Optimizing Alkyl Side Chains in Difluorobenzene-Rhodanine Small-Molecule Acceptors for Organic Solar Cells

A series of small molecules, T-2FB-T-ORH, T-2FB-T-BORH, and T-2FB-T-HDRH, were synthesized to have a thiophene-flanked difluorobenzene (T-2FB-T) core and alkyl-substituted rhodanine (RH) end groups for their use as nonfullerene acceptors (NFAs) in organic solar cells (OSCs). Octyl, 2-butyloctyl (BO), and 2-hexyldecyl (HD) alkyl side chains were introduced into RHs to control the material's physical properties based on the length and size of the alkyl chains. The optical properties of the three NFAs were found to be almost the same, irrespective of the alkyl chain length, whereas the molecular crystallinity and material solubility significantly differed depending on the alkyl side chains. Owing to the sufficient solubility of T-2FB-T-HDRH, OSCs based on PTB7-Th and T-2FB-T-HDRH were fabricated. A power conversion efficiency of up to 4.49% was obtained by solvent vapor annealing (SVA). The AFM study revealed that improved charge mobility and a smooth and homogeneous film morphology without excessive aggregation could be obtained in the SVA-treated film.

Development, synthesis and validation of improved c-Myc/Max inhibitors

The pathophysiological foundations of various diseases are often subject to alteration through the utilization of small compounds, rendering them invaluable tools for the exploration and advancement of novel therapeutic strategies. Within the scope of this study, we meticulously curated a diverse library of novel small compounds meticulously designed to specifically target the c-Myc/Max complex. We conducted in vitro examinations of novel c-Myc inhibitors across a spectrum of cancer cell lines, including PANC1 (pancreatic adenocarcinoma), MCF7 (breast carcinoma), DU-145 (prostate carcinoma), and A549 (lung cancer). The initial analysis involved a 25 μM dose, which enabled the identification of potent anticancer compounds effective against a variety of tumour types. We identified c-Myc inhibitors with remarkable potency, featuring IC50 values as low as 1.6 μM and up to 40 times more effective than the reference molecule in diminishing cancer cell viability. Notably, c-Myc-i7 exhibited exceptional selectivity, displaying 37-fold and 59-fold preference for targeting prostate and breast cancers, respectively, over healthy cells. Additionally, we constructed drug-likeness models. This study underscores the potential for in vitro investigations of various tumour types using novel c-Myc inhibitors to yield ground-breaking and efficacious anticancer compounds.

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.

Rhodanine Derivatives Containing 5-Aryloxypyrazole Moiety as Anti-inflammatory and Anticancer Agents

In this study, a series of rhodanine derivatives containing 5-aryloxypyrazole moiety were identified as potential agents with anti-inflammatory and anticancer properties. Most of the synthesized compounds demonstrated anti-inflammatory and anticancer activity. Notably, compound 7 g (94.1 %) exhibited significant anti-inflammatory activity compared with the reference drugs celecoxib (52.5 %) and hydrocortisone (79.4 %). Compound 7 g, at various concentrations, effectively inhibited nitric oxide (NO) production in a dose-dependent manner. Western blot results showed that compound 7 g could prevents LPS-induced expression of inflammatory mediators in macrophages. Enzyme-linked immunosorbent assay (ELISA) assay suggested that 7 g is a promising compound capable of blocking the downstream signaling of COX-2. In summary, these findings indicate that compound 7 g could be a promising candidate for further investigation.

New 3-amino-2-thioxothiazolidin-4-one-based inhibitors of acetyl- and butyryl-cholinesterase: synthesis and activity

Aim: 2-Thioxothiazolidin-4-one represents a versatile scaffold in drug development. The authors used it to prepare new potent acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors that can be utilized, e.g., to treat Alzheimer's disease. Materials & methods: 3-Amino-2-thioxothiazolidin-4-one was modified at the amino group or active methylene, using substituted benzaldehydes. The derivatives were evaluated for inhibition of AChE and BChE (Ellman's method). Results & conclusion: The derivatives were obtained with yields of 52-94%. They showed dual inhibition with IC50 values from 13.15 μM; many compounds were superior to rivastigmine. The structure-activity relationship favors nitrobenzylidene and 3,5-dihalogenosalicylidene scaffolds. AChE was inhibited noncompetitively, whereas BChE was inhibited with a mixed type of inhibition. Molecular docking provided insights into molecular interactions. Each enzyme is inhibited by a different binding mode.

