Compounds, Volume 5, Issue 4 (December 2025) – 10 articles

Aged green tea leaves, particularly from Shan Tuyet trees, represent an underutilized source of catechins—key antioxidant compounds with known health benefits. This study aims to optimize and compare three green extraction methods—Hot Water Extraction (HWE), Ultrasound-Assisted Extraction (UAE), and Ethanol–Water Extraction (EthE)—for catechin recovery from mature tea leaves. A Box–Behnken design (BBD) under Response Surface Methodology (RSM) was used to evaluate the effects of different extraction conditions. Total catechin content was quantified by HPLC, and antioxidant activities were measured using DPPH, FRAP, ORAC, and cellular antioxidant activity (CAA) assays. Results showed that while UAE and HWE produced total catechin yields of 206.0 mg/g and 202.0 mg/g, respectively, their biological efficacy was profoundly different. HWE, operating at a higher temperature (82 °C), induced significant thermal degradation, evidenced by high levels of catechin epimerization (EGCG/GCG ratio = 3.62) and hydrolysis. This loss of structural integrity resulted in the lowest cellular antioxidant activity (CAA) of 98.3 µmol QE/g. In contrast, the optimized UAE process (78 °C, 55 min, 290 W) preserved catechin stereochemistry (EGCG/GCG ratio = 9.86), yielding the highest CAA (185.2 µmol QE/g). These findings demonstrate that UAE acts as the optimal green strategy for producing high-yield, functionally superior extracts from mature tea leaves. Full article

Biofouling by mussels is responsible for serious economic losses worldwide. In Argentina, Limnoperna fortunei (Dunker, 1857) and Brachidontes rodriguezii (d’Orbigny, 1842) are common and abundant bivalve species of great interest, inhabiting freshwater and marine coasts, respectively. Both species are considered fouling pests for coastal industrial facilities that use untreated water as part of their processes. To chemically control mussel biofouling, it is necessary to find efficient and environmentally friendly non-biocidal compounds. In this work, we report the antifouling activity of three phenolic compounds (hydroquinone, resorcinol, and catechol) and their respective acetylated derivatives against L. fortunei and B. rodriguezii mussels. Classic ecotoxicity tests with Artemia salina were also performed. Acetylated phenolic compounds were synthesized in the laboratory by sustainable chemistry procedures. Results revealed the importance of hydroquinone, resorcinol, and catechol and their diacetylated derivatives for preventing the settlement of both these mussels, in a non-biocide way. Ecotoxicity bioassays revealed that these compounds were not toxic, with the exception of resorcinol. We propose the incorporation of these compounds in solution into closed circuits and water sprinkler anti-fire systems to prevent the settlement of L. fortunei and their inclusion in antifouling paints to prevent the settlement of B. rodriguezii. These results highlight a new friendly alternative for controlling mussels. Full article

Nucleobases play diverse structural and functional roles in biological systems. Understanding the fundamental properties of nucleobases is important for their applications as chemical probes of nucleic acid function. As the nucleobases are modified to tune their fluorescence or binding properties, their physical properties such as pK_a may also change. Unlike the canonical nucleobases, modified nucleobases are less well understood in terms of their acid-base properties. Previously, theoretical pK_a values of canonical, naturally modified, and aza-/deaza-modified nucleobases were determined. In this study, the theoretical pK_a values for 25 different fluorescent modified nucleobases (55 total pK_a values) were calculated by using an ab initio quantum mechanical method employing the B3LYP density functional with 6-31+G(d,p) basis set along with an implicit–explicit solvation model. The results of these computations are compared to known experimental pK_a values. The ability to estimate theoretical pK_a values will be beneficial for further development and applications of fluorescent nucleobases. Full article

