Light-Activated Pharmacological Tools for Exploring the Cholinergic System

Cholinergic transmission plays a critical role in both the central and peripheral nervous systems, affecting processes such as learning, memory, and inflammation. Conventional cholinergic drugs generally suffer from poor selectivity and temporal precision, leading to undesired effects and limited therapeutic efficacy. Photopharmacology aims to overcome the limitations of traditional drugs using photocleavable or photoswitchable ligands and spatiotemporal patterns of illumination. Spanning from muscarinic and nicotinic modulators to cholinesterase inhibitors, this review explores the development and application of light-activated compounds as tools for unraveling the role of cholinergic signaling in both physiological and pathological contexts, while also paving the way for innovative phototherapeutic approaches.

Design, synthesis, antiproliferative activity, and molecular dynamics simulation of pyrazoline-based derivatives as dual EGFR and HER-2 inhibitors

The dual targeting of EGFR and HER2 is an established anticancer strategy. A novel series including two distinct scaffolds, A (chalcone-based compounds, 4a-n) and B (pyrazoline-based compounds, 5a-n), was developed and synthesized. The antiproliferative efficacy of 4a-n and 5a-n was examined against a panel of four cancer cell lines. The findings indicated that pyrazoline derivatives 5a-n exhibited more efficacy than chalcone compounds 4a-n. Compounds 4n, 5d, and 5g were identified as the most effective antiproliferative derivatives. These compounds were further investigated as dual EGFR/Her2 inhibitors. Compound 5d inhibited EGFR-TK and HER2 significantly, with IC50 values of 0.126 and 0.061 μM, respectively. Moreover, compound 5d can induce a percentage of pre-G1 apoptosis by 78.53% in cell cycle analysis and cause early apoptosis with necrosis percent of 5.28. Docking and MD simulation illustrated the significant cytotoxic activity of the 5d compound and how it can be a promising scaffold with anticancer activity.

Protocol for perfusing human axillary lymph nodes ex vivo to study structure and function in real time

Lymph nodes regulate immunity and maintain fluid balance in health and disease. Here, we present a protocol that uses normothermic perfusion to sustain patient-derived lymph nodes ex vivo for up to 24 h to study their structure and function. We describe steps for setting up both thermoregulatory and perfusion circuits, cannulating human lymph nodes, and perfusion. This protocol can be used to study how human lymph nodes change in cancer and other diseases, and/or in response to perturbations, including drugs. For complete details on the use and execution of this protocol, please refer to Barrow-McGee et al.1.

In Situ Labeling of Pathogenic Tau Using Photo-Affinity Chemical Probes

Tau aggregation plays a crucial role in the development of Alzheimer's disease (AD). Developing specific techniques that can isolate pathogenic tau from brain tissue is important for understanding tauopathies and advancing targeted therapies. Here, we develop photoaffinity small molecular probes and a novel method for in situ tissue labeling and investigate their activity in interacting with tau in cells and AD patient brains. Based on the reported chemical structures of tau PET tracers, we designed and synthesized two tau-specific probes, namely, Tau-2 and Tau-4. After validation in cell, mouse model, and patient brain samples, our photolabeling results suggested that Tau-2 effectively labels soluble tau in cell and mouse models, while Tau-4 selectively binds high-molecular-weight tau aggregates in late-stage AD patient brain tissues. Proteomic analysis verified the specific isolation of pathogenic tau from AD brain samples. Collectively, these findings underscore the potential of our photoaffinity probes as powerful tools for investigating tau proteins and neurofibrillary tangles in neurodegenerative diseases.

Expanding Diversity of Fused Steroid-Quinoline Hybrids by Sequential Amination/Annulation/Aromatization Reactions

Viable alternative approaches to a variety of ring A and ring D-fused steroid-quinoline hybrids, along with ring A, D-fused, and/or ring A-fused, side chain-substituted steroid-bis-quinolines were explored by means of sequential amination/annulation/aromatization reactions of suitable ketosteroids with 2-acyl-substituted anilines. Key factors directing the chemoselective behavior of polyfunctionalized substrates were investigated. Remarkably, the use of TMSOTf as an alternative promoter/catalyst enabled the direct synthesis of the desired hybrids, avoiding the protection/deprotection steps of the conventional procedures when the starting substrates contained labile functional groups.

Repurposing the phenylthiazole scaffold with 1,3,4-oxadiazole for selective, potent and well-tolerated antifungal activity

Invasive fungal infections (IFIs) represent a critical health threat, particularly among immunocompromised individuals, with mortality rates reaching up to 50%. The growing resistance to existing antifungal therapies necessitates the development of novel agents. Here, we rationally designed phenylthiazole-based oxadiazole derivatives to enhance selectivity and potency against resistant fungal strains. Among the tested compounds, compound 35 (which emerged as a lead candidate) demonstrated potent activity against Candida albicans (MIC = 1-2 μg mL-1), Candida glabrata (MIC = 0.5-1 μg mL-1), and multidrug-resistant Candida auris (MIC = 2-4 μg mL-1), outperforming fluconazole and matching amphotericin B. Additionally, compound 35 showed minimal cytotoxicity (88% cell viability at 16 μg mL-1) and negligible hemolytic activity, indicating a superior safety profile.

Site-selective cleavage of peptides and proteins targeting aromatic amino acid residues

The site-selective cleavage of peptides and proteins at specific amino acid residues is an important strategy for the modification of biomolecules as it can potentially transmute the reactivity profile of the whole molecule. Moreover, precise cleavage of a specific amide bond in peptides and proteins has enormous applications in the domains of chemical biology, genetics, and protein engineering. Among the 20 proteinogenic amino acids, tryptophan (Trp, W), tyrosine (Tyr, Y), phenylalanine (Phe, F) and histidine (His, H) are classified as aromatic amino acids that maintain the function of protein folding through hydrophobic and π-π interactions. Thus, scissoring at a specific site of an aromatic amino acid may alter the structure and function of a peptide or protein. In the last 60-70 years, great success has been achieved in the development of methods for the aromatic amino acid (AAA)-selective cleavage of peptides and proteins. Generally, aromatic side chains are derivatized in the presence of specific reagents. Consequently, either the downstream or the upstream amide bond of the aromatic side chain is activated, and hydrolysis of the amide bond splits the peptide. Unfortunately, a systematic review covering this methodological development of the AAA-selective fission of peptide is lacking to date. Thus, in this review, we aim to showcase the up-to-date progress in the site-selective rupture of peptide bonds at aromatic amino acid residues with an emphasis on the postulated mechanisms, enabling future researchers to further drive progress in this research field.

Semiautomated Total Synthesis of the Cyclic Lipodepsipeptide Anikasin

The total synthesis of Pseudomonas-derived cyclic lipodepsipeptide anikasin was achieved. Using a depsipeptide building block and balanced protecting groups on the branching d-allo-Thr residue, the synthesis was established semiautomatically on a synthesizer. Buffered deprotections minimized side reactions and afforded synthetic anikasin and its enantiomer. Biological activity studies indicated that anikasin's mode of action is directly resulting from its physicochemical properties.