Arylidene and amino spacer-linked rhodanine-quinoline hybrids as upgraded antimicrobial agents

Antibiotic resistance associated with various microorganisms such as Gram-positive, Gram-negative, fungal strains, and multidrug-resistant tuberculosis increases the risk of healthcare survival. Preliminary therapeutics becoming ineffective that might lead to noteworthy mortality presents a crucial challenge for the scientific community. Hence, there is an urgent need to develop hybrid compounds as antimicrobial agents by combining two or more bioactive heterocyclic moieties into a single molecular framework with fewer side effects and a unique mode of action. This review highlights the recent advances (2013-2023) in the pharmacology of rhodanine-linked quinoline hybrids as more effective antimicrobial agents. In the drug development process, linker hybrids acquire the top position due to their excellent π-stacking and Van der Waals interaction with the DNA active sites of pathogens. A molecular hybridization strategy has been optimized, indicating that combining these two bioactive moieties with an arylidene and an amino spacer linker increases the antimicrobial potential and reduces drug resistance. Moreover, the structure-activity relationship study is discussed to express the role of various functional groups in improving and decrementing antimicrobial activities for rational drug design. Also, a linker approach may accelerate the development of dynamic antimicrobial agents through molecular hybridization.

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

Rhodanines and their derivatives are known to have many pharmacological activities that can be modulated through different functionalization sites. One of the most studied modification in those scaffolds is the introduction of a benzylidene moiety on C5 via a Knoevenagel reaction. Here, a facile synthesis of 5-arylidenerhodanines via a Knoevenagel reaction in an ʟ-proline-based deep eutectic solvent (DES) is reported. This method is fast (1 h at 60 °C), easy, catalyst-free and sustainable as no classical organic solvents were used. The expected compounds are recovered by a simple filtration after hydrolysis and no purification is required. Those derivatives were studied for their antioxidant activities and the results are consistent with those reported in the literature indicating that phenolic compounds are the more active ones.

Rhodanine derivatives: An insight into the synthetic and medicinal perspectives as antimicrobial and antiviral agents

Rhodanine or 2-Thioxothiazolidin-4-one is a privileged heterocyclic compound offering a wide opportunity for structural modification, lead development, and modification. It is one of the highly decorated scaffolds in the drug discovery process. Rhodanine derivatives possess a plethora of biological activities due to their ability to interact with a diverse range of protein targets, which provide tremendous opportunities to discover new drugs with different modes of action. The most common strategy for developing novel rhodanine derivatives is the introduction of structurally diverse substituents at the C-5 or N-3, or both positions. Since the inception of Epralestat into the market in 1992, the exploration of rhodanine-3-acetic acids has led to the development of novel leads against different biological targets such as MRSA, HHV-6, Mycobacterial tuberculosis, dengue, etc. In the current pandemic era, some rhodanine compounds have been explored against SARS-CoV-2. In recent years, rhodanine and its derivatives have witnessed significant progress in developing new drug leads as potential antimicrobial and antiviral agents. Different synthetic methodologies and recent developments in the medicinal chemistry of rhodanine derivatives, including biological activities, their mechanistic aspects, structure-activity relationships, and in silico findings, have been compiled in the present review. This article will benefit the scientific community and offer perspectives on how these scaffolds as privileged structures might be exploited in the future for rational design and discovery of rhodanine-based bio-active molecules.

N-Derivatives of (Z)-Methyl 3-(4-Oxo-2-thioxothiazolidin-5-ylidene)methyl)-1H-indole-2-carboxylates as Antimicrobial Agents-In Silico and In Vitro Evaluation

Herein, we report the experimental evaluation of the antimicrobial activity of seventeen new (Z)-methyl 3-(4-oxo-2-thioxothiazolidin-5-ylidene)methyl)-1H-indole-2-carboxylate derivatives. All tested compounds exhibited antibacterial activity against eight Gram-positive and Gram-negative bacteria. Their activity exceeded those of ampicillin as well as streptomycin by 10-50 fold. The most sensitive bacterium was En. Cloacae, while E. coli was the most resistant one, followed by M. flavus. The most active compound appeared to be compound 8 with MIC at 0.004-0.03 mg/mL and MBC at 0.008-0.06 mg/mL. The antifungal activity of tested compounds was good to excellent with MIC in the range of 0.004-0.06 mg/mL, with compound 15 being the most potent. T. viride was the most sensitive fungal, while A. fumigatus was the most resistant one. Docking studies revealed that the inhibition of E. coli MurB is probably responsible for their antibacterial activity, while 14a-lanosterol demethylase of CYP51Ca is involved in the mechanism of antifungal activity. Furthermore, drug-likeness and ADMET profile prediction were performed. Finally, the cytotoxicity studies were performed for the most active compounds using MTT assay against normal MRC5 cells.

