Journal of the Serbian Chemical Society

Le Chatelier’s principle and metabolism: Biothermodynamic analysis of the metabolic pathway for synthesis of glucagon

2025-11-16T18:39:40+01:00

Glucagon is the main catabolic hormone in the human organism. Glucagon has been well studied from the aspect of life and biomedical sciences. However, no analysis of glucagon based on chemical thermodynamics can be found in the literature. The approach of biothermodynamics would allow to study the driving force of glucagon production, as well as provide an understanding of the process from the aspect of the fundamental laws of nature. This research reports an analysis of glucagon with the methodology of biothermodynamics. Based on the protein sequences, chemical and thermodynamic characterization of glucagon, proglucagon, preproglucagon and related peptides is performed, with the atom counting method and Patel–Erickson–Battley model. Reactions of translation at the ribosomes and post-translational processing are formulated and their driving force (Gibbs energy change) is calculated. The process of translation at the ribosomes that produces preproglucagon is studied from the aspect of chemical thermodynamics. Based on Gibbs energy, an analysis is performed of the metabolic pathway for production of glucagon. The role of Le Chatelier’s principle in coupling of the reactions in the metabolic pathway is studied. Finally, a discussion is made of applications of the biothermodynamic methodology in omics research for determination of feasibility of metabolic pathways.

Optimizing ethylene plant utilities via hybrid artificial neural network and first-principles modeling

2025-10-27T11:35:07+01:00

In this study, a hybrid modeling approach combining first-principles equations with an artificial neural network was developed to reduce operating costs and carbon emissions in process utility systems of an ethylene plant. The artificial neural network accurately predicted turbine power outputs under various operating conditions, with low maximum absolute percentage errors across all three turbines, demonstrating its ability to effectively capture nonlinear system behavior. The economic analysis showed that natural gas prices have a greater cumulative impact on operating expenses than the carbon tax due to their greater variability. Although the carbon tax has a higher local sensitivity, the steady increase in natural gas prices represents a persistent economic burden. This demonstrates the importance of managing fuel costs and monitoring changes in carbon policy to mitigate sudden increases in operating costs. With increasing output, the operating costs of the propylene and cracked gas turbines rose almost linearly, with the costs per megawatt rising more sharply for the propylene turbine. The ethylene turbine significantly impacted operating expenses despite lower output, showing that small output changes can affect costs. Overall, the proposed methodology provides a reliable framework for optimizing energy performance, predicting fuel consumption and supporting operational decision-making in large-scale processes.

Synthesis and biological evaluation of some drug-like scaffolds of benzo- and pyrido-fused medium-sized N-heterocycles obtained via intramolecular Friedel–Crafts acylation reactions

2026-01-03T03:00:27+01:00

An unprecedented, concise and environmentally-friendly protocol for the synthesis of benzo-and pyrido-annulated azocinones, azoninones and azecinones 8a–h via Friedel–Crafts reactions is described. These simple and efficient procedures involve cycliacylations of heterocyclic esters 7a–h in the presence of catalytic amount of AlCl₃/CH₃NO₂ or TfOH or PPA catalysts as the key step. Starting amides 3a–d were readily obtained by coupling reactions of acryloyl chlorides 2a and b with pyridin-2-amines 1a and b. Developed strategy offers some high selectivity reactions, mild reaction conditions and easy access to complex medium-sized N-heterocycles in moderate to good yields. All tetracyclic fused compounds have been screened for antimicrobial activity.

Removal of Pb(II), Cd(II), and Zn(II) from landfill soil and leachate using a graphene oxide membrane

2025-10-06T13:54:38+02:00

Since rainwater extracts toxic metals from landfills, creating harmful leachate, developing methods to remove these metals is necessary. This work presents a method of toxic metal ions removal from a loam-type soil consisting of washing the soil with a mild washing agent to extract toxic metals in a leachate, and a purification of the leachate by filtering it through a synthesized graphene oxide (GO) membrane. As washing agents, the pure water and a mild solution of HCl (0.01 M) were tested. The GO membrane was synthesized using natural Madagascar graphite. The solution of HCl showed a significantly higher washing efficiency of Zn(II), Cd(II), and Pb(II) cations than pure water due to its acidic nature. An intrinsic GO membrane with an interlayer distance of 0.68–0.74 nm (before and after filtration) and a thickness of ~0.70 µm yielded rejections of 99.80%, 96.15%, and 44.00% for Pb(II), Cd(II) and Zn(II) ions, respectively. Molecular dynamics simulation showed that ions are retained in the GO interfaces due to the narrow interlayer distance, leading to membrane fouling. Nevertheless, the high rejections of Pb(II) and Cd(II) support the possibility of purifying landfill soil leachate by the GO membrane.

