity against MDR cancer models (collateral sensitivity), 5) Targeting GSH-detoxifying systems, 6) Overcoming apoptosis resistance by inducing necrosis and paraptosis, 7) Reactivation of mutated p53, 8) Restoration of sensitivity to DNA-damaging anticancer therapy, and 9) Overcoming drug resistance through modulation of the immune system. Through this approach, we would like to draw attention to Schiff bases and their metal complexes representing highly interesting anticancer drug candidates with the ability to overcome MDR.

The role of the oxime group in the excited state deactivation processes of indirubin

The introduction of an oxime group into indirubin (INR) derivatives, including INROx, MINROx, and 6-BrINROx, and its impact on the spectral and photophysical properties of INR was investigated using a combination of fast-transient absorption (fs-TA/fs-UC) and steady-state fluorescence techniques. The oxime group introduces structural modifications that promote a rapid keto-enol tautomeric equilibrium and enhance the excited-state proton transfer (ESPT) process compared to its analogue, INR. In the oxime-indirubin derivatives investigated, the ESPT process is notably more efficient than what is observed in INR and indigo, occurring extremely fast (<1 ps) in all solvents, except for the viscous solvent glycerol. The more rapid deactivation mechanism precludes the formation of an intermediate species (syn-rotamer), as observed with INR. These findings are corroborated by time-dependent density functional theory (TDDFT) calculations. The work demonstrates that introducing an oxime group to INR, whether in nature or in the laboratory, results in an enhancement of its photostability.

New anthracene-based Oxime-Palladium complexes loaded on albumin nanoparticles, in vitro cytotoxicity, mathematical release mechanism studies and biological macromolecules interaction investigation

In this research work, two new palladium complexes [trans-Pd(C15H10NOCH3)2]Cl2 (1) and [cis- Pd(C15H10NOCH3)(PPh3)2Cl]Cl (2) were synthesized using an alkoxyme ligand named isophethalaldoxime. Then structure characterization has been done by FT-IR and different NMR (1H, 13C and 31P) spectroscopy. Then, their interactions with biological macromolecules including deoxyribonucleic acid and bovine serum albumin were studied using various spectroscopic methods such as UV-Vis absorption, fluorescence emission spectroscopy and circular dichroism. The results showed the binding of the prepared complexes to the deoxyribonucleic acid via grooves and different binding sites of bovine serum albumin. Fluorescence emission data showed that the mechanism of extinction of albumin emission by these compounds is static. Competitive titration was performed on albumin with eosin-Y, ibuprofen and digoxin as site markers I, II and III. The antitumor activity and toxicity of these compounds were evaluated on cancer cell lines A549 (leukemia) and K562 by in-vitro cytotoxicity test. The IC50 values showed the good activity of these complexes in inhibiting cancer cells. In the last section, the release mechanism of synthesized complexes from albumin nanoparticles (BNPs) was investigated and theoretical calculations were performed that showed Korsmeyer-Peppas mechanism for complex (1) and Quadratic mechanism for complex (2).

Profiling Novel Quinuclidine-Based Derivatives as Potential Anticholinesterase Drugs: Enzyme Inhibition and Effects on Cell Viability

The cholinergic system, relying on the neurotransmitter acetylcholine (ACh), plays a significant role in muscle contraction, cognition, and autonomic nervous system regulation. The enzymes acetylcholinesterase, AChE, and butyrylcholinesterase, BChE, responsible for hydrolyzing ACh, can fine-tune the cholinergic system's activity and are, therefore, excellent pharmacological targets to address a range of medical conditions. We designed, synthesized, and profiled 14 N-alkyl quaternary quinuclidines as inhibitors of human AChE and BChE and analyzed their impact on cell viability to assess their safety in the context of application as potential therapeutics. Our results showed that all of the 14 tested quinuclidines inhibited both AChE and BChE in the micromolar range (Ki = 0.26 - 156.2 μM). The highest inhibition potency was observed for two bisquaternary derivatives, 7 (1,1'-(decano)bis(3-hydroxyquinuclidinium bromide)) and 14 (1,1'-(decano)bis(3-hydroxyiminoquinuclidinium bromide)). The cytotoxic effect within 7-200 μM was observed only for monoquaternary quinuclidine derivatives, especially those with the C12-C16 alkyl chain. Further analysis revealed a time-independent mechanism of action, significant LDH release, and a decrease in the cells' mitochondrial membrane potential. Taking all results into consideration, we can confirm that a quinuclidine core presents a good scaffold for cholinesterase binding and that two bisquaternary quinuclidine derivatives could be considered as candidates worth further investigations as drugs acting in the cholinergic system. On the other hand, specific cell-related effects probably triggered by the free long alkyl chain in monoquaternary quinuclidine derivatives should not be neglected in future N-alkyl quaternary quinuclidine derivative structure refinements. Such an effect and their potential to interact with other specific targets, as indicated by a pharmacophore model, open up a new perspective for future investigations of these compounds' scaffold in the treatment of specific conditions and diseases other than cholinergic system-linked disorders.

