Search Results (979)

Quinoline-2,4-dione derivatives represent an essential class of heterocycle scaffolds that have demonstrated wide applications in modern drug discovery. However, the efficient construction of 3,3-difluoro-quinoline-2,4-diones with broad substrate generality remains a significant challenge and has not yet been reported. Herein, we developed the nickel-catalyzed intramolecular radical cyclization of 2-bromo-2,2-difluoro-N-(2-cyanoaryl)acetamides to achieve various 3,3-difluoro-quinoline-2,4-diones in good yields. The scalability and practical applicability of this method were demonstrated through large-scale reactions. Full article

Background: Phenothiazine derivatives bearing trifluoromethyl substituents have attracted increasing interest as multifunctional scaffolds in drug repositioning strategies, particularly in cancer and infectious diseases. Structural modification of classical phenothiazines by incorporation of a quinoline moiety has previously been shown to enhance biological activity. Objectives: The present study aimed to develop an efficient synthesis of 8-trifluoromethylquinobenzothiazines and to evaluate the anticancer and antibacterial potential of their N-substituted analogues inspired by triflupromazine, trifluoperazine, and fluphenazine. Methods: 6H-8-Trifluoromethylquinobenzothiazine was synthesized by cyclization of 2-amino-4-trifluoromethylbenzenethiol and 3-bromo-2-chloroquinoline. The resulting quinobenzothiazine, unsubstituted at the nitrogen atom, was subjected to N-alkylation reactions to afford eleven new 6-dialkylaminoalkyl derivatives. Structural elucidation was performed using NMR and HRMS techniques. Anticancer activity was evaluated by MTT assay against human breast (MDA-MB-231), pancreatic (Mia-PaCa-2), and lung (A-549) carcinoma cell lines, as well as normal HaCaT keratinocytes. Antibacterial activity was assessed by MIC/MBC determination against selected Gram-positive and Gram-negative reference strains and clinical isolates. Results: Among the synthesized compounds, derivatives 8 and 12 exhibited the most favorable anticancer profiles, showing micromolar cytotoxicity (IC₅₀ ≈ 4–10 µM) against lung and pancreatic cancer cells combined with moderate selectivity toward cancer cells over normal keratinocytes. Compound 6 displayed lower cytotoxic potency but a notably high selectivity index due to minimal toxicity toward normal cells. In antibacterial assays, compound 3 exhibited activity against Gram-positive bacteria, including a methicillin-resistant Staphylococcus aureus isolate, with MIC values ranging from 7.8 to 15.6 µg/mL. The corresponding MBC values were equal to or twofold higher than the MICs (MBC/MIC = 1–2), fulfilling commonly accepted criteria for bactericidal activity (MBC/MIC ≤ 4). OD-based growth kinetics confirmed concentration-dependent inhibition of S. aureus growth. Conclusions: The obtained results identify 8-trifluoromethylquinobenzothiazines as a promising class of multifunctional compounds. Selected derivatives combine anticancer activity with acceptable selectivity or display potent antibacterial effects against clinically relevant Gram-positive pathogens. Full article