Design, Synthesis and Biological Assessment of Rhodanine-Linked Benzenesulfonamide Derivatives as Selective and Potent Human Carbonic Anhydrase Inhibitors

A novel series of twenty-five rhodamine-linked benzenesulfonamide derivatives (7a-u and 9a-d) were synthesized and screened for their inhibitory action against four physiologically relevant human (h) carbonic anhydrase (CA) isoforms, namely hCA I, hCA II, hCA IX, and hCA XII. All the synthesized molecules showed good to excellent inhibition against all the tested isoforms in the nanomolar range due to the presence of the sulfonamide as a zinc binding group. The target compounds were developed from indol-3-ylchalcone-linked benzenesulfonamide where the indol-3-ylchalcone moiety was replaced with rhodanine-linked aldehydes or isatins to improve the inhibition. Interestingly, the molecules were slightly more selective towards hCA IX and XII compared to hCA I and II. The most potent and efficient ones against hCA I were 7h (K_I 22.4 nM) and 9d (K_I 35.8 nM) compared to the standard drug AAZ (K_I 250.0 nM), whereas in case of hCA II inhibition, the derivatives containing the isatin nucleus as a tail were preferred. Collectively, all compounds were endowed with better inhibition against hCA IX compared to AAZ (K_I 25.8 nM) as well as strong potency against hCA XII. Finally, these newly synthesized molecules could be taken as potential leads for the development of isoform selective hCA IX and XII inhibitors.

Design, Synthesis, and Antiproliferative Activity of Novel Neocryptolepine-Rhodanine Hybrids

A series of novel neocryptolepine-rhodanine hybrids (9a,b, 11a-d, 14, and 16a,b) have been synthesized by combining neocryptolepine core 5 modified at the C-11 position with rhodanine condensed with the appropriate aryl/hetero aryl aldehydes. Based on these findings, the structures of the hybrids were confirmed by spectral analyses. By employing the MTT assay, all hybrids were tested for their in vitro antiproliferative activity against two cancer cell lines, including MDA-MB-231 (human breast) and HepG-2 (hepatocellular carcinoma). Interestingly, the IC50 values of all hybrids except 9b and 11c showed activity comparable to the standard anticancer drug, 5-fluorouracil, against HepG-2 cancer cells. Furthermore, the cytotoxicity of all the synthesized hybrids was investigated on a normal skin human cell line (BJ-1), and the results showed that these compounds had no significant cytotoxicity toward these healthy cells at the highest concentration used in this study. This study also indicated that the active hybrids exert their cytotoxic activity via the induction of apoptosis. A molecular docking study was used to shed light on the molecular mechanism of their anticancer activity. The docking results revealed that the hybrids exert their mode of action through DNA intercalation. Furthermore, in silico assessment for pharmacokinetic properties was performed on the most potent compounds, which revealed candidates with good bioavailability, high tolerability with cell membranes, and positive drug-likeness values.

5-Arylidenerhodanines as P-gp Modulators: An Interesting Effect of the Carboxyl Group on ABCB1 Function in Multidrug-Resistant Cancer Cells

Multidrug resistance (MDR) is considered one of the major mechanisms responsible for the failure of numerous anticancer and antiviral chemotherapies. Various strategies to overcome the MDR phenomenon have been developed, and one of the most attractive research directions is focused on the inhibition of MDR transporters, membrane proteins that extrude cytotoxic drugs from living cells. Here, we report the results of our studies on a series newly synthesized of 5-arylidenerhodanines and their ability to inhibit the ABCB1 efflux pump in mouse T-lymphoma cancer cells. In the series, compounds possessing a triphenylamine moiety and the carboxyl group in their structure were of particular interest. These amphiphilic compounds showed over 17-fold stronger efflux pump inhibitory effects than verapamil. The cytotoxic and antiproliferative effects of target rhodanines on T-lymphoma cells were also investigated. A putative binding mode for 11, one of the most potent P-gp inhibitors tested here, was predicted by molecular docking studies and discussed with regard to the binding mode of verapamil.

