Can a Small Change in the Heterocyclic Substituent Significantly Impact the Physicochemical and Biological Properties of (Z)-2-(5-Benzylidene-4-oxo-2-thioxothiazolidin-3-yl)acetic Acid Derivatives?

Rhodanine-3-acetic acid derivatives are attractive compounds with versatile effects. What is very important is that compounds of this type have many biological properties. They are tested, among others, as fluorescent probes for bioimaging and aldose reductase inhibitors. Rhodanine-3-acetic acid derivatives also have antibacterial, antifungal and anticancer activity. The presented work demonstrates that a slight change in the five-membered heterocyclic substituent significantly affects the properties of the compounds under consideration. Three rhodanine-3-acetic acid derivatives (A-1-A-3) were obtained in the Knoevenagel condensation reaction with good yields, ranging from 54% to 71%. High thermal stability of the tested compounds was also demonstrated above 240 °C. The absorption and emission maxima in polar and non-polar solvents were determined. Then, the possibility of using the considered derivatives for fluorescence bioimaging was checked. Compounds A-1 and A-2 were successfully used as fluorescent dyes of fixed cells of mammalian origin. In addition, biological activity tests against bacteria and fungi were carried out. Our results showed that A-1 and A-2 showed the most excellent antimicrobial activity among the newly synthesized compounds, especially against Gram-positive bacteria.

Analyzing Interaction of Rhodacyanine Inhibitor 'MKT-077' with Plasmodium falciparum HSP70s.

INTRODUCTION: MKT-077 and its derivatives are rhodacyanine inhibitors that hold potential in the treatment of cancer, neurodegenerative diseases and malaria. These allosteric drugs act by inhibiting the ATPase action of heat shock proteins of 70 kDa (HSP70). MKT-077 accumulates in the mitochondria and displays differential activity against HSP70 homologs. METHODS: The four Plasmodium falciparum HSP70s (PfHSP70) are present in various subcellular locations to perform distinct functions. In the present study, we have used bioinformatics tools to understand the interaction of MKT-077 at the ADP and HEW (2-amino 4 bromopyridine) binding sites on PfHSP70s. Our molecular docking experiments predict that the mitochondrial and endoplasmic reticulum PfHSP70 homologs are likely to bind MKT-077 with higher affinities at their ADP binding sites. RESULTS: Binding analysis indicates that the nature of the identified interactions is primarily hydrophobic. We have also identified specific residues of PfHSP70s that are involved in interacting with the ligand. CONCLUSION: Information obtained in this study may form the foundation for the design and development of MKT-077-based drugs against malaria.

Rhodanine Derivatives as Anticancer Agents: QSAR and Molecular Docking Studies.

BACKGROUND: Rhodanine derivatives have a proven wide range of biological activities. OBJECTIVE: The aim of this study was to evaluate the cytotoxic effect of a series of rhodanine derivatives and investigate the quantitative structure-activity relationships, as well as binding modes to tyrosine kinase. METHODS: Cytotoxic effect on cell proliferation (CaCo-2, HeLa, MDCK-1, Hut-78, K562) in vitro was evaluated by the MTT viability assay. QSAR analysis was performed with Dragon descriptors using QSARINS software. Molecular docking was performed on the tyrosin kinase (c-Src) (PDB ID: 3G6H) using iGEMDOCK. RESULTS: Compounds with the best inhibiting activity toward all cell lines were the ones possessing only one group in the C2 of the phenyl ring. QSAR study on the cytotoxic activity against Human T cell lymphoma achieved the model that satisfies the fitting and internal cross-validation criteria (R2 = 0.75; Q2 LOO = 0.64). Descriptors included in the model (MATS2e, MATs7e, RDF060p) revealed the importance of the presence of atoms with higher polarizability in the outer region of molecules. The findings of the molecular docking study performed on the c-Src are in accordance with the results of the QSAR study. The key interactions with binding site residues were achieved through oxygen atoms from phenoxy and rhodanine groups and rhodanine sulphur atoms. CONCLUSION: Rhodanine derivatives could be developed as novel tyrosine kinase inhibitors in the treatment of leukemia.

