Exploring rhodanine linked enamine-carbohydrazide derivatives as mycobacterial carbonic anhydrase inhibitors: Design, synthesis, biological evaluation, and molecular docking studies.

With the rise of multidrug-resistant tuberculosis, the imperative for an alternative and superior treatment regimen, incorporating novel mechanisms of action, has become crucial. In pursuit of this goal, we have developed and synthesized a new series of rhodanine-linked enamine-carbohydrazide derivatives, exploring their potential as inhibitors of mycobacterial carbonic anhydrase. The findings reveal their efficacy, displaying notable selectivity toward the mycobacterial carbonic anhydrase 2 (mtCA 2) enzyme. While exhibiting moderate activity against human carbonic anhydrase isoforms, this series demonstrates promising selectivity, positioning these compounds as potential antitubercular agents. Compound 6d was the best one from the series with a Ki value of 9.5 µM toward mtCA 2. Most of the compounds displayed moderate to good inhibition against the Mtb H37Rv strain; compound 11k showed a minimum inhibitory concentration of 1 µg/mL. Molecular docking studies revealed that compounds 6d and 11k show metal coordination with the zinc ion, like classical CA inhibitors.

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.

New Hybrid Tetrahydropyrrolo[3,2,1-ij]quinolin-1-ylidene-2-thioxothiazolidin-4-ones as New Inhibitors of Factor Xa and Factor XIa: Design, Synthesis, and In Silico and Experimental Evaluation.

Despite extensive research in the field of thrombotic diseases, the prevention of blood clots remains an important area of study. Therefore, the development of new anticoagulant drugs with better therapeutic profiles and fewer side effects to combat thrombus formation is still needed. Herein, we report the synthesis and evaluation of novel pyrroloquinolinedione-based rhodanine derivatives, which were chosen from 24 developed derivatives by docking as potential molecules to inhibit the clotting factors Xa and XIa. For the synthesis of new hybrid derivatives of pyrrolo[3,2,1-ij]quinoline-2-one, we used a convenient structural modification of the tetrahydroquinoline fragment by varying the substituents in positions 2, 4, and 6. In addition, the design of target molecules was achieved by alkylating the amino group of the rhodanine fragment with propargyl bromide or by replacing the rhodanine fragment with 2-thioxoimidazolidin-4-one. The in vitro testing showed that eight derivatives are capable of inhibiting both coagulation factors, two compounds are selective inhibitors of factor Xa, and two compounds are selective inhibitors of factor XIa. Overall, these data indicate the potential anticoagulant activity of these molecules through the inhibition of the coagulation factors Xa and XIa.

Synthesis and biological evaluation of novel rhodanine-based structures with antiviral activity towards HHV-6 virus.

An increased awareness of diseases associated with Human herpesvirus 6 (HHV-6) infection or reactivation has resulted in a growing interest in the evaluation of the best treatment options available for the clinical management of HHV-6 disease. However, no compound has yet been approved exclusively for HHV-6 infection treatment. For this reason, the identification of anti-HHV6 compounds provides a valuable opportunity for developing efficient antiviral therapies. A possible target for antiviral drugs is the virus-cell fusion step. In this study, we synthetized potential fusion intermediates inhibitors based on the rhodanine structure. The obtained derivatives were tested for cytotoxicity and for antiviral activity in human cells infected with HHV6. Level of infection was monitored by viral DNA quantification at different time points up to 7 days post infection. Among the synthetized derivatives, 9e showed a significative inhibitory effect on viral replication that lasted over 7 days, probably attributable to the particular combination of hydrophilic and hydrophobic substituents to the rhodanine moiety. Our results support the use of these amphipathic fusion inhibitors for the treatment of HHV-6 infections.

Synthesis and Antibacterial Evaluation of Rhodanine and Its Related Heterocyclic Compounds against S.†aureus and A.†baumannii.

