Search Results (3,320)

The 1,3,4-thiadiazole core has attracted significant attention due to its unique electronic structure, physicochemical properties, and wide-ranging pharmacological potential. This heterocyclic scaffold exhibits a broad spectrum of biological activities, often attributed to its capacity to modulate enzyme function, interact with receptors, and disrupt key biochemical pathways in both pathogens and host cells. Additionally, 1,3,4-thiadiazoles typically display favorable pharmacokinetic properties, including high metabolic stability and appropriate lipophilicity, which enhance their drug-likeness and bioavailability. This review presents an overview of antibacterial and antifungal compounds bearing the 1,3,4-thiadiazole scaffold that have been reported over the past five years. This publication details the chemical structures of novel 1,3,4-thiadiazole derivatives and reports the results of antibacterial and antifungal activity assays conducted against a range of microbial strains. Furthermore, it provides conclusions regarding the structural features that influence the observed biological activity of the synthesized compounds. Antimicrobial activity assessments conducted against ten Gram-negative and nine Gram-positive bacterial strains revealed that 79 newly synthesized 1,3,4-thiadiazole derivatives exhibited either superior inhibitory efficacy relative to standard reference antibiotics or achieved a high level of bacterial growth suppression, defined as 90–100% inhibition. In antifungal assays, the compounds were evaluated against 25 fungal species representing 15 genera. Among the tested derivatives, 75 compounds demonstrated antifungal potency exceeding that of reference antifungal agents or produced growth inhibition within the 90–100% range. The information provided herein may serve as a valuable resource for medicinal and agricultural chemists engaged in the development of novel drug candidates and plant protection agents. Full article

This review updates the field of enantioselective copper-catalysed domino reactions promoted by chiral green copper catalysts, covering the literature since 2017. These complexes are derived from a diversity of chiral ligands, including mostly bisoxazolines and biphosphines along with monophosphines, N-heterocyclic carbenes, proline derivatives, phosphoric acids, phosphoramidates, and different types of N,N-ligands. The review shows that asymmetric copper catalysis, that suits the growing demand for greener processes, offers a real opportunity to replace toxic and expensive metals in the near future. Full article

Nitrile imines and nitrile oxides are capable of undergoing (3+2)-cycloaddition reactions at double and triple carbon–carbon, carbon-heteroatom, or heteroatom–heteroatom bonds of various dipolarophiles, forming five-membered heterocyclic compounds. When cyclic dipolarophiles bearing an exocyclic carbon–nitrogen double bond (exo-C=N) are introduced into the reaction with these dipoles, spiro-fused 1,2,4-triazoline or 1,2,4-oxadiazoline cycles are formed. Such reactions can provide efficient synthetic approaches to spiro-heterocyclic compounds with enhanced biological activity. This review comprehensively summarizes the literature data on the 1,3-dipolar cycloaddition of nitrile imines and nitrile oxides to exo-C=N bonds for spiro compound synthesis. The research area covers reactions of both saturated and unsaturated dipolarophiles, monocyclic and polycyclic molecules, as well as compounds containing one to three heteroatoms, with special emphasis on systems containing biologically significant heterocyclic pharmacophores. Recent advances in reaction techniques, such as microwave and ultrasonic activation, as well as one-pot and diffusion protocols, are also mentioned. Full article

This review surveys the last twenty years of the Pd^II-catalysed oxaheterocyclisation of alkenes bearing a hydroxylated tether as well as the plausible subsequent in situ reactions, the intramolecular C–O bond formation being the first step of a domino process involving, among others, the Heck reaction, etherification, esterification and lactonisation. Versatile intermediates usable for the total synthesis of natural products have been thus produced. The proposed reaction mechanisms are highlighted with, as far as possible, personal comments. Full article

This study aims to screen out high-yield protease lactic acid bacteria (LAB) from cheese and analyze the flavor and functional characteristics of their fermentation of corn protein hydrolysate (CPH). Lacticaseibacillus rhamnosus ZYN-71 and Limosilactobacillus fermentum ZYN-76 were isolated and screened by traditional biological methods. Then, the two strains synergistically fermented CPH, and it was found that the scavenging rate of DPPH, ·OH, and O²⁻· and the chelating ability of Fe²⁺ of the fermented CPH increased by 22.85%, 3.82%, 63.37%, and 43.27%, respectively. Meanwhile, the solubility, water-holding capacity, oil-holding capacity, foaming property, foam stability, emulsification property, and emulsification stability had also been improved to varying degrees. The aroma of the CPH after fermentation mainly consisted of aldehydes (20.2%) and nitrogen heterocyclic compounds (19.4%), and the content of off-flavor components was reduced. LAB fermentation effectively improves the practical problems existing in the current application of corn proteolytic products. This research can provide a research basis for corn protein-related products. Full article