New insights into iron uptake in Streptococcus mutans: evidence for a role of siderophore-like molecules

Streptococcus mutans, a gram-positive coccus commonly found in the human oral cavity, is the primary causative agent of dental caries as well as infective endocarditis. Bacteria produce potent iron chelators called siderophores to absorb iron. Because, there are few studies on siderophore-mediated iron transport in S. mutans, the current study investigates the presence of such a mechanism in S. mutans GS-5. Deferration of culture medium and different concentrations of 2, 2'-Bipyridyl has been used to simulate iron-restricted conditions. Iron restriction alters the colony morphology and slows bacterial growth. Cross-feeding conditioned medium into an iron-restricted medium promotes bacterial growth, indicating the presence of siderophore-like molecules. This was further confirmed by Chrome Azurol S (CAS) assay and Modified CAS-agar assay. Cśaky's and Arnow's assays detected the presence of hydroxamate and catecholate-type molecules in optimal and iron-restricted conditions, respectively. Further, the siderophore-like molecules were extracted and purified with thin layer chromatography (TLC). TLC elutes were also found to be positive for iron-chelation in CAS-agar assay and aided growth of S. mutans under iron-restricted conditions. LC-MS analysis of culture supernatants under iron-restricted conditions identified iron-binding small molecules, including a catechol structural motif. Computational analysis utilizing KEGG and BLASTp suggested homologues of siderophore biosynthesis and transport proteins, including genes associated with mutanobactin production. These findings indicate a possible siderophore-mediated iron uptake mechanism in S. mutans GS-5, warranting further molecular studies and advanced spectroscopic characterization of this unidentified siderophore. Once confirmed, this mechanism can be used as a potential drug target to control streptococcal infection.

Citrus flavonoids for overcoming breast cancer resistance to methotrexate: identification of potential targets of nobiletin and sinensetin

Breast cancer is a potentially fatal illness that affects millions of women worldwide. Methotrexate (MTX) may be beneficial for treating breast cancer; however, high doses and prolonged use can cause drug resistance. Although certain citrus flavonoids-nobiletin, sinensetin, tangeretin, hesperidin, hesperetin, and naringenin-may overcome resistance to chemotherapy, no study has investigated MTX resistance. This study investigated the potential of natural chemicals, specifically nobiletin and sinensetin, to overcome MTX resistance in breast cancer cells using MTX-resistant MCF-7 (MCF-7/MTX) and MCF-7 cells. Protein targets of citrus flavonoids were identified from multiple databases and were collected using Venny 2.1. Microarray data of MCF-7 and MCF-7/MTX cells were acquired from the Gene Expression Omnibus. Subsequently, we constructed a protein-protein interaction network and selected the hub proteins. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, drug- and disease-gene enrichment analyses, genetic alteration examination, receiver operating characteristic curve analysis, mRNA levels analysis, prognostic value analysis, and molecular docking analysis were performed along with in vitro experiments. Cytotoxicity of citrus flavonoids (individually and combined) was assessed in MCF-7/MTX cells. Nobiletin and sinensetin significantly enhanced the cytotoxicity of MTX in MCF-7/MTX cells. BCL2L1, CDK1, EGFR, PTGS2, PLK1, MMP2, ACHE, ABCG2, and KIT genes were enriched in cholinesterase activity, cell cycle regulation, and the PI3K/Akt signaling pathway. Nobiletin and sinensetin impeded PLK1, CDK1, and ACHE activities based on molecular docking. Nobiletin and sinensetin in combination with MTX may overcome breast cancer cell resistance to MTX.

Halogen bond-catalyzed Pictet-Spengler reaction

We report an efficient halogen bond-catalyzed Pictet-Spengler reaction using diaryliodonium salts as catalysts as a metal-free alternative to traditional acid catalysis. Through systematic optimization, exceptional catalytic activity was achieved with only 0.5 mol% of a simple dibenzoiodolium with a perfluorinated borate counterion. The protocol demonstrates a broad substrate scope, converting various N-protected tryptamines and diverse carbonyl compounds (aromatic, heteroaromatic, and aliphatic aldehydes) into the corresponding tetrahydro-β-carbolines (THβCs) in up to 98% yield. The reaction versatility was further demonstrated by a successful oxa-variant using tryptophol. Control experiments revealed the crucial role of halogen bonding in ensuring efficient reaction progress.

DRLiPS: a novel method for prediction of druggable RNA-small molecule binding pockets using machine learning

Ribonucleic Acid (RNA) is the central conduit for information transfer in the cell. Identifying potential RNA targets in disease conditions is a challenging task, given the vast repertoire of functional non-coding RNAs in a human cell. A potential druggable target must satisfy several criteria, including disease association, cellular accessibility, binding pockets for drug-like molecules, and minimal cross-reactivity. While several methods exist for prediction of druggable proteins, they cannot be repurposed for RNAs due to fundamental differences in their binding modality. Taking all these constraints into account, a new structure-based model, Druggable RNA-Ligand binding Pocket Selector (DRLiPS), is developed here to predict binding site-level druggability of any given RNA target. A novel strategy for sampling negative binding sites in RNA structures using three parallel approaches is demonstrated here to improve model specificity: backbone motif search, exhaustive pocket prediction, and blind docking. An external blind test dataset has also been curated to showcase the model's generalizability to both experimental and modelled apo state RNA structures. DRLiPS has achieved an F1-score of 0.70, precision of 0.61, specificity of 0.89, and recall of 0.73 on this external test dataset, outperforming two existing methods, DrugPred_RNA and RNACavityMiner. Further analysis indicates that the features selected for model-building generalize well to both apo and holo states with a backbone RMSD tolerance of 3 Å. It can also predict the effect of binding site single point mutations on druggability, which can aid in optimizing synthetic RNA aptamers for small molecule recognition. The DRLiPS model is freely accessible at https://web.iitm.ac.in/bioinfo2/DRLiPS/.

Methods for kinetic evaluation of reversible covalent inhibitors from time-dependent IC50 data

Potent reversible covalent inhibitors are often slow in establishing their covalent modification equilibrium, resulting in time-dependent inhibition. While these inhibitors are commonly assessed using IC50 values, there are no methods available to analyze their time-dependent IC50 data to provide their inhibition (K i and ) and covalent modification rate (k 5 and k 6) constants, leading to difficulty in accurately ranking drug candidates. Herein, we present an implicit equation that can estimate these constants from incubation time-dependent IC50 values and a numerical modelling method, EPIC-CoRe, that can fit these kinetic parameters from pre-incubation time-dependent IC50 data. The application of these new methods is demonstrated by the evaluation of a known inhibitor, saxagliptin, providing results consistent with those obtained by other known methods. This work introduces two new practical methods of evaluation for time-dependent reversible covalent inhibitors, allowing for rigorous characterization to enable the fine-tuning of their binding and reactivity.

Ligand-induced assembly of antibody variable fragments for the chemical regulation of biological processes

Precise control of biological processes by the application of small molecules can increase the safety and efficiency of therapies. Adverse side effects of small molecule signals and/or immunogenicity of regulatory domains hinder their biomedical utility. Here, we designed small molecule-responsive switches, based on the conditional reassembly of human antibody variable fragments, called Fv-CID switches. The principle was validated using high-affinity antibodies against nicotine and β-estradiol to construct chemically responsive transcription factors. Further, we developed an Fv-CID switch responsive to bio-inert, clinically approved compound fluorescein, which was used to control the activity of chimeric antigen receptor (CAR) T cells and bispecific T cell engagers (BiTEs) in vivo. This study provides a framework to regulate the expression of endogenous genes, combine multiple chemical signals, and regulate T cell-based immunotherapy in an animal cancer model using a clinically approved small molecule regulator that could be customized for regulating therapeutic proteins or cells.

Functionalized ZIF-8 as a versatile platform for drug delivery and cancer therapy: strategies, challenges and prospects

This review discusses the functionalization strategies of ZIF-8 and challenges and future developments in ZIF-8-based platforms for drug delivery and cancer therapy. We systematically evaluate a series of innovative ZIF-8 functionalization methods, including atomic doping, introduction of targeting molecules, and biomimetic mineralization technology, to achieve precise drug release. These functionalization strategies significantly enhance the targeted delivery and controlled release properties of ZIF-8, broaden the diversity of drug delivery systems, maximize therapeutic effects, and minimize systemic toxicity. In addition, this review explores the important role of ZIF-8 in tumor therapy. Its ability to encapsulate multiple therapeutic agents and its responsiveness to the tumor microenvironment significantly improve the therapeutic effect and reduce the side effects of traditional treatments. By integrating multiple therapeutic agents and performing surface modification, ZIF-8-based platforms may provide personalized and efficient treatment options for drug-resistant or recurrent cancers. This review also comprehensively discusses the synthesis methods, drug loading capacity, and potential clinical applications of ZIF-8, emphasizing the need to optimize its large-scale production and reproducibility. In addition, further studies on the long-term biocompatibility and biodegradability of ZIF-8-based systems are essential to ensure their safety in long-term treatment. In summary, this review highlights the structural advantages and significant therapeutic potential of ZIF-8 and calls for the transition of ZIF-8 from laboratory research to clinical application to provide more targeted, efficient, and friendly cancer treatment options.

