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Mutations of isocitrate dehydrogenase 1 (IDH1) are key biomarkers for glioma classification, but current methods for detection of mutated IDH1 (mIDH1) require invasive tissue sampling and cannot be used for longitudinal studies. Positron emission tomography (PET) imaging with mIDH1-selective radioligands is a promising alternative approach that could enable non-invasive assessment of the IDH status. In the present work, we developed efficient protocols for the preparation of four 18F-labeled derivatives of the mIDH1-selective inhibitor olutasidenib. All four probes were characterized by cellular uptake studies with U87 glioma cells harboring a heterozygous IDH1 mutation (U87-mIDH) and the corresponding wildtype cells (U87-WT). In addition, the most promising probe was evaluated by PET imaging in healthy mice and mice bearing subcutaneous U87-mIDH and U87-WT tumors. Although all four probes inhibited mIDH1 with variable potencies, only one of them ([18F]mIDH-138) showed significantly higher in vitro uptake into U87-mIDH compared to U87-WT cells. In addition, PET imaging with [18F]mIDH-138 in mice demonstrated good in vivo stability and low non-specific uptake of the probe, but also revealed significantly higher uptake into U87-WT compared to U87-mIDH tumors. Finally, application of a two-tissue compartment model (2TCM) to the PET data indicated that preferential tracer uptake into U87-WT tumors results from higher specific binding rather than from differences in tracer perfusion. In conclusion, these results corroborate recent findings that mIDH1-selective inhibition may not directly correlate with mIDH1-selective target engagement and indicate that in vivo engagement of wildtype and mutated IDH1 may be governed by factors that are not faithfully reproduced by in vitro assays, both of which could complicate development of PET probes. [ABSTRACT FROM AUTHOR]

Series of indole‐1,3,4‐thiadiazole compounds (IT 1–7) were synthesized and characterized by FT‐IR, 1H NMR, 13C NMR and ESI‐MS spectral data. Further, the compounds (IT 1–7) were screened for antidiabetic, antioxidant and anti‐inflammatory activities. Most of these compounds exhibited moderate to good antidiabetic, antioxidant and anti‐inflammatory activities against α‐amylase enzyme, ABTS and lipoxygenase enzyme, respectively. Among these, IT‐1 displayed the better activity compared to that of standard drugs. The mechanism of binding of IT‐1, IT‐5 and IT‐6 with a transporter protein, human serum albumin was investigated by fluorescence spectroscopic and circular dichroism studies. These compounds quenched the intrinsic fluorescence intensity of HSA and moderate binding was evident from the values of binding constants which are in the order of 105 M−1. The molecular docking studies of the compounds were performed against human pancreatic alpha‐amylase in complex with montbretin A (PDB ID: 4W93). The studied compounds interacted with amino acid residues (ASP197, GLU240 and TYR151) which were similar to that of the reference drug, acarbose. The ADME properties of designed compounds were studied using SwissADME software. All the compounds obeyed Lipinski's rule of five. All the compounds showed low or non‐toxicity towards different toxicity classes as analyzed using ProTox‐II online tool. [ABSTRACT FROM AUTHOR]

RNA-binding proteins are essential regulators of RNA processing and function. Translational repression assays can be used to study how they interact with specific RNA sequences by insertion of such a consensus sequence into the 5’ untranslated region of a reporter mRNA and measuring reporter protein translation. The straightforward set-up of these translational repression assays avoids the need for the isolation of the protein or the RNA providing speed, robustness and a low-cost method. Here, we report the optimization of the assay to function with linear RNA sequences instead of the previously reported hairpin type sequences to allow the study of a wider variety of RNA-binding proteins. Multiplication of a consensus sequence strongly improves the signal allowing analysis by both fluorescence intensity measurements and flow cytometry.

