Compounds Of Interest Research Articles

Reactions and Biological Activities of Hydrazonoyl Halides.

This review covers the literature information on the chemistry of hydrazonoyl halides with different substrates to give heterocyclic compounds. From the foregoing survey, it seems this provides a useful and convenient strategy for the synthesis of numerous heterocyclic derivatives. The subject of such reactions is still ongoing and undoubtedly will provide new fused functionalized compounds of both industrial and biological interest. A literature survey revealed that a great deal of interest has been focused on the synthesis of functionalized heterocyclic compounds due to their wide range of biological activities, such as contact dermatitis, anthelmintic, antiviral, antimicrobial, herbicidal, and anti-cancer. On the other hand, hydrazonoyl halides are interesting synthons for valuable bioactive heterocyclic compounds. The reaction of hydrazonoyl halides with various types of substrates gave a huge number of different heterocyclic systems. In this review, we collected all reactions of hydrazonoyl halides with different moieties and classified them as aryl diazo of monoheterocycles, aryldiazo of 5,5-bis-heterocycles, aryldiazo of 5,6-bis-heterocycles, aryldiazo of 6,6-bis-heterocycles, aryldiazo of 5,5,6-tri-heterocycles, aryldiazo of 5,6,6-tri-heterocycles, aryldiazo of 6,6,6-tri-heterocycles, hetero annulation of bisheterocycles, hetero annulation of tri-heterocycles, hetero-annulation of tetra-heterocycles, synthesis of spiro-heterocycles, heterocyclic ring transformations, and 1,3-dipolar cycloaddition reactions catalyzed by transition metals using hydrazonoyl halides as substrates.Most reaction types have been successfully applied and used in the production of biologically active compounds. The aim of the present survey is to consider in the reader the opportunity interactions and biological activities of hydrazonoyl halides. The information of several artificial paths and varied physics-chemical factors of such heterocycles made a special consideration of chemists in different fields to yield a combinatorial library and carry out thorough efforts in the search for hydrazonoyl halides.

Supramolecular biosolvent extraction of antioxidants from orange peel residues from the tea industry

The growing interest in natural antioxidants across various industries has spurred the development and use of alternative green methods for valorizing plant biomass. Supramolecular solvents (bioSUPRAS), composed of self-assembled amphiphilic aggregates, have shown significant potential for the recovery of high-value compounds from plant biomass for industrial applications while adhering to numerous green chemistry principles. In this study, we evaluated various bioSUPRAS (sponge bioSUPRAS of 1,2-octanediol and cubosomic bioSUPRAS of 1,2-hexanediol) and different extraction conditions for the recovery of antioxidants from orange peel waste generated by the tea industry. Sponge bioSUPRAS were selected as optimal and the best conditions for formation consisted of a medium of 15 % v/v of 1,3-propanediol as co-solvent and 85 % v/v of water (acidified with 1 % v/v acetic acid). The most suitable extraction conditions were 1:12 mL:g bioSUPRAS-to-solid ratio at room temperature for 30 min, resulting in a maximum yield of 12.9 ± 1.4 mg GAE/g. Using liquid chromatography coupled with high-resolution tandem mass spectrometry (LC-QTOF), we screened and quantified the natural compounds of interest, identifying the flavonoid hesperidin as the dominant antioxidant at 2.6 ± 0.06 mg/g. This research presents a promising method for valorizing underutilized orange peel waste and highlights the potential of these extracts as ingredients in new value-added formulations.

Filamentous fungi as emerging cell factories for the production of aromatic compounds.

Microbial production of aromatic compounds from renewable feedstocks has gained increasing interest as a means towards sustainable production of chemicals. The potential of filamentous fungi for production of aromatic compounds has nonetheless not yet been widely exploited. Notably, many filamentous fungi can naturally break down lignin and metabolize lignin-derived aromatic compounds. A few examples where a fungal cell factory, often of Aspergillus spp., is used to produce an aromatic compound, typically through the conversion of one compound to another, have already been reported. In this review, we summarize fungal biosynthesis of biotechnologically interesting aromatic compounds. The focus is on compounds produced from the shikimate pathway. Biorefinery-relevant efforts for valorizing residual biomass or lignin derived compounds are also discussed. The advancement in engineering tools combined with the increasing amounts of data supporting the discovery of new enzymes and development of new bioprocesses has led to an increased range of potential production hosts and products. This is expected to translate into a wider utilization of fungal cell factories for production of aromatic compounds.