Ameliorating heavy metal-induced oxidative stress in valerian: The role of melatonin

2025-06-12T10:09:39+02:00

Heavy metals ubiquitously found in soil and water, represent a serious environmental problem that disrupts plant mineral nutrition homeostasis, osmotic balance and metabolism. The application of some biostimulants can alleviate these disruptions. Melatonin as a signal molecule, and antioxidant plays an important role in plant growth and stress tolerance due to its ability to directly neutralize reactive oxygen and nitrogen species. The reduction or mitigation of heavy metals adverse effects in valerian plants grown in open field conditions using melatonin was investigated in this study. High-pressure liquid chromatography coupled with a fluorescence detector was used to identify and quantify melatonin concentration in valerian root extracts. Also, the physiological and biochemical status of plants under abiotic stress was examined, especially in 100 µM melatonin pre-treated plants. Higher concentrations of endogenous melatonin were measured in roots of Cd and Zn treated plants. Melatonin application alleviated the negative effect of Cd, particularly evident in Cd-melatonin treatment which restored or enhanced bioactive compound levels. Melatonin effectively mitigates Cd and Zn-induced stress in valerian by enhancing both non-enzymatic and enzymatic antioxidant systems and promoting the synthesis of protective compounds. These findings highlight melatonin’s potential as a sustainable biostimulant to support plant resilience and productivity in heavy metal-stressed environments.

Removal of nickel(II) ions during water purification with ferrous sulfate. Part 2. Structure and composition of iron(III) hydroxide precipitates

2025-10-23T14:42:47+02:00

A comparative analysis of the composition and structure of freshly precipitated iron(III) hydroxide precipitates obtained from a solution of iron(II) sulfate in the presence of sodium sulfate (400 mg L^-1) at pH 7 and 8, before and after the sorption of nickel ions onto them, was carried out. Using IR and Raman spectroscopy, X-ray phase and thermogravimetric analysis, it was shown that the precipitates have the general (gross) formula Fe₂O₃×2H₂O and contain small amounts of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH). It has been established that the sorption of nickel ions onto these precipitates is not accompanied by chemisorption, i.e., no mixed compounds between iron and nickel are formed. The point of zero charge of the precipitate particles is at pH 5.4, with a positive zeta potential below and a negative zeta potential above this pH. The introduction of nickel ions into the solution leads to the appearance of a second zero charge point at pH 10.2.

Enhanced photocatalytic performance of ZnO/Cu2O composite for the degradation of methylene blue under the synergy effect

2026-01-21T13:29:36+01:00

In order to investigate the catalytic degradation efficiency of ZnO//Cu₂O composite, the nanocomposite was synthesized via one-pot method and the template of SDS. The crystal structure, microscopic morphology, chemical composition, specific surface area, pore size distribution and optical absorption property of the composite were characterized. Under the irradiation of xenon lamp, the photocatalytic performance of the composite was evaluated by degrading methylene blue (MB). The aforementioned characterization showed that the synthesized composite consisted of ZnO (hexagonal wurtzite) and Cu₂O (cubic crystal). Due to the mediation of SDS template, the particles were nanoscale with uniform distribution of Cu, Zn and O elements and contained abundant mesopores. The photo-response range of the composite expanded to the visible region because of the combination of ZnO and Cu₂O. Degradation ratio of MB catalyzed by ZnO/Cu₂O maintained about 92 % within 100 min after five recycling, demonstrating promising potentiality for photocatalytic applications. The enhanced photocatalytic performance maybe related to the mediation of SDS during the preparation process and the synergy effect between ZnO and Cu₂O.

Inclusion of H3PW12O40 in cyclodextrin as a catalyst for oleic acid esterification

2025-11-12T08:57:11+01:00

This study focuses on the use of cyclodextrins (β-CD and HP-β-CD) as host materials to immobilize 20 wt. % tungstophosphoric acid, H₃PW₁₂O₄₀ (HPW), and their application as catalysts for the esterification of oleic acid, a fatty acid commonly found in many vegetable oils and frequently used as a biodiesel feedstock, into methyl oleate using methanol, the most commonly preferred alcohol for this reaction. The catalytic performances of these hybrid materials were compared with those of HPW incorporated into polyacrylamide hydrogel (20 wt. % HPW/PAAm) and HPW supported on silica (20 wt. % HPW/SiO₂), a conventional inorganic support. All materials were characterized by various techniques. For all supports, the Keggin structure of H₃PW₁₂O₄₀ was retained after immobilization, as confirmed by FT-IR and Raman spectroscopies. XRD and SEM analyses suggested the formation of inclusion complexes in the HPW/ /β-CD and HPW/HP-β-CD systems, as well as the successful incorporation of HPW into the PAAm matrix. In the esterification reaction carried out at 60 °C for 3 h, bulk HPW, HPW/PAAm and HPW/β-CD exhibited high catalytic activity, achieving methyl oleate yields of 97, 94 and 69 %, respectively, significantly higher than that obtained with the silica-supported catalyst (41 %).