Mutations of isocitrate dehydrogenase 1 (IDH1) are key biomarkers for glioma classification, but current methods for detection of mutated IDH1 (mIDH1) require invasive tissue sampling and cannot be used for longitudinal studies. Positron emission tomography (PET) imaging with mIDH1-selective radioligands is a promising alternative approach that could enable non-invasive assessment of the IDH status. In the present work, we developed efficient protocols for the preparation of four 18F-labeled derivatives of the mIDH1-selective inhibitor olutasidenib. All four probes were characterized by cellular uptake studies with U87 glioma cells harboring a heterozygous IDH1 mutation (U87-mIDH) and the corresponding wildtype cells (U87-WT). In addition, the most promising probe was evaluated by PET imaging in healthy mice and mice bearing subcutaneous U87-mIDH and U87-WT tumors. Although all four probes inhibited mIDH1 with variable potencies, only one of them ([18F]mIDH-138) showed significantly higher in vitro uptake into U87-mIDH compared to U87-WT cells. In addition, PET imaging with [18F]mIDH-138 in mice demonstrated good in vivo stability and low non-specific uptake of the probe, but also revealed significantly higher uptake into U87-WT compared to U87-mIDH tumors. Finally, application of a two-tissue compartment model (2TCM) to the PET data indicated that preferential tracer uptake into U87-WT tumors results from higher specific binding rather than from differences in tracer perfusion. In conclusion, these results corroborate recent findings that mIDH1-selective inhibition may not directly correlate with mIDH1-selective target engagement and indicate that in vivo engagement of wildtype and mutated IDH1 may be governed by factors that are not faithfully reproduced by in vitro assays, both of which could complicate development of PET probes.

Abstract Qualitative NMR spectroscopic and quantitative calorimetric binding studies were performed to characterize the interaction of nontoxic mimics of the V-type nerve agent VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate) and the Novichok nerve agent A-234 (ethyl (1-(diethylamino)ethylidene)phosphoramidofluoridate) with a series of receptors in 100 mM aqueous phosphate buffer at pH 7.4 and 37 °C. These investigations provided information about the preferred geometry with which the nerve agent mimics are included into the receptor cavities and about the stability of the complexes formed. According to the results, the positively charged VX mimic prefers to bind to cation receptors such as sulfonated calixarenes and an acyclic cucurbituril but does not noticeably interact with cyclodextrins. While binding to the acyclic cucurbituril is stronger than that to calixarenes, the mode of inclusion into the sulfonatocalix[4]arene cavity is better suited for the development of scavengers that bind and detoxify V-type nerve agents. The neutral Novichok mimic, on the other hand, only interacts with the acyclic cucurbituril with a strength required for scavenger development. These binding studies thus provided guidelines for the further development of nerve agent scavengers.

The binding studies of DNA with small molecules have been an emerging field of research all the time since DNA as the genetic material is a major biological target for various drugs. Interpretation of small molecule-DNA binding helps in understanding their interactions with designing new drugs of greater medicinal activity. Posaconazole is an antifungal drug in the class of triazoles which are known to possess numerous pharmacological properties. In this work, the nature of the binding of posaconazole with calf-thymus DNA has been studied using spectroscopic techniques and molecular docking studies. A binding constant of the order of 103 M−1 was observed from UV–visible and fluorescence studies for the interaction between posaconazole and calf-thymus DNA. The fluorescence property of posaconazole was found to be quenched by calf-thymus DNA with a quenching constant of the order of 103 M−1. Competitive displacement of ethidium bromide and Hoechst 33258 by posaconazole using fluorescence technique suggested minor groove binding of posaconazole in calf-thymus DNA. Confirmation of the binding mode was further complemented by the viscosity measurement and DNA melting studies followed by KI quenching experiments. The studies on the effect of ionic strength on the binding suggested a possible role of electrostatic force in the interaction. Molecular docking studies reflected a crescent shape of the posaconazole within the minor groove of calf-thymus DNA validating the experimental findings showing the residues involved in the interaction. [ABSTRACT FROM AUTHOR]

RNA-binding proteins are essential regulators of RNA processing and function. Translational repression assays can be used to study how they interact with specific RNA sequences by insertion of such a consensus sequence into the 5' untranslated region of a reporter mRNA and measuring reporter protein translation. The straightforward set-up of these translational repression assays avoids the need for the isolation of the protein or the RNA providing speed, robustness and a low-cost method. Here, we report the optimization of the assay to function with linear RNA sequences instead of the previously reported hairpin type sequences to allow the study of a wider variety of RNA-binding proteins. Multiplication of a consensus sequence strongly improves the signal allowing analysis by both fluorescence intensity measurements and flow cytometry. [ABSTRACT FROM AUTHOR]