Anticancer Profile of Rhodanines: Structure-Activity Relationship (SAR) and Molecular Targets-A Review.

The rhodanine core is a well-known privileged heterocycle in medicinal chemistry. The rhodanines, as subtypes of thiazolidin-4-ones, show a broad spectrum of biological activity, including anticancer properties. This review aims to analyze the anticancer features of the rhodanines described over the last decade in the scientific literature. The structure-activity relationship of rhodanine derivatives, as well as some of the molecular targets, were discussed. The information contained in this review could be of benefit to the design of new, effective small molecules with anticancer potential among rhodanine derivatives or their related heterocycles.

Review of anticancer potentials and structure-activity relationships (SAR) of rhodanine derivatives.

Rhodanine has been recognized as a privileged scaffold in medicinal chemistry due to its well-known ability to demonstrate a broad range of biological activities. The possibility of structural diversification has contributed to the significance of rhodanine structure in effective drug discovery and design. Many studies have confirmed the potential of rhodanine-derived compounds in the treatment of different types of cancer through the apoptosis induction mechanism. Furthermore, most of the rhodanine derivatives exhibited remarkable anticancer activity in the micromolar range while causing negligible cytotoxicity to normal cells. This review critically describes the anticancer activity profile of reported rhodanine compounds and the structure-activity relationships (SAR) to highlight the value of rhodanine as the core structure for future cancer drug development as well as to assist the researchers in rational drug design.

Discovery of facile amides-functionalized rhodanine-3-acetic acid derivatives as potential anticancer agents by disrupting microtubule dynamics.

Microtubule dynamics are crucial for multiple cell functions, and cancer cells are particularly sensitive to microtubule-modulating agents. Here, we describe the design and synthesis of a series of (Z)-2-(5-benzylidene-4-oxo-2-thioxothiazolidin-3-yl)-N-phenylacetamide derivatives and evaluation of their microtubule-modulating and anticancer activities in vitro. Proliferation assays identified I20 as the most potent of the antiproliferative compounds, with 50% inhibitory concentrations ranging from 7.0 to 20.3 µM with A549, PC-3, and HepG2 human cancer cell lines. Compound I20 also disrupted cancer A549 cell migration in a concentration-dependent manner. Immunofluorescence microscopy, transmission electron microscopy, and tubulin polymerisation assays suggested that compound I20 promoted protofilament assembly. In support of this possibility, computational docking studies revealed a strong interaction between compound I20 and tubulin Arg ß369, which is also the binding site for the anticancer drug Taxol. Our results suggest that (Z)-2-(5-benzylidene-4-oxo-2-thioxothiazolidin-3-yl)-N-phenylacetamide derivatives could have utility for the development of microtubule-stabilising therapeutic agents.

The dual inhibition against the activity and expression of tyrosine phosphatase PRL-3 from a rhodanine derivative.

Increasing evidences demonstrated that PRL-3 was associated with metastatic potential in a variety of cancers including CRC, gastric cancer, ovarian cancer and so on. PRL-3 knock down inhibited the development of metastasis by reducing the size of primary tumors and inhibiting the invasion and growth of cancer cells. Therefore, PRL-3 is a promising diagnostic marker and therapeutic target in tumors. So far, only several PRL-3 inhibitors have been reported. In this study, six rhodanine derivatives were synthesized and characterized. The compounds were evaluated against tyrosine phosphatase PRL-3. Among these compounds, 5-(5-chloro-2-(trifluoromethyl)benzylidene)-2-thioxothiazolidin-4-one (4) could effectively inhibit PRL-3 with IC50 value of 15.22 µM. Fluorescent assays suggested compound 4 tightly bound to tyrosine phosphatase PRL-3 with the molar ratio of 1:1, and the binding constant of 1.74 × 106 M-1. Compound 4 entered into SW-480 cells, selectively inhibited the expression of PRL-3 and increased the phosphorylation of PRL-3 substrates, and decreased the survival rate of SW-480 cells with IC50 of 6.64 µM and induced apoptosis. The results revealed that compound 4 is a dual functional inhibitor against the activity and expression of PRL-3 and a promising anti-cancer candidate targeting PRL-3.