The Fundamental Role of Oxime and Oxime Ether Moieties in Improving the Physicochemical and Anticancer Properties of Structurally Diverse Scaffolds

The present review explores the critical role of oxime and oxime ether moieties in enhancing the physicochemical and anticancer properties of structurally diverse molecular frameworks. Specific examples are carefully selected to illustrate the distinct contributions of these functional groups to general strategies for molecular design, modulation of biological activities, computational modeling, and structure-activity relationship studies. An extensive literature search was conducted across three databases, including PubMed, Google Scholar, and Scifinder, enabling us to create one of the most comprehensive overviews of how oximes and oxime ethers impact antitumor activities within a wide range of structural frameworks. This search focused on various combinations of keywords or their synonyms, related to the anticancer activity of oximes and oxime ethers, structure-activity relationships, mechanism of action, as well as molecular dynamics and docking studies. Each article was evaluated based on its scientific merit and the depth of the study, resulting in 268 cited references and more than 336 illustrative chemical structures carefully selected to support this analysis. As many previous reviews focus on one subclass of this extensive family of compounds, this report represents one of the rare and fully comprehensive assessments of the anticancer potential of this group of molecules across diverse molecular scaffolds.

Effect of Fusidic Acid and Some Nitrogen-Containing Derivatives on Liposomal and Mitochondrial Membranes

The paper assesses the membranotropic action of the natural antibiotic fusidic acid (FA) and its derivatives. It was found that a FA analogue with ethylenediamine moiety (derivative 2), in contrast to native FA and 3,11-dioxime analogue (derivative 1), is able to increase the mobility of the lipid bilayer in the zone of lipid headgroups, as well as to induce permeabilization of lecithin liposome membranes. A similar effect of derivative 2 is also observed in the case of rat liver mitochondrial membranes. We noted a decrease in the microviscosity of the mitochondrial membrane and nonspecific permeabilization of organelle membranes in the presence of this agent, which was accompanied by a decrease in mitochondrial Δψ and OXPHOS efficiency. This led to a reduction in mitochondrial calcium retention capacity. The derivatives also reduced the production of H2O2 by mitochondria. The paper considers the relationship between the structure of the tested compounds and the observed effects.

Pharmacokinetics of a New Neuroprotector - Indenoquinoxalinone Derivative after Intravenous Administration in Rabbits and Rats

The specific JNK inhibitor and NO donor 11H-indeno[1,2-b]quinoxalin-11-one oxime (IQ-1) demonstrated pronounced neuroprotective properties in an in vivo model of ischemic stroke in rats. The pharmacokinetic behavior of IQ-1 was studied in two animal species (rats, rabbits) after intravenous administration in a dose of 1 mg/kg. IQ-1 concentrations in venous blood plasma were measured by the liquid chromatography-tandem mass spectrometry method. The pharmacokinetics of IQ-1 was adequately described by the two-compartmental model. The calculated C0 for IQ-1 in rabbit and rat plasma were 2239.83±1229.55 and 1552.50±182.23 ng/ml, respectively. Two animal species are characterized by extensive tissue distribution of IQ-1 (Vss exceeded the total body water in rabbits and rats by 3.6 and 5.6 times, respectively) and high clearance values (88-94% of hepatic blood flow).