A Synthetically Accessible Small-Molecule Inhibitor of USP5-Cav3.2 Calcium Channel Interactions with Analgesic Properties

Cav3.2 calcium channels are important mediators of nociceptive signaling in the primary afferent pain pathway, and their expression is increased in various rodent models of chronic pain. Previous work from our laboratory has shown that this is in part mediated by an aberrant expression of deubiquitinase USP5, which associates with these channels and increases their stability. Here, we report on a novel bioactive rhodanine compound (II-1), which was identified in compound library screens. II-1 inhibits biochemical interactions between USP5 and the Cav3.2 domain III-IV linker in a dose-dependent manner, without affecting the enzymatic activity of USP5. Molecular docking analysis reveals two potential binding pockets at the USP5-Cav3.2 interface that are distinct from the binding site of the deubiquitinase inhibitor WP1130 (a.k.a. degrasyn). With an understanding of the ability of some rhodanines to produce false positives in high-throughput screening, we have conducted several orthogonal assays to confirm the validity of this hit, including in vivo experiments. Intrathecal delivery of II-1 inhibited both phases of formalin-induced nocifensive behaviors in mice, as well as abolished thermal hyperalgesia induced by the delivery of complete Freund's adjuvant (CFA) to the hind paw. The latter effects were abolished in Cav3.2 null mice, thus confirming that Cav3.2 is required for the action of II-1. II-1 also mediated a robust inhibition of mechanical allodynia induced by injury to the sciatic nerve. Altogether, our data uncover a novel class of analgesics─well suited to rapid structure-activity relationship studies─that target the Cav3.2/USP5 interface.

Straightforward Regio- and Diastereoselective Synthesis, Molecular Structure, Intermolecular Interactions and Mechanistic Study of Spirooxindole-Engrafted Rhodanine Analogs

Straightforward regio- and diastereoselective synthesis of bi-spirooxindole-engrafted rhodanine analogs 5a-d were achieved by one-pot multicomponent [3 + 2] cycloaddition (32CA) reaction of stabilized azomethine ylide (AYs 3a-d) generated in situ by condensation of L-thioproline and 6-chloro-isatin with (E)-2-(5-(4-chlorobenzylidene)-2,4-dioxothiazolidin-3-yl)-N-(2-morpholinoethyl)acetamide. The bi-spirooxindole-engrafted rhodanine analogs were constructed with excellent diastereo- and regioselectivity along with high chemical yield. X-ray crystallographic investigations for hybrid 5a revealed the presence of four contiguous stereocenters related to C11, C12, C19 and C22 of the spiro structure. Hirshfeld calculations indicated the presence of many short intermolecular contacts such as Cl...C, S...S, S...H, O...H, N...H, H...C, C...C and H...H interactions. These contacts played a very important role in the crystal stability. The polar nature of the 32CA reaction was studied by analysis of the conceptual DFT reactivity indices. Theoretical study of this 32CA reaction indicated that it takes place through a non-concerted two-stage one-step mechanism associated with the nucleophilic attack of AY 3a to the electrophilic ethylene derivative.

2-Thioxothiazolidin-4-one Analogs as Pan-PIM Kinase Inhibitors

Proviral integration site for Moloney murine leukemia virus (PIM) kinases are proto-oncogenic kinases involved in the regulation of several cellular processes. PIM kinases are promising targets for new drug development because they play a major role in many cancer-specific pathways, such as survival, apoptosis, proliferation, cell cycle regulation, and migration. Here, 2-thioxothiazolidin-4-one derivatives were synthesized and evaluated as potent pan-PIM kinase inhibitors. Optimized compounds showed single-digit nanomolar IC₅₀ values against all three PIM kinases with high selectivity over 14 other kinases. Compound 17 inhibited the growth of Molm-16 cell lines (EC₅₀ = 14 nM) and modulated the expression of pBAD and p4EBP1 in a dose-dependent manner.

Assessment of copper accumulation in archived liver specimens from cats

OBJECTIVES

The aim of this study was to assess hepatic copper concentrations and zonal distribution in cat liver specimens.

METHODS

For this study, 121 archived, formalin-fixed, paraffin-embedded liver specimens from cats were used. Tissue sections were stained for copper with rhodanine and scored from 0 (no copper accumulation) to 5 (panlobular copper accumulation). The tissue specimens were then deparaffinized and hepatic copper concentrations were measured using flame atomic absorption spectroscopy.

