Multicomponent reactions (MCRs) are valuable synthetic tools that allow for the efficient synthesis of complex molecules in a short amount of time, using straightforward synthetic operations and requiring only a single purification step. Additionally, when MCRs are coupled with post-transformation processes, they can yield polyheterocycles that may have significant applications in both biological and materials science. In this context, we herein report the synthesis of a novel polyheterocycle: 2-benzyl-6-(3-((7-chloroquinolin-4-yl)amino)propyl)-3-morpholino-7-(4-(pyridin-2-yl)phenyl)-6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-one. This compound was synthesized through a one-pot sequence involving an Ugi-Zhu-3CR coupled to a cascade N-acylation / aza-Diels–Alder cycloaddition / aromatization (decarboxylation-dehydration). The starting reagents included the 4-(pyridin-2-yl)benzaldehyde, which serves as the luminescent ligand scaffold; N¹-(7-chloroquinolin-4-yl)propane-1,3-diamine containing the privileged quinoline motif; 2-isocyano-1-morpholino-3-phenylpropan-1-one; and maleic anhydride, used to initiate the post-transformation process. The reaction was catalyzed by ytterbium(III) triflate, conducted in chlorobenzene as the solvent, with microwave irradiation providing the necessary heat. The target polyheterocycle was obtained in 95 minutes, achieving an atomic economy of 88% and a yield of 75%. Structural characterization was performed by using 1D (¹H, ¹³C) and 2D (COSY, HSQC, HMBC) NMR spectroscopy, and the molecular mass was confirmed by high-resolution mass spectrometry (HRMS). These results illustrate the effectiveness of MCRs as a powerful strategy for expanding chemical diversity.

A robust and sensitive multiresidue analytical method based on liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed and validated for the simultaneous determination of 40 fungicides from diverse chemical classes, including strobilurins, triazoles, imidazoles, benzimidazoles, carbamates, dicarboximides, pyrimidines, and anilinopyrimidines. Target analytes included commonly used active substances such as azoxystrobin, boscalid, carbendazim, cyazofamid, prochloraz, and tebuconazole. These fungicides are widely applied in agriculture for fungal disease control but require strict monitoring due to health and environmental concerns.

Sample preparation utilized an optimized QuEChERS extraction protocol combined with dispersive solid-phase extraction (d-SPE) cleanup to reduce matrix interferences and ensure high analyte recovery. Chromatographic separation was achieved on a reversed-phase C18 column using gradient elution of water and methanol/acetonitrile with 0.1% formic acid, with occasional addition of ammonium formate to enhance peak shape and ionization efficiency.

Detection was performed using electrospray ionization (ESI) in both positive and negative ion modes with scheduled multiple reaction monitoring (sMRM), enabling selective and sensitive quantification of structurally diverse fungicides in complex matrices.

Method validation followed SANTE/11312/2021 guidelines, showing excellent linearity (R² > 0.99), recoveries between 70% and 120%, repeatability with relative standard deviations (RSD) below 20%, and limits of quantification (LOQ) below 10 µg/kg for most analytes. Matrix effects were evaluated and compensated using matrix-matched calibration.

This validated LC-MS/MS method provides a powerful tool for routine high-throughput monitoring of fungicide residues in food and environmental samples, supporting regulatory compliance with maximum residue limits (MRLs) set by the European Union and other authorities.

The imidazo[1,2-a] pyridine (IMPs) scaffold has attracted considerable attention due to wide range of photophysical and biological properties, because it has great interests in different fields such as medicinal, chemistry, and material sciences.

Isocyanide based multicomponent reactions (I-MCR), particularly the Groebke-Blackburn-Bienaymé (GBB), is considered as election synthetic one-pot process for the rapid and efficient synthesis of IMP analogs. IMCR synthetic strategies are efficient with several desirable characteristics in synthesis like atom economy, operational simplicity, high overall yields, broad functional group tolerance and its ability to generate fluorophores or bioactive molecular frameworks with pharmacological relevance.

In this context the green synthesis via IMCR strategies have emerged as rapidly growing and efficient protocols to promote a more sustainable and environmentally friendly one-pot process, minimizing the use of toxic solvent or catalyst. In this context, herein we described a novel one pot green synthesis of IMPs via GBBR, using water as election solvent.

Based on the synthesis of IMPs, this sustainable approach not only aligns with the principles and metrics of green chemistry, but also enables the efficient synthesis of highly fluorescent molecules with tunable photophysical properties. These compounds show great potential for applications in chemical sensing, optoelectronic devices, and biological imaging. Furthermore, the methodology reduces waste generation, minimizes the use of hazardous reagents.

Seaweed represents a sustainable and underexplored source of bioactive compounds with potential applications in health, functional food and well-being. This study presents the characterization of extracts from the macroalgae, Gracilaria sp. (red), Ulva sp. (green) and Fucus vesiculosus (brown), cultivated in ALGAplus company (Portugal). The aim was to identify promising bioactive compounds for the future development of high-value products for potential health and well-being applications.