Development and Assessment of 1,5-Diarylpyrazole/Oxime Hybrids Targeting EGFR and JNK-2 as Antiproliferative Agents: A Comprehensive Study through Synthesis, Molecular Docking, and Evaluation

New 1,5-diarylpyrazole oxime hybrid derivatives (scaffolds A and B) were designed, synthesized, and then their purity was verified using a variety of spectroscopic methods. A panel of five cancer cell lines known to express EGFR and JNK-2, including human colorectal adenocarcinoma cell line DLD-1, human cervical cancer cell line Hela, human leukemia cell line K562, human pancreatic cell line SUIT-2, and human hepatocellular carcinoma cell line HepG2, were used to biologically evaluate for their in vitro cytotoxicity for all the synthesized compounds 7a-j, 8a-j, 9a-c, and 10a-c. The oxime containing compounds 8a-j and 10a-c were more active as antiproliferative agents than their non-oxime congeners 7a-j and 9a-c. Compounds 8d, 8g, 8i, and 10c inhibited EGFR with IC50 values ranging from 8 to 21 µM when compared with sorafenib. Compound 8i inhibited JNK-2 as effectively as sorafenib, with an IC50 of 1.0 µM. Furthermore, compound 8g showed cell cycle arrest at the G2/M phase in the cell cycle analysis of the Hela cell line, whereas compound 8i showed combined S phase and G2 phase arrest. According to docking studies, oxime hybrid compounds 8d, 8g, 8i, and 10c exhibited binding free energies ranging from -12.98 to 32.30 kcal/mol at the EGFR binding site whereas compounds 8d and 8i had binding free energies ranging from -9.16 to -12.00 kcal/mol at the JNK-2 binding site.

TQ-Ox, a novel synthetic derivative of thymoquinone on ovarian cancer cells in vitro

There are many studies in the literature on thymoquinone (TQ)-related cancer cells and models, and there is no relevant study investigating the efficacy of the oxime derivative of TQ (TQ-Ox). This study synthesized TQ-Ox and examined its cytotoxic, genotoxic and apoptotic properties in ovarian cancer cells. The structure TQ-Ox was confirmed with NMR. The cytotoxicity by luminometric ATP, intracellular reactive oxygen species (iROS) by fluorometric, intracellular calcium (iCa2+) by fluorometric, mitochondrial membrane potential (MMP) by flow cytometry, glutathione (GSH) levels with GSH/GSSG-Glo assay, DNA damage by comet assay, and apoptosis by acridine orange/ethidium bromide dye were determined. Concentrations of TQ-Ox were statistically increased cytotoxicity, DNA damage, apoptosis, iROS, and iCa2+ in a concentration-dependent manner (p < 0.001). Besides, MMP and GSH levels also decreased statistically significantly (p < 0.001) with increasing concentrations. TQ-Ox would be an effective treatment option by increasing cytotoxicity, genotoxicity, and apoptosis in ovarian carcinoma.

Unlocking the Potential: Novel NSAIDs Hybrids Unleash Chemopreventive Power toward Liver Cancer Cells through Nrf2, NF-κB, and MAPK Signaling Pathways

HCC is a highly aggressive malignancy with limited treatment options. In this study, novel conjugates of non-steroidal anti-inflammatory drugs (NSAIDs)-Ibuprofen and Ketoprofen-with oleanolic acid oximes derivatives (OAO) were synthesized, and their activity as modulators of signaling pathways involved in HCC pathogenesis was evaluated in normal THLE-2 liver cells, and HCC-derived HepG2 cells. The results demonstrated that conjugation with OAO derivatives reduces the cytotoxicity of parent compounds in both cell lines. In THLE-2 cells, treatment with conjugates resulted in increased activation of the Nrf2-ARE pathway. An opposite effect was observed in HepG2 cells. In the later reduction of NF-κB, it was observed along with modulation of MAPK signaling pathways (AKT, ERK, p38, p70S6K, and JNK). Moreover, STAT3, STAT5, and CREB transcription factors on protein levels were significantly reduced as a result of treatment with IBU- and KET-OAO derivatives conjugates. The most active were conjugates with OAO-morpholide. Overall, the findings of this study demonstrate that IBU-OAO and KET-OAO derivative conjugates modulate the key signaling pathways involved in hepatic cancer development. Their effect on specific signaling pathways varied depending on the structure of the conjugate. Since the conjugation of IBU and KET with OAO derivatives reduced their cytotoxicity, the conjugates may be considered good candidates for the prevention of liver cancer.