RESULTS

Tissue samples were categorized into four groups based on histopathologic findings: (1) no significant histopathologic hepatic changes (n = 66); (2) hepatic steatosis (n = 18); (3) inflammatory or infectious disease (n = 24); and (4) neoplasia (n = 13). Of the 121 specimens, 13 (11%) stained positive for copper, with three having a score ⩾3. Thirty-seven specimens (31%) had copper concentrations above the reference interval ([RI] <180 µg/g dry weight liver). Copper concentrations in cats with hepatic inflammatory or infectious disease were significantly higher than cats with hepatic steatosis (P = 0.03). Copper-staining score and concentration were positively correlated (r_s = 0.46, P <0.001).

CONCLUSIONS AND RELEVANCE

Despite the fact that 31% of specimens had copper concentrations above the RI, only 11% showed positive copper staining and only 2.5% had a score ⩾3. Our findings suggest that hepatic copper concentrations greater than the upper limit of the RI are relatively common in cats. Further studies to determine the factors that influence hepatic copper staining in cats and to establish contemporary RIs for hepatic copper in healthy cats are warranted.

Accurate Measurement of Copper Overload in an Experimental Model of Wilson Disease by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Wilson disease is a rare inherited autosomal recessive disorder. As a consequence of genetic alterations in the ATP7B gene, copper begins to accumulate in the body, particularly in the liver and brain. Affected persons are prone to develop liver cancer and severe psychiatric and neurological symptoms. Clinically, the development of corneal Kayser-Fleischer rings and low ceruloplasmin concentrations (<20 mg/dL) are indicative of Wilson disease. However, the detection of elevated hepatic copper content (>250 µg/g dry weight) alone is still considered as the best but not exclusive diagnostic test for Wilson disease. Presently, specific copper stains (e.g., rhodanine) or indirect staining for copper-associated proteins (e.g., orcein) are widely used to histochemically visualize hepatic copper deposits. However, these procedures only detect lysosomal copper, while cytosolic copper is not detectable. Similarly, elemental analysis in scanning electron microscope with energy dispersive X-ray analysis (EDX) often leads to false negative results and inconsistencies. Here, we tested the diagnostic potential of laser ablation inductively-coupled mass spectrometry (LA-ICP-MS) that allows quantitative analysis of multiple elements. Comparative studies were performed in wild type and the Atp7b null mouse model. We propose LA-ICP-MS as a versatile and powerful method for the accurate determination of hepatic copper in people with Wilson disease with high spatial resolution.

Green Synthesis, Biological Activity Evaluation, and Molecular Docking Studies of Aryl Alkylidene 2, 4-thiazolidinedione and Rhodanine Derivatives as Antimicrobial Agents

AIMS AND OBJECTIVE

The magic scaffolds rhodanine and thiazolidine are very important heterocyclic compounds in drug design and discovery. Those are important heterocyclic compounds that have attracted a great deal of attention due to the fact that they exhibit a variety of bioactivities including antibacterial, antifungal, antiviral, antimalarial, and anti-inflammatory activities. These agents often exhibit selective toxicity. The goal of this study was molecular docking, green and solvent-free efficient synthesis of a new series of hetero/aromatic substituted rhodanine and thiazolidine analogues and then investigation of their antimicrobial activity.

MATERIALS AND METHODS

To a mixture of TZD or rhodanine (1 mmol) in the presence of ionic liquid ChCl/urea, various aldehyde (1 mmol) was added. After completion of the reaction, obtained crude compound was collected by filtration and products were recrystallized from ethanol. The binding-free energy between all synthesized compounds with 3EEJ protein (C. glabrata enzyme) were obtained by molecular docking studies. These compounds were evaluated using microdilution method against (ATCC 6538) and (ATCC 12228) Gram-negative, (ATCC 8739) and (ATCC 9027) as Gram-positive and (ATCC 1012), (ATCC 339), C. (ATCC 1057), (ATCC 503), (ATCC 340) and (ATCC 194) as fungi.

RESULTS

All of the acceptable products were determined by 1H NMR, 13C NMR, Mas and FT-IR spectroscopy. The binding-free energy between compounds 10a and 10b with 3EEJ protein were found to be -8.08 kcal/mol and -8.15 kcal/mol, respectively. These compounds having a heteroaromatic ring attached to the TZD or rhodanine core showed excellent antimicrobial activity with MIC values of 0.25-8 μg/mL (compound 10a) and 0.5-16 μg/mL (compound 10b) against the most tested fungi strains, Gram-positive and Gram-negative bacteria.