Intermolecular Oxidopyrylium (5 + 2) Cycloaddition/Reductive Ring-Opening Strategy for the Synthesis of α-Methoxytropones.

α-Methoxytropone is a structural motif found in various natural products and other compounds of interest to the scientific community but remains a synthetic challenge. The present Note describes the synthesis of variously substituted α-methoxytropones and related compounds through an intermolecular 3-hydroxy-4-pyrone-based oxidopyrylium (5 + 2) cycloaddition followed by a samarium iodide-mediated reductive ring-opening. The strategy is highlighted in the synthesis of a novel AC-ring analogue of colchicine to compare it to existing methods.

Solvent-Free Approaches for the Synthesis of Lophine Derivatives

AbstractSolvent-free synthesis comes with many advantages such as cost reduction, waste reduction, ease of operation, sustainability, environmentally benign operations, etc. These benefits have prompted many chemists to develop new protocols for solvent-free synthesis of various interesting chemical compounds. One such class of compounds is 2,4,5-triarylimidazoles, commonly known as lophines due to their applications in materials science, chemo- and bio-sensors, and pharmacology. This article focuses on solvent-free synthesis of lophine derivatives via different protocols, including the use of inorganic-, organic-, and biocatalysts; solid-supported catalysts; microwave-mediated heating; and grinding.

High-sensitivity pump-probe spectroscopy with a dual-comb laser and a PM-Andi supercontinuum.

Amplifier-based pump-probe systems, while versatile, often suffer from complexity and low measurement speeds, especially when probing samples require low excitation fluences. To address these limitations, we introduce a pump-probe system that leverages a 60-MHz single-cavity dual-comb oscillator and an ultra-low noise supercontinuum. The setup can operate in equivalent time sampling or in programmable optical delay generation modes. We employ this system to study the wavelength-dependent excited-state dynamics of the non-fullerene electron acceptor Y6, a compound of interest in solar cell development, with excitation fluences as low as 1 nJ/cm2, well below the onset of nonlinear exciton annihilation effects. Our measurements reach a shot-noise limited sensitivity in differential transmission of 3.4·10-7. The results demonstrate the system's potential to advance the field of ultrafast spectroscopy.

Harnessing the optimization of enzyme catalytic rates in engineering of metabolic phenotypes.

The increasing availability of enzyme turnover number measurements from experiments and of turnover number predictions from deep learning models prompts the use of these enzyme parameters in precise metabolic engineering. Yet, there is no computational approach that allows the prediction of metabolic engineering strategies that rely on the modification of turnover numbers. It is also unclear if modifications of turnover numbers without alterations in the host's transcriptional regulatory machinery suffice to increase the production of chemicals of interest. Here, we present a constraint-based modeling approach, termed Overcoming Kinetic rate Obstacles (OKO), that uses enzyme-constrained metabolic models to predict in silico strategies to increase the production of a given chemical, while ensuring specified cell growth. We demonstrate that the application of OKO to enzyme-constrained metabolic models of Escherichia coli and Saccharomyces cerevisiae results in strategies that can at least double the production of over 40 compounds with little penalty to growth. Interestingly, we show that the overproduction of compounds of interest does not entail only an increase in the values of turnover numbers. Lastly, we demonstrate that a refinement of OKO, allowing also for manipulation of enzyme abundance, facilitates the usage of the available compendia and deep learning models of turnover numbers in the design of precise metabolic engineering strategies. Our results expand the usage of genome-scale metabolic models toward the identification of targets for protein engineering, allowing their direct usage in the generation of innovative metabolic engineering designs for various biotechnological applications.