Carbon Monoxide and Prokaryotic Energy Metabolism

Carbon monoxide (CO) plays a multifaceted role in both physiology and pathophysiology. At high levels, it is lethal to humans due to its tight binding to globins and cytochrome c oxidase. At low doses, CO can exhibit beneficial effects; it serves as an endogenous signaling molecule and possesses antibacterial properties, which opens up possibilities for its use as an antimicrobial agent. For this purpose, research is in progress to develop metal-based CO-releasing molecules, metal-free organic CO prodrugs, and CO-generating hydrogel microspheres. The energy metabolism of prokaryotes is a key point that may be targeted by CO to kill invading pathogens. The cornerstone of prokaryotic energy metabolism is a series of membrane-bound enzyme complexes, which constitute a respiratory chain. Terminal oxidases, at the end of this chain, contain hemes and are therefore potential targets for CO. However, this research area is at its very early stage. The impact of CO on bacterial energy metabolism may also provide a basis for biotechnological applications in which this gas is present. This review discusses the molecular basis of the effects of CO on microbial growth and aerobic respiration supported by different terminal oxidases in light of recent findings.

Molecular Determinants of Affinity and Isoform Selectivity in Protein─Small Molecule Hybrid Inhibitors of Carbonic Anhydrase

Multiple studies have demonstrated the benefit of engineering hybrid ligands that combine the unique benefits of small molecules and proteins or peptides. However, the molecular complexity of hybrid ligands generates a parameter space so large it cannot be exhaustively explored. We systematically evaluated the impact of one molecular design element, conjugation site, on the discovery of functional protein-small molecule hybrids (PriSMs). We utilized a library of yeast-displayed fibronectin domain variants with amino acid and loop length diversity in the paratope and a single cysteine at one of 18 possible conjugation sites. The protein variants were coupled with maleimide-functionalized acetazolamide and sorted via competitive flow cytometry to discover potent and selective inhibitors of three isoforms of carbonic anhydrase. Deep sequencing of the resultant populations of functional PriSMs revealed an isoform-dependent distribution of conjugation site preferences. The top PriSMs showed potency and selectivity gains up to 23- and 100-fold (in this case, for CA-II vs CA-XII, with a 43-fold selectivity gain for CA-II vs CA-IX) relative to PEG2-acetazolamide alone. The presented study expands our fundamental understanding of the role of conjugation site in PriSM function and informs future PriSM engineering efforts by highlighting the benefit of conjugation site diversity in PriSM libraries.

Triazination/IEDDA Cascade Modular Strategy Installing Pyridines/Pyrimidines onto Tyrosine Enables Peptide Screening and Optimization

Modular chemical postmodification of peptides is a promising strategy that supports the optimization and innovation of hit peptide therapeutics by enabling rapid derivatization. However, current methods are primarily limited to traditional bio-orthogonal strategies and chemical ligation techniques, which require the preintroduction of non-natural amino acids and impose fixed methods that limit peptide diversity. Here, we developed the Tyrosine-1,2,3-Triazine Ligation (YTL) strategy, which constructs novel linkages (pyridine and pyrimidine) through a "one-pot, two-step" process combining SNAr and IEDDA reactions, promoting modular post modification of Tyr-containing peptides. After optimizing the YTL strategy and establishing standard procedures, we successfully applied it to the solid-phase postmodification of various biorelated peptides, such as the synthesis of dual-mode imaging probes and long-acting GLP-1 analogs. As a proof of concept, a library of 384 amphipathic peptides was constructed using YTL based on 96-well microfiltration plates. Modular modifications were then performed on the screened template tripeptide RYR, leading to the generation of 20 derivatives. The antibacterial activity of these derivatives was systematically characterized, identifying Z8 as a potential antibacterial candidate.

Antiparasitic and Antifungal Activities of Cetyl-Maritima, a New N-Cetyl-Modified Maritima Derivative

Background/Objectives: New drugs are urgently needed for the treatment of neglected tropical diseases including leishmaniasis and eumycetoma, as well as globally occurring parasitic diseases such as toxoplasmosis. Fragrances, both natural and synthetic, were shown to be a rich source for the development of new anti-infectives and warrant deeper investigations. Exemplarily, we synthetically optimized the fragrance 4-(4,8-dimethyl-3,7-nonadienyl)-pyridine, a.k.a. Maritima, a pyridine derivative with marine odor. Methods: A new cationic N-cetyl-modified derivative of Maritima (dubbed Cetyl-Maritima), obtained by alkylation of Maritima, was tested for its activity against Madurella mycetomatis (M. mycetomatis) fungi, as well as against Toxoplasma gondii (T. gondii) and Leishmania major (L. major) protozoal parasites. Results: Cetyl-Maritima was found to be more strongly antifungal than the parent Maritima and a known antibiotic cetylpyridinium salt. Cetyl-Maritima also showed a similar activity against T. gondii parasites and, most notably, exhibited sub-micromolar activity against L. major amastigotes. Conclusions: The considerable antileishmanial activity of Cetyl-Maritima might lead to the development of a new potent and cost-effective drug candidate for the therapy of leishmaniasis and other infectious diseases caused by kinetoplastid parasites.

Unraveling human transferrin-tryptamine interactions: a computational and biophysical approach to Alzheimer's disease therapeutics

Neurodegeneration is a progressive loss of neurons that leads to affected cognitive and motor functions and is characterized by neurodegenerative disorders (NDs). Human transferrin (Htf) is a blood plasma glycoprotein that binds to iron and regulates the free iron in biological fluids. Free iron is a potent neurotoxin associated with the generation of Reactive oxygen species (ROS) and is ultimately linked to oxidative stress and neuronal damage. Thus, targeting iron homeostasis is an attractive strategy for the management of NDs, viz. Alzheimer's disease (AD). Tryptamine (Trp) is a naturally occurring monoamine, that has demonstrated promising roles in AD therapeutics. The present study aims to delineate the binding mechanism of Trp with Htf employing computational and spectroscopic approaches. Molecular docking ascertained the vital residues governing the Htf-Trp complex formation. Further, Molecular dynamic (MD) studies ascertained the structural dynamics and stability of the complex, implying that the binding of Trp causes minimal structural alterations in Htf, suggestive of the stability of the complex. The results from fluorescence spectroscopy demonstrated the binding of Trp with Htf with a binding constant (K) of 0.48 × 106 M-1, validating the in silico observations. This study provides a platform to understand the binding mechanism that may lead to novel therapeutic approaches targeting AD.

Inhibition of the Parkinson's Disease-Related Protein DJ-1 by Endogenous Neurotoxins of the 1,2,3,4-Tetrahydroisoquinoline Family

The protein DJ-1 appears to play a protective role in the development of Parkinson's disease (PD). Here, we show that endogenous neurotoxins of the 1,2,3,4-tetrahydroisoquinoline family (TIQs), formed upon reaction of various aldehydes such as methylglyoxal (MGO) with the neurotransmitter dopamine, act as irreversible inhibitors of the esterase activity of human DJ-1, with IC50 values between 15 and 57 μM. The presence of a catechol function appears to be essential for these inhibitory effects, which may be at the origin of the oxidation of cysteine 106, a crucial residue in the DJ-1 active site, thereby leading to DJ-1 inhibition. We also show that these endogenous neurotoxins inhibit the protective effects of DJ-1 against glycated guanosine diphosphate (GDP) formation and against alpha-synuclein (aSyn) aggregation induced by MGO. In total, the observed inhibition of DJ-1 by these endogenous neurotoxins may contribute to their damaging effects on the nervous system and, should be taken into account in therapeutic strategies for PD and related disorders.