CONCLUSION

A convenient and rapid method has been developed for the synthesis of rhodanine and thiazolidine-2,4-dione (TZD) derivatives as efficient antimicrobial agents using a Deep Eutectic Ionic Liquids (DEILs) choline chloride urea under solvent-free condition. Among the newly synthesized compounds, (Z)-5-((quinoxalin-3-yl) methylene) thiazolidine-2, 4-dione (10a) and (Z)- 5- ((quinoxalin-3-yl) methylene)-2-thioxothiazolidin-one (10b) exerted the promising effect and these compounds can be considered to be further probed as inhibitors of cgDHFR enzyme.

Indian childhood cirrhosis - down but not out: Report of a rare case with a practical clinicopathological diagnostic approach

Indian childhood cirrhosis is an entity believed to be on the verge of extinction. We present the case of a 13-month-old girl presenting acutely with jaundice, fever, and persistently increasing bilirubin. Investigations revealed direct hyperbilirubinemia, elevated transaminases, anemia, a blood with few schistocytes, positive direct coombs test, and deranged prothrombin time. Viral, autoimmune, and metabolic workup was unremarkable. Ultrasonography showed chronic liver disease, portal hypertension, and ascites. Due to numerous confounding factors and a low index of suspicion, the diagnosis of Indian childhood cirrhosis remained elusive and was clinched only on liver biopsy, albeit more than three weeks later, shortly after which the child expired. The timing and technique of the liver biopsy may have profound impact on the ultimate clinical outcome. Close coordination between the clinical and pathological teams is essential for deciphering acute presentations where the etiology is uncertain. We highlight the clinical considerations, varied morphological pointers, and offer a diagnostic algorithm facilitating the consideration of this disease.

Design, synthesis, biological evaluation, and molecular modeling studies of rhodanine derivatives as pancreatic lipase inhibitors

A series of rhodanine-3-acetic acid derivatives were synthesized via Knoevenagel condensation of rhodanine-3-acetic acid with various substituted aromatic aldehydes. The synthesized derivatives were screened in vitro for understanding the inhibitory potential towards pancreatic lipase (PL), a key enzyme responsible for the digestion of dietary fats. Derivative 8f exhibited a potential inhibitory activity towards PL (IC₅₀ = 5.16 µM), comparable to that of the standard drug, orlistat (0.99 µM). An increase in the density of the aromatic ring resulted in potential PL inhibition. The enzyme kinetics of 8f exhibited a reversible competitive-type inhibition, similar to that of orlistat. Derivative 8f exhibited a MolDock score of -125.19 kcal/mol in docking studies, and the results were in accordance with their PL inhibitory potential. Furthermore, the reactive carbonyl group of 8f existed at a distance adjacent to Ser152 (≈3 Å) similar to that of orlistat. Molecular dynamics simulation (10 ns) of the 8f-PL complex revealed a stable binding conformation of 8f in the active site of PL (maximum root mean square displacement of ≈2.25 Å). The present study identified novel rhodanine-3-acetic acid derivatives with promising PL inhibitory potential, and further lead optimization might result in potent PL inhibitors.

Introducing Broadened Antibacterial Activity to Rhodanine Derivatives Targeting Enoyl-Acyl Carrier Protein Reductase

Broadened antibacterial activity was introduced to rhodanine derivatives targeting Mycobacterial tuberculosis enoyl-acyl carrier protein reductase (Mtb InhA) by recruiting feature of xacins to bring DNA Gyrase B inhibitory capability. This is significant for preventing further bacterial injections in the tuberculosis treatment. The most potent compound Cy14 suggested comparable bioactivity (IC₅₀ = 3.18 µM for Mtb InhA; IC₅₀ = 10 nM for DNA Gyrase B) with positive controls. Structure-activity relationship discussion and molecular docking model revealed the significance of rhodanine moiety and derived methoxyl on meta-position, pointing out orientations for future modification.

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.

