STUDIA CHEMIA - Issue no.2 / 2025 - Table of contents

The optoelectronic properties of some thiophene-containing triarylamines derived formally from triphenyl amine by enlarging one, two, or all phenyl groups with phenyl, thiophene-phenyl, bithiophene, or terthiophene units, along with the molecular structure and the supramolecular arrangement of the molecules in the lattices, were revealed by spectroscopic and, in the case of two of the compounds, single crystal X-ray diffractometry investigations. This study confirms that solid-state interactions and conformations significantly influence the absorption and emission characteristics of these compounds, essential factors in designing efficient photovoltaic materials.

Keywords: triarylamine, absorption and emission spectra, single crystal X-ray diffractometry, C-H⋅⋅⋅π and heteroatom⋅⋅⋅π contacts

This study aimed to develop kinetic models that describe the preclinical drug interaction data between quetiapine, an atypical antipsychotic, and bioactive compounds derived from turmeric rhizome. The potential risk of interaction between these substances could alter the disposition of quetiapine and impact its efficacy. During the development of the kinetic models, first-order kinetic processes were assumed, and several hypotheses were evaluated, including the number of compartments for distribution, the presence of lag time in quetiapine absorption, the presystemic formation of its metabolite, and the relative bioavailability between the study groups. The most accurate models suggest that interactions between quetiapine and curcumin occur primarily at the intestinal level, as the systemic metabolism constant remained unaltered. Conversely, coadministration with curcuminoids and piperine markedly affected systemic metabolism, likely due to hepatic enzyme inhibition, resulting in a 59.6% increase in the relative bioavailability of quetiapine. The developed models successfully integrated data for quetiapine and norquetiapine, both as standalone administration and in combination with curcumin or curcuminoid-piperine bioactive compounds, capturing their disposition within the framework of pharmacokinetic interactions.

Keywords: kinetic modeling, quetiapine, norquetiapine, curcumin, curcuminoids, drug interactions

This study reports the development of a dermato-cosmetic hydrogel combining retinol (2% wt) and bioactive glass (1.25% wt) in a Carbopol-based matrix enriched with hyaluronic acid. The formulation was synthesized using high-shear dispersion and evaluated through TGA, DSC, FTIR, and XRD. Thermal analysis indicated strong water-polymer interactions, while FTIR and XRD confirmed amorphous structure favorable for controlled release. The hydrogel showed high conductivity (25000 μS/cm) and alkaline pH (12.4), attributed to its 85% water and triethanolamine content. Turbiscan and microscopy confirmed physical stability. Microbiological tests confirmed sterility. In vivo VISIA analysis on five volunteers over 45 days revealed visible improvements in wrinkles, pores, red areas, UV spots, and porphyrins, with notable changes as early as day 14. These results support the hydrogel’s potential for effective and well-tolerated dermal delivery of retinol.

Keywords: retinol, hydrogel, dermal delivery, stability, bioglass

The present study investigates the impact of different extraction methods—accelerated solvent extraction (ASE), ultrasound-assisted extraction (UAE), and maceration on the yield, phytochemical composition, antioxidant activity, and antimicrobial potential of Chelidonium majus extracts. ASE demonstrated the highest extraction yield (85.7%) and alkaloid content (5.4 mg AE/ml), correlating with enhanced antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans (lowest MIC values: 3.12%, 2.50%, and 6.25%, respectively). UAE resulted in the highest polyphenol content (15.2 mg GAE/ml) and antioxidant capacity (12.8 ± 1.5 μmol Trolox/ml), suggesting its effectiveness in preserving antioxidant compounds. Maceration produced the lowest bioactive compound yield and biological activity. These findings indicate that ASE is optimal for antimicrobial applications, while UAE is preferable for antioxidant-enriched extracts. The results provide valuable insights for optimizing C. majus extraction in pharmaceutical, food, and cosmetic formulations.