Optimization of Hydrocarbon Production in Catalytic Pyrolysis of Macaúba Epicarp and Macaúba and Baru Endocarps

The objective of this study was to examine the catalytic pyrolysis process of three distinct types of biomasses: baru endocarp (ENB), macaúba endocarp (ENM), and macaúba epicarp (EPM). This was performed with the aim of optimizing the production of hydrocarbons and other volatile compounds of interest through the use of different catalysts. The catalysts utilized in this study were calcium oxide (CaO), phosphate mining waste (PO), niobium pentoxide (Nb2O5), and Ni/Nb2O5. The methodology entailed pyrolyzing the biomass at temperatures spanning from 508 °C to 791 °C, utilizing a micropyrolyzer in conjunction with a gas chromatograph with mass spectrometry (GC/MS) for product analysis. An experimental design was implemented to assess the impact of catalyst concentration and temperature on the yield and composition of the volatile products. The findings demonstrated that CaO was efficacious in deoxygenating the compounds, particularly at elevated temperatures, thereby promoting the generation of saturated and unsaturated hydrocarbons. In contrast, Nb2O5 was effective in the formation of oxygenated compounds, particularly carboxylic acids and phenols. Ni/Nb2O5 has been shown to be effective in the production of cyclic, aromatic, alkadienes, and alkenes hydrocarbons. Phosphate mining waste exhibited moderate performance, with potential for specific applications at high temperatures, with important production of cyclic, aromatic, and alkane hydrocarbons. Among the biomasses, EPM demonstrated the greatest potential for hydrocarbon production, indicating its suitability for the development of advanced biofuels. This study advances our understanding of the catalytic pyrolysis of alternative biomasses and underscores the pivotal role of catalysts in optimizing the process, offering invaluable insights for the sustainable production of biofuels and interest in renewable chemicals.

Facile Approach for the Fabrication of Vapor Sensitive Spin Transition Composite Nanofibers

In this work polymer nanofibers were functionalized by incorporation of the spin transition (ST) compound [Fe(H2btm)2(H2O)2]Cl2 (FeH2btm) (H2btm = di(1H‐tetrazol‐5‐yl)methane). FeH2btm is an interesting compound due to its ability to reversibly and sensitively switch between high spin (HS) and low spin (LS) state when exposed to common volatile compounds (VOC) like ammonia and methanol. By using polyvinylidene fluoride (PVDF) as the main compound, inhibiting interactions between the complex and polymer were minimized. By using UV‐Vis spectroscopy, the visible and reversible switching between HS and LS state when exposed to an ammonia or hydrochloric acid atmosphere was confirmed. Powder X‐Ray diffraction (PXRD), scanning electron microscopy (SEM) and energy dispersive X‐Ray spectroscopy (EDX) show a homogenous distribution of FeH2btm with no major crystalline accumulations and a mean fiber diameter of 106 ± 20 nm. The composite fiber has a similarly high thermal stability as the pure FeH2btm, as shown by thermogravimetric analysis (TGA). Mössbauer spectroscopy indicates an incomplete spin transition after exposition to ammonia. This could be due to low permeability of the VOC into the composite fiber.

Preclinical Positron Emission Tomography with Body Conforming Animal Molds for Cloud-Based Automated Image Analysis in Mice.

Positron Emission Tomography (PET) is a molecular imaging modality that can be used to investigate a multitude of pharmacological questions, such as biomarker modulation, receptor occupancy, and biodistribution of compounds of interest. In biodistribution studies, experimental subjects are often longitudinally imaged after receiving the test article. The images are then analyzed to derive the compound's distribution profile in various organs at different timepoints. This constitutes a crucial step in drug development to understand the distribution and potentially binding profile of an investigative compound. Standard/manual methods of PET imaging-based biodistribution analyses, however, are labor-intensive and time-consuming and are often associated with high inter-operator variability. Further, it is challenging to keep the animals' positions consistent across different timepoints. To address these shortcomings, a series of mouse Body Conforming Animal Molds (BCAMs) were used to enable rigid and consistent positioning of animals during PET/CT imaging acquisition. Further, a Software-as-a-Service (SaaS) platform consisting of a cloud-based Organ Probability Map (OPM) and an artificial intelligence-powered segmentation tool were employed to enable reliable and automated quantitation of in vivo PET imaging data. The workflow presented here includes (1) prepping mice for imaging with the BCAMs, including the proper implantation of subcutaneous tumors to be compatible with the molds, (2) acquiring PET/CT images with BCAMs using the G8 scanner, and 3) performing automated organ segmentation and biodistribution analysis using the cloud-based SaaS. [18F]FDG was used as an exemplar tracer here, but other biomarkers and/or radio-labeled compounds can be readily adapted into the workflow. This procedure can be executed accurately and effectively with minimal training, and the automated PET data analysis yielded satisfactory results consistent with the manual method.