Antimicrobial resistance is a serious challenge to modern medicine. Besides imposing high financial burden, multidrug resistant infections are directly responsible for high morbidity and mortality. Even though a number of antibiotics are currently available to treat infections caused by ESKAPE organisms, more and more bacterial strains are becoming resistant to these drugs. Prevailing circumstances pose an urgent unmet need for the development of newer antimicrobials to treat the infections caused by MDR organisms. Rhodanine and structurally related 5-membered heterocycles possess wide range of pharmacological activities. A number of these derivatives have shown good to potent inhibition against various microorganisms. They are reported to alter the function of DNA gyrase B, metallo-ß-lactamases, penicillin binding protein (PBP), Mur ligases, RNA polymerase, Enoyl ACP reductases, 1-deoxy-d-xylulose-5-phosphate reductoisomerase. etc which are vital in bacterial growth, survival and replication. In this study, we have generated a library of Rhodanine and related 5 membered heterocyclic derivatives and screened them against a panel of pathogens. Among all the compounds, 2a-i, 3a-b, 3g, 4, 6b-c, 6e, 6g, 12a-b and 14b-c have demonstrated good to moderate inhibition against S. aureus (MIC 0.125-8 µg/mL). Further, compound 17b demonstrated moderate activity against A. baumannii (MIC 8 µg/mL). In addition, compounds 2a, 2e, 4, 6c, 6g and 14b have shown good to mild inhibition against MDR S. aureus including VRSA (MIC 0.5-16 µg/mL) with good selectivity index 20-1600. In addition, compound 2e inhibited the growth gradually after 6 h in time kill kinetic studies and not antagonized with the tested FDA approved drugs.

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.

Discovery of Cinnamylidene Derivative of Rhodanine with High Anthelmintic Activity against Rhabditis sp.

The treatment of parasitic infections requires the application of chemotherapy. In view of increasing resistance to currently in-use drugs, there is a constant need to search for new compounds with anthelmintic activity. A series of 16 cinnamylidene derivatives of rhodanine, including newly synthesized methoxy derivatives (1-11) and previously obtained chloro, nitro, and diethylamine derivatives (12-16), was investigated towards anthelmintic activity. Compounds (1-16) were evaluated against free-living nematodes of the genus Rhabditis sp. In the tested group of rhodanine derivatives, only compound 2 shows very high biological activity (LC50 = 0.93 µg/µL), which is higher than the reference drug albendazole (LC50 = 19.24 µg/µL). Crystal structures of two compounds, active 2 and inactive 4, were determined by the X-ray diffraction method to compare molecular geometry and search for differences responsible for observed biological activity/inactivity. Molecular modelling and selected physicochemical properties prediction were performed to assess the potential mechanism of action and applied in the search for an explanation as to why amongst all similar compounds only one is active. We can conclude that the tested compound 2 can be further investigated as a potential anthelmintic drug.

Synthesis, Crystal Structures, Lipophilic Properties and Antimicrobial Activity of 5-Pyridylmethylidene-3-rhodanine-carboxyalkyl Acids Derivatives.

The constant increase in the resistance of pathogenic bacteria to the commonly used drugs so far makes it necessary to search for new substances with antibacterial activity. Taking up this challenge, we obtained a series of rhodanine-3-carboxyalkyl acid derivatives containing 2- or 3- or 4-pyridinyl moiety at the C-5 position. These compounds were tested for their antibacterial and antifungal activities. They showed activity against Gram-positive bacteria while they were inactive against Gram-negative bacteria and yeast. In order to explain the relationship between the activity of the compounds and their structure, for selected derivatives crystal structures were determined using the X-ray diffraction method. Modeling of the isosurface of electron density was also performed. For all tested compounds their lipophilicity was determined by the RP-TLC method and by calculation methods. On the basis of the carried-out research, it was found that the derivatives with 1.5 N···S electrostatics interactions between the nitrogen atom in the pyridine moiety and the sulfur atom in the rhodanine system showed the highest biological activity.

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.