Protective Effects of Novel Substituted Triazinoindole Inhibitors of Aldose Reductase and Epalrestat in Neuron-like PC12 Cells and BV2 Rodent Microglial Cells Exposed to Toxic Models of Oxidative Stress: Comparison with the Pyridoindole Antioxidant Stobadine.

Aldose reductase (AR) catalyzes the conversion of glucose to sorbitol in a NADPH-dependent reaction, thereby increasing the production of reactive oxygen species (ROS). Since AR activation is linked to redox dysregulation and cell damage in neurodegenerative diseases, AR inhibitors (ARIs) constitute promising therapeutic tools for the treatment of these disorders. Among these compounds, the novel substituted triazinoindole derivatives cemtirestat (CMTI) and COTI, as well as the clinically employed epalrestat (EPA) and the pyridoindole-antioxidant stobadine (STB), were tested in both PC12 cells and BV2 microglia exposed to four different neurotoxic models. These include (1) oxidative stress with hydrogen peroxide (H2O2), (2) mitochondrial complex IV inhibition with NaN3, (3) endoplasmic reticulum-stress and lipotoxicity induced by palmitic acid/bovine serum albumin (PAM/BSA), and (4) advanced carbonyl compound lipotoxicity by 4-hydroxynonenal (4-HNE). All toxic compounds decreased cell viability and increased ROS formation in both PC12 and BV2 cells in a concentration-dependent manner (1-1000 µM; NaN3 < H2O2≈PAM/BSA < 4-HNE). In PC12 cells, EPA increased cell viability in all toxic models only at 1 µM, whereas CMTI restored baseline viability in all toxic models. COTI afforded protection against lipotoxicity, while STB only prevented H2O2-induced toxicity. Except for the 4-HNE model, EPA prevented ROS generation in all other toxic models, whereas CMTI, COTI, and STB prevented ROS production in all toxic models. In BV2 cells, EPA and CMTI restored baseline cell viability in all toxic models tested, while COTI and STB did not prevent the loss of viability in the NaN3 model. All ARIs and STB efficiently prevented ROS formation in all toxic models in a concentration-independent manner. The differential protective effects evoked by the novel ARIs and STB on the toxic models tested herein provide novel and relevant comparative evidence for the design of specific therapeutic strategies against neurodegenerative events associated with neurological disorders.

The Importance of Rhodanine Scaffold in Medicinal Chemistry: A Comprehensive Overview.

After the clinical use of epalrestat that contains a rhodanine ring, in type II diabetes mellitus and diabetic complications, rhodanin-based compounds have become an important class of heterocyclic in the field of medicinal chemistry. Various modifications to the rhodanine ring have led to a broad spectrum of biological activity of these compounds. Synthesis of rhodanine derivatives, depended on advenced throughput scanning hits, frequently causes potent and selective modulators of targeted enzymes or receptors, which apply their pharmacological activities through different mechanisms of action. Rhodanine-based compounds will likely stay a privileged scaffold in drug discovery because of different probability of chemical modifications of the rhodanine ring. We have, therefore reviewed their biological activities and structure activity relationship.

(4-Oxo-2-thioxothiazolidin-3-yl)acetic acids as potent and selective aldose reductase inhibitors.