Toxicity and Repellency of (E/Z)-3-Butylidenephthalide: A Natural Compound Isolated from Ligusticum porteri Root Extract Evaluated Against Imported Fire Ants (Hymenoptera: Formicidae)

Imported fire ants are pests of significant importance, especially in the southern United States. We tested (E/Z)-3-butylidenephthalide, a natural compound that was isolated from the ethanolic extract of Ligusticum porteri roots, as a repellent and toxicant against workers of imported fire ants. A series of serial concentrations, starting from 156 µg/g until failure, were tested using digging bioassays. Workers removed significantly less sand from the vials treated with (E/Z)-3-butylidenephthalide as compared to the ethanol control. Based on sand removal data, (E/Z)-3-butylidenephthalide treatment resulted in a more significant digging suppression against red imported fire ant workers at concentrations ranging between 19.5 and 0.6 µg/g than the solvent control whereas sand removal at 0.3 µg/g was similar with the solvent control. Black imported fire ants showed repellency at serial concentrations ranging between 19.5 and 0.15 µg/g whereas the hybrid imported fire ants showed repellency between 19.5 and 4.9 µg/g. In DEET treatments, red and black imported fire ants showed repellency at dosages of 125 to 62.5 µg/g, whereas the treatment failed at the dose of 15.6 µg/g in hybrid fire ants. (E/Z)-3-butylidenephthalide with LC50 values of 11 and 16.4 µg/g was toxic against red and black imported fire ants, respectively, followed by hybrid imported fire ants (LC50 = 104.7 µg/g). Fipronil with LC50 values of 0.49, 0.33, and 0.53 µg/g against red, black, and hybrid fire ants, respectively, was more toxic than (E/Z)-3-butylidenephthalide. In residual bioassay, toxic activity lasted for 3 weeks at dosages of 250 and 500 μg/g against HIFA. In residual bioassay, toxic activity lasted for 3 weeks at dosages of 250 and 500 μg/g against HIFA. The high repellency and toxicity of (E/Z)-3-butylidenephthalide against imported fire ants makes it a natural compound of interest for further evaluation under natural field conditions.

Effects of temperature, relative humidity and soil organic carbon content on soil-air partitioning coefficients of volatile PFAS

Soil-air partitioning coefficient (KSA) values are often used to assess the environmental fate of organic contaminants in soil. Till now, sufficient KSA values have not yet been measured for many compounds of interest, including some emerging pollutants such as volatile PFAS. Moreover, the effects of environmental factors such as temperature, relative humidity and soil organic carbon content on KSA of volatile PFAS are also unclear. In this study, the KSA values of target volatile PFAS were measured under various temperature (20–40 °C), relative humidity (30–100 %) and soil organic carbon content (2.1 %–8.0 %) using a modified solid-phase fugacity meter. The results showed that higher temperatures, higher relative humidity and lower organic carbon content in soil may accelerate the diffusion of target volatile PFAS. Furthermore, the KSA measurements were used to derive a multiple linear regression model to depict the relationship between logKSA and temperature, relative humidity, soil organic carbon content and PFAS-specific logKOA. When compared with the predictions obtained from semi-empirical model, we argued that the multiple linear regression model is more robust and easier to implement for target volatile PFAS or other emerging volatile PFAS than the semi-empirical approach to help depict the diffusion process at target volatile PFAS contaminated sites.

Transcriptomic Analysis During Olive Fruit Development and Expression Profiling of Fatty Acid Desaturase Genes.