Au‐catalyzed hydroamination proceeds well for alkynes but not alkenes. We report gas‐phase binding energies of alkenes and alkynes to a cationic Au center, which indicate that differences in binding are not the origin of the disparate chemical behavior. We further report the synthesis and characterization of 2‐aminoalkylgold complexes, which would be the intermediates in a hypothetical Au‐catalyzed hydroamination of styrene. The reactivity of the well‐characterized and isolable complexes reveals that protonation or alkylation of the 2‐aminoalkylgold complexes results in amine elimination in solution, and in the gas phase, indicating that the failure of Au‐catalyzed alkene hydroamination derives from a non‐competitive protodeauration step. We analyze possible transition states for the protodeauration, and identify an insufficiently strong Au‐proton interaction as the reason that the transition states lie too high in energy to compete. [ABSTRACT FROM AUTHOR]

• The interactions of anamphiphilic drug(Propranolol Hydrochloride, PPL) with cationic surfactants was evaluated by the surface tension methods. • The non-ideal or synergistic behavior of the mixed systems studied were explored by using several physical models. • Several thermodynamic parameters of mixed micellization were measured. • The synergism between PPL and cationic surfactants was also confirmed by UV–visible spectroscopy. The interactions of amphiphilic drug(propranolol hydrochloride, PPL) with cationic surfactants, such as dodecyltrimethylammoniumbromide(DTAB), tetradecyltrimethylammonium bromide (TTAB), trimethyltetradecylammonium chloride(TTAC) and tetyltrimethylammonium bromide(CTAB), in an aqueous medium were evaluated. The surface tension measurement was used to examine the mixed micellization behavior and surface properties of drug-surfactant mixtures. The nonideal or synergistic behaviors of the mixed systems were explored by using several physical models, such as Clint, Rubingh, Rosen, and Motomura models, based on regular solution theory and pseudophase approximation. In addition, the synergism between PPL and cationic surfactants was also confirmed using ultraviolet–visible spectroscopy. The stoichiometric ratios, binding constants, and free energy changes of the drug–surfactant mixtures were computed using Benesi–Hildebrand (B–H) theory. [ABSTRACT FROM AUTHOR]

Enantioselective molecular recognition of chiral molecules that lack specific interaction sites for hydrogen bonding or Lewis acid–base interactions remains challenging. Here we introduce the concept of tailored chiral π‐surfaces toward the maximization of shape complementarity. As we demonstrate for helicenes it is indeed possible by pure van‐der‐Waals interactions (π–π interactions and CH–π interactions) to accomplish enantioselective binding. This is shown for a novel benzo[ghi]perylene trisimide (BPTI) receptor whose π‐scaffold is contorted into a chiral plane by functionalization with 1,1′‐bi‐2‐naphthol (BINOL). Complexation experiments of enantiopure (P)‐BPTI with (P)‐ and (M)‐[6]helicene afforded binding constants of 10 700 M−1 and 550 M−1, respectively, thereby demonstrating the pronounced enantiodifferentiation by the homochiral π‐scaffold of the BPTI host. The enantioselective recognition is even observable by the naked eye due to a specific exciplex‐type emission originating from the interacting homochiral π‐scaffolds of electron‐rich [6]helicene and electron‐poor BPTI. [ABSTRACT FROM AUTHOR]

There are many fluorescence-based applications that can be used to characterize molecular interactions. However, available methods often depend on site-specific labeling techniques or binding-induced changes in conformation or size of the probed target molecule. To overcome these limitations, we applied a ratiometric dual-emission approach that quantifies ligand-induced spectral shifts with sub-nanometer sensitivity. The use of environment-sensitive near-infrared dyes with the method we describe enables affinity measurements and thermodynamic characterization without the explicit need for site-specific labeling or ligand-induced conformational changes. We demonstrate that in-solution spectral shift measurements enable precise characterization of molecular interactions for a variety of biomolecules, including proteins, antibodies, and nucleic acids. Thereby, the described method is not limited to a subset of molecules since even the most challenging samples of research and drug discovery projects like membrane proteins and intrinsically disordered proteins can be analyzed. [ABSTRACT FROM AUTHOR]