Keywords: Chelidonium majus, accelerated solvent extraction, ultrasound-assisted extraction, alkaloids, flavonoids, polyphenols, antimicrobial activity, antioxidant capacity, extraction efficiency

The study examines the antioxidant, antidiabetic, antihyperlipidemic, and antiobesity properties of the 80% methanol extract prepared from the aerial parts of Aethionema schistosum, a plant widely distributed in certain regions. The extract was evaluated in vitro for its inhibitory effects on α-glucosidase (antidiabetic), α-amylase (antidiabetic), pancreatic lipase (antiobesity), and pancreatic cholesterol esterase (antihyperlipidemic) enzymes. It exhibited moderate α-glucosidase inhibition (99.15±0.04%) compared to acarbose (56.94±3.88%). The DPPH radical scavenging activity of the extract at a concentration of 2 mg/ml was measured at 80.50±1.23%. This value is considered close to the inhibitory effect of ascorbic acid, which was recorded at 90.60±0.29% at the same concentration. The extract's total phenol (74.73±4.76 mg GAE/g) and flavonoid (42.80±2.25 mg QE/g) contents were measured, and chlorogenic acid was identified as a major compound via HPLC. This is the first study to analyze the phytochemical composition and enzyme inhibitory effects of A. schistosum. Further research is needed to isolate its bioactive compounds and assess its therapeutic potential through diverse in vitro and in vivo models, highlighting its potential in drug discovery efforts.

Keywords: Antidiabetic, Antioxidant, Aethionema schistosum, Reverse phase-HPLC

In this study, Xanthoria parietina samples were collected from different regions of Türkiye like Yozgat (Xp3), Izmit (Xp14), and Kütahya (Xp20). Anthracenedione, anthraquinone (parietin) contents of the lichens were determined quantitatively by GC-MS and spectrophotometric methods. The interaction of lichen extracts with pBR322 DNA and CT-DNA was examined by performing an agarose gel electrophoresis method. The cell proliferative activities of Xanthoria parietina samples were tested against the colon cancer cell line (DLD-1) by MTT assay. As a results of the GC-MS and spectrophotometric analysis, the highest and the lowest parietin contents were found for Xp20 and Xp14 extracts, respectively. These results were supported by those of the DNA cleavage, binding, and toxicity studies. The Xp14 sample can be considered as a drug that could be a new approach to cancer treatment, as it has the lowest polyaromatic hydrocarbon content and is not toxic for the cell.

Keywords: Xanthoria parietina; parietin; DNA cleavage; cytotoxicity; colon cancer, GC/MS

Cherry stalks, as primary by-products of sour cherry (Prunus cerasus L.) and sweet cherry (Prunus avium L.) harvesting, are often considered agricultural and industrial waste. However, cherry stalks are recognized in traditional and ethno medicine for their therapeutic properties, due to their high content of natural antioxidants. In this study, the concentrations of total phenolic and total flavonoid compounds, as well as antioxidant activity, were evaluated in different cherry stalk extracts (aqueous, methanol, ethanol, and acetone) obtained from sweet cherry cultivars, sour cherry cultivars, and a wild cherry sample. The results depended on the cultivar and the solvent used for extraction. The highest concentrations of total phenolic and total flavonoid compounds were observed in acetone extracts. In various antioxidant tests, the antioxidant activity varied depending on the genotype.

Keywords: antioxidant capacity, cherry, extraction solvent, Prunus avium L., Prunus cerasus L., phenolics, stalks

This study aimed to develop new analytical strategies for the simultaneous determination of atorvastatin calcium (ATVC) and ezetimibe (EZE) in pharmaceutical formulations. The proposed methods included a chemometric approach using the partial least squares (PLS) technique with spectrophotometric data, first derivative zero-crossing, ratio spectra first derivative, and HPLC-DAD. PLS analysis was conducted using specialized software, with calibration performed in the 223–280 nm range at Δλ = 4 nm intervals. In the first derivative zero-crossing method, absorbance values at 245.2 nm for ATVC and 224.8 nm for EZE were used. The ratio spectra first derivative method quantified ATVC at 232.6 nm and EZE at 223.1 nm. HPLC-DAD analysis was carried out using an XBridge C18 column with a mobile phase of 20 mM NaH₂PO₄:ACN (50:50 v/v), (240 nm, 1.0 mL/min). The linearity ranges were 1–20 μg/mL, 2–10 μg/mL, and 0.05–1.0 μg/mL, respectively. The methods were validated according to ICH guidelines, with no significant statistical differences observed (ANOVA, p > 0.05). Recovery from tablet formulations ranged from 95.43% to 102.28%. The PLS technique was highlighted as an environmentally friendly analytical approach. These validated methods demonstrated high sensitivity, accuracy, and reproducibility for routine pharmaceutical analysis.