Experimental and theoretical studies on structural changes in the microtubule affinity-regulating kinase 4 (MARK4) protein induced by N-hetarenes: a new class of therapeutic candidates for Alzheimer's disease

Introduction

Alzheimer's disease (AD) is a neurodegenerative disorder that progressively affects the cognitive function and memory of the affected person. Unfortunately, only a handful of effective prevention or treatment options are available today. Microtubule affinity-regulating kinase 4 (MARK4) is a serine/threonine protein that plays a critical role in regulating microtubule dynamics and facilitating cell division. The dysregulated expression of MARK4 has been associated with a range of diseases, including AD.

Methods

In this study, we synthesized a series of N-hetarenes via Pd(0)-catalyzed Suzuki-Miyaura cross coupling reaction. All compounds were characterized using multi-spectroscopic techniques and evaluated for their activity against the MARK4 enzyme through ATPase inhibition assays. The experimental data was further supported by computational and quantum chemical calculations. We also computed the drug-likeness, bioavailability, and toxicity (ADME/T) profiles of the compounds.

Results

Six new 4-(6-(arylpyrimidin-4-yl)piperazine-1-carboximidamides 5-10 were prepared in good yields. ATPase inhibition assay conducted on these compounds demonstrated IC50 values in micromolar range (5.35 ± 0.22 to 16.53 ± 1.71 μM). Among the tested compounds, 4-(6-(p-tolyl)pyrimidin-4-yl)piperazine-1-carboximidamide (5; IC50 = 5.35 ± 0.22 μM) and 4-(6-(benzo[b]thiophen-2-yl)pyrimidin-4-yl)piperazine-1-carboximidamide (9; IC50 = 6.68 ± 0.80 μM) showed the best activity. The binding constant (K), as determined by the fluorescence quenching assay was estimated to be 1.5 ± 0.51 × 105 M-1 for 5 and 1.14 ± 0.26 × 105 M-1 for 9. The results of molecular docking and MD simulation studies against MARK4 (PDB: 5ES1) indicated that compounds were able to bind the ATP binding pocket of the MARK4, leading to its stabilization. Additionally, ADME/T analysis revealed a high degree of drug-likeness of the compounds.

Conclusion

We demonstrated that 4-(6-(arylpyrimidin-4-yl)piperazine-1-carboximidamides) are a promising class of N-hetarenes for developing next-generation anti-AD drugs. The reported class of compounds inhibited MARK4 activity in-vitro at micromolar concentration by targeting the ATP-binding pocket. These findings provide valuable insights for future drug design.

Synthesis, in silico and in vitro antimicrobial efficacy of some amidoxime-based benzimidazole and benzimidamide derivatives

Amidoximes are employed as building blocks to synthesise heterocyclic motifs with biological significance. They are very reactive and are used as prodrugs of amidine. This present study unveils the synthesis of amidoxime-based benzimidazole and benzimidamide motifs and evaluates their in silico and in vitro antimicrobial potential as future drug candidates. The compounds (2a, 2b, 4a-c) were synthesized using multi-step synthetic pathways. The synthesised compounds were characterised using physico-chemical examination, 1H- and 13C-NMR, DEPT-135, and FT-IR spectroscopic analyses. The in silico antimicrobial potentials of the synthesized compounds were carried out against glucosamine-6-phosphate synthase of E. coli (PDB ID: 2VF5), and N-myristoyltransferase (NMT) of C. albicans (PDB ID: 1IYL), while the in vitro antimicrobial screening was investigated against selected bacteria and fungi. The in silico studies were carried out using predicted ADMET screening, molecular docking, MM-GBSA, induced-fit docking (IFD), and molecular dynamics (MD) simulation studies. Furthermore, the in vitro experimental validations were performed using the agar diffusion method and the standard antibacterial and antifungal drugs used were gentamicin and ketoconazole respectively. The predicted toxicity test of the compounds showed no significant risk, except for 4c, which showed high tumorigenic risk. Compounds 2b and 2a gave better binding energies; -8.0 kcal mol-1 for 2VF5 and -11.7 kcal mol-1 for 1IYL, respectively. The antimicrobial zone of inhibition and minimum inhibitory concentration values were 40 mm and 3.90 mg mL-1 against S. mutans, then 42 mm and 1.90 mg mL-1 against C. albicans. Potential antimicrobial drug candidates have been identified in this report and should be explored for future preclinical research.

Spiroindoline quinazolinedione derivatives as inhibitors of P-glycoprotein: potential agents for overcoming multidrug resistance in cancer therapy

Multidrug resistance (MDR) presents a major challenge for effectiveness of chemotherapy. This study investigates the effectiveness of spiroindoline quinazolinediones in reversing MDR mediated by P-glycoprotein (P-gp) overexpression in cancer cells. A series of synthesized hybrid spiro[indoline-3,2'-quinazoline]-2,4'(3'H)-dione derivatives (compounds 5a-5l) were analyzed for their ability to enhance rhodamine 123 (Rhd123) accumulation in the MES-SA/DX5 cell line using flow cytometry. The MTT assay was also employed to evaluate the compounds' effectiveness in reversing drug resistance. Additionally, docking studies and molecular dynamics simulations were conducted to investigate the interaction of these compounds with the P-gp transporter. The Rhd123 accumulation assay in MDR cancer cells revealed that most compounds, in particular 5f, 5g, 5h, 5i, 5j, 5k, and 5l, exhibited significant potential as P-gp inhibitors. Among the tested derivatives, compounds 5g and 5l demonstrated the best effects, and increased Rhd123 accumulation up to 12.9 times compared to untreated cells. Additionally, compounds 5f through 5 l bearing methylbenzyl (5f), benzyl (5g), pentyl (5 ), p-bromobenzyl (5i), p-chlorobenzyl (5j), dichlorobenzyl (5k), and tert-butylbenzyl (5l) substituents on the isatin ring effectively restored sensitivity to doxorubicin at their non-toxic concentrations in resistant MES-SA/DX5 cells. Among these, compound 5l at 5 μM exhibited the highest inhibitory potential, and lowered doxorubicin's IC50 value 10.1 times compared to control. Moreover, in silico investigation identified the potential interactions of test compounds with critical residues of P-gp involved in its efflux function. Our study suggests that the synthesized spiroindoline quinazolinediones may have high potentials as agents capable of reversing MDR in cancer cells.

Indolylmaleimide derivatives as a new class of anti-leishmanial agents: synthesis and biological evaluation

Leishmaniasis is a neglected tropical disease, primarily affecting poor and developing countries. The present therapeutic approach faces various limitations, such as concerns regarding toxicity, route of administration, and the emergence of drug resistance. Therefore, there is a critical need to identify novel scaffolds to combat this fatal parasitic infection. Leishmanial DNA topoisomerase 1B is a heterodimeric protein and plays a crucial role in resolving topological problems during various biological processes. It is structurally distinct from its human counterparts, making it an attractive target for drug discovery. In this study, we synthesized various aminated indolylmaleimide derivatives targeting the leishmanial topoisomerase 1B enzyme. In vitro leishmanicidal assays on Leishmania promastigotes identified one highly potent hit (3m), showing considerable inhibition with single-digit micromolar IC50 values. Moreover, molecular docking analysis of the potent hit (3m) confirmed its strong binding affinity with the enzyme. Thus, the hit molecule (3m) holds promise as a lead for developing novel therapeutic strategies against leishmaniasis.