The obtained aqueous extracts were purified by precipitation with ethanol, resulting for each seaweed in a polysaccharide-free extract and a polysaccharide fraction. All the extracts and fractions were analysed for total phenolic content (TPC), antioxidant activity by DPPH method and bioactive compound profile by high-performance liquid chromatography with diode array detection (HPLC-DAD).

The polysaccharide-free extract from the red seaweed showed the highest total phenolic content (0.76 mg/mg) and antioxidant activity (27.4% for 0.5 mg/mL). An enrichment of compounds was also observed in the obtained purified extract’s HPLC-DAD chromatographic profile compared to the initial extract. Therefore, the identification of the compounds present in this purified extract by high-resolution mass spectrometry will be presented. Safety assessments of the purified extract included in vivo tests using Artemia salina and in vitro MTT assays on HaCaT keratinocytes. No toxicity was observed, and 96% cell viability was obtained, respectively.

The obtained results reinforce the potential of Gracilaria sp. as a promising marine biotechnological resource of non-toxic, bioactive and antioxidant compounds with application in dermatological formulations, food supplements and other innovative solutions in the areas of health and well-being.

1,3,5-Thiadiazines are an important class of heterocyclic compounds with a wide range of practical uses. Among all possible strategies for constructing a 1,3,5-thiadiazine scaffold, one should especially highlight the direction based on various variants of the Mannich reaction – double aminomethylation of various S,N-binucleophilic substrates (thioamides, dithiocarbamates, 2-mercaptoazoles and –azines, thiolactams, etc.), thiomethylation of amines and other N-nucleophiles, etc. Due to its efficiency, ease of implementation, and availability of initial reagents, this approach is now perhaps the most popular method among heterocyclist chemists that allows for the production of partially hydrogenated 1,3,5-thiadiazines (or perhydro-1,3,5-thiadiazines) in a single synthetic operation.

It is known from the literature that active methylene compounds, and in particular Meldrum's acid, readily react with heterocumulenes such as isothiocyanates, carbon disulfide etc. to form 1,3-dinucleophilic reagents. We decided to study the behavior of the reaction product of Meldrum's acid with phenyl isothiocyanate – triethylammonium 1-(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)(phenylamino)methanethiolate – under the conditions of the aminomethylation reaction. It has been established that the mentioned thiolate reacts by double aminomethylation with aqueous HCHO and primary aliphatic and aromatic amines to form 1,3,5-thiadiazine derivatives - 2,2-dimethyl-5-(3-phenyl-1,3,5-thiadiazinan-2-ylidene)-1,3-dioxane-4,6-diones that were not previously described in the literature. The sope and limitations of the reaction as well as the properties of the obtained 1,3,5-thiadiazine derivatives are discussed.

The development of environmentally friendly and efficient synthetic processes that minimize the use and generation of hazardous substances is one of the main goals of green chemistry. One powerful strategy to achieve this goal involves the use of versatile a convergent, synthetic tools with high atom economy and operational simplicity, such as Isocyanide-Based Multicomponent Reactions (IMCRs).

IMCRs have attracted significant interest in both academic and industry fields due to their efficiency synthesized target molecules in one-pot process. Reducing the number of steps, minimizing waste generated during the purification of intermediates. On the other hand, ultrasound irradiation (USI) in chemistry change reactivity, improve yields and selectivity, reduce reaction times, energy consumption and waste production, use of water as solvent instead of organic solvents, activation of catalysts, etc. The synthesis of Imidazo[1,2-α]pyridines (IMPs), via IMCR has several advantages over multistep and or conventional synthetic strategies. The Groebke-Blackburn-Bienaymé reaction (GBB) is the method of choice for synthesizing IMPs. The synthesis of IMPs with fluorescent properties; as emerging as a research field focus in the development of novel greener strategies. To date the GBB synthesis of IMPs using cheap catalysts such as p-toluenesulfonic acid (TsOH) assisted by USI is practically unreported. In the present work, we describe the TsOH-catalyzed GBB reaction by USI for the synthesis of a library of IMP analogs.

Introduction
Benzodiazepines are a family of compounds with recognised central nervous system depressant action, widely used as anxiolytics, anticonvulsants and sedatives^1-3. In this context, N'-substituted 2-aminoacetanilides are key synthetic precursors for obtaining new 1,4-benzodiazepin-2-ones with potential biological activity.

This study summarised and conducted a structural analysis of acetanilides, characterised by the presence of a semi-rigid amide bond that enables E/Z isomerism. Structural analysis is essential, as the conformation adopted can determine the obtaining of compounds with potential biological activity ⁴.

Methods
N'-substituted 2-aminoacetanilides were synthesised using a two-step procedure: in the first step, anilines were acylated with chloroacetyl chloride; in the second step, these intermediates underwent a nucleophilic substitution reaction with methylamine.

The products obtained were purified by recrystallisation and characterised by determining their melting point and using spectroscopic techniques. Subsequently, theoretical calculations were performed using Gaussian 03 software. The structures were optimised using the DFT method (B3LYP/6-311G[d,p] in vacuum) and then their isotropic shielding tensors were obtained using the GIAO-B3LYP/6-31+G(d,p) method in chloroform. The isotropic shielding values of 1H were converted into chemical shifts by subtracting the analogous values of TMS⁵.