Keywords: Atorvastatin calcium, Ezetimibe, Chemometric, Spectrophotometry, HPLC, Validation, Green Chemistry

This study investigates the antimicrobial potential and physicochemical performance of PLA-based biocomposite films incorporated with bioglass, oregano essential oil, and diacetin as a green plasticizer. Designed for use in food packaging applications, the films aim to serve as biodegradable, active barriers against microbial contamination while ensuring environmental compatibility and material safety. Initial microbiological screening identified the PB2 formulation comprising 70% PLA, 25% diacetin, 3% bioglass, and 2% oregano oil as the most effective antimicrobial composition. PB2 achieved a 79% inhibition of bacterial growth after two days and maintained 65% suppression after 14 days, confirming its long-term antimicrobial efficacy. To gain a comprehensive understanding of PB2’s behavior, extensive characterization was performed. FTIR spectroscopy confirmed the successful incorporation of functional groups from both PLA and active additives. TGA and DSC analyses revealed enhanced thermal stability and a delayed glass transition (Tg>83 °C), attributed to the stiffening effect of bioglass. SEM and AFM investigations demonstrated uniform nanoparticle dispersion and low surface roughness (Ra=30.1 nm), ensuring good structural homogeneity. Mechanical testing showed reduced tensile strength but significantly increased elongation at break, indicating greater ductility due to matrix amorphization promoted by diacetin. Altogether, the results support the potential of PB2 as a multifunctional, antimicrobial biocomposite film suitable for food-grade and biomedical applications.

Keywords: diacetin, oregano oil, bioglass, antimicrobial barrier, active food packaging

The degradation of amoxicillin was accomplished using TiO2 nanotubes photocatalysts decorated with Au nanoparticles and containing reduced graphene or nitrogen-doped graphene under visible light exposure. The structural and morphological characterization confirmed the presence of gold nanoparticles and graphene, and the optical properties showed light absorption into visible region. The best results in the degradation of amoxicillin (up to 60%) were reached in the presence of the photocatalyst with nitrogen-doped graphene. A basics kinetic study showed a physical adsorption of the amoxicillin on the catalyst surface, and that the photodegradation step followed the pseudo-first kinetic model with the apparent kinetic constant of 0.0039 min-1.

Keywords: amoxicillin, titania nanotubes, reduced graphene, nitrogen-doped graphene, photodegradation

In the recent decades, the exploration of agro-wastes and other renewable biomass wastes as a precursor of heterogeneous catalysts for transesterification has become more fascinating in contrast to the conventional homogeneous catalysts. This is mainly attributed by its peculiar characteristics such as easy separation, reusability, cost effectiveness, eco friendliness, etc. Hence, the potential of banana inflorescence (BI), a byproduct of banana cultivation with less economic value was investigated herein, for the development of a competent heterogeneous catalyst for profitable biodiesel production from Used cooking oil (UCO). The transformation in porosity, surface area and chemical composition of banana inflorescence, brought about by calcination was examined by Scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), Powder X-ray diffractogram (XRD), Fourier transform infrared spectroscopy (FTIR) and Energy Dispersive X-ray Spectroscopy (EDS) analysis. The conversion was enumerated by Nuclear magnetic resonance (1H NMR) spectroscopy and it was observed that transesterification using 2 wt% catalyst, 9:1 methanol to oil molar ratio for a reaction time of 75 min at 65 ºC showed a fatty acid methyl ester (FAME) conversion of 98.62%.

Keywords: Banana inflorescence; Used cooking oil; Calcination; Biodiesel

In this study, TiO2-based catalysts were synthesized using a modified sol-gel method. The catalysts were prepared at two different pH values (10 and 13) and were subsequently doped with zirconia to improve their photocatalytic performance. The physico-chemical properties of the catalysts, including structural, textural, morphological, and thermal properties, were studied using XRD, BET, SEM, and TG/DTA methods, respectively. The photocatalytic activity of the synthesized catalysts was tested in the degradation/decolorization reaction of methylene blue dye. The results indicated that the synthesis parameters and zirconia doping had a significant impact on the catalysts' physico-chemical characteristics and, therefore, their activity. It can be pointed out that catalysts with improved properties and enhanced photocatalytic activity can be obtained by carefully selecting and optimizing synthesis conditions, as well as by modifying or doping them with a suitable dopant.

Keywords: TiO2, ZrO2-doping