Decoding Hairpin Structure Stability in Lin28-Mediated Repression

The Lin28 protein is well known for its role in inhibiting the biogenesis of microRNAs (miRNAs) that belong to the let-7 family. The Lin28 and let-7 axes are associated with several types of cancers. It is imperative to understand the underlying mechanism to treat these cancers in a more efficient way. In this study, we employed all-atom molecular dynamics simulation as a research tool to investigate the interaction formed between Lin28 and the precursor element of let-7d, one of the 12 members of the let-7 family. By constructing systems of an intact sequence length of preE-let-7d, our simulations suggest that both the loop region of the hairpin structure and the GGAG sequence can form stable interactions with the cold shock domain (CSD) and zinc knuckle domain (ZKD) regions of the protein, respectively. The system, by deleting the nucleotides GGAG at the 3' terminal, indicates that the loop region is more responsible for its ability in bypassing the binding and repression of Lin28. Additionally, using let-7c-2, which can bypass Lin28 regulation, as a template, we constructed systems with mutated loop region sequences in miRNAs and tested their stabilities. Our simulation results coincide well with experimental observations. Based on both simulation results and statistical analysis from two databases, we hypothesized that two factors, namely, the interaction between terminal nucleotides and the ring tension originating from the middle nucleotides, can significantly influence their stabilities. Systems combining strong and weak terminal interactions with large and small ring tensions were recruited to validate our hypothesis. Our findings offer a new perspective and shed light on strategies for designing sequences to regulate the interactions formed between proteins and hairpin structures.

Targeting Bacterial RNA Polymerase: Harnessing Simulations and Machine Learning to Design Inhibitors for Drug-Resistant Pathogens

The increase in antimicrobial resistance presents a major challenge in treating bacterial infections, underscoring the need for innovative drug discovery approaches and novel inhibitors. Bacterial RNA polymerase (RNAP) has emerged as a crucial target for antibiotic development due to its essential role in transcription. RNAP is a molecular motor, and its function relies heavily on the dynamic shifts between multiple conformational states. While biochemical and structural experimental methods offer crucial insights into static RNAP-drug interactions, they fall short in capturing the dynamics at a molecular level. By integrating experimental data with advanced computational techniques like Markov State Models (MSMs), Generalized Master Equation (GME) Models and other machine-learning models constructed from molecular dynamics (MD) simulations, researchers can elucidate novel cryptic pockets that open transiently for antibiotic compounds and gain a more nuanced and comprehensive understanding of RNAP-drug interactions. This integrated approach not only deepens our fundamental knowledge but also enables more targeted and efficient antibiotic design strategies. In this Perspective, we highlight how this synergy between experimental and computational methods has the potential to open new pathways for innovative drug design and combination therapies that may help turn the tide in the ongoing battle against antibiotic-resistant bacteria.

The role of fructose-1,6-bisphosphatase 1 on regulating the cancer progression and drug resistance

Fructose-1,6-bisphosphatase 1 (FBP1) is the enzyme that limits the process of gluconeogenesis as it facilitates the hydrolysis of fructose-1,6-bisphosphate(F-1,6-BP) to produce fructose-6-phosphate(F6P) and inorganic phosphate. Gluconeogenesis is the production of glucose from small carbohydrate substrates. The gluconeogenic process is typically suppressed in cancer because it inhibits glycolysis. Apart from its involvement in cellular glucose metabolism, FBP1 also plays a role in gene transcription, mRNA translation and stability regulation, and the immune microenvironment of tumors. Because of its multifaceted functions, the mechanisms by which FBP1 is involved in tumor development are complex. Moreover, FBP1 deficiency is associated with radiation and chemotherapy resistance and poor prognosis in cancer patients. Restoration of FBP1 expression in cancer cells is expected to hold promise for cancer therapy. However, up to now few reviews have systematically summarized the important functional mechanisms of FBP1 in tumorigenesis and the small molecule compounds that restore FBP1 expression. Therefore, this article addresses the question "How does FBP1 contribute to cancer progression, and can targeting FBP1 be a potential therapeutic approach?" by summarizing the effects of FBP1 on cancer development and progression as well as its mediated drug resistance and the future clinical applications of potential small molecule modulators targeting FBP1.

Structure-guided design of a truncated heterobivalent chemical probe degrader of IRE1α

IRE1α is an ER protein involved in the unfolded protein response (UPR) and dysregulation of the ER stress pathway has been implicated in several diseases. Inhibitors of the cytoplasmic endonuclease or kinase domains of the enzyme have limited utility and targeted degradation would address additional scaffolding functions of the protein. Here, we describe the design and development of IRE1α proteolysis targeting chimeras (PROTACs) based on a lysine-reactive salicylaldehyde RNase inhibitor, and present the structure-activity relationships (SARs) that delivered the first highly selective degraders of a native ER-membrane associated protein. Medicinal chemistry optimization exploited ternary complex computational modelling to inform design, HiBiT-SpyTag IRE1α degradation and NanoBRET cereblon occupancy cell-based assays to generate SARs, and mass spectrometry-based proteomics to assess broad selectivity in an unbiased manner. Merging IRE1α and CRBN ligand chemotypes provided the truncated chimera CPD-2828 with physicochemical properties more akin to an oral molecular glue degrader than a traditional PROTAC.

Photocatalyzed elaboration of antibody-based bioconjugates

Antibody-drug conjugates (ADCs) represent a promising class of targeted therapeutics, combining the specificity of antibodies with the potency of cytotoxic drugs to enhance therapeutic efficacy while minimizing off-target effects. The development of new chemical methods for bioconjugation is essential to generate ADCs and to optimize their stability, efficacy, and safety. Traditional conjugation methods often face challenges related to site-selectivity and heterogeneous product mixtures, highlighting the need to develop new, innovative chemical strategies. Photoredox chemistry emerges as a powerful tool in this context, enabling precise, mild, and selective modifications of peptides and proteins. By harnessing light to drive chemical transformations, photoredox techniques can facilitate the synthesis of antibody bioconjugates. This perspective will discuss the drive to develop and empower photoredox methods applied to antibody functionalization.

Morphinan Alkaloids and Their Transformations: A Historical Perspective of a Century of Opioid Research in Hungary

The word opium derives from the ancient Greek word ὄπιον (ópion) for the juice of any plant, but today means the air-dried seed capsule latex of Papaver somniferum. Alkaloid chemistry began with the isolation of morphine from crude opium by Friedrich Wilhelm Adam Sertürner in 1804. More than a century later, Hungarian pharmacist János Kabay opened new perspectives for the direct isolation of morphine from dry poppy heads and straw without the labor-intensive harvesting of opium. In 2015, Kabay's life and achievements obtained official recognition as constituting a «Hungarikum», thereby entering the national repository of matters of unique cultural value. To this day, the study of Papaver alkaloids is a focus of medicinal chemistry, the (perhaps unstated) aspiration of which is to obtain an opioid with lesser abuse potential and side effects, while retaining good analgesic properties. We begin this review with a brief account of opiate biosynthesis, followed by a detailed presentation of semisynthetic opioids, emphasizing the efforts of the Alkaloida Chemical Company, founded in 1927 by János Kabay, and the morphine alkaloid group of the University of Debrecen.

Minimalistic bis-triarylpyridinium cations: effective antimicrobials against bacterial and fungal pathogens

A series of twelve compounds from the family of 2,4,6-triarylpyridinium cations have been synthesized, chemically characterized (1H, 13C NMR, HRMS), and microbiologically evaluated (MIC determination against S. aureus, E. faecalis, E. coli, P. aeruginosa, and C. albicans). These compounds are quaternary ammonium cations (QACs), classified as either mono-QACs or bis-QACs. The mono-QACs are further divided into those with short (three-carbon) and long (twelve-carbon) pendant chains. An additional structural variable is the number of bromine atoms attached to the aromatic rings, ranging from zero to three. The major findings of this study are: (a) bis-QACs exhibit notably higher antimicrobial activity than mono-QACs; (b) an increased number of bromine atoms on the structure appears to diminish antimicrobial properties and (c) one of the compounds (1a) shows particularly promising properties as a broad spectrum antimicrobial, given its low MICs across all five pathogenic microorganisms studied. Preliminary assays with C. albicans show that 1a has a strong mitochondrial activity, causing a remarkable mitochondrial membrane depolarization in this organelle. Taken together, this study positions triarylpyridinium cations-previously unexplored as antimicrobials-as promising candidates for future drug development, especially in light of the growing concern over drug-resistant microorganisms.