(4-Oxo-2-thioxothiazolidin-3-yl)acetic acids exhibit a wide range of pharmacological activities. Among them, the only derivative used in clinical practice is the aldose reductase inhibitor epalrestat. Structurally related compounds, [(5Z)-(5-arylalkylidene-4-oxo-2-thioxo-1,3-thiazolidin-3-yl)]acetic acid derivatives were prepared previously as potential antifungal agents. This study was aimed at the determination of aldose reductase inhibitory action of the compounds in comparison with epalrestat and evaluation of structure-activity relationships (SAR). The aldose reductase (ALR2) enzyme was isolated from the rat eye lenses, while aldehyde reductase (ALR1) was obtained from the kidneys. The compounds studied were found to be potent inhibitors of ALR2 with submicromolar IC50 values. (Z)-2-(5-(1-(5-butylpyrazin-2-yl)ethylidene)-4-oxo-2-thioxothiazolidin-3-yl)acetic acid (3) was identified as the most efficacious inhibitor (over five times more potent than epalrestat) with mixed-type inhibition. All the compounds also exhibited low antiproliferative (cytotoxic) activity to the HepG2 cell line. Molecular docking simulations of 3 into the binding site of the aldose reductase enzyme identified His110, Trp111, Tyr48, and Leu300 as the crucial interaction counterparts responsible for the high-affinity binding. The selectivity factor for 3 in relation to the structurally related ALR1 was comparable to that for epalrestat. SAR conclusions suggest possible modifications to improve further inhibition efficacy, selectivity, and biological availability in the group of rhodanine carboxylic acids.

New N-ribosides and N-mannosides of rhodanine derivatives with anticancer activity on leukemia cell line: Design, synthesis, DFT and molecular modelling studies.

N-ribosylation and N-mannosylation compounds have a great role in compounds activity as anticancer. The reaction of 2-thioxo-4-thiazolidinone (rhodanine) derivatives, as aglycon part, was done with ribofuranose and mannopyranose sugars (glycone part) followed by deacetylation without cleavage of the rhodanine under acidic medium. Conformational analysis has been studied using NMR methods (2D, DQF-COSY, HMQC and HMBC). All final the new deprotected nucleosides were screened against leukemia 1210, and were found to be considerably less potent (Ic50% 1.4-10.6 µM) than doxorubicin (Ic50% 0.02 µM). Compounds 10d and 10e which contain ribose moiety have better activity than those with mannose sugar. DFT calculations with B3LYP/6-31 + G (d) level were used to analyze the electronic and geometric characteristics deduced from the stable structure of the compounds. The principal quantum chemical descriptors showed a good correlation with the experimental observations. Rapid Overlay Comparison Similarity (ROCS) study was operated to explain the compounds similarity and to figure out the most important pharmacophoric features.

Targeted co-delivery of the aldose reductase inhibitor epalrestat and chemotherapeutic doxorubicin via a redox-sensitive prodrug approach promotes synergistic tumor suppression.

Rapidly growing evidence suggests a strong dependence of a polyol pathway enzyme Aldose Reductase (AR) in cancer progression and invasion. Thus, inhibiting the AR through therapeutic inhibitors has a potential application in cancer treatment. Epalrestat (EPR) is the only marketed AR inhibitor with proven safety and efficacy in the management of complications like diabetic neuropathy. However, its short half-life and highly hydrophobic nature restrict its use as an anticancer agent. In the present study, we first developed a redox-sensitive prodrug of EPR by conjugating Tocopherol Polyethylene Glycol Succinate (TPGS) which can form a self-assembled micellar prodrug (EPR-SS-TPPGS). Subsequently, to achieve synergistic chemotherapeutic efficacy Doxorubicin (Dox) was co-loaded into the EPR-SS-TPGS micelles where the system is disrupted in a tumor redox environment and co-delivers Dox and EPR in a ratiometric manner. We then employed TPGS conjugated vitamin-B6 as a targeting moiety and prepared the mixed micelles to facilitate VTC receptor-mediated uptake. The encapsulation of Dox and EPR with the developed prodrug approach showed significant synergies with increased intracellular accumulation and redox triggered release in MDA-MB-231 and 4T1 cell lines leading to superior cell cycle arrest, mitochondrial membrane potential, and apoptosis. Prolonged circulation half-life and tumor site bioavailability were achieved for both the drugs with the developed approach. Surprisingly, EPR and Dox combination significantly down-regulated the CD44 receptor expression which is the main contributing factor of tumor metastasis. Furthermore, in vivo evaluation demonstrated a significant reduction in Dox-induced cardiotoxicity. In summary, this nanoencapsulation paradigm of AR inhibitors with chemotherapeutic agents lays the foundation of new opportunities in combination chemotherapy.