5-Aryl-furan derivatives bearing a phenylalanine- or isoleucine-derived rhodanine moiety as potential PTP1B inhibitors.

Two series of 5-aryl-furan derivatives bearing a phenylalanine- or isoleucine-derived rhodanine moiety were identified as competitive protein tyrosine phosphatase 1B (PTP1B) inhibitors. Among the compounds studied, 5g was found to have the best PTP1B inhibitory potency (IC50 = 2.66 ± 0.16 µM) and the best cell division cycle 25 homolog B (CDC25B) inhibitory potency (IC50 = 0.25 ± 0.02 µM). Enzymatic data together with molecular modeling results demonstrated that the introduction of a sec-butyl group at the 2-position of the carboxyl group remarkably improved the PTP1B inhibitory activity.

QM/MM analysis, synthesis and biological evaluation of epalrestat based mutual-prodrugs for diabetic neuropathy and nephropathy.

Herein, a quantum mechanics/molecular mechanics (QM/MM) based biotransformation study was performed on synthetically feasible mutual-prodrugs of epalrestat which have been identified from an in-house database developed by us. These prodrugs were submitted to quantum polarized ligand docking (QPLD) with the CES1 enzyme followed by MM-GBSA calculation. Electronic aspects of transition state of these prodrugs were also considered to study the catalytic process through density functional theory (DFT). ADMET analysis of prodrugs was then carried out to assess the drug-likeness. On the basis of in-silico results, the best five prodrugs were synthesized and further evaluated for their neuroprotective and nephroprotective potential in high-fat diet-streptozotocin (HFD-STZ) induced diabetes in rat model. Clinically relevant molecular manifestations of diabetic complications (DC) including aldose reductase (ALR2) activity and oxidative stress markers such as reduced glutathione (GSH), catalase (CAT), and thiobarbituric acid reactive substances (TBARS) were determined in blood plasma as well as tissues of the brain and kidneys. The histopathological examination of these organs was also carried out to see the improvement in structural deformities caused due to neuropathy and nephropathy. Finally, in-vivo pharmacokinetic study was performed for the best two prodrugs to assess the improvement in biopharmaceutical attributes of parent drugs. Overall, EP-G-MFA and EP-MFA have significantly reduced the hyperglycemia-induced ALR2 activity, levels of oxidative stress markers, and manifested about a two-fold increase in the biological half-life (T1/2) of parent drugs. The overall findings of this study suggest that methyl ferulate conjugated prodrugs of epalrestat may be considered as potential protective agents in diabetic neuropathy and nephropathy.

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.

SAR by kinetics for drug discovery in protein misfolding diseases.

To develop effective therapeutic strategies for protein misfolding diseases, a promising route is to identify compounds that inhibit the formation of protein oligomers. To achieve this goal, we report a structure-activity relationship (SAR) approach based on chemical kinetics to estimate quantitatively how small molecules modify the reactive flux toward oligomers. We use this estimate to derive chemical rules in the case of the amyloid beta peptide (Aß), which we then exploit to optimize starting compounds to curtail Aß oligomer formation. We demonstrate this approach by converting an inactive rhodanine compound into an effective inhibitor of Aß oligomer formation by generating chemical derivatives in a systematic manner. These results provide an initial demonstration of the potential of drug discovery strategies based on targeting directly the production of protein oligomers.

A Concise Approach to N-Substituted Rhodanines through a Base-Assisted One-Pot Coupling and Cyclization Process.

An efficient approach to obtain functionalized rhodanines was developed through a base-assisted one-pot coupling and continuous cyclization of a primary amine, carbon disulfide, and methyl (2-chloroacetyl)carbamate. This conversion tolerates a broad range of functional groups and can be used to scale the preparation of N-substituted rhodanines in excellent yields.

Discovery of 1,3-diphenyl-1H-pyrazole derivatives containing rhodanine-3-alkanoic acid groups as potential PTP1B inhibitors.