Experimental and Computational Investigation of the Oxime Bond Stereochemistry in c-Jun N-terminal Kinase 3 Inhibitors 11H-Indeno[1,2-b]quinoxalin-11-one Oxime and Tryptanthrin-6-oxime

11H-Indeno[1,2-b]quinoxalin-11-one oxime (IQ-1) and tryptanthrin-6-oxime are potent c-Jun N-terminal kinase 3 (JNK-3) inhibitors demonstrating neuroprotective, anti-inflammatory and anti-arthritic activity. However, the stereochemical configuration of the oxime carbon-nitrogen double bond (E- or Z-) in these compounds was so far unknown. In this contribution, we report the results of the determination of the double bond configuration in the solid state by single crystal X-ray diffraction and in solution by 1D and 2D NMR techniques and DFT calculations. It was found that both in the solid state and in solution, IQ-1 adopts the E-configuration stabilized by intermolecular hydrogen bonds, in contrast to previously assumed Z-configuration that could be stabilized only by an intramolecular hydrogen bond.

(E)-1-(5-Methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)ethan-1-one Oxime

The reaction of 1-(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)ethan-1-one (1) with excess hydroxylamine hydrochloride (2 mole equivalents) in dry ethanol afforded (E)-1-(5-methyl-1-(4-nitrophenyl)-1H-1,2,3-triazol-4-yl)ethan-1-one oxime (2) in 86% yield. The structure of the new heterocycle 2 was confirmed using nuclear magnetic resonance spectroscopy, single crystal X-ray and elemental analysis.

The Structural Diversity and Biological Activity of Steroid Oximes

Steroids and their derivatives have been the subject of extensive research among investigators due to their wide range of pharmacological properties, in which steroidal oximes are included. Oximes are a chemical group with the general formula R1R2C=N-OH and they exist as colorless crystals and are poorly soluble in water. Oximes can be easily obtained through the condensation of aldehydes or ketones with various amine derivatives, making them a very interesting chemical group in medicinal chemistry for the design of drugs as potential treatments for several diseases. In this review, we will focus on the different biological activities displayed by steroidal oximes such as anticancer, anti-inflammatory, antibacterial, antifungal and antiviral, among others, as well as their respective mechanisms of action. An overview of the chemistry of oximes will also be reported, and several steroidal oximes that are in clinical trials or already used as drugs are described. An extensive literature search was performed on three main databases-PubMed, Web of Science, and Google Scholar.

Cytotoxicity-related effects of imidazolium and chlorinated bispyridinium oximes in SH-SY5Y cells

Current research has shown that several imidazolium and chlorinated bispyridinium oximes are cytotoxic and activate different mechanisms or types of cell death. To investigate this further, we analysed interactions between these oximes and acetylcholine receptors (AChRs) and how they affect several signalling pathways to find a relation between the observed toxicities and their effects on these specific targets. Chlorinated bispyridinium oximes caused time-dependent cytotoxicity by inhibiting the phosphorylation of STAT3 and AMPK without decreasing ATP and activated ERK1/2 and p38 MAPK signal cascades. Imidazolium oximes induced a time-independent and significant decrease in ATP and inhibition of the ERK1/2 signalling pathway along with phosphorylation of p38 MAPK, AMPK, and ACC. These pathways are usually triggered by a change in cellular energy status or by external signals, which suggests that oximes interact with some membrane receptors. Interestingly, in silico analysis also indicated that the highest probability of interaction for all of our oximes is with the family of G-coupled membrane receptors (GPCR). Furthermore, our experimental results showed that the tested oximes acted as acetylcholine antagonists for membrane AChRs. Even though oxime interactions with membrane receptors need further research and clarification, our findings suggest that these oximes make promising candidates for the development of specific therapies not only in the field of cholinesterase research but in other fields too, such as anticancer therapy via altering the Ca2+ flux involved in cancer progression.