Heparin, an essential plasma-derived therapy, acts as a naturally occurring anticoagulant and is essential in various physiological processes. Due to its complex structure, repeating units of sulfated glycosaminoglycan, it attracts attention in the field of commercial pharmaceuticals. In recent decades, significant advancements have been made in the development of economical adsorbents designed especially for the extraction of heparin from the intestinal mucosa of pigs, as evidenced by investments from various pharmaceutical industries. This requirement arises from the demand for efficient, scalable extraction methods for natural sources. In this study, we investigated the application of beta zeolites to increase the recovery of heparin from real porcine mucosa samples, emphasizing materials with greater adsorption surfaces, higher thermal stability, and increased porosity. According to our research, the zeolite CP814E’s macropores and huge surface area allow it to adsorb up to 20.6 mg·g⁻¹ (39%) of heparin from actual mucosa samples. We also investigated the adsorbent’s surface conditions, which are essential for efficient heparin recovery, and adjusted temperature and pH to enhance heparin uptake. These findings demonstrate that zeolite-based adsorbents can enhance the extraction of heparin effectively for use in medicinal applications. Full article

Background/Objectives: The rise in antibiotic resistance presents a serious and urgent global health challenge, emphasizing the need to develop new therapeutic compounds. This study focuses on the design and evaluation of a novel series of hybrid molecules that combine the 2-quinolone and 1,2,3-triazole pharmacophores, both recognized for their broad-spectrum antimicrobial properties. Methods: A library of 29 candidate molecules was first designed using in silico techniques, including QSAR modeling, ADMET prediction, molecular docking, and molecular dynamics simulations, to optimize antibacterial activity and drug-like properties. The most promising compounds were then synthesized and characterized by ¹H and ¹³C NMR APT, mass spectrometry (MS), Fourier-transform infrared (FT-IR) spectroscopy, and UV-Vis spectroscopy. Results: Antibacterial evaluation revealed potent activity against both Gram-positive and Gram-negative bacterial strains, with minimum inhibitory concentration (MIC) values ranging from 0.019 to 1.25 mg/mL. Conclusions: These findings demonstrate the strong potential of 2-quinolone–triazole hybrids as effective antibacterial agents and provide a solid foundation for the development of next-generation antibiotics to combat the growing threat of bacterial resistance. Full article

This study investigates the hydrothermal liquefaction (HTL) of sewage sludge across a temperature range of 250–375 °C, combined with selective solvent extraction and catalytic hydrotreatment to produce high-quality biocrude. Four solvents including dichloromethane (DCM), hexane, ethyl butyrate (EB), and ethyl acetate (EA), were used to evaluate temperature-dependent extraction performance and product quality. Biocrude yields increased from 250 °C to a maximum at 350 °C for all solvents: hexane (9.3–18.1%), DCM (16.3–49.7%), EB (17.6–50.1%), and EA (9.6–23.5%). A yield decline was observed at 375 °C due to secondary cracking and gasification. Elemental analysis revealed that hexane and EB extracts had higher carbon (up to 61.6 wt%) and hydrogen contents, while DCM retained the most nitrogen (up to 3.96 wt%) due to its polarity. Sulfur remained below 0.5 wt% in all biocrudes. GC–MS analysis of 350 °C biocrudes showed fatty acids as dominant components (43–53%), especially palmitic acid, along with ketones, amides, and heterocyclic compounds. Hydrotreatment using Ni/SiO₂–Al₂O₃ significantly enhanced biocrude quality by increasing alkane content by 40–60% and reducing nitrogen levels by up to 75%, with higher heating values reaching 38–44 MJ/kg. These findings demonstrate the integrated potential of HTL process tuning, green solvent extraction, and catalytic upgrading for converting sewage sludge into cleaner, energy-dense biofuels. Full article

This review covers article and patent data obtained mostly within the period 2013–2024 on the synthesis and biological activity of quinazolines [a]-annelated by five-membered heterocycles. Pyrrolo-, (iso)indolo-, pyrazolo-, indazolo-, (benz)imidazo-, (benz)thiazolo-, and triazolo- [a]quinazoline systems have shown multiple potential activities against numerous targets. We highlight that most research efforts are directed to design of anticancer, antibacterial, anti-inflammatory, and other agents of azolo[a]quinazoline nature. This review emphases both the medicinal chemistry aspects of pyrrolo[a]-, (iso)indolo[a]-, and azolo[a]quinazolines and the comprehensive synthetic strategies of quinazolines annelated at the N(1)–C(2) bond from the perspective of drug development and discovery. Full article