Development and Characterization of LasR Immobilized Monolithic Column for Screening Active Ingredients as Quorum Sensing Inhibitors Against P. aeruginosa in Natural Products

Background and Aim

The enzyme/protein immobilized monolithic capillary combined with liquid chromatography-mass spectrometry is an efficient screening strategy for the corresponding agonist/antagonist. LasR is the potential therapeutic target since it plays a vital role in the colonization and invasion of Pseudomonas aeruginosa (P. aeruginosa). Therefore, reagents that inhibit LasR may be effective against P. aeruginosa. To screen and find LasR inhibitors rapidly, a LasR-immobilized monolithic capillary column was prepared and characterized.

Methods

Firstly, the recombinant LasR protein was prepared in E. coli. Then, the LasR protein was immobilized to the surface of poly (glycidyl methacrylate-co-poly(ethylene glycol)diacrylate)-ethylenediamine monolithic column. The affinity and stability of prepared column was also evaluated. Furthermore, the prepared column was applied to fishing LasR inhibitor in Scutellaria baicalensis Georgi extract. The interaction of the screening compound to LasR was confirmed through molecular docking.

Results

The recombinant active LasR protein was prepared in E. coli. After purification and validation, a comparative ligand fishing monolithic column was prepared through immobilizing LasR to the surface of the poly (glycidyl methacrylate-co-poly(ethylene glycol)diacrylate)-ethylenediamine through amidation reaction. The LasR was successfully immobilized to the monolithic column characterizing by Fourier transform infrared spectroscopy and scanning electron microscopy. The activity of immobilized LasR was reserved as it has affinity to the nature ligand 3-oxo-C12-HSL and stablied within 24 h at 4 °C. In the Scutellaria baicalensis Georgi extract, baicalein was screened as a potential LasR inhibitor. The molecular docking results and the in vivo evaluation confirmed the activity of baicalein.

Conclusion

The proposed LasR immobilized monolithic column is a viable strategy in screening LasR inhibitors. It can be considered as a possible alternative to traditional methods for screening LasR inhibitors as drug candidates against P. aeruginosa.

The Importance of Murine Models in Determining In Vivo Pharmacokinetics, Safety, and Efficacy in Antimalarial Drug Discovery

New chemical entities are constantly being investigated towards antimalarial drug discovery, and they require animal models for toxicity and efficacy testing. Murine models show physiological similarities to humans and are therefore indispensable in the search for novel antimalarial drugs. They provide a preclinical basis (following in vitro assessments of newly identified lead compounds) for further assessment in the drug development pipeline. Specific mouse strains, non-humanized and humanized, have successfully been infected with rodent Plasmodium species and the human Plasmodium species, respectively. Infected mice provide a platform for the assessment of treatment options being sought. In vivo pharmacokinetic evaluations are necessary when determining the fate of potential antimalarials in addition to the efficacy assessment of these chemical entities. This review describes the role of murine models in the drug development pipeline. It also explains some in vivo pharmacokinetic, safety, and efficacy parameters necessary for making appropriate choices of lead compounds in antimalarial drug discovery. Despite the advantages of murine models in antimalarial drug discovery, certain limitations are also highlighted.

Advanced sperm preservation techniques in yellow spotted mountain newts Neurergus derjugini enhance genetic management and conservation efforts

Advances in cold storage and cryopreservation of amphibian sperm are critical for the genetic management and conservation of threatened species. This study represents the first investigation into the sperm of the yellow spotted mountain newt (Neurergus derjugini), focusing on both short-term and long-term storage for future reproductive efforts. We examined the effects of seven extenders on sperm motility over time at three storage temperatures (4 ± 1 °C, 9 ± 1 °C, and 20 ± 1 °C). Additionally, we assessed the impact of 16 cryoprotectants on sperm motility and morphology post-thawing. Following the identification of the most effective freezing medium, we evaluated sperm DNA fragmentation to ensure viability. Our results indicate that 10% Holtfreter's solution is the optimal extender for short-term storage at all three temperatures, maintaining sperm motility for up to 15 days at 4 °C. For long-term storage, a combination of 10% Holtfreter's solution and 10% DMSO was found to best preserve sperm motility, morphology, and minimize DNA fragmentation after thawing. These findings underscore the importance of specific extenders and temperature treatments in enhancing sperm functionality, thereby supporting successful assisted reproductive technologies (ART) for endangered species.

Synthesis and Evaluating the Anticandidal Activities of Triazino[4,3-a]Quinolinecarboxylate Derivatives: A Promising Approach to Combat Candida Infections

This study aimed to synthesize novel triazino[4,3-a]quinolinecarboxylate compounds (4, 6, 8, and 10) and evaluate these compounds for their antifungal activity against Candida species. Compound 8 was a standout candidate which demonstrated superior efficacy against C. albicans (minimum inhibitory concentration [MIC] = 45 µg/mL), C. glabrata (MIC = 32 µg/mL), C. parapsilosis (MIC = 36 µg/mL) and C. guilliermondii (MIC = 32 µg/mL) compared to Miconazole (MIC = 50-60 µg/mL). Furthermore, the induced morphological and ultra-structural changes by compound 8 on Candida cells are analyzed by light and transmission electron microscopy. Significant alterations in the viability and the architecture of Candida cells highlight the potential of compound 8 as a lead for further use as an antifungal drug. SARs displayed that substitution with the cyano group (as in compounds 8 and 10) was critical for anticandida potency. A molecular docking study of the most active compounds 8 and 10 was conducted inside 14α-demethylase (CYP51) to predict the binding mode of these compounds as antifungal. The most active compound 8 (MIC = 32-45 µg/mL) demonstrated the highest binding energy score which is equal to -8.93 kcal/mol. The findings of the in vitro anticandidal potential have been supported by molecular docking studies.

NQO1-Responsive Prodrug for in Cellulo Release of Cytochalasin B as Cancer Cell-Targeted Migrastatic

Migrastatic drugs targeting cell motility and suppressing invasiveness of solid tumors, have the potential to bring about a paradigm shift in the treatment of solid cancer. Cytochalasin B (CB) is a potent migrastatic compound, but its clinical use is limited by poor selectivity. Here, a NQO1-responsive prodrug, BQTML-CB is developed, synthesized in three steps from cytochalasin B derived from Preussia similis G22. BQTML-CB is selectively activated in NQO1-positive cancer cells, releasing active CB. In vitro, BQTML-CB significantly inhibits proliferation and migration in NQO1-positive U-2OS cells, causing actin disruption and cytokinesis abnormalities, while sparing NQO1-negative B16-F1 cells. The prodrug shows reduced effects on human neutrophils, indicating reduced immunosuppressive activity of BQTML-CB compared to CB. Co-culture studies reveal a beneficial bystander effect, as cleaved CB diffused into adjacent NQO1-deficient cells. These findings support BQTML-CB as a cancer-targeted prodrug with selective antiproliferative and migrastatic properties, highlighting the potential of C7-OH-modified cytochalasans in cancer therapy.