Synthesis and biological evaluation of purine-pyrazole hybrids incorporating thiazole, thiazolidinone or rhodanine moiety as 15-LOX inhibitors endowed with anticancer and antioxidant potential.

Novel purine-pyrazole hybrids combining thiazoles, thiazolidinones and rhodanines, were designed and tested as 15-LOX inhibitors, potential anticancer and antioxidant agents. All tested compounds were found to be potent 15-LOX inhibitors with IC50 ranging from 1.76 to 6.12 µM. The prepared compounds were evaluated in vitro against five cancer cell lines: A549 (lung), Caco-2 (colon), PC3 (prostate), MCF-7 (breast) and HepG-2 (liver). Compounds 7b and 8b displayed broad spectrum anticancer activity against the five tested cell lines (IC50 = 18.5-95.39 µM). While, compound 7h demonstrated moderate anticancer activity against lung A549 and colon Caco-2 cell lines. Antioxidant screening revealed that six compounds (5a, 5b, 6b, 7b, 7h and 8b) with IC50 ranging from 0.93 to 14.43 µg/ml were found to be more potent scavengers of 2,2- diphenyl-1-picrylhydrazyl (DPPH) than the reference ascorbic acid with IC50 value of 15.34 µg/ml. Compounds 7b, 7h and 8b, when evaluated for their antioxidant activity, where found to be potent DPPH scavengers. Moreover, compound 7b displayed twice the potency of ascorbic acid as NO scavenger. Docking study was performed to elucidate the possible binding mode of the most active compounds with the active site of 15-LOX enzyme. Collectively, the purine-pyrazole hybrids having thiazoline or thizolidinone moieties (7b, 7h and 8b) constitute a promising scaffold in designing more potent 15-LOX inhibitors with anticancer and antioxidant potential.

A conceptual review of rhodanine: current applications of antiviral drugs, anticancer and antimicrobial activities.

Rhodanines are accepted as advantaged heterocycles in medicinal chemistry as one of the 4-thiazolidinones subtypes. The aim of this paper is to analyze the features of rhodanine and its application in pharmacy and medicine. Some of the properties of rhodanine such as antiviral, anticancer, antimicrobial, and drug discovery have recently been reported. Although there are still vague points in the structure and mechanism of polymerization of this substance, there is a significant increase in the use of rhodanine in medicine. In this review paper, it can be said that we have provided a general overview of the recent advances in the rhodanine-based material which its application is more in the field of drug discovery and anticancer activity. The review starts with a summary of the antiviral activity of rhodanine-based materials and nanocomposites in general. Then in the next step, the detailed description is followed on their applications in the fields of anticancer activity, drug discovery, and an innovative type of rhodanine (RH) and thiohydantoin (TH) derivatives were created and combined in order to recognize tau pathology in the brains of patients with Alzheimer's disease (AD). Through this review, we hope to promote rhodanine and its role in medicine and pharmacy becomes more prominent.

Synthesis of Novel Fluorine Compounds Substituted-4-thiazolidinones Derived from Rhodanine Drug as Highly Bioactive Probes.