Background/Objectives: Autism spectrum disorder (ASD) is biologically heterogeneous, and immune-linked variation may be associated with differences in tryptophan–kynurenine pathway (KP) metabolism. Here, we report a targeted urinary profile of KP metabolites, NAD (nicotinamide adenine dinucleotide), and neopterin in a Bulgarian pediatric ASD cohort to describe within-cohort patterns and associations. Methods: Second-morning, acid-stabilized spot urine was collected from 73 children with ASD in Bulgaria (3–13 years; 57 males; 16 females). No contemporaneous neurotypical control group was enrolled; therefore, laboratory-provided reference limits are reported only as contextual benchmarks and are not interpreted as ASD-specific abnormalities. Tryptophan (TRP), kynurenine (KYN), kynurenic acid (KYNA), 3-hydroxykynurenine (3-HK), quinolinic acid (QUIN), NAD, and neopterin were quantified and derived indices were computed (KYN/TRP × 1000; QUIN/KYNA). Non-parametric statistics, Benjamini–Hochberg false discovery rate (FDR) correction, and Spearman correlation analyses were applied. Results: Neopterin was strongly associated with QUIN and KYN in creatinine-normalized data (QUIN: ρ = 0.59, q36 = 2.64 × 10⁻⁷; KYN: ρ = 0.54, q36 = 3.69 × 10⁻⁶); these associations persisted when reconstructed as absolute concentrations (e.g., QUIN_abs: ρ = 0.68, q36 = 2.69 × 10⁻¹⁰) and after partial Spearman correlation controlling for spot creatinine (partial ρ = 0.46, q = 2.52 × 10⁻⁴). One NAD value was <LOQ and was imputed as ½LOQ; sensitivity analyses did not materially change inference. Conclusions: In this ASD-only cross-sectional dataset, urinary neopterin levels co-varied with urinary KYN and QUIN and with KP indices. Clinical interpretation and causal inference require controlled and longitudinal studies with richer covariate capture. Full article

Background: Heterocycle compounds with acridine, quinoline, indole, and pyridine nuclei are potentially active for anticancer activity since they can promote inhibition of vital enzymes, decreasing cell survival after binding to biomolecules. However, unspecific biological interactions can result in unwanted effects, which should be defined during the synthesis and proposition of new molecules. Thus, the objective of this study was to investigate the biological and teratogenic effects of four nitrogen heterocycles proposed for anticancer therapy. Methods: Four 2-cyano-N-phenylacrylamine type derivatives containing acridine (3a), quinoline (3b), indole (3c), and pyridine (3d) nuclei were synthesized and characterized. They were evaluated for their ability to interact with DNA, physicochemical and pharmacokinetic predictions, in vitro and in silico methodologies, besides in vitro inhibition of the Topoisomerase IIα enzyme, antiproliferative activity in tumor and non-tumor cells, hemolytic activity with human erythrocytes, and in vivo toxicological studies with zebrafish embryos. Results: UV–vis absorption studies with ssDNA revealed different spectroscopic effects, with binding constants (Kb) ranging from 1.41 × 10⁵ to 6.46 × 10⁴ M⁻¹. The fluorescence quenching constant (Ksv) with ethidium bromide (EB) varied between 0.53 and 0.67 × 10³ M⁻¹. The compounds intercalated into DNA base pairs, a mechanism confirmed by molecular docking, with 3b (quinoline) showing the most substantial interaction. All derivatives exhibited antitopoisomerase IIα activity at 100 μM and were cytotoxic against MCF-7 and T47-D breast tumor cells, particularly against the more aggressive T47-D lineage. No hemolytic activity was observed in human erythrocytes. In vivo assays in zebrafish embryos showed no toxicological or cardiotoxic effects. However, all compounds altered superoxide dismutase (SOD) and catalase (CAT) enzymatic activity, requiring further studies on reactive oxygen species (ROS) generation to assess potential adverse effects. Furthermore, significant results were observed in the physicochemical and pharmacokinetic parameters of the synthesized compounds. Conclusions: The findings highlight the quinoline derivative (3b) as the most promising nitrogen heterocycle due to its antiproliferative activity and biomolecular interactions without adverse effects in zebrafish embryos, distinguishing it from clinically available agents. Full article

