Aqueous microwave-assisted one-pot synthesis of N-substituted rhodanines

Novel Thiazolidinedione and Rhodanine Derivatives Regulate Glucose Metabolism, Improve Insulin Sensitivity, and Activate the Peroxisome Proliferator-Activated γ Receptor

Sixteen novel thiazolidinedione (TZD) and rhodanine (RD) derivatives were designed and synthesized by introducing a pyrimidine moiety at different sites of pioglitazone's structure. The effects of synthesized compounds on regulating glucose metabolism, improving insulin sensitivity, and activating the peroxisome proliferator-activated γ receptor (PPAR-γ) were evaluated in βTC6 cells. Compounds TZDs # 7a, 7b, 7c, and 29 reduced the basal insulin secretion by ∼20.0-67.0% and increased insulin secretion stimulated by glucose by ∼25.0-50.0% compared to control. Compounds TZDs # 14 and 21 and RDs # 33a-b and 33d-f increased basal insulin secretion by ∼20.0-100.0%, while its glucose-stimulated secretion remained unchanged. These findings suggested that the former compounds can act as antihypoglycemic during fasting and antihyperglycemic during postprandial conditions. The latter compounds should be administered before meals to avoid their hypoglycemic effect. Additionally, both TZDs and RDs improved insulin sensitivity by increasing glucose uptake by 17.0-155.0% relative to control. In silico molecular docking of synthesized drugs onto the PPAR-γ structure revealed exothermic binding modes through hydrogen bonding, van der Waals forces, and π-π stacking with binding affinities of -6.02 to -9.70 kcal/mol. Insights into the structure-activity relationship revealed that the introduction of pyrimidine linked to sulfonyl or peptide groups accounted for increased antidiabetic activity. These results demonstrated novel TZDs and RDs with high potency in stimulating insulin secretion, enhancing insulin sensitivity, and activating PPAR-γ relative to pioglitazone. They are recommended for further development as potential antidiabetic agents.

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.

Synthesis and Characterization of Novel Thiazolidinones and Thioxothiazolidinones Derived from Substituted Indole

Based on recent discoveries concerning the numerous biological properties of thiazolidinones and thiosemicarbazones, new N-substituted heterocyclic derivatives have been designed by combining the indole ring with thioxothiazolidinone, thiazolidinone or thiosemicarbazone. Thus, a series of new thioxothiazolidinone, thiazolidinone, or thiosemicarbazone derivatives bearing indole-based moiety have been designed, synthesized, and developed in good yields.

Fullerene-Based Triads with Controlled Alkyl Spacer Length as Photoactive Materials for Single-Component Organic Solar Cells

Two kinds of dumbbell-shaped acceptor-donor-acceptor (A-D-A)-type triad single-component (SC) photovoltaic molecules based on a benzodithiophene-rhodanine (BDTRh) core and [6,6]-phenyl-C₆₁ butyric acid (PC₆₁BA) termini, BDTRh-C₂-PC₆₁BA and BDTRh-C₁₀-PC₆₁BA, were synthesized by modulating the alkyl (C2 and C10) spacer lengths. Both SC photovoltaic structures had similar UV-vis spectra in solution, but BDTRh-C₁₀-PC₆₁BA showed a significantly higher absorption coefficient as a thin film. In films, a more facile intermolecular photo-induced charge transfer was observed for BDTRh-C₁₀-PC₆₁BA in the broad-band transient absorption measurements. BDTRh-C₁₀-PC₆₁BA also exhibited a higher hole mobility (by 25 times) and less bimolecular recombination than BDTRh-C₂-PC₆₁BA. By plotting the normalized external quantum efficiency data, a higher charge-transfer state was measured for BDTRh-C₁₀-PC₆₁BA, reducing its voltage loss. A higher power conversion efficiency of ∼2% was obtained for BDTRh-C₁₀-PC₆₁BA, showing higher open-circuit voltage, short-circuit current density, and fill factor than those of BDTRh-C₂-PC₆₁BA devices. The different carrier dynamics, voltage loss, and optical and photoelectrical characteristics depending on the spacer length were interpreted in terms of the film morphology. The longer decyl spacer in BDTRh-C₁₀-PC₆₁BA afforded a significantly enhanced intermolecular ordering of the p-type core compared to BDTRh-C₂-PC₆₁BA, suggesting that the alkyl spacer length plays a critical role in controlling the intermolecular packing interaction.