Insights into biofilm-mediated mechanisms driving last-resort antibiotic resistance in clinical ESKAPE pathogens

The rise of antibiotic-resistant bacteria poses a grave threat to global health, with the ESKAPE pathogens, which comprise Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp. being among the most notorious. The World Health Organization has reserved a group of last-resort antibiotics for treating multidrug-resistant bacterial infections, including those caused by ESKAPE pathogens. This situation calls for a comprehensive understanding of the resistance mechanisms as it threatens public health and hinder progress toward the Sustainable Development Goal (SDG) 3: Good Health and Well-being. The present article reviews resistance mechanisms, focusing on emerging resistance mutations in multidrug-resistant ESKAPE pathogens, particularly against last-resort antibiotics, and describes the role of biofilm formation in multidrug-resistant ESKAPE pathogens. It discusses the latest therapeutic advances, including the use of antimicrobial peptides and CRISPR-Cas systems, and the modulation of quorum sensing and iron homeostasis, which offer promising strategies for countering resistance. The integration of CRISPR-based tools and biofilm-targeted approaches provides a potential framework for managing ESKAPE infections. By highlighting the spread of current resistance mutations and biofilm-targeted approaches, the review aims to contribute significantly to advancing our understanding and strategies in combatting this pressing global health challenge.

Small-molecule allosteric activator of ubiquitin-specific protease 7 (USP7)

Ubiquitin-specific protease 7 (USP7) is a deubiquitylase essential for cell homeostasis, DNA repair, and regulation of both tumor suppressors and oncogenes. Inactivating USP7 mutations have been associated with Hao-Fountain Syndrome (HAFOUS), a rare neurodevelopmental disorder. Although a range of USP7 inhibitors have been developed over the last decade, in the context of HAFOUS as well as oncogene regulation, USP7 activators may represent a more relevant approach. To address this challenge, we report the discovery and characterization of a small-molecule activator of USP7 called MS-8. We showed that MS-8 activates USP7 by engaging the allosteric C-terminal binding pocket of USP7, thus mimicking the allosteric autoactivation by the USP7 C-terminal tail. We observed that MS-8 engages and activates mutant USP7 in a cellular context, impacting downstream proteins. Taken together, our study provides validation of the USP7 activator that paves the way towards novel activation-driven USP7 pharmacology.

Design, synthesis, and evaluation of carboxylic acid-substituted celecoxib isosteres as potential anti-inflammatory agents

A library comprising twenty-four isosteric derivatives of celecoxib substituted with carboxylic acid (labeled as 5a-5x), was synthesized and characterized through 1H NMR, 13C NMR, HRMS, and elemental analysis. Molecular docking studies revealed that all compounds successfully docked into the binding pocket of COX-2, and the introduction of carboxyl group enhances the interaction between the derivatives and COX-2. The compounds were further evaluated for cell toxicity, and in vitro anti-inflammatory activity. Notably, compound 5l exhibited significant inhibition of both COX-2 and NO release in vitro in comparison to the standard compound, displaying the highest selectivity towards the COX-2 enzyme (SI = 295.9) in comparison to celecoxib (SI = 261.3). 5l also exhibited the most potent anti-inflammatory activity and safety (ulcer index = 5.2) in vivo comparable to celecoxib at the same concentration. Through the molecular modeling and dynamics analysis, it was observed that compound 5l effectively stabilized within the active binding site of COX-2 through strong hydrogen bond interactions, and through the ADMET studies investigated the physiochemical properties and drug-likeliness behavior of compound 5l. In conclusion, compound 5l demonstrated to be a potential selective COX-2 anti-inflammatory candidate with reduced gastrointestinal risks.

Bioinspired complex cellulose nanorod-architectures: A model for dual-responsive smart carriers

The synergy between nanomaterials as solid supports and supramolecular concepts has resulted in nanomaterials with hierarchical structure and enhanced functionality. Herein, we developed and investigated innovative supramolecular functionalities arising from the synergy between organic moieties and the preexisting nanoscale soft material backbones. Based on these complex molecular nano-architectures, a new nanorod carbohydrate polymer carrier was designed with bifunctional hairy nanocellulose (BHNC) to reveal dual-responsive advanced drug delivery (ADD). This carrier scavenges K+-ions within cancer cells, while simultaneously releasing doxorubicin, combining ion homeostasis disruption with targeted drug delivery. The BC ADD system resulted from cross-linking dibenzo-18-crown-6-ether (DB18C6) with BHNC particles. To enhance cellular internalization and facilitate tracking of uptake, the cellulose nanorod carrier was labeled with biotin and fluorescein isothiocyanate, referred to as BCFB. The BHNC serves as the backbone, while the immobilized DB18C6 moieties can capture doxorubicin via complex formation. The BCFB complex molecular nanorod carriers exhibit distinct ADD profiles with pH and K+-responsiveness. They were evaluated as biocompatible carriers for ADD in MDA-MB-231 breast cancer cells, including quantification of nanoparticle uptake and flow cytometry with KHOS cells. These cellulose-based carriers possess unique structure and properties with potential utility as phase transfer catalysts and as adsorbents for diverse waterborne contaminants.

Macrocyclic phage display for identification of selective protease substrates

Traditional methods for identifying selective protease substrates have primarily relied on synthetic libraries of linear peptides, which offer limited sequence and structural diversity. Here, we present an approach that leverages phage display technology to screen large libraries of chemically modified cyclic peptides, enabling the identification of highly selective substrates for a protease of interest. Our method uses a reactive chemical linker to cyclize peptides on the phage surface, while simultaneously incorporating an affinity tag and a fluorescent reporter. The affinity tag enables capture of the phage library and subsequent release of phages expressing optimal substrates upon incubation with a protease of interest. The addition of a turn-on fluorescent reporter allows direct quantification of cleavage efficiency throughout each selection round. The resulting identified substrates can then be chemically synthesized, optimized and validated using recombinant enzymes and cells. We demonstrate the utility of this approach using Fibroblast Activation Protein alpha (FAPα) and the related proline-specific protease, dipeptidyl peptidase-4 (DPP4), as targets. Phage selection and subsequent optimization identified substrates with selectivity for each target that have the potential to serve as valuable tools for applications in basic biology and fluorescence image-guided surgery (FIGS). Overall, our strategy provides a rapid and unbiased platform for effectively discovering highly selective, non-natural protease substrates, overcoming key limitations of existing methods.

N-(9-Acridinyl) Amino Acid Derivatives: Synthesis and In Vitro Evaluation of Anti-Toxoplasma gondii Activity

Background/Objectives: Acridine, an aromatic heterocyclic compound, serves as a basis for the synthesis of potent bioactive derivatives, displaying a broad spectrum of biological activity, such as antibacterial, antitumor, and antiparasitic activity. With the ability to undergo various types of electrophilic substitutions, introducing different side chains could lead to compounds being active towards various and potentially multiple biotargets. Toxoplasma gondii, a ubiquitous protozoan parasite with worldwide distribution, poses a major health threat, particularly in immunocompromised patients and fetuses. Current treatment options for toxoplasmosis are scarce, with notable limitations, especially regarding side myelotoxicity and inactivity towards T. gondii cysts, causing a need for novel drug candidates. The aim of this study was to evaluate selected N-(9-acrydinil) amino acid derivatives as potential anti-T. gondii agents. Methods: Synthesis of new derivatives was performed using a two-step method, with the initial mixing of 9-chloroacridine with methanol and sodium alkoxide solution and subsequent adding of appropriate amino acids. Cytotoxicity of the tested compounds was evaluated on the Vero cell line using a MTT assay, while their anti-T. gondii activity was investigated using T. gondii RH strain tachyzoites. Results: CC50 values of the derivatives ranged from 41.72 to 154.10 µM. Anti-T. gondii activity, displayed as a reduction in the number of viable tachyzoites compared to the untreated control, ranged from 0 to 33.3%. One of the derivatives displayed activity comparable to the standard treatment option while retaining acceptable cytotoxicity. Esterification, presence of aromatic substituents and the length of the amino acid side chain were identified as key factors that affect both toxicity and activity of these derivatives. Conclusions: Promising results obtained throughout this study provide guidelines for further structural modifications of N-(9-acrydinil) amino acid derivatives in order to synthesize drug candidates competitive to standard treatment options for toxoplasmosis.