Preparation of oxime compound lipid droplet-specifically labeled fluorescent probe and its application in cell imaging

Fluorescent probes can facilitate our further comprehension of the functional and physiological roles of LDs and thus promote the development of effective therapeutic approaches. Oxime compounds are widely used due to their good crystallinity and high reactivity. However, the majority oximes fluorescent probes are usually employed for the detection of HCIO, and the application of oximes in fluorescently labeled LD_S is poorly reported. In this paper, three kinds of LDs fluorescent probes (NAP-a, NAP-b and NAP-c) with D-π-A structure were synthesized by simple synthesis method with 1,8-naphthalimide as fluorescent matrix and oxime group as electron donor. These probes were highly sensitive to polarity, and possessed good photostability and low cytotoxicity. Co-staining experiments showed that these probes could target LDs and the fluorescence image was green. These probes NAP-a, NAP-b and NAP-c possessed high Pearson coefficient (HeLa cells: 0.91, 0.95, 0.86) and Manders coefficient (HeLa cells: 0.91, 0.96, 0.86) with Nile Red. Interestingly, the dynamic variations in their size, shape and distribution could be clearly observed in the oleic acid-treated cell model of LDs. Imaging of zebrafish was performed and green fluorescence was collected in zebrafish. These excellent properties make oxime compound fluorescent probes a promising fluorescent probes for studying LDs and metabolic diseases. This study opens up a new way for the preparation of LDs fluorescent probe.

The stable "F-SO2 +" donor provides a mild and efficient approach to nitriles and amides

In this update, we developed a mild, efficient and practical method using fluorosulfuryl imidazolium salt A as an environment friendly promoter for conversion of oximes to nitriles or amides via β-elimination or Beckmann rearrangement in almost quantitative yield in 10 minutes. The target products were generated in gram-scale and could be collected through crystallization without silica gel column purification in excellent yield.

Quantification of a promising JNK inhibitor and nitrovasodilator IQ-1 and its major metabolite in rat plasma by LC-MS/MS

Background: IQ-1 is a promising c-Jun-N-terminal kinase inhibitor and nitrovasodilator. An LC-MS/MS method was validated to determine IQ-1 isomers and major metabolite IQ-18 in rat plasma. Materials & methods: The analytes were extracted using ethyl acetate. The chromatographic separation was performed on a C8 column (150 × 4.6 mm, 5 μm) under acetonitrile-water (5 mM ammonium formate buffer, pH 2.93) gradient elution. Multiple reaction monitoring was used for MS/MS detection in the positive ion mode. Results: The method was fully validated over the range of 0.1-400 ng/ml (Z-isomer), 0.9-3600 ng/ml (E-isomer), 5.0-4000 (IQ-18). Conclusion: This method has been successfully applied to pharmacokinetic studies of IQ-1 and IQ-18 in rats after a single oral dose of IQ-1 (50 mg/kg).

New insights into the characteristics of DRAK2 and its role in apoptosis: From molecular mechanisms to clinically applied potential

As a member of the death-associated protein kinase (DAPK) family, DAP kinase-associated apoptosis-inducing kinase 2 (DRAK2) performs apoptosis-related functions. Compelling evidence suggests that DRAK2 is involved in regulating the activation of T lymphocytes as well as pancreatic β-cell apoptosis in type I diabetes. In addition, DRAK2 has been shown to be involved in the development of related tumor and non-tumor diseases through a variety of mechanisms, including exacerbation of alcoholic fatty liver disease (NAFLD) through SRSF6-associated RNA selective splicing mechanism, regulation of chronic lymphocytic leukemia and acute myeloid leukemia, and progression of colorectal cancer. This review focuses on the structure, function, and upstream pathways of DRAK2 and discusses the potential and challenges associated with the clinical application of DRAK2-based small-molecule inhibitors, with the aim of advancing DRAK2 research.