Organophosphate pesticides are among the most persistent and toxic contaminants in aquatic environments, requiring effective strategies for detection and remediation. In this work, density functional theory (DFT) calculations were employed to investigate the adsorption of nine representative organophosphates (glyphosate, malathion, diazinon, azinphos-methyl, fenitrothion, parathion-methyl, disulfoton, tokuthion, and ethoprophos) on mercaptobenzothiazole disulfide (MBTS) and MBTS-functionalized graphene (G–MBTS). All simulations were performed in aqueous solution using the SMD solvation model with dispersion corrections and counterpoise correction for basis set superposition error. MBTS alone displayed a range of affinities, suggesting potential selectivity across the organophosphates, with adsorption energies ranging from 0.27 to 1.05 eV, malathion being the strongest binder and glyphosate the weakest. Anchoring of MBTS to graphene was found to be highly favorable (1.26 eV), but the key advantage is producing stable adsorption platforms that promote planar orientations and $\pi$–$\pi$/dispersive interactions. But the key advantage is not stronger binding but the tuning of interfacial electronic properties: all G–MBTS–OP complexes show uniform, narrow HOMO-LUMO gaps (∼0.79 eV) and systematically larger charge redistribution. These features are expected to enhance electrochemical readout even when adsorption strength was comparable or slightly lower (0.47–0.88 eV) relative to MBTS alone. A Quantum Theory of Atoms in Molecules (QTAIM) analysis of the G–MBTS–malathion complex revealed a dual stabilization mechanism: multiple weak C–H⋯$\pi$ interactions with graphene combined with stronger S⋯O and hydrogen-bonding interactions with MBTS. These results advance the molecular-level understanding of pesticide–surface interactions and highlight MBTS-functionalized graphene as a promising platform for the selective detection of organophosphates in water. Full article

Boron-dipyrromethene (BODIPY) has attracted extensive research attention in recent years due to its excellent photophysical properties, good chemical stability, and structural tunability, demonstrating broad application in fields such as fluorescence imaging, electroluminescence, biosensing and medical diagnostics. Researchers have extensively studied the synthesis, properties, and applications of BODIPY derivatives. This review summarizes five synthetic methods for the BODIPY core, with comparative analysis of their respective advantages, limitations and applicable scopes, aiming to provide valuable references for the future design and synthesis of BODIPY derivatives. Full article

Low-crystalline hydroxyapatite was synthesized from an aqueous solution of calcium chloride (CaCl₂)_, and a mixed-anionic (HPO₄²⁻ и CO₃²⁻) aqueous solution prepared from potassium hydrophosphate trihydrate (K₂HPO₄ 3Н₂О), and potassium carbonate (K₂CO₃). The interaction of K₂CO₃ and K₂HPO₄ salts during synthesis from a mixed-anionic solution in the reaction zone without additional regulation provided the pH level necessary for the synthesis of hydroxyapatite. For comparison, as references, powders were also synthesized from an aqueous solution of CaCl₂ and from aqueous solutions of either K₂HPO₄ or K₂CO₃. The phase composition of the powder synthesized from aqueous solutions of CaCl₂ and K₂HPO₄ included brushite (CaНРО₄·2H₂O). The phase composition of the powder synthesized from aqueous solutions of CaCl₂ and K₂CO₃ included calcite (CaCO₃). The phase composition of all synthesized powders contained potassium chloride (sylvine, KCl), as a reaction by-product. After heat treatment at 1000 °C of the powder containing low-crystalline hydroxyapatite and KCl, powder of chlorapatite (Са₁₀(РО₄)₆Cl₂) was obtained. After heat treatment of a powder containing brushite (CaНРО₄·2H₂O) and KCl at 800 and 1000 °C, a powder with the phase composition including β-calcium pyrophosphate (β-Ca₂P₂O₇), β-calcium orthophosphate (β-Ca₃(PO₄)₂), and potassium-calcium pyrophosphate (K₂CaP₂O₇) was obtained. Heat treatment of calcite (CaCO₃) powder at 800 °C, as expected, led to the formation of calcium oxide (CaO). Synthesized powders, including biocompatible minerals such as hydroxyapatite, chlorapatite, brushite, monetite, calcium pyrophosphate, calcium potassium pyrophosphate, tricalcium phosphate, and calcite, can be used for the creation of biocompatible inorganic materials or composite materials with a biocompatible polymer matrix. The potassium chloride present in the synthesized powders can act as one of the precursors of biocompatible minerals, such as chlorapatite or calcium potassium pyrophosphate, or it can be treated as a removable inorganic porogen. Full article