AIM AND OBJECTIVE: It is known that rhodanine drug has various biocidal activities. The aim of this work was to improve the structure of rhodanine drug via alkylation at N, S, and O- centers in addition to the introduction of fluorine atoms. The new fluorinated modified rhodanines 2-16 were evaluated as enzymatic probes for cellobiase activity produced by fungi and as CDK2 inhibitors of tumor cells. MATERIALS AND METHODS: Novel fluorine substituted N-alkyl, S-alkyl and amino-rhodanines were obtained via Hydroxy methylation, Mannich reactions, chlorination and amination of 5-(4'-fluorophenylene)-2-thioxothiazolidin- 4-one, and the enzymatic effects of cellobiase produced by fungi and /or CDK2 inhibition of tumor cells were evaluated. RESULTS: Most of the targets were obtained in high yield and in the form of very pure crystals with characteristic colors. Only compounds 5, 8, 10, 13, and 14 exhibited a higher activity as cellobiase while compounds 2 and 5 showed a highly enzymatic effect on tumor cells. In addition, compounds 2 and 10 can be used as Olomoucine (standard referees). CONCLUSION: Various N, S and O-alkyl derivatives of fluorine-substituted rhodanines were prepared via a simple method and used as enzymatic probes for cellobiase activity produced by fungi and CDK2 inhibitors for tumor cells. The more bioactive compounds had rich fluorine atoms as p-fluorophenyl and p-fluorobenzoyl bearing N, S, O-alkyl rhodanine. The highly active compounds may be used as enzymatic materials for various biological transformations in the future.

Design and synthesis of biaryloxazolidinone derivatives containing a rhodanine or thiohydantoin moiety as novel antibacterial agents against Gram-positive bacteria.

Novel biaryloxazolidinone derivatives containing a rhodanine or thiohydantoin moiety were designed, synthesized and evaluated for their antibacterial activity. The key compounds 7 and 9 were synthesized by the knoevenagel condensation of intermediate aldehyde 5 with rhodanine derivatives 6a-6b. The preliminary study showed that compounds 7, 9 and 10e exhibited potent antibacterial activity with MIC values of 0.125 µg/mL against S. aureus, MRSA, MSSA, LREF and VRE pathogens, using linezolid and radezolid as the positive controls. The most promising compound 10e exhibited potent antibacterial activity against tested clinical isolates of MRSA, MSSA, VRE and LREF with MIC values in the range of 0.125-0.5 µg/mL, and the potency of 10e against clinical isolates of LREF was 64-fold higher than that of linezolid. Moreover, compound 10e was non-cytotoxic with an IC50 value of 91.04 µM against HepG2 cell. Together, compound 10e might serve as a novel antibacterial agent for further investigation.

Spectroscopic and In Silico DNA Binding Studies on the Interaction of Some New N-Substituted Rhodanines with Calf-thymus DNA: In Vitro Anticancer Activities.

BACKGROUND: In this era of science, cancer is a black dot on the face of humankind. Consequently, the search of promising anticancer agents continues. AIMS: Here we designed and synthesized new N-substituted rhodanines (RD1-7), evaluated their multispectroscopic interaction with calf thymus DNA, in silico and anticancer studies against MDA-MB-231cancer cell line. METHODS: By MTT assay rhodanine RD1 was found to be the most potent with IC50 value of 72.61 µM. In addition, DNA binding studies (UV-vis and fluorescence) revealed strong binding affinity of RD1-7 with DNA (Kb in the range of 1.5-7.4 × 105 M-1). Moreover, molecular docking study, experimental DNA binding and anticancer studies are all well agreed to each other. RESULTS: It was observed that H-bonding and hydrophobic attractions were responsible for stability of DNAcompound adducts. Besides, the reported rhodanines (RD1-7) were found as minor groove binders of DNA. Concisely, RD1-7 indicated promising pharmacological properties and hence, shows auspicious future for the development of novel anticancer agents. CONCLUSION: The reported rhodanines showed excellent anticancer properties. Therefore, the described rhodanines may be used as potential anticancer agents in the future.

A Fluorescent Turn-On Carbazole-Rhodanine Based Sensor for Detection of Ag+ Ions and Application in Ag+ Ions Imaging in Cancer Cells.