Design, synthesis and biological evaluation of novel O-substituted tryptanthrin oxime derivatives as c-Jun N-terminal kinase inhibitors

The c-Jun N-terminal kinase (JNK) family includes three proteins (JNK1-3) that regulate many physiological processes, including inflammatory responses, morphogenesis, cell proliferation, differentiation, survival, and cell death. Therefore, JNK represents an attractive target for therapeutic intervention. Herein, a panel of novel tryptanthrin oxime analogs were synthesized and evaluated for JNK1-3 binding (K_d) and inhibition of cellular inflammatory responses (IC₅₀). Several compounds exhibited submicromolar JNK binding affinity, with the most potent inhibitor being 6-(acetoxyimino)indolo[2,1-b]quinazolin-12(6H)-one (1j), which demonstrated high JNK1-3 binding affinity (K_d = 340, 490, and 180 nM for JNK1, JNK2, and JNK3, respectively) and inhibited lipopolysaccharide (LPS)-induced nuclear factor-κB/activating protein 1 (NF-κB/AP-1) transcription activity in THP-1Blue cells and interleukin-6 (IL-6) production in MonoMac-6 monocytic cells (IC₅₀ = 0.8 and 1.7 μM, respectively). Compound 1j also inhibited LPS-induced production of several other proinflammatory cytokines, including IL-1α, IL-1β, granulocyte-macrophage colony-stimulating factor (GM-CSF), monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor (TNF) in MonoMac-6 cells. Likewise, 1j inhibited LPS-induced c-Jun phosphorylation in MonoMac-6 cells, directly confirming JNK inhibition. Molecular modeling suggested modes of binding interaction of selected compounds in the JNK3 catalytic site that were in agreement with the experimental JNK3 binding data. Our results demonstrate the potential for developing anti-inflammatory drugs based on these nitrogen-containing heterocyclic systems.

Novel Oxime Synthesized from a Natural Product of Senecio nutans SCh. Bip. (Asteraceae) Enhances Vascular Relaxation in Rats by an Endothelium-Independent Mechanism

Senecio nutans Sch. Bip. and its constituents are reported to have antihypertensive effects. We isolated metabolite−1, a natural compound from S. nutans (4-hydroxy-3-(isopenten-2-yl)-acetophenone), and synthesized novel oxime − 1 (4-hydroxy-3-(isopenten-2-yl)-acetophenoxime) to evaluate their effect on vascular reactivity. Compounds were purified (metabolite−1) or synthetized (oxime−1) and characterized using IR and NMR spectroscopy and Heteronuclear Multiple Quantum Coherence (HMQC). Using pharmacological agents such as phenylephrine (PE) and KCl (enhancing contraction), acetylcholine (ACh), L-NAME (nitric oxide (NO) and endothelial function), Bay K8644-induced CaV1.2 channel (calcium channel modulator), and isolated aortic rings in an organ bath setup, the possible mechanisms of vascular action were determined. Pre-incubation of aortic rings with 10−5 M oxime−1 significantly (p < 0.001) decreased the contractile response to 30 mM KCl. EC50 to KCl significantly (p < 0.01) increased in the presence of oxime−1 (37.72 ± 2.10 mM) compared to that obtained under control conditions (22.37 ± 1.40 mM). Oxime−1 significantly reduced (p < 0.001) the contractile response to different concentrations of PE (10−7 to 10−5 M) by a mechanism that decreases Cav1.2-mediated Ca2+ influx from the extracellular space and reduces Ca2+ release from intracellular stores. At a submaximal concentration (10−5 M), oxime−1 caused a significant relaxation in rat aorta even without vascular endothelium or after pre-incubate the tissue with L-NAME. Oxime−1 decreases the contractile response to PE by blunting the release of Ca2+ from intracellular stores and blocking of Ca2+ influx by channels. Metabolite−1 reduces the contractile response to KCl, apparently by reducing the plasma membrane depolarization and Ca2+ influx from the extracellular space. These acetophenone derivates from S. nutans (metabolite−1 and oxime−1) cause vasorelaxation through pathways involving an increase of the endothelial NO generation or a higher bioavailability, further highlighting that structural modification of naturally occurring metabolites can enhance their intended pharmacological functions.