Results and Conclusions

The synthesised compounds were obtained with good yields and high reproducibility. The ¹H NMR spectra indicated the presence of a single rotamer, whose identity was confirmed by theoretical calculations. These preliminary results support the synthetic and analytical approach, providing a solid basis for the rational design of new benzodiazepines with potential pharmacological applications.

It is known that thioamides containing hydrogen atoms in the α-position of the thiocarbamoyl group exhibit a CH-acidic character. This property is widely used to produce various heterocycles (in particular, nicotinamide derivatives) through reactions of such thioamides with 1,3-dielectrophiles. Nicotinamides are present in living systems, and as medicines can be used to treat a wide range of diseases.The purpose of the work: synthesis of new nicotinamide derivatives based on monothiomalondianilide and investigation of their properties. According to the known method, we synthesized the initial monothiomalondianilide starting from phenyl isothiocyanate and acetylacetone. The structure of monothiomalondianilide is confirmed by spectral data, as well as X-ray results. Next , the reaction of monothiomalondianilide with arylidenemalonitriles, available by the Knoevenagel reaction, or with aromatic aldehydes and malonitrile in the presence of a base (multicomponent approach) leads to the formation of cyclic Michael adducts - nicotinamide derivatives. New compounds have been studied spectrally (FTIR, NMR 1H, 13C), the structure is confirmed by X-ray diffraction data. In the future, it is planned to expand the library of products, as well as study their properties. According to the results of molecular docking using the GalaxyWeb Sagittarius protocol, one of the products has affinity (ΔG = -22.586 kcal/mmol) to the protein complex H-Ras:SOS (PDB ID 6pf6, UniprotIDP04818), which indicates the potential prospects of studying the antitumor properties of the compound.

This study presents an efficient and sustainable method for synthesizing 1,3-oxathiolan-5-ones, a class of sulfur- and oxygen-containing heterocycles with relevance in medicinal chemistry and organic synthesis.[1] The method employs a novel heterogeneous catalytic system based on magnetite nanoparticles (MNPs) to promote the intramolecular cyclodehydration of commercial ketones with thioglycolic acid under microwave irradiation. Unlike conventional approaches, typically limited to aldehydes, this solvent-free protocol enables the use of ketones, achieving excellent yields in just 40 minutes at 90 °C using 10 mol% of MNPs and 250 W microwave power.

A design of experiments (DoE) approach was used to optimize the reaction parameters, revealing that irradiation time and the presence of MNPs were the most significant factors affecting the yield. Under optimized conditions, different 1,3-oxathiolan-5-ones were obtained in excellent yields and isolated via simple crystallization.

Importantly, the MNPs exhibited remarkable reusability, retaining their catalytic activity over five consecutive cycles with no significant loss in performance. Their magnetic nature enabled straightforward recovery using an external magnet, enhancing the process sustainability.

This work highlights the advantages of microwave-assisted organic synthesis (MAOS) for achieving rapid, clean, and energy-efficient transformations.

The synergy between MNP catalysis, microwave activation, and statistical optimization offers a powerful strategy for the preparation of heterocycles, paving the way for the future development of bioactive molecules.

[1] (a) Al-Majedy, Y.K. et al., Bioorg. Med. Chem. 2016, 24, 317–324. (b) Hassan, M.Z. et al., Bioorg. Chem. 2016, 67, 127–141. (c) Cihlar, T.; Ray, A.S., Antiviral Res. 2010, 85, 39–58.

In acidic environments, acid phosphatases (EC 3.1.3.2) play a crucial role in hydrolyzing phosphate ester linkages. Two isoforms of Acid phosphatases namely AP-I and AP-II were purified to homogeneity from the seeds of Erythrina indica using a combination of gel filtration and affinity chromatography techniques. The purification process involved multiple steps to ensure the enzymes were free from other seed components, thereby facilitating detailed characterization. We report in this study the active site characterization of acid phosphatase form AP-I. AP-I active site of the purified AP-I was characterized in detail through chemical modification studies, which revealed the presence of one residue each of carboxylate, tryptophan, and serine amino acid. Substrate protection experiments using p-nitrophenyl phosphate effectively prevented the modification of all three residues, suggesting their essential role in the enzyme's active site. These experiments provided strong evidence that these residues are directly involved in the catalytic process. Kinetic studies of the partially inactivated enzyme, achieved through the use of specific modifying agents Dicyclohexylcarbodiimide (DCCD) for carboxylate, N-Bromosuccinimide (NBS) for tryptophan, and Phenylmethylsulfonyl fluoride (PMSF) for serine, further confirmed the involvement of these residues in the catalytic mechanism. The results demonstrated that the inactivation of any of these residues significantly impaired the enzyme's activity, highlighting their critical roles in the catalytic process. The results provide a comprehensive understanding of the active site architecture and the catalytic mechanism of AP-I function.