A New Synthesis Strategy for Rhodanine and Its Derivatives

Rhodanine and its derivatives have been known as privileged structures in pharmacological research because of their wide spectrum of biological activities, but the synthesis method of rhodanine skeleton is limited. In this paper, not only rhodanine skeleton, but also N-aryl rhodanines can be directly prepared via the reaction of thioureas and thioglycolic acid in one step catalyzed by protic acid, which provides a new approach of the synthesis of rhodanine and its derivatives. The developed strategy is straightforward, efficient, atom economical, and convenient in good yields.

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.

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.

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.

Protein-Ligand Empirical Interaction Components for Virtual Screening

A major shortcoming of empirical scoring functions is that they often fail to predict binding affinity properly. Removing false positives of docking results is one of the most challenging works in structure-based virtual screening. Postdocking filters, making use of all kinds of experimental structure and activity information, may help in solving the issue. We describe a new method based on detailed protein-ligand interaction decomposition and machine learning. Protein-ligand empirical interaction components (PLEIC) are used as descriptors for support vector machine learning to develop a classification model (PLEIC-SVM) to discriminate false positives from true positives. Experimentally derived activity information is used for model training. An extensive benchmark study on 36 diverse data sets from the DUD-E database has been performed to evaluate the performance of the new method. The results show that the new method performs much better than standard empirical scoring functions in structure-based virtual screening. The trained PLEIC-SVM model is able to capture important interaction patterns between ligand and protein residues for one specific target, which is helpful in discarding false positives in postdocking filtering.

Identification of novel pyrazole–rhodanine hybrid scaffolds as potent inhibitors of aldose reductase: design, synthesis, biological evaluation and molecular docking analysis

A series of novel pyrazole–rhodanine derivatives was designed, synthesized, and biologically evaluated for their potential inhibitory effect on both aldehyde reductase (ALR1) and aldose reductase (ALR2).

New 5-ylidene rhodanine derivatives based on the dispacamide A model

A practical approach for the preparation of (5Z) 5-ylidene rhodanine derivatives bearing the (4,5-dihalogeno-pyrrol-2-yl)carbamoyl fragment of dispacamide A is reported. The new compounds were obtained in good yields (19-88 %) by Knoevenagel condensation according to a solution-phase microwave dielectric heating protocol in the presence of organic bases (piperidine, TEA, and AcONa) from a set of N-substituted rhodanines 2(a-i). The ten synthetic products 3(a-j) have been synthesized with a Z-geometry about their exocyclic double bond and the structure of one of these compounds (3) was confirmed by a single X-ray diffraction analysis. The new (5Z) 5-ylidene rhodanine derivatives 3(a-j) were tested against eight protein kinases.

Thiazolidinone-peptide hybrids as dengue virus protease inhibitors with antiviral activity in cell culture

The protease of dengue virus is a promising target for antiviral drug discovery. We here report a new generation of peptide-hybrid inhibitors of dengue protease that incorporate N-substituted 5-arylidenethiazolidinone heterocycles (rhodanines and thiazolidinediones) as N-terminal capping groups of the peptide moiety. The compounds were extensively characterized with respect to inhibition of various proteases, inhibition mechanisms, membrane permeability, antiviral activity, and cytotoxicity in cell culture. A sulfur/oxygen exchange in position 2 of the capping heterocycle (thiazolidinedione-capped vs rhodanine-capped peptide hybrids) has a significant effect on these properties and activities. The most promising in vitro affinities were observed for thiazolidinedione-based peptide hybrids containing hydrophobic groups with Ki values between 1.5 and 1.8 μM and competitive inhibition mechanisms. Rhodanine-capped peptide hybrids with hydrophobic substituents have, in correlation with their membrane permeability, a more pronounced antiviral activity in cell culture than the thiazolidinediones.