Synthesis and Bioactivity Evaluation of N-Arylsulfonylindole Analogs Bearing a Rhodanine Moiety as Antibacterial Agents

Due to the rapidly growing bacterial resistance to antibiotics and the scarcity of novel agents under development, bacterial infections are still a pressing global problem, making new types of antibacterial agents, which are effective both alone and in combination with traditional antibiotics, urgently needed. In this paper, seven series of N-arylsulfonylindole analogs 5–11 bearing rhodanine moieties were synthesized, characterized, and evaluated for antibacterial activity. According to the in vitro antimicrobial results, half of the synthesized compounds showed potent inhibition against four Gram-positive bacteria, with MIC values in the range of 0.5–8 µg/mL. For multidrug-resistant strains, compounds 6a and 6c were the most potent, with MIC values of 0.5 µg/mL, having comparable activity to gatifloxacin, moxiflocaxin and norfloxacin and being 128-fold more potent than oxacillin (MIC = 64 µg/mL) and 64-fold more active than penicillin (MIC = 32 µg/mL) against Staphylococcus aureusATCC 43300.

Efficient Polymer Solar Cells with High Open-Circuit Voltage Containing Diketopyrrolopyrrole-Based Non-Fullerene Acceptor Core End-Capped with Rhodanine Units

Herein we report the synthesis of a novel A-D-A-D-A non-fullerene small-molecule acceptor (NFSMA) bearing a diketopyrrolopyrrole (DPP) acceptor central core coupled to terminal rhodanine acceptors via a thiophene donor linker (denoted as MPU1) for use in non-fullerene polymer solar cells (PSCs). This NFSMA exhibits a narrow optical band gap (1.48 eV), strong absorption in the 600-800 nm wavelength region of the solar spectrum, and a lowest unoccupied energy level of -3.99 eV. When the mixture of a medium band gap D-A copolymer P (1.75 eV) was used as donor and MPU1 as acceptor, the blend film showed a broad absorption profile from 400 to 850 nm, beneficial for light harvesting efficiency of the resulted polymer solar cell. After optimization of the donor-to-acceptor weight ratios and concentration of solvent additive, the P-MPU1-based PSC exhibited a power conversion efficiency of 7.52% (J_sc= 12.37 mA/cm², V_oc = 0.98 V, and fill factor = 0.62), which is much higher than that for a P3HT-MPU1-based device (2.16%) prepared under identical conditions. The higher value for the P-MPU1-based device relative to the P3HT-MPU1-based one is related to the low energy loss and more balanced charge transport in the device based on the P donor. These results indicate that alteration of the absorption spectra and electrochemical energy levels of non-fullerene acceptors, and appropriate selection of the polymer donor with complementary absorption profile, is a promising means to further boost the performance of PSCs.

Dithienobenzodithiophene-Based Small Molecule Organic Solar Cells with over 7% Efficiency via Additive- and Thermal-Annealing-Free Processing

Here we introduce a novel small molecule based on dithienobenzodithiophene and rhodanine, DTBDT-Rho, developed to study the effect of the rhodanine substitutuent on small molecule bulk heterojunction (BHJ) solar cells. DTBDT-Rho possesses distinct crystalline characteristics, sufficient solubility in chlorinated solvents, and broad absorption properties. Therefore, solution-processed BHJ photovoltaic cells made with DTBDT-Rho:PC₇₁BM blends showed an extremely high power conversion efficiency (PCE; 7.10%); notably, this PCE value was obtained without the use of additives or thermal treatments. To our knowledge, the PCE over 7% is a significantly powerful value among rhodanine-based small molecule BHJ solar cells without additives or thermal treatments.

Crystal structure of (Z)-3-allyl-5-(3-bromo-benzyl-idene)-2-sulfanyl-idene-1,3-thia-zolidin-4-one

In the title compound, C13H10BrNOS2, the rhodanine (systematic name: 2-sulfanyl-idene-1,3-thia-zolidin-4-one) and the 3-bromo-benzyl-idene ring systems are inclined slightly, forming a dihedral angle of 5.86 (12)°. The rhodanine moiety is linked to an allyl group at the N atom and to the 3-bromo-benzyl-idene ring system. The allyl group, C=C-C, is nearly perpendicular to the mean plane through the rhodanine ring, maling a dihedral angle of 87.2 (5)°. In the crystal, mol-ecules are linked by pairs of C-H⋯O hydrogen bonds, forming inversion dimers with an R 2 (2)(10) ring motif.