Glycine receptors (GlyRs) are essential for inhibitory neurotransmission in the central nervous system (CNS) and represent promising targets against neurological disorders. Several indole alkaloids from Gelsemium species have been shown to modulate GlyRs. Notably, the anxiolytic and analgesic properties of certain Gelsemium alkaloids appear to depend on GlyR modulation. However, prior studies have focused on only a few indole alkaloids, leaving the activity of other Gelsemium compound classes unexplored. This study employed an integrative in silico approach to investigate the interactions between GlyR α1 and α3 subtypes and 162 structurally diverse Gelsemium compounds. Physicochemical, pharmacokinetic, and toxicological analyses identified compounds with favorable bioavailability in the CNS. Molecular docking revealed that indolic alkaloids bind the GlyR orthosteric site with profiles comparable to the reference Gelsemium compound, gelsemine. Molecular dynamics simulations confirmed the stability and conformational integrity of selected ligand-receptor complexes. Overall, novel potential GlyR modulators were identified, with several compounds showing a promising selectivity profile towards GlyR α1 and α3 subtypes. These findings further support the therapeutic potential of Gelsemium alkaloids and provide a foundation for further pharmacological and toxicological validation. Full article

An analysis was conducted to investigate how reaction system turbulence affects the butadiene-isoprene copolymerization in the presence of the TiCl₄ + Al(i-Bu)₃ catalytic system. A model was developed, which integrates CFD simulations of TiCl₄ + Al(i-Bu)₃ particle breakage based on population balance equations with the kinetic modeling of the butadiene-isoprene copolymerization. It was established that an increase in turbulent kinetic energy leads to a reduction in catalyst particle size, an increase in active site concentration, an acceleration of the copolymerization process, and a decrease in the average molecular weights of the copolymer. Furthermore, catalytic activity correlates with both the average and maximum values of turbulent kinetic energy in the reaction system, whereas the effect of the average residence time of catalytic particles under turbulent conditions is insignificant. Based on these results, recommendations were provided for optimizing the impact of reaction system turbulence on TiCl₄ + Al(i-Bu)₃ particles to enhance the butadiene-isoprene copolymerization rate and achieve precise control over the molecular weight characteristics of the copolymer. The findings of this study can be applied to optimize the synthesis technology of the cis-1,4 butadiene-isoprene copolymer, which is used in the production of frost-resistant rubber. Full article

Hancornia speciosa Gomes (H. speciosa) is present in several regions of Brazil. It is a plant traditionally used in the treatment of various diseases. This study aims to provide a comprehensive overview of scientific publications and patents related to H. speciosa, emphasizing its primary applications and potential utility. For scientific prospection, an extensive search for relevant publications was carried out in the Scopus database. For technological prospection, the Instituto Nacional de Propriedade Intelectual (INPI) and World Intellectual Property Organization (WIPO) databases were utilized. Research on H. speciosa spans across multiple domains, including agronomy, gastronomy, technology, and pharmaceuticals, revealing the identification of numerous pharmacologically interesting compounds, such as rutin, chlorogenic acid, bornesitol, and various triterpenes, such as Lupeol, α- and β-amyrin, and their respective acetates. Regarding patents, there is a notable emphasis on gastronomic applications, with only a limited number of patents dedicated to technological and health-related areas. The increasing interest in H. speciosa is evident from the various studies investigating the biological properties of its compounds, such as anti-inflammatory, antihypertensive, and antidiabetic actions. Additionally, there is significant potential for further exploration and advancement of research in the pharmaceutical and technological sectors. Full article