Deuterium-labelled amino acids have found extensive applications in such research areas as pharmaceutical, bioanalytical, neutron diffraction, inelastic neutron scattering, in analysis of drug metabolism using mass spectrometry (MS), and, structuring of biomolecules by NMR. For these reasons, interest in new methodologies for the deuterium labelling of amino acids and the extent of their applications are equally rising. The ideal method will be able to label target compounds rapidly and cost-effectively by the direct exchange of a hydrogen atom by a deuterium atom. Most of these exchange reactions can often be carried out directly on the final target compound or a late intermediate in the synthesis, and often D₂O can be used as the deuterium source. This review aims to provide a high-level overview of the chemical deuteration of amino acids in various groups (aromatic, heterocyclic, and non-aromatic α-amino acids). It primarily focuses on metal-catalyzed H/D exchange under hydrothermal conditions, with some attention given to studies on stereoselectivity and chemically synthesized perdeuteration and selective deuteration. In addition, we present different methods tested, manipulated, and developed for versatile new scalable protocols for preparation of selective and perdeuterated biologically important amino acids and their enzymatic and kinetic resolution to give pure enantiomers. Different methods for the synthesis of stereocontrolled selective and perdeuterated amino acids, including synthetic, and methods for preparing optically pure amino acids are presented. Full article

Diaza-peptidomimetics are constrained compounds that mimic the biological efficacy of peptides while offering increased stability. We have previously reported the synthesis of bis-cyclic guanidine heterocyclic peptidomimetics as opioid ligands with mixed μ-, κ- and δ-opioid receptor interactions and their potential activity as novel analgesics. Using the same approach, we report here the synthesis of sulfonated and piperazine-tethered bis-cyclic guanidines and their in vitro screening results from radioligand competition binding assays at the μ- (MOR), δ- (DOR), and κ- (KOR) opioid receptors. Full article

Photocatalytic synthesis of heterocycles has emerged as a versatile strategy in organic synthesis. Among various heterocycles, five membered heterocycles such as pyrroles, indoles and their derivatives have great significance based on their pharmaceutical applications. Diverse photocatalysts have shown great potential in synthesis of nitrogen heterocycles either through radical-based mechanism or via energy transfer pathway. Compared to other synthesis routes, the photocatalytic approach offers unique advantages including green synthesis, one step reaction and approaching the challenging reaction to prepare nitrogen heterocycles. Tuning redox potential or tailoring triplet state energies of photocatalysts can play crucial role in selective and efficient synthesis of nitrogen heterocycles. In this review we have briefly covered the latest developments demonstrated for photocatalytic synthesis of five membered nitrogen heterocycles including pyrroles and indoles and their derivatives. We also discuss the existing challenges, bottlenecks and the future outlook in this field, aiming to advance photocatalytic strategies of producing five membered nitrogen heterocycles as valuable tools in modern synthetic chemistry. Full article

1,4-Thiazine S,S-dioxide 1, the cis- and trans-isomers 2 and 3 of its precursor 2,6-diethoxy-1,4-oxathiane S,S-dioxide, and diethyl 2,3-dihydro-1,4-thiazine-3,5-dicarboxylate S,S-dioxide 4 have been fully characterised, both in solution by ¹H and ¹³C NMR and in the solid state by X-ray diffraction. Simulation has been used to model the unexpectedly complex ¹H NMR spectra and arrive at a full assignment of all chemical shifts and coupling constants. The crystal structures of both 1 and 4, which adopt, respectively, boat and half-chair conformations, are dominated by strong NH to O=S hydrogen bonding leading to chains of molecules. In the case of 4, the NMR data point to an equatorial position of the C(2)-ester group in solution, while in the crystal, this adopts an axial orientation. Compounds 2 and 3 adopt chair conformations both in solution and in the solid state with ring inversion on the NMR timescale leading to unexpected simplification of the spectra in the case of 3. Full article

Nitrogen-containing heterocycles are essential compounds in nature, and their structural and functional diversity inspired the synthesis of a wide range of derivatives with diverse applications as pharmaceuticals, agrochemicals, dyes, polymers, cosmetics, etc. Among them, N-fused heterocycles represent an important category, due to their high potential as biologically active agents. Pyrazolo[5,1-c][1,2,4]triazoles, a class of nitrogen heterobicycles, have multiple applications as dyes and pigments. Also, a number of compounds containing this structure have been investigated for their biological activities. All the main experimental results published in the literature (both articles and patents) regarding the latter are summarized in this review. Full article

A total of 24 novel steroidal derivatives were synthesized, including 1,3,4-thia(selena)diazolines and structurally unique spirothiadiazolines, obtained through intramolecular cyclization under standard acetylation conditions. This strategy was further extended to the construction of a novel dimeric compound bearing a thiadiazoline linker. Seleno- and thiosemicarbazone precursors were derived from various functionalized steroidal monomers and dimers via straightforward synthetic protocols. Key intermediates included aldehyde 7 and ketones 16, 19, and 24. Rotameric equilibria were observed in certain thiosemicarbazones, attributed to partial double-bond character in the N–CS bond. Cyclization yielded heterocyclic systems as epimeric mixtures, and in some cases, inseparable mixtures of isomers were obtained due to low diastereoselectivity. Full structural elucidation of epimeric pairs was achieved using 2D NMR and IR spectroscopy, with compounds 2, 3, 5, 11, 17, 27, 28a, and 28b further confirmed by single-crystal X-ray diffraction. Preliminary antiproliferative assays against human cancer cell lines revealed GI₅₀ values below 10 µM for compounds 21, 22, and 27. Full article