The development of efficient, reproducible, and environmentally benign protocols for the synthesis of bioactive heterocycles remains highly desirable, particularly in resource-limited settings. Owing to its structural features and synthetic accessibility, sulfur heterocyclic (SH) compounds were identified as a novel molecule with potential pharmacological relevance. While previous studies have extensively explored solvent polarity and catalytic systems, limited attention has been given to their applicability in semi-urban and remote laboratory environments. This study aimed to (i) optimize the yield of SH using different solvent–catalyst systems, (ii) confirm its structure through IR and ¹H NMR spectroscopy, and (iii) develop a field-appropriate, scalable synthesis protocol. SH was synthesized using various solvent–catalyst combinations, including ethanol–ZnCl₂, DMSO–FeCl₃, and toluene–Cu(OAc)₂, and the reaction yields were compared. Functional group analysis was performed using IR spectroscopy, while structural confirmation was achieved through ¹H NMR analysis. Among the systems evaluated, ethanol–ZnCl₂ afforded the highest conversion, indicating superior catalytic efficiency and solvent compatibility. IR spectra exhibited characteristic NH and CN stretching bands at 3320 cm⁻¹ and 2200 cm⁻¹, respectively. The ¹H NMR spectrum showed aromatic proton signals in the range of 7.2–7.8 ppm and a deshielded NH signal at 9.5 ppm, suggesting intramolecular hydrogen bonding. The protocol demonstrated good reproducibility and suitability for field-level implementation. In conclusion, SH-01, synthesized from benzaldehyde, thiourea, and malononitrile under optimized ethanol–L-proline conditions, was successfully synthesized and structurally validated using accessible and environmentally benign reagents. The developed methodology offers a scalable and sustainable approach for application in resource-constrained laboratories, highlighting the importance of solvent–catalyst synergy and supporting future studies in green chemistry and bioactivity evaluation.
The freshwater crab Paratelphusa jacquemontii is a vital component of aquatic ecosystems in South Asia, particularly in India, Sri Lanka, and Bangladesh. While it plays a key role in nutrient cycling and serves as a food source, concerns have emerged regarding its potential toxicity due to bioaccumulation of environmental pollutants. The accumulation of heavy metals (Cd, Pb, and Hg) and pesticide residues in crab tissues (muscle, gills, and hepatopancreas) obtained from contaminated and reference sites is assessed in this work. The findings showed that crabs from industrial areas had far higher concentrations of Pb and Cd. Hepatopancreas > gills > muscle was the order of tissue-specific accumulation. Seasonal differences showed that pesticide residues were higher during the monsoon season. These results point to possible health and ecological dangers connected to eating infected crabs. The study emphasizes the necessity of ongoing observation and better environmental management techniques.
Nitrogen-containing heterocycles constitute one of the most significant and versatile classes of compounds in pharmaceutical chemistry due to their remarkable structural diversity and wide range of biological activities. A substantial proportion of approved drugs and clinical candidates incorporate nitrogen heterocyclic motifs, highlighting their central role in modern drug discovery and development. In recent years, growing advances in synthetic methodologies, computational drug design, and biological evaluation have accelerated the exploration of nitrogen-containing heterocycles for therapeutic applications. This review provides a comprehensive overview of recent advances in nitrogen-containing heterocycles with an emphasis on their pharmaceutical relevance. The review discusses major classes of nitrogen heterocycles, including five-membered rings such as pyrroles, imidazoles, pyrazoles, triazoles, and six-membered systems such as pyridines, pyrimidines, quinolines, and triazines, along with fused and polycyclic nitrogen heterocycles. These scaffolds have demonstrated a broad spectrum of pharmacological activities, including anticancer, antimicrobial, antiviral, anti-inflammatory, antidiabetic, and central nervous system activities. Special attention is given to structure–activity relationship (SAR) studies that illustrate how the incorporation of nitrogen atoms influences molecular properties such as basicity, hydrogen bonding, lipophilicity, metabolic stability, and target binding affinity. Recent progress in synthetic strategies, including green chemistry approaches, multicomponent reactions, microwave-assisted synthesis, and catalytic methods, has enabled the efficient and sustainable preparation of complex nitrogen heterocycles. Advances in these methodologies have significantly reduced reaction times, improved yields, and enhanced functional group tolerance, making them highly attractive for pharmaceutical applications. Furthermore, the integration of computational tools such as molecular docking, quantitative structure–activity relationship (QSAR) modelling, and artificial intelligence-based drug design has facilitated the rational development of nitrogen-containing heterocycles with optimized pharmacokinetic and pharmacodynamic profiles. The review also highlights selected examples of FDA-approved drugs and late-stage clinical candidates containing nitrogen heterocycles, emphasizing their therapeutic significance and clinical success. Emerging trends such as hybrid heterocyclic systems, bio isosteric replacement, and heterocycle-based prodrugs are discussed as promising strategies for overcoming drug resistance and improving efficacy and safety profiles. Despite the remarkable progress, challenges such as toxicity, selectivity, and synthetic complexity remain and are briefly addressed.
Chalcones (1,3-diaryl-2-propen-1-ones) represent a versatile class of bioactive molecules widely explored for antimicrobial drug development. Structural hybridization of chalcones with nitrogen-containing heterocycles has attracted significant attention due to the synergistic enhancement of biological activity achieved by combining multiple pharmacophores within a single molecular framework. This review provides a comprehensive overview of recent developments in nitrogen heterocycle-linked chalcone hybrids, with particular emphasis on indole-, triazole-, pyrazole-, and quinoline-based derivatives. Synthetic methodologies including Claisen–Schmidt condensation, Cu(I)-catalyzed azide–alkyne cycloaddition, Vilsmeier–Haack formylation, and heterocyclic cyclization strategies are discussed in detail. Reported antimicrobial investigations demonstrate that several hybrids exhibit potent activity against Gram-positive and Gram-negative bacteria as well as pathogenic fungi, with minimum inhibitory concentrations approaching those of established therapeutic agents. Structure–activity relationship analyses highlight the crucial influence of electron-withdrawing substituents, heterocyclic nitrogen positioning, and molecular planarity on target affinity. Furthermore, molecular docking studies support multi-target interactions, particularly against microbial DNA gyrase and lanosterol 14α-demethylase, rationalizing the observed bioactivity. Collectively, nitrogen heterocycle-linked chalcones constitute promising lead scaffolds for the development of next-generation antimicrobial agents and merit further pharmacological and clinical exploration.
Morus nigra L., a widely distributed medicinal plant, is increasingly recognized for its rich phytochemical profile and potential therapeutic applications. The present study focuses on the systematic isolation, characterisation, and biological evaluation of phytochemicals present in the leaves of Morus nigra L. Crude extracts were prepared using solvents of varying polarity, followed by fractionation through chromatographic techniques such as column chromatography and TLC. Major classes of secondary metabolites, including proteins, carbohydrates, phenolics, tannins, flavonoids, saponins, glycosides, steroids, terpenoids, alkaloids, were identified. Structural characterisation of isolated compounds was accomplished using spectroscopic methods, including FTIR, ¹HNMR, ¹³C NMR and GC–MS. Overall, the findings highlight Morus nigra L. as a promising natural source of bioactive compounds.