Advances in the therapeutic potentials of ligands of the apelin receptor APJ

Angiotensin II protein J receptor, APJ, is a type A G protein coupled receptor. Endogenous apelin and elabela peptides stimulate APJ via distinct signalling profiles. A complex signalling map of elabela-stimulated APJ was published in 2022. Dimerization or oligomerization of APJ with itself or other receptor(s) can affect APJ signalling. Apelin has been shown to tolerate mutations and/or modifications at multiple sites without abolishing activity. This offers a great opportunity to design and engineer variants with desired signalling profiles and enhanced resistance to breakdown by peptidases. Several biased agonists with enhanced therapeutic potential have been generated. APJ agonists have therapeutic potential in multiple diseases including cardiovascular, renal, pulmonary and metabolic diseases, and viral infections. APJ antagonists may have therapeutic potential in cancer and retinopathy, and in related diseases in which unwanted angiogenesis is to be halted. A growing understanding of APJ signalling pathways and the robust therapeutic potential of associated ligands for many serious diseases will stimulate the clinical development of APJ ligands.

Pyrimidine-based dual-target inhibitors targeting epidermal growth factor receptor for overcoming drug resistance in cancer therapy(2006-present)

The epidermal growth factor receptor (EGFR) is a pivotal member of the epidermal growth factor receptor family, exerting crucial regulatory influence on cellular physiological processes, particularly in relation to cell growth, proliferation, and differentiation. In recent years, numerous EGFR inhibitors have been introduced to the market; unfortunately, the effectiveness of single-target EGFR inhibitors has been compromised due to the development of drug resistance caused by EGFR mutations. Despite attempts by some researchers to address this issue through combination therapy with two or more drugs, instances of dose-limiting toxicities have been observed. Consequently, EGFR dual-target inhibitors have emerged as a burgeoning field in cancer treatment, offering a novel therapeutic option for solid tumors with the added benefits of reduced risk of resistance, lower dosage requirements, diminished toxicity profiles, and enhanced efficacy. At present, a series of EGFR dual-target inhibitors with diverse structures have been developed successively. In this study, we initially investigated the pyrimidine-based EGFR dual-target inhibitors that have been reported in the past two decades and categorized them into aminopyrimidine derivatives and heterocyclic pyrimidine derivatives with increased molecular complexity. Subsequently, we comprehensively summarized the biological activity and structure-activity relationship of this class of inhibitors in the context of cancer therapy, while also exploring potential opportunities and challenges associated with their application in this field. The present study provides a partial framework to guide future endeavors in drug development.

Insights into NEK2 inhibitors as antitumor agents: From mechanisms to potential therapeutics

NEK2, a serine/threonine protein kinase, is integral to mitotic events such as centrosome duplication and separation, microtubule stabilization, spindle assembly checkpoint, and kinetochore attachment. However, NEK2 overexpression leads to centrosome amplification and chromosomal instability, which are significantly associated with various malignancies, including liver, breast, and non-small cell lung cancer. This overexpression could facilitate tumor development and confer resistance to therapy by promoting aberrant cell division and centrosome amplification. Consequently, inhibiting NEK2 is considered as a promising strategy for oncological therapy. To date, no small molecule NEK2-specific inhibitors have advanced into clinical trials, highlighting the necessity for optimized design and the deployment of innovative technologies. In this review, we will provide a comprehensive summary of the chemical structure, biological functions, and disease associations of NEK2, focusing on the existing NEK2 small molecule inhibitors, especially their structure-activity relationships, limitations, and research strategies. Our objective is to provide valuable insights for the future development of NEK2 inhibitors and analysis of challenges faced in translating these findings into clinical applications.

Quaternary ammonium chitosan-functionalized mesoporous silica nanoparticles: A promising targeted drug delivery system for the treatment of intracellular MRSA infection

The limited membrane permeability and bacterial resistance pose significant challenges in the management of intracellular drug-resistant bacterial infections. To overcome this issue, we developed a bacterial-targeted drug delivery system based on quaternary ammonium chitosan-modified mesoporous silica nanoparticles (MSN-NH2-CFP@HACC) for the treatment of intracellular Methicillin-resistant Staphylococcus aureus (MRSA) infections. This system utilizes amino-functionalized mesoporous silica nanoparticles to efficiently load cefoperazone (CFP), and the nanoparticles' surface is coated with 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) to target bacteria and enhance macrophage uptake. The findings indicate that MSN-NH2-CFP@HACC nanoparticles are efficiently internalized by macrophages, demonstrate accelerated drug release in acidic environments, and exhibit enhanced antibacterial properties, effectively suppressing the proliferation and intracellular escape of MRSA. Moreover, HACC enhances the bacterial capture ability of the nanoparticles and reduces resistance by disrupting bacterial membrane structures and inhibiting bacterial β-lactamase activity. In a murine model of MRSA bacteremia, MSN-NH2-CFP@HACC exhibited remarkable antibacterial efficacy and significantly attenuated severe inflammatory responses. In conclusion, MSN-NH2-CFP@HACC represent a promising antibiotic delivery system with exceptional antibacterial efficacy and favorable biocompatibility, thus presenting a novel strategy for addressing intracellular drug-resistant bacterial infections and demonstrating significant potential for clinical application.

Photocatalytic Radical Azido/Fluorosulfonylation of Unactivated Alkenes: Accessing Hubs Bridging CuAAC and SuFEx Click Chemistry

Herein, we describe the successful development of an azido-fluorosulfonylation reaction of alkenes under photoredox catalysis, which could allow the installation of the two "clickable" groups, -N3 and -SO2F, on a C-C double bond, with TMSN3 as the azide source. The utilization of the difunctionalization products is also demonstrated in the construction of a library of 1,2,3-triazolesulfonyl fluoride compounds as well as drug molecule ligation by merging copper-catalyzed azide-alkyne cycloaddition (CuAAC) and sulfur(VI) fluoride exchange (SuFEx), the two generations of click reactions. Mechanistic studies suggest a radical fluorosulfonylation/azidation mechanism and unveil FSO2N3 as a new and potential fluorosulfonyl radical precursor.

From Traditional Efficacy to Drug Design: A Review of Astragali Radix

Astragali Radix (AR), a traditional Chinese herbal medicine, is derived from the dried roots of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao (A. membranaceus var. mongholicus, AMM) or Astragalus membranaceus (Fisch.) Bge (A. membranaceus, AM). According to traditional Chinese medicine (TCM) theory, AR is believed to tonify qi, elevate yang, consolidate the body's surface to reduce sweating, promote diuresis and reduce swelling, generate body fluids, and nourish the blood. It has been widely used to treat general weakness and chronic illnesses and to improve overall vitality. Extensive research has identified various medicinal properties of AR, including anti-tumor, antioxidant, cardiovascular-protective, immunomodulatory, anti-inflammatory, anti-diabetic, and neuroprotective effects. With advancements in technology, methods such as computer-aided drug design (CADD) and artificial intelligence (AI) are increasingly being applied to the development of TCM. This review summarizes the progress of research on AR over the past decades, providing a comprehensive overview of its traditional efficacy, botanical characteristics, drug design and distribution, chemical constituents, and phytochemistry. This review aims to enhance researchers' understanding of AR and its pharmaceutical potential, thereby facilitating further development and utilization.

Regioselective Pyrazole Synthesis via Base-Mediated [3+2] Cycloaddition of 2-Alkynyl-1,3-Dithianes and Sydnones

We present a novel base-mediated [3+2] cycloaddition for the regioselective synthesis of polysubstituted pyrazoles using 2-alkynyl-1,3-dithianes and sydnones. By exploiting the umpolung and nucleophilic properties of 2-alkynyl-1,3-dithianes, this method achieves efficient pyrazole construction under mild conditions with excellent regioselectivity, broad functional group tolerance, and diverse substrate compatibility. Furthermore, the unique reactivity of the dithianyl group enables facile derivatization and synthesis of highly functionalized pyrazoles.