Sepsis, characterized with high risk of life‐threatening organ dysfunction, represents a major cause of health loss and the World Health Organization (WHO) labelled sepsis as the most urgent unmet medical need in 2017. The emerging biological understanding of the role of RIPK1 in sepsis has opened up an exciting opportunity to explore potent and selective RIPK1 inhibitors as an effective therapeutic strategy for SIRS and sepsis therapy. Herein, we have synthesized a class of highly potent dual‐mode RIPK1 inhibitors occupying both the allosteric and the ATP binding pockets, exemplified by compound 21 (ZB‐R‐55) which is about 10‐fold more potent than GSK2982772, and exhibits excellent kinase selectivity, good oral pharmacokinetics and good therapeutic effects in the LPS‐induced sepsis model, suggesting that compound ZB‐R‐55 is a highly promising preclinical candidate. [ABSTRACT FROM AUTHOR]

[Display omitted] • 1,3,4-oxadiazole-thiazolidine-2,4-dione hybrid compounds (TOT-1 to 15) were synthesized, characterized and screened for various biological activities. • Single-crystal X-ray diffraction data was collected for the intermediate compound, TOT and its structure was proposed. • The compounds, TOT 12–15 exhibited significant anti-cancer activity. • Molecular docking studies were carried out. Two synthetic methods were proposed for the preparation of a new series of thiophene-1,3,4-oxadiazole-thiazolidine-2,4-dione hybrids (TOT-1 to 15) and their structures were elucidated based on spectral data. Studies on cytotoxicity, ROS, cellular uptake and interactions of TOT-14 with calf thymus DNA were carried out. Anticancer activity of compounds, TOT-1 to 15 on breast cancer (MCF-7) cell lines was investigated. The IC 50 values for the standard, epirubicin hydrochloride and TOT-12, 13, 14 and 15 were found to be 6.78, 5.52, 6.53, 4.83 and 5.57 µg/mL, respectively. Notably, TOT-14 exhibited a remarkable antiproliferative activity with a strikingly selective inhibitory effect compared to standard. This specific selectivity could be attributed to the synergistic effect of increased cellular uptake and generation of higher ROS in cancer cells after irradiation. The binding constant of 4.25 x 103 M−1 indicated the moderate interaction between TOT-14 and ct-DNA. The docking score of TOT derivatives was substantially identical to the docking score of epirubicin hydrochloride. The designed molecules complied with the requirements for drug-likeness and ADME. [ABSTRACT FROM AUTHOR]

In the fields of pharmacology and life sciences, it is essential to study how prescribed drugs interact with carrier proteins in human serum albumin. The current study has evaluated the binding properties of rhodanine derivative; (z)-2-(4-(5-((3-(3-chlorophenyl)-1-phenyl-1H-pyrazol-4-oxo-2-thioxothiazolidin-3-yl)benzamido)acetic acid (P3CL) on bovine serum albumin (BSA) by biophysical approach. BSA is a homology model of Human serum albumin. Due to the cost-effectiveness of Human Serum Albumin (HSA) we have studied the binding properties of rhodanine derivative (P3CL) on BSA. The BSA-P3CL interactions were investigated by fluorescence spectroscopy and revealed the presence of a static quenching mechanism. P3CL possesses good binding affinity on BSA with binding constant K P3CL = 5.36330 × 10 13 M -1 binding free energy. We have calculated the binding free energy, the number of binding sites, and the binding constants. The establishment of hydrogen bonds and the active participation of amino acids in drug binding were confirmed by molecular docking studies. As conventional processes for the investigation of pharmacological drugs, therapeutic combinations, and coordinated drug intake, the offered strategies are simple to comprehend, accurate, and rapid to put into practice. Our findings will support an additional investigation into ligand's pharmacological activity.Communicated by Ramaswamy H. Sarma.