The olive fruit is a drupe whose development and ripening takes several months from flowering to full maturation. During this period, several biochemical and physiological changes occur that affect the skin color, texture, composition, and size of the mesocarp. The final result is a fruit rich in fatty acids, phenolic compounds, tocopherols, pigments, sterols, terpenoids, and other compounds of nutritional interest. In this work, a transcriptomic analysis was performed using flowers (T0) and mesocarp tissue at seven different stages during olive fruit development and ripening (T1-T7) of the 'Picual' cultivar. A total of 1755 genes overexpressed at any time with respect to the flowering stage were further analyzed. These genes were grouped into eight clusters based on their expression profile. The gene enrichment analysis revealed the most relevant biological process of every cluster. Highlighting the important role of hormones at very early stages of fruit development (T1, Cluster 1), whereas genes involved in fatty acid biosynthesis were relevant throughout the fruit developmental process. Hence, genes coding for different fatty acid desaturase (SAD, FAD2, FAD3, FAD4, FAD5, FAD6, and FAD7) enzymes received special attention. In particular, 26 genes coding for different fatty acid desaturase enzymes were identified in the 'Picual' genome, contributing to the improvement of the genome annotation. The expression pattern of these genes during fruit development corroborated their role in determining fatty acid composition.

Portable Miniature Mass Spectrometry for Enhanced On-Site Detection of Analytes in Complex Samples by Integrating Solid-Phase Microextraction and Nano-Electrospray Ionization.

On-site mass spectrometry (MS) analysis plays a crucial role in timely understanding chemical compositions of field samples but presents a challenge to miniaturization, portability, and sensitivity. In this work, a portable MS approach was developed by integrating biocompatible solid-phase microextraction (SPME) and a nano-electrospray ionization (nESI) emitter into a kit to couple miniature MS (mMS). The SPME fiber was used for on-site extractive sampling of analytes from complex liquid samples and living organisms and was then inserted into an nESI emitter for on-site MS analysis via the facile kit. The limit of detection was found to be at the pg/mL level for various compounds tested. Acceptable relative standard deviation (RSD) values (5.5-7.6%, n = 6) were obtained for direct measurement of analytes in complex matrixes; acceptable linear responses (0.1-50 ng/mL) and matrix effects (76.0-82.6%) were also found. Enhanced detection of compounds of interest in various real samples, such as food samples, human fluids, environmental water, and living organisms, was unambiguously demonstrated. Our experimental data showed that SPME-nESI-mMS is a promising tool for on-site analysis of various complex samples in significant applications including but not limited to food safety, environmental monitoring, forensic investigation, and bioanalysis.

Improvement of the production of pequi almond (Caryocar brasiliense Camb.) protein hydrolysates through ultrasound-assisted enzymolysis: Impact on hydrolysis kinetics, structure and functional properties of hydrolysates

This study investigated the kinetics of ultrasound (US)-assisted hydrolysis of pequi almond protein (PAP) and the conformational and multifunctional characteristics of the hydrolysates. The US-assisted enzymolysis of PAP using Alcalase® was conducted in a US bath (25 kHz, 38 W/L) for 180 min at 60 °C and pH 7.5. The results showed an increase in the rate of proteolysis by 11.3 %, leading to a higher final degree of hydrolysis (25.2 %) and a greater concentration of TCA-soluble proteins after 45 min and 180 min (29 % and 8 %, respectively). Both conventional and US-assisted hydrolysis led to the breakdown of the protein structure, forming low molecular weight peptides (<15 kDa). However, US-assisted hydrolysis demonstrated greater fragmentation of the PAP surface, enhancing enzymatic efficacy. Intrinsic fluorescence and UV spectroscopy indicated increased exposure of hydrophobic groups throughout hydrolysis, and FTIR spectroscopy revealed changes in the amide bands, suggesting structural transitions in the protein. Finally, the hydrolysates obtained from the USassisted reaction showed higher solubility (≤27 % at pH 6.0), foaming capacity (≤82 % at pH 6.0), and antioxidant activity (≤40 %). Therefore, these results indicate the potential of the US to improve the performance of Alcalase® in the hydrolysis of PAP, producing compounds of industrial interest.