Background: The effects of fasting on serum kynurenines (KYNs) have been reported; however, no data are available on whether fasting also modifies their urinary excretion. Kidney organic anion transporters are involved in KYNs excretion, suggesting that changes in serum levels may result from altered urinary elimination. Considering the important role of KYNs in regulating various physiological processes, it is crucial to understand the factors that determine their blood concentrations. The present study aimed to determine the effect of an 8-day fasting period on the concentrations of KYNs in both serum and urine. Methods: Thirteen participants underwent an 8-day fast. The exercise test was performed at baseline after an overnight fast and after 8 days of fasting. Results: Fasting increased the serum concentrations of 3-hydroxykynurenine (3-HK), anthranilic acid (AA), picolinic acid (PA), kynurenic acid (KYNA), and xanthurenic acid (XANA). Conversely, serum kynurenine (KYN) and quinolinic acid (QA) decreased, while 3-hydroxyanthranilic acid (3-HAA) remained unchanged. In urine, KYN, 3-HK, XANA and QA increased after fasting, whereas AA and PA did not change. Conclusions: In conclusion, these findings indicate that fasting generally increases serum kynurenines (KYNs), which are associated with enhanced urinary excretion, suggesting that fasting may stimulate their synthesis. In the case of anthranilic acid (AA) and picolinic acid (PA), their increase in serum does not influence their urinary excretion. Conversely, a decrease in serum KYN and quinolinic acid (QA) may result from enhanced urinary excretion. Full article

Mitochondria govern energy transfer, redox balance, and cell fate. Tryptophan catabolism generates kynurenines (KYNs) that can tune mitochondrial function, with growing evidence that G protein-coupled receptor 35 (GPR35), aryl hydrocarbon receptor (AhR), and N-methyl-D-aspartate receptors (NMDA receptors) link extracellular cues to adenosine 5 prime triphosphate (ATP) maintenance, calcium (Ca²⁺) handling, mitophagy, and inflammasome control. In parallel, quinolinic acid (QA)-driven de novo nicotinamide adenine dinucleotide (NAD⁺) synthesis connects KYN flux to tricarboxylic acid (TCA) cycle activity and sirtuin programs across tissues. Key gaps remain: receptor pharmacology is rarely integrated with NAD⁺ economics and respiration, and clinical workflows still lack single-run assays that quantify both kynurenine and TCA nodes. We therefore integrate receptor proximal signaling, QA-driven NAD⁺ supply, and unified liquid chromatography–mass spectrometry (LC-MS) measurement into one translational framework spanning kynurenic acid (KYNA), KYN, 3-hydroxykynurenine (3-HK), and QA, using mitochondrial endpoints as the common readout. We synthesize evidence for mitochondrial GPR35 signaling that preserves ATP, AhR programs that tune oxidative defenses and mitophagy, and NMDA receptor antagonism that limits excitotoxic stress. These mechanisms are linked to QA-dependent NAD⁺ biogenesis and alpha ketoglutarate control points, then aligned with chromatography and ionization choices suited to routine LC-MS workflows. This receptor to organelle framework couples KYN flux to respiratory control and provides a practical roadmap for standardized single-run LC-MS panels. It can strengthen target validation in ischemia, neurodegeneration, psychiatry, and oncology while improving biomarker qualification through harmonized analytics and decision-grade readouts. Full article

The kynurenine pathway (KP) is the primary route of tryptophan metabolism and a key interface linking immune activation, metabolic state, and neurochemical signaling. Although KP biomarkers are widely studied in psychiatric disorders, their interpretation remains inconsistent, in part due to biological context and compartmentalization. In this narrative review, we integrate evidence across peripheral and central systems to clarify how age, sex hormones, metabolic health, inflammation, and behavioral factors systematically bias KP flux and shape biomarker readouts. We re-examine the interpretation of the kynurenine/tryptophan ratio in light of differential IDO1 and TDO2 regulation, blood–brain barrier constraints, and cell-specific downstream metabolism that governs neuroprotective and neurotoxic outputs. We further synthesize clinical evidence linking KP alterations to symptom severity, cognitive dysfunction, treatment resistance, and suicidality, highlighting quinolinic acid as a mechanistic node connecting immune activation to glutamatergic dysregulation. Together, this framework reframes the kynurenine pathway not as a static biomarker of disease, but as a context-sensitive metabolic system with direct implications for study design, risk stratification, and personalized approaches in psychiatry. Full article