Two series of 1,3-diphenyl-1H-pyrazole derivatives containing rhodanine-3-alkanoic acid groups were identified as competitive protein tyrosine phosphatase 1B (PTP1B) inhibitors. Among the compounds studied, IIIv was found to have the best in vitro inhibition activity against PTP1B (IC50 = 0.67 ±â€¯0.09 µM) and the best selectivity (9-fold) between PTP1B and T-cell protein tyrosine phosphatase (TCPTP). Molecular docking studies demonstrated that compounds IIIm, IIIv and IVg could occupy simultaneously at both the catalytic site and the adjacent pTyr binding site. These results provide novel lead compounds for the design of inhibitors of PTP1B as well as other PTPs.

Discovery of novel N-methyl carbazole tethered rhodanine derivatives as direct inhibitors of Mycobacterium tuberculosis InhA.

InhA (Enoyl-ACP reductase) plays a crucial role in the biosynthetic pathway of cell wall synthesis in Mycobacterium tuberculosis (Mtb). Isoniazid (INH) is an important first-line drug, which inhibits InhA. The rapid increase in resistance to INH and currently marketed drugs as well as emergence of MDR-TB and XDR-TB has complicated the diagnosis and treatment of Mtb with ever increasing threat to human kind. Herein, we report novel N-methyl carbazole derivatives as potential anti-TB compounds acting directly via InhA inhibition. All the synthesized final compounds were screened against Mtb virulent cell line H37Rv and investigated the InhA enzyme inhibition. Interestingly, compound 9e displayed promising inhibition (91%) at 50 µM concentration and IC50 of 2.82 µM against InhA. To understand the ligand receptor interaction between compound 9e and InhA, molecular docking and molecular dynamics experiments were performed. The computational results were in agreement with the observed experimental data. Further, the cytotoxicity studies on mammalian cells revealed that all the compounds were safe.

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.

Discovery and development of novel rhodanine derivatives targeting enoyl-acyl carrier protein reductase.

A series of rhodanine derivatives RB1-RB23 were synthesized through a two-round screening. Their Mycobacterial tuberculosis (Mtb) InhA inhibitory activity and Mtb growth blocking capability were evaluated. The most potent hit compound RB23 indicated comparable InhA inhibiton (IC50 = 2.55 µM) with the positive control Triclosan (IC50 = 6.14 µM) and Isoniazid (IC50 = 8.29 µM). Its improved growth-blocking effect on Mtb and low toxicity were attractive for further development. The docking simulation revealed the possible binding pattern of this series and picked the key interacted residues as Ser20, Phe149, Lys165 and Thr196. The 3D-QSAR model visualized the SAR discussion and hinted new information. Modifying the surroundings near rhodanine moiety might be promising attempts in later investigations.

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.

The green synthesis and molecular docking of novel N-substituted rhodanines as effective inhibitors for carbonic anhydrase and acetylcholinesterase enzymes.

Recently, inhibition effects of enzymes such as acetylcholinesterase (AChE) and carbonic anhydrase (CA) has appeared as a promising approach for pharmacological intervention in a variety of disorders such as epilepsy, Alzheimer's disease and obesity. For this purpose, novel N-substituted rhodanine derivatives (RhAs) were synthesized by a green synthetic approach over one-pot reaction. Following synthesis the novel compounds, RhAs derivatives were tested against AChE and cytosolic carbonic anhydrase I, and II (hCAs I, and II) isoforms. As a result of this study, inhibition constant (Ki) were found in the range of 66.35 ±â€¯8.35 to 141.92 ±â€¯12.63 nM for AChE, 43.55 ±â€¯14.20 to 89.44 ±â€¯24.77 nM for hCA I, and 16.97 ±â€¯1.42 to 64.57 ±â€¯13.27 nM for hCA II, respectively. Binding energies were calculated with docking studies as -5.969, -5.981, and -9.121 kcal/mol for hCA I, hCA II, and AChE, respectively.