Molecular docking, synthesis and preliminary evaluation of hybrid molecules of benzothiazole cross-linked with hydroxamic acid by certain linkers as HDAC inhibitors

Background Molecular hybridization in drug design is proved to be very successful approach to provide new chemical entities with potential activities and desirable physicochemical properties. Histone deacetylases (HDACs) are involved in controlling the behavior and acetylation of histone and non-histone proteins and their inhibition causes block of cell growth, differentiation, changes in gene expression, and death. Consequently, HDAC inhibitors may lead to anticytotoxic activity. An approach of synthesizing hybrid molecules of benzothiazole cross-linked with hydroxamic acid via an amino acid or aminoalkanoic acid was considered. This approach is expected to optimize the anticytotoxic activity of the proposed compounds. Methods Hybrid molecules of benzothiazole cross-linked with hydroxamic acid (2A-E) were synthesized and their chemical structures were confirmed by spectral analyses (FT-IR, 1H-NMR and 13C-NMR). These were subjected to molecular docking on HDAC8 (PDB ID: 1T69). Computational methods were employed using the SwissADME server to predict the ADME parameters and other physicochemical properties. The cytotoxicity evaluation was performed using MTT colorimetric assay. Results Hybrids (2A-E) recorded lower ΔG (-6.322 to - 9.46) than Vorinostat (SAHA, -5.375). ΔG is an affinity scoring function (kcal/mol) and is employed to rank the candidate poses as the sum of the electrostatic and Van der Waals energies. Benzothiazole cross-linked with hydroxamic acid by a p-aminobenzoic acid (2E) has recorded the lowest docking score of -9.460 and this may refer to the possibility of high inhibitory activity. The hybrids showed no violation from Lipinski’s rule and complied with parameters with low possible passive oral absorption and no penetration into BBB. Hybrid molecules of benzothiazole recorded very interesting results, particularly, 2D and 2E which showed significant and remarkable activity. Conclusions Hybrid molecules of benzothiazole cross-linked with hydroxamic acid recorded very interesting results, particularly, compounds 2D and 2E which showed significant and remarkable activity on lung cancer cell line type A549.

Five new species of endophytic Penicillium from rubber trees in the Brazilian Amazon.

The Amazon rainforest is the world's most diverse ecosystem, full of fauna and flora. Among the trees that make up the forest are the rubber trees of the genus Hevea (H. brasiliensis and H. guianensis), which stand out for the industrial use of latex. It was previously shown that endophytic fungi colonize the leaves, stems, and roots of Hevea spp. In this study, 47 Penicillium spp. and three Talaromyces spp. isolates were analyzed using specific DNA barcodes: internal transcribed spacers region (ITS), β-tubulin (BenA), calmodulin (CaM), and the DNA-dependent RNA polymerase II second largest subunit (RPB2) genes and additionally, for species delimitation, the genealogical concordance phylogenetic species recognition (GCPSR) criteria were applied. The phylogenetic analyses placed the Penicillium isolates into four sections Lanata-Divaricata, Sclerotiora, Citrina, and Fasciculata. The morphological and molecular characteristics resulted in the discovery of five new species (P. heveae sp. nov., P. acrean sp. nov., P. aquiri sp. nov., P. amazonense sp. nov., and P. pseudomellis sp. nov.). The five new species were also compared to closely related species, with observations on morphologically distinguishing features and colony appearances. Bayesian inference and maximum likelihood analysis have supported the placement of P. heveae sp. nov. as a sister group to P. globosum; P. acrean sp. nov. and P. aquiri sp. nov. as sister groups to P. sumatrense; P. amazonense sp. nov. closely related to isolates of P. rolfsii, and P. pseudomellis sp. nov. closely related to P. mellis. The study of endophytic Penicillium species of rubber trees and the description of five new taxa of Penicillium sect. Citrina, Lanata-Divaricata, and Sclerotiora as endophytes add to the fungal biodiversity knowledge in native rubber trees. Reports of fungi in native tropical plants may reveal taxonomic novelties, potential pathogen control agents, and producers of molecular bioactive compounds of medical and agronomic interest.