Three novel metal complexes of the tridentate ligand 4-nitro-2-(quinolin-8-yliminomethyl)phenol (NQP) were synthesized and fully characterized using elemental analysis, TGA, magnetic susceptibility, FT-IR, NMR, and UV–Vis spectroscopy. Stoichiometric studies and characterization data proposed square-planar Pd(II), tetrahedral Zn(II), and octahedral Fe(III) geometries. Density functional theory calculations (B3LYP and B3LYP/6-311G(d,p) with LANL2DZ for metals) showed good agreement with experimental findings and revealed enhanced nonlinear optical properties, as evidenced by increased polarizability and hyperpolarizability values. Biological studies demonstrated significant antimicrobial activity, with the Pd–NQP complex exhibiting superior efficacy against bacterial and fungal strains compared to ofloxacin and fluconazole, following the order NQP < Zn < Fe < Pd. Cytotoxicity assays against Hep-G2, MCF-7, and HCT-116 cell lines revealed strong anticancer activity, particularly for the Pd(II) complex (IC₅₀ = 6.35–12.95 μ_g/μL), comparable to cisplatin. All complexes showed higher DPPH radical scavenging activity than ascorbic acid and strong DNA-binding affinity. Antimicrobial activity was further validated experimentally, while molecular docking studies elucidated favorable binding interactions with microbial proteins and cancer-related targets. Full article

Chronic Obstructive Pulmonary Disease (COPD) is a complex inflammatory lung condition characterized by oxidative stress, changes in airway structure, and gradually worsening airflow blockage. Existing treatments offer only symptomatic management, emphasizing the need for multi-target therapeutic interventions. This study employed a combined approach of network pharmacology and molecular docking to investigate the therapeutic effects of bioactive compounds derived from Cladophora glomerata on COPD. Disease-associated genes were collected from GeneCards, Online Mendelian Inheritance in Man (OMIM), and National Center for Biotechnology Information (NCBI), while compounds from C. glomerata and their predicted molecular targets were obtained from SwissTargetPrediction. A cross-comparison of targets related to compounds and diseases revealed nine common genes, among which three central genes TP53, CASP8, and EGFR were identified using protein–protein interaction (PPI) network analysis. Analysis of gene–disease interactions highlighted Tumor Protein p53 (TP53) and Epidermal Growth Factor Receptor (EGFR) as major regulatory targets. GeneMANIA-based functional and co-expression analysis revealed predominant physical interactions (77.64%) and co-expression relationships (8.01%), highlighting strong functional connectivity among the identified genes. Molecular docking further confirmed that C. glomerata derived compounds, particularly Quinoline, 1,2,3,4-tetrahydro-1-((2-phenylcyclopropyl)sulfonyl)-, trans- (Pubchem ID: 91709903) (−7.5 kcal/mol) and1,2,4-Oxadiazole, 3-(1,3-benzodioxol-5-yl)-5-[(4-iodo-1H-pyrazol-1-yl)methyl]- (Pubchem ID: 5301194) (−7.3 kcal/mol), exhibit favorable predicted binding affinities toward EGFR and TP53 in molecular docking analysis. Overall, these insights suggest that Cladophora glomerata compounds may modulate key COPD-related pathways through multi-target interactions, providing a scientific basis for future experimental studies and the development of marine-derived therapeutic agents for COPD management. Full article

Neurodegenerative diseases, such as Parkinson’s and Alzheimer’s, are becoming an increasingly serious challenge for modern medicine because of the significant increase in incidence and the narrow range of effective therapeutic strategies. In recent years, the kynurenine pathway, which is one of the main pathways of tryptophan metabolism, responsible for the synthesis of products that act oppositely in the CNS including neurotoxic (quinolinic acid) and neuroprotective products, has gained increasing recognition as a potential therapeutic target. Abnormalities in the production of these metabolites, causing a disruption of homeostasis in the CNS, often lead to the development of inflammation, which can cause oxidative stress or neuronal death. This paper aims to discuss strategies useful in modulation of the kynurenine pathway, based on increasing the production of neuroprotective metabolites and reducing the synthesis of neurotoxic compounds, as well as to outline the progress in preclinical and clinical studies and the challenges encountered in these studies, among others, in the search for new KP inhibitors. The pharmacological (IDO and KMO inhibitors) and non-pharmacological (physical activity, diet) strategies are discussed, as well as new approaches from combination and targeted therapies. Together with the results of preclinical studies, they demonstrate the high utility of this target in the treatment of neurodegeneration. Despite its promising activity, further key studies are needed to fully understand the mechanisms involved in metabolism, which may translate into increased efficacy of developed therapies in the future. Full article