Fibrinogen C domain-containing protein 1 (FIBCD1) is an immune protein proposed to be involved in host recognition of chitin on the surface of pathogens. As FIBCD1 readily binds acetylated molecules, we have determined the high-resolution crystal structures of a recombinant fragment of the FIBCD1 C-terminal domain complexed with small N-acetyl-containing ligands to determine the mode of recognition. All ligands bind at the conserved N-acetyl-binding site (S1) with galactose and glucose-derived ligands rotated 180° relative to each other. One subunit of a native structure derived from protein expressed in mammalian cells binds glycosylation from a neighboring subunit, in an extended binding site. Across the various structures, the primary S1 binding pocket is occupied by N-acetyl-containing ligands or acetate, with N-acetyl, acetate, or sulfate ion in an adjacent pocket S1(2). Inhibition binding studies of N-acetylglucosamine oligomers, (GlcNAc) n , n = 1, 2, 3, 5, 11, via ELISA along with microscale thermophoresis affinity assays indicate a strong preference of FIBCD1 for longer N-acetylchitooligosaccharides. Binding studies of mutant H396A, located beyond the S1(2) site, showed no significant difference from wildtype, but K381L, within the S1(2) pocket, blocked binding to the model ligand acetylated bovine serum albumin, suggesting that S1(2) may have functional importance in ligand binding. The binding studies, alongside structural definition of diverse N-acetyl monosaccharide binding in the primary S1 pocket and of additional, adjacent binding pockets, able to accommodate both carbohydrate and sulfate functional groups, suggest a versatility in FIBCD1 to recognize chitin oligomers and other pathogen-associated carbohydrate motifs across an extended surface., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

The Tobamovirus helicase plays an important role in virus proliferation and host interaction. They can also be targets for antiviral drugs. Tobacco mosaic virus (TMV) is well controlled by ningnanmycin (NNM), but whether it acts on other virus helicases of Tobamovirus virus is not clear. In this study, we expressed and purified several Tobamovirus virus helicase proteins and analyzed the three–dimensional structures of several Tobamovirus virus helicases. In addition, the binding of Tobamovirus helicase to NNM was also studied. The docking study reveals the interaction between NNM and Tobamovirus virus helicase. Microscale Thermophoresis (MST) experiments have shown that NNM binds to Tobamovirus helicase with a dissociation constant of 4.64–12.63 μM. Therefore, these data are of great significance for the design and synthesis of new effective anti–plant virus drugs. [Display omitted] • Several Tobamovirus virus helicases were expressed in E. coli. • Predict the potential binding sites of multiple Tobamovirus virus helicases and small molecular compounds. • An in vitro drug screening model based on Tobamovirus virus helicases as potential targets was established. [ABSTRACT FROM AUTHOR]

• The synthesized compounds displayed potent in vitro antidiabetic activity. • The single-crystal X-ray investigation validated the molecular structure. • The interaction of compounds with HSA has been studied. • Molecular docking studies were carried out. 2,4-thiazolidinedione-phenothiazine molecular hybrids, 9a–9t were synthesized, characterized and screened for antidiabetic activities viz., α -amylase inhibition and glucose uptake assay. The synthesized compounds were characterized by spectroscopic techniques. The molecule 9p was grown into single crystals, and its crystal structure and refinement data were deliberated. Most of the compounds displayed a significant to moderate α-amylase inhibition and glucose uptake activity. The compounds, 9m-9p showed a significant α-amylase inhibition with IC 50 values (83.7 ± 0.7 - 60.8 ± 0.8 µM), which are greater than that of the standard, acarbose (101.7 ± 2.0 µM). Most of the compounds showed good glucose uptake assay and compounds, 9a- 9 g showed IC 50 values in the range of 169.8 ± 1.2 - 213.3 ± 0.5 µM which are ∼2-fold greater compared to that of the standard, metronidazole (441.5 ± 2.1 µM). The compound, 9l showed acceptable values for both α-amylase inhibition (IC 50 = 130.6 ± 2.0 µM) and glucose uptake assay (IC 50 = 459.3 ± 2.2 µM) compared to those of the standard. Molecular docking studies confirmed interactions of the compounds with the human pancreatic α-amylase protein with PDB ID: 2QV4. Further, the interactions of 9o and 9p with human serum albumin were also investigated. [Display omitted] [ABSTRACT FROM AUTHOR]