The antibacterial potential of ciprofloxacin hybrids against Staphylococcus aureus

Staphylococcus aureus (S. aureus), an important pathogen of both humans and animals, is able to cause a variety of infections at any site of the body. The evolution of S. aureus resistance is notorious, and the widespread of drug-resistant S. aureus, especially methicillin-resistant S. aureus (MRSA), has made the treatment difficult in recent decades. Nowadays, S. aureus is among the leading causes of bacterial infections, creating an urgent need for the development of novel antibacterial agents. Ciprofloxacin, characterized by high clinical efficacy, is a broad-spectrum antibacterial agent with frequency of prescription for various Gram-positive and Gram-negative pathogens, many of which are resistant to a wide range of antibiotics. However, the long-term and widespread use of this antibiotic has led to the emergence of ciprofloxacin-resistant pathogens, and ciprofloxacin-resistant S. aureus has been noted in clinical practice. Ciprofloxacin hybrids have been recognized as advanced chemical entities to simultaneously modulate multiple drug targets in bacteria, so ciprofloxacin hybrids have the potential to overcome drug resistance. The present review provides an overview of ciprofloxacin hybrids with anti-S. aureus potential that have been reported in the last decade with emphasis on their structure-activity relationships and mechanisms of action.

Imidazopyridazine Acetylcholinesterase Inhibitors Display Potent Anti-Proliferative Effects in the Human Neuroblastoma Cell-Line, IMR-32

Imidazo[1,2-b]pyridazine compounds are a new class of promising lead molecules to which we have incorporated polar nitro and amino moieties to increase the scope of their biological activity. Two of these substituted 3-nitro-6-amino-imidazo[1,2-b]pyridazine compounds (5c and 5h) showed potent acetylcholinesterase (AChE) inhibitory activity (IC₅₀ 40–50 nM), which we have previously reported. In this study, we wanted to test the biological efficacy of these compounds. Cytotoxicity assays showed that compound 5h mediated greater cell death with over 43% of cells dead at 100 μM and activation of caspase 3-mediated apoptosis. On the other hand, compound 5c mediated a dose-dependent decrease in cell proliferation. Both compounds showed cell cycle arrest in the G₀/G₁ phase and reduced cellular ATP levels leading to activation of adenosine monophosphate-activated protein kinase (AMPK) and enhanced mitochondrial oxidative stress. It has to be noted that all these effects were observed at doses beyond 10 μM, 200-fold above the IC₅₀ for AChE inhibition. Both compounds also inhibited bacterial lipopolysaccharide-mediated cyclooxygenase-2 and nitric oxide release in primary rat microglial cells. These results suggested that the substituted imidazo (1,2-b) pyridazine compounds, which have potent AChE inhibitory activity, were also capable of antiproliferative, anti-migratory, and anti-inflammatory effects at higher doses.

Chemical Composition and Immunomodulatory Activity of Essential Oils from Rhododendron albiflorum

Rhododendron (Ericaceae) extracts contain flavonoids, chromones, terpenoids, steroids, and essential oils and are used in traditional ethnobotanical medicine. However, little is known about the immunomodulatory activity of essential oils isolated from these plants. Thus, we isolated essential oils from the flowers and leaves of R. albiflorum (cascade azalea) and analyzed their chemical composition and innate immunomodulatory activity. Compositional analysis of flower (REO_Fl) versus leaf (REO_Lv) essential oils revealed significant differences. REO_Fl was comprised mainly of monoterpenes (92%), whereas sesquiterpenes were found in relatively low amounts. In contrast, REO_Lv was primarily composed of sesquiterpenes (90.9%), with a small number of monoterpenes. REO_Lv and its primary sesquiterpenes (viridiflorol, spathulenol, curzerene, and germacrone) induced intracellular Ca²⁺ mobilization in human neutrophils, C20 microglial cells, and HL60 cells transfected with N-formyl peptide receptor 1 (FPR1) or FPR2. On the other hand, pretreatment with these essential oils or component compounds inhibited agonist-induced Ca²⁺ mobilization and chemotaxis in human neutrophils and agonist-induced Ca²⁺ mobilization in microglial cells and FPR-transfected HL60 cells, indicating that the direct effect of these compounds on [Ca²⁺]_i desensitized the cells to subsequent agonist activation. Reverse pharmacophore mapping suggested several potential kinase targets for these compounds; however, these targets were not supported by kinase binding assays. Our results provide a cellular and molecular basis to explain at least part of the beneficial immunotherapeutic properties of the R. albiflorum essential oils and suggest that essential oils from leaves of this plant may be effective in modulating some innate immune responses, possibly by inhibition of neutrophil migration.