Tryptophan (TRP) is a proteinogenic and nutritionally essential amino acid involved in the formation of numerous bioactive substances. A crucial role in the TRP molecule is played by indole, a bicyclic ring formed by benzene and pyrrole, which confers hydrophobic and antioxidant properties and the ability to act as a ligand for aryl hydrocarbon and pregnane X receptors. The first parts of the article examine sources, nutritional requirements, and three pathways of TRP catabolism. Physiologically, ~5% of dietary TRP is catabolized through the pathway forming serotonin and melatonin in the brain and enterochromaffin cells of the gut, ~85% through the pathway resulting in the formation of nicotinamide nucleotides and kynurenine and its derivatives in the liver and immune cells, and ~10% in gut microbiota to indole derivatives. Alterations of individual TRP catabolism pathways in aging, alcoholism, inflammatory bowel disease, metabolic syndrome, renal insufficiency, liver cirrhosis, cancer, and nervous diseases, e.g., depression, Alzheimer’s and Parkinson’s diseases, multiple sclerosis, and schizophrenia, are examined in the central section. The final sections are devoted to the benefits and adverse effects of TRP supplementation, the therapeutic use of various TRP metabolites, and the pharmacological targeting of enzymes, transporters, and receptors involved in TRP catabolism. It is concluded that all pathways of TRP catabolism are altered across a broad spectrum of human illnesses, and further investigation is needed to understand their role in disease pathogenesis better. The goal for clinical research is to explore options for TRP-targeted therapies and their integration into new therapeutic strategies. Full article

Quinolines are key heterocyclic motifs with broad utility in pharmaceuticals, agrochemicals, and materials science. The development of efficient and sustainable synthetic routes to access structurally diverse quinolines remains an important goal in organic chemistry. This review focuses on the recent advances in palladium-catalyzed strategies for quinoline synthesis, emphasizing oxidative and tandem annulation methods. Reactions are categorized by substitution patterns on the quinoline scaffold—namely 2-aryl, 4-substituted, 2,3-, 2,4- and 3,4-disubstituted, 2,3,4-trisubstituted, and annulated derivatives—to facilitate mechanistic comparisons and highlight structural scope. Together, the reviewed strategies showcase the range of mechanistic possibilities available for constructing quinoline scaffolds via palladium catalysis. Overall, these Pd-catalyzed approaches offer powerful and versatile tools for the synthesis of complex quinoline frameworks, providing valuable alternatives to classical heterocycle forming reactions. Full article

Parkinson’s disease (PD) has been associated with some types of food and drugs. Here, we query PubMed for the association of PD with foods and drugs, using a list of 217,776 compounds derived from the Human Metabolome Database (HMDB). To calculate associations, a Python script was developed to query PubMed for co-citations of PD with each compound, and adjust this count for compound abundance. Notably, PD is found to be associated with small-molecule drugs, adjunctive therapies, contraindicated drugs, diagnostic agents, biomarkers, conditional essential molecules, and inducers. Drugs include L-dopa (49%), carbidopa (63%), benserazide (50%), entacapone (74%), tolcapone (56%), rasagiline (76%), selegiline (46%), pargyline (4%), ropinirole (61%), pramipexole (56%), lisuride (27%), cabergoline (16%), bromocriptine (12%), and zonisamide (9%). Adjunctive therapies include droxidopa (33%), trihexyphenidyl (28%), biperiden (17%), amantadine (24%), memantine (7%), rivastigmine (13%), donepezil (6%), galantamine (4%), domperidone (6%), clonazepam (4%), tetrabenazine (16%), mazindol (13%), quetiapine (6%), and clozapine (4%). Contraindicated drugs include haloperidol (4%), sulpiride (3%), and methyldopa (6%). Diagnostic agents include FP-CIT (60%) and beta-CIT (43%). Biomarkers include 3-methoxytyrosine (48%) and homovanillic acid (12%). Endogenous cofactors include tetrahydrobiopterin (4%) and Coenzyme Q10 (4%). Chemical inducers of PD include 6-hydroxydopamine (40%), N-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 78%), tetrahydropyridine (77%), probenecid (4%), quinolinic acid (4%), 1,2,3,4-tetrahydroisoquinoline (TIQ, 16%), salsolinol (32%), rotenone (25%), and β-Methylamino-L-alanine (BMAA, 29%). Notably, our study highlights conditional essential endogenous cofactors associated with PD and emphasizes rational directions for investigation in PD. Full article