3,8-Disubstituted Pyrazolo[1,5-a]quinazoline as GABAA Receptor Modulators: Synthesis, Electrophysiological Assays, and Molecular Modelling Studies

As a continuation of our study in the field of GABAA receptor modulators, we report the design and synthesis of new pyrazolo[1,5-a]quinazoline (PQ) bearing at the 8-position an oxygen or nitrogen function. All the final compounds and some intermediates, showing the three different forms of the pyrazolo[1,5-a]quinazoline scaffold (5-oxo-4,5-dihydro, -4,5-dihydro, and heteroaromatic form), have been screened with an electrophysiological technique on recombinant GABAAR (α1β2γ2-GABAAR), expressed in Xenopus laevis oocytes, by evaluating the variation in produced chlorine current, and permitting us to identify some interesting compounds (6d, 8a, 8b, and 14) on which further functional assays were performed. Molecular modelling studies (docking, minimization of complex ligand–receptor, and MD model) and a statistical analysis by a Hierarchical Cluster Analysis (HCA) have collocated these ligands in the class corresponding to their pharmacological profile. The HCA results are coherent with the model we recently published (Proximity Frequencies), identifying the residues γThr142 and αHis102 as discriminant for the agonist and antagonist profile.

Synthetic Routes to 2-aryl-1H-pyrrolo[2,3-b]pyridin-4-amines: Cross-Coupling and Challenges in SEM-Deprotection

7-Azaindoles are compounds of considerable medicinal interest. During development of the structure–activity relationship for inhibitors of the colony stimulated factor 1 receptor tyrosine kinase (CSF1R), a specific 2-aryl-1H-pyrrolo[2,3-b]pyridin-4-amine was needed. Two different synthetic strategies were evaluated, in which the order of the key C-C and C-N cross-coupling steps differed. The best route relied on a chemoselective Suzuki–Miyaura cross-coupling at C-2 on a 2-iodo-4-chloropyrrolopyridine intermediate, and subsequently a Buchwald–Hartwig amination with a secondary amine at C-4. Masking of hydroxyl and pyrroles proved essential to succeed with the latter transformation. The final trimethylsilylethoxymethyl (SEM) deprotection step was challenging, as release of formaldehyde gave rise to different side products, most interestingly a tricyclic eight-membered 7-azaindole. The target 2-aryl-1H-pyrrolo[2,3-b]pyridin-4-amine (compound 3c) proved to be 20-fold less potent than the reference inhibitor, confirming the importance of the N-3 in the pyrrolopyrimidine parent compound for efficient CSF1R inhibition.

Mechanistic basis of activation and inhibition of protein disulfide isomerase by allosteric antithrombotic compounds

BackgroundProtein disulfide isomerase (PDI) is a promising target for combating thrombosis. Extensive research over the past decade has identified numerous PDI-targeting compounds. However, limited information exists regarding how these compounds control PDI activity, which complicates further development. ObjectivesTo define the mechanism of action of 2 allosteric antithrombotic compounds of therapeutic interest, quercetin-3-O-rutinoside and bepristat-2a. MethodsA multipronged approach that integrates single-molecule spectroscopy, steady-state kinetics, single-turnover kinetics, and site-specific mutagenesis. ResultsPDI is a thiol isomerase consisting of 2 catalytic a domains and 2 inactive b domains arranged in the order a-b-b'-a'. The active sites CGHC are located in the a and a' domains. The binding site of quercetin-3-O-rutinoside and bepristat-2a is in the b' domain. Using a library of 9 Förster resonance energy transfer sensors, we showed that quercetin-3-O-rutinoside and bepristat-2a globally alter PDI structure and dynamics, leading to ligand-specific modifications of its shape and reorientation of the active sites. Combined with enzyme kinetics and mutagenesis of the active sites, Förster resonance energy transfer data reveal that binding of quercetin-3-O-rutinoside results in a twisted enzyme with reduced affinity for the substrate. In contrast, bepristat-2a promotes a more compact conformation of PDI, in which a greater enzymatic activity is achieved by accelerating the nucleophilic step of the a domain, leading to faster formation of the covalent enzyme–substrate complex. ConclusionThis work reveals the mechanistic basis underlying PDI regulation by antithrombotic compounds quercetin-3-O-rutinoside and bepristat-2a and points to novel strategies for furthering the development of PDI-targeting compounds into drugs.