Carbazole - Rhodanine conjugate is an effective fluorescent host for silver ions through fluorometric transformation from green to red color with a hyperchromic emission. An intramolecular charge transfer process derived from carbazole towards rhodanine favors interaction of thiocarbonyl S and carboxylic acid O of the rhodanine moiety towards Ag+ ion. Carbazole - rhodanine dyad accomplishes the lowest detection limit of 12.8 × 10-9 M and high quantum efficiency. A fluorescence reversibility of the probe with I- ion surges reutilization of sensor molecule as an Ag+ ion probe with minimal loss in the fluorescent efficiency. This fluorescent ligand is a biocompatible probe and is also a proficient candidate for fluorescent imaging of Ag+ ion in live cells.

Novel Rhodanine Derivative, 5-[4-(4-Fluorophenoxy) phenyl]methylene-3-{4-[3-(4-methylpiperazin-1-yl) propoxy]phenyl}-2-thioxo-4-thiazolidinone dihydrochloride, Induces Apoptosis via Mitochondria Dysfunction and Endoplasmic Reticulum Stress in Human Colon Cancer Cells.

We previously reported that 5-[4-(4-fluorophenoxy) phenyl] methylene-3-{4-[3-(4-methylpiperazin-1-yl)propoxy]phenyl}-2-thioxo-4-thiazolidinone dihydrochloride (KSK05104) has potent, selective and metabolically stable IKKß inhibitory activities. However, the apoptosis-inducing of KSK05104 and its underlying mechanism have not yet been elucidated in human colon cancer cells. We show that KSK05104 triggered apoptosis, as indicated by externalization of Annexin V-targeted phosphatidylserine residues in HT-29 and HCT-116 cells. KSK05104 induced the activation of caspase-8, -9, and -3, and the cleavage of poly (ADP ribose) polymerase-1 (PARP-1). KSK05104-induced apoptosis was significantly suppressed by pretreatment with z-VAD-fmk (a broad caspase inhibitor). KSK05104 also induced release of cytochrome c (Cyt c), apoptosis inducing factor (AIF), and endonuclease G (Endo G) by damaging mitochondria, resulting in caspase-dependent and -independent apoptotic cell death. KSK05104 triggered endoplasmic reticulum (ER) stress and changed the intracellular calcium level ([Ca2+]i). Interestingly, treatment with KSK05104 activated not only ER stress marker proteins including inositol-requiring enzyme 1-alpha (IRE-1α) and protein kinase RNA-like endoplasmic reticulum kinase (PERK), but also µ-calpain, and caspase-12 in a time-dependent manner. KSK05104-induced apoptosis substantially decreased in the presence of BAPTA/AM (an intracellular calcium chelator). Taken together, these results suggest that mitochondrial dysfunction and ER stress contribute to KSK05104-induced apoptosis in human colon cancer cells.

Environmentally Friendly Approach to Knoevenagel Condensation of Rhodanine in Choline Chloride: Urea Deep Eutectic Solvent and QSAR Studies on Their Antioxidant Activity.

A series of rhodanine derivatives was synthesized in the Knoevenagel condensation of rhodanine and different aldehydes using choline chloride:urea (1:2) deep eutectic solvent. This environmentally friendly and catalyst free approach was very effective in the condensation of rhodanine with commercially available aldehydes, as well as the ones synthesized in our laboratory. All rhodanine derivatives were subjected to 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity investigation and quantitative structure-activity relationship (QSAR) studies were performed to elucidate their structure-activity relationship. The best multiple linear QSAR model demonstrate a stability in the internal validation and Y-randomization (R² = 0.81; F = 24.225; Q²loo = 0.72; R²Yscr = 0.148). Sphericity of the molecule, ratio of symmetric atoms enhanced atomic mass along the principle axes in regard to total number of atoms in molecule, and 3D distribution of the atoms higher electronegativity (O, N, and S) in molecules are important characteristic for antioxidant ability of rhodanine derivatives. Molecular docking studies were carried out in order to explain in silico antioxidant studies, a specific protein tyrosine kinase (2HCK). The binding interactions of the most active compound have shown strong hydrogen bonding and van der Waals interactions with the target protein.