Background: Heterocyclic compounds are particularly important in medicinal chemistry. With a range of therapeutic uses, benzimidazoles and quinolines are both key heterocycles in medicinal chemistry. A number of hybrid heterocyclic compounds have been reported in recent years because they typically have better therapeutic properties than single heterocyclic rings. Methods: A literature search was conducted across relevant scientific literature from peer-reviewed sources, using keywords, including “benzimidazole”, “quinoline”, “benzimidazole-quinoline hybrids”, “antibacterial”, “antifungal”, “antimalarial” and “hybrid complexes”. Results: This review summarizes the synthetic methodologies for benzimidazole–quinoline hybrids, benzimidazole– quinolinones, and benzimidazole–quinoline metal complexes, along with their antimicrobial and antimalarial activities and the reported structure–activity relationship (SAR) studies. The importance of halogen substitution, particularly with chlorine and fluorine atoms, as well as the structure of the linker between the benzimidazole and quinoline rings—specifically chain length, the presence of oxygen, sulfur, or nitrogen atoms, and heterocyclic moieties—is highlighted. A series of benzimidazole–quinoline hybrids exhibit antimalarial and antitrypanosomal activities or show enhanced antimicrobial properties due to the incorporation of a five-membered heterocycle in addition to the two existing heterocyclic rings. Notably, several hybrids from different compound series exhibit very low minimum inhibitory concentrations (MICs) in the range of 1–8 µg/mL, along with low cytotoxicity, supporting their potential for further investigation as antimicrobial agents. Conclusions: This review summarizes the synthetic methods, medicinal properties, and structure–activity relationship (SAR) studies of benzimidazole–quinoline hybrids reported between 2002 and 2026. Full article

In the search for solutions to the global health threat posed by antimicrobial resistance, the development of new compounds is crucial. In this context, the in vitro testing of known indolizinoquinolinedione analogs 1–7 revealed that N,N-syn regioisomers are more active than N,N-anti regioisomers. In particular, compound 2 (ethyl 5,12-dihydro-5,12-dioxoindolizino[2,3-g]quinoline-6-carboxylate) exhibited the most significant activity against Bacillus subtilis, B. cereus, Staphylococcus aureus, and methicillin-resistant S. aureus (MRSA) bacteria. The reported increased bioactivity of metal complexes and their ability to overcome drug resistance through metal coordination have induced the study of new metal complexes of compound 2. FT-IR spectroscopy combined with DFT-simulated spectra confirmed the C=O chelation in all Zn, Cu, and Mn complexes 8–10. ESI-MS isotopic cluster analysis and UV-Vis-derived Job’s plot provided significant evidence for 1:1 chelation. Finally, ¹H NMR data were correlated to the DFT-calculated charge distribution. Complexes 8–10 displayed similar activity against B. subtilis, although this was lower than that for 2, and there were comparable effects with 2 and vancomycin antibiotic against S. aureus. FTsZ protein as a potential target of B. subtilis and DNA gyrase of S. aureus and MRSA were studied by docking calculations, revealing a good correlation with the in vitro results. Full article