Synthesis and biological evaluation of (E)-1-(substituted)-3-phenylprop-2-en-1-ones bearing rhodanines as potent anti-microbial agents

Herein, we report the design, syntheses and in vitro anti-microbial activity of two series of rhodanines with chalcone moiety. Anti-microbial tests showed that some of the synthesized compounds exhibited good inhibition (MIC = 1-8 µg/mL) against multi-drug-resistant Gram-positive organisms, including methicillin resistant and quinolone-resistant Staphylococcus aureus, in which the compound 4g was found to be the most potent with minimum inhibitory concentration (MIC) value of 1 µg/mL against two methicillin-resistant S. aureus.

Design and synthesis of L- and D-phenylalanine derived rhodanines with novel C5-arylidenes as inhibitors of HCV NS5B polymerase

Hepatitis C virus (HCV) NS5B polymerase is a key target for anti-HCV therapeutics development. Herein, we report the synthesis and in vitro evaluation of anti-NS5B polymerase activity of a molecular hybrid of our previously reported lead compounds 1 (IC50=7.7 μM) and 2 (IC50=10.6 μM) as represented by hybrid compound 27 (IC50=6.7 μM). We have explored the optimal substituents on the terminal phenyl ring of the 3-phenoxybenzylidene moiety in 27, by generating a set of six analogs. This resulted in the identification of compound 34 with an IC50 of 2.6 μM. To probe the role of stereochemistry towards the observed biological activity, we synthesized and evaluated the D-isomers 41 (IC50=19.3 μM) and 45 (IC50=5.4 μM) as enantiomers of the l-isomers 27 and 34, respectively. The binding site of compounds 32 and 34 was mapped to palm pocket-I (PP-I) of NS5B. The docking models of 34 and 45 within the PP-I of NS5B were investigated to envisage the molecular mechanism of inhibition.

The Rhodadyns, a New Class of Small Molecule Inhibitors of Dynamin GTPase Activity

Six focused rhodanine-based libraries, 60 compounds in total, were synthesized and evaluated as potential dynamin I GTPase inhibitors. Twenty-six were more potent than the lead compound with 13 returning IC50 values ≤10 μM, making the Rhodadyn series among the most active dynamin inhibitors reported. Two analogues were highly effective at blocking receptor-mediated endocytosis: C10 and D10 with IC50(RME) = 7.0 ± 2.2 and 5.9 ± 1.0 μM, respectively. These compounds are equipotent with the best reported in-cell dynamin inhibitors.

Rhodanine and thiohydantoin derivatives for detecting tau pathology in Alzheimer's brains

A novel series of rhodanin (RH) and thiohydantoin (TH) derivatives were designed and synthesized for detecting tau pathology in the brains of patients with Alzheimer's disease (AD). In experiments in vitro using tau and β-amyloid (Aβ) aggregates, the TH derivative, TH2, showed high specific binding to tau aggregates. In hippocampal sections obtained from AD patients, TH2 intensely stained neurofibrillary tangles. In experiments using normal mice, [(125)I]TH2 showed good uptake (1.54%ID/g, 2 min postinjection) into and a rapid washout (0.25%ID/g, 60 min postinjection) from the brain. [(123)I]TH2 should be further investigated as a potential imaging agent for detecting tau pathology.

Structure-based virtual screening, synthesis and SAR of novel inhibitors of hepatitis C virus NS5B polymerase

Hepatitis C virus (HCV) NS5B polymerase is a key target for the development of therapeutic agents aimed at the treatment of HCV infections. Here we report on the identification of novel allosteric inhibitors of HCV NS5B through a combination of structure-based virtual screening, synthesis and structure-activity relationship (SAR) optimization approach. Virtual screening of 260,000 compounds from the ChemBridge database against the tetracyclic indole inhibitor binding pocket of NS5B (allosteric pocket-1, AP-1), sequentially down-sized the library by 4 orders of magnitude to yield 23 candidates. In vitro evaluation of the NS5B inhibitory activity of the in-silico selected compounds resulted in 17% hit rate, identifying two novel chemotypes. Of these, compound 3, bearing the rhodanine scaffold, proved amenable for productive SAR exploration and synthetic modification. As a result, 25 derivatives that exhibited IC₅₀ values ranging from 7.7 to 68.0 μM were developed. Docking analysis of lead compound 28 within the tetracyclic indole- and benzylidene-binding allosteric pockets (AP-1 and AP-3, respectively) of NS5B revealed topological similarities between these two pockets. Compound 28, a novel rhodanine analog with NS5B inhibitory potency in the low micromolar level range may be a promising lead for future development of more potent NS5B inhibitors.