The oxovanadium(IV) Schiff base metal complex (ISNPV) have been synthesized as well as characterized by using micro analytical and traditional spectroscopic techniques. The spectral findings were utilized to validate the formation of ISNPV with structure exhibited square pyramidal geometry. The in vitro antibacterial activities of ISNPV were investigated to five different bacterial stains such as S. aureus , S. epidermidis , B. cereus , B. amyloliquefaciens and B. subtilis . The obtained result have suggested that the ISNPV has highest antibacterial activity against S. aureus than the other bacterial stains. The in vitro antioxidant activity like DPPH free radical scavenging assay method was studied by ISNPV in DMSO medium. Because it scavenges all free radicals, the ISNPV possesses higher antioxidant activity than the free ligand. UV-visible absorption and emission spectral techniques were used to investigate the binding of CT-DNA to the ISNPV. Both the spectral data indicate that the ISNPV binds the double helix structure of CT-DNA via an intercalation mode. Additionally, investigate the interactions of ISNPV with the protein molecules like BSA/HAS has been investigated using absorption and emission techniques. The absorption intensity of metal complex increases as well as the emission intensity of protein molecules ability decreases due to the binding nature of ISNPV with BSA/HSA protein molecules. The binding nature of ISNPV with bio molecules such as CT-DNA, BSA and HSA was also validated using molecular docking approach.

• Three characteristic phenylethanol glycosides (PhGs) were selected to investigate the cytotoxicity on hela cells. • The binding mechanism of three phgs with human serum albumin (HSA) were elaborated by spectroscopic, microscopic, and simulative technologies. • A rare fluorescence increase behavior was observed when phgs 3 was added into HSA solution. Phenylethanol glycosides (PhGs) possessing various biological activities and good safety, are a large group of natural compounds extensively distributed in plant species. However, the interaction of PhGs with human serum albumin (HSA) is not reported, which is of guiding significance to expound the absorption and metabolism mechanism of PhGs in vivo. In this work, three natural PhGs containing biogenetic relationships, namely acteoside, cistanoside F, and decaffeoylacteoside were selected to investigate the cytotoxicity activity on human cervical cancer cell line (HeLa). Further, the binding affinity and mechanism of three PhGs with HSA were comprehensively elaborated by fluorescence spectroscopy, nuclear magnetic resonance, circular dichroism, atomic force microscopy and molecular docking. The results displayed that three PhGs inhibited the HeLa cells growth in a concentration-dependent manner with the IC 50 values of 22.84, 78.20 and 47.86 μM, respectively. Fluorescence spectra demonstrated the fluorescence strength of HSA was obviously quenched by acteoside and cistanoside F, while amazingly the fluorescence strength of HSA was enhanced by decaffeoylacteoside. Spectroscopic technologies demonstrated three PhGs can be bound to HSA with the higher affinity (the binding constant K a of PhGs 1, 2 and 3 was 1.23, 1.14 and 0.65 × 105, respectively) mainly through hydrophobic forces and hydrogen bonds, and the secondary configuration of HSA after treating with the PhGs was also mainly α -helix. Microscopic technology exhibited that HSA became more expanded and dispersed when combined with the PhGs. Molecular docking presented the molecular recognition pattern and evaluated the stability of the binary system between the PhGs and HSA. [Display omitted] [ABSTRACT FROM AUTHOR]

The human peptide transporter hPEPT1 (SLC15A1) is responsible for uptake of dietary di- and tripeptides and a number of drugs from the small intestine by utilizing the proton electrochemical gradient, and hence an important target for peptide-like drug design and drug delivery. hPEPT1 belongs to the ubiquitous major facilitator superfamily that all contain a 12TM core structure, with global conformational changes occurring during the transport cycle. Several bacterial homologues of these transporters have been characterized, providing valuable insight into the transport mechanism of this family. Here we report the overexpression and purification of recombinant hPEPT1 in a detergent-solubilized state. Thermostability profiling of hPEPT1 at different pH values revealed that hPEPT1 is more stable at pH 6 as compared to pH 7 and 8. Micro-scale thermophoresis (MST) confirmed that the purified hPEPT1 was able to bind di- and tripeptides respectively. To assess the in-solution oligomeric state of hPEPT1, negative stain electron microscopy was performed, demonstrating a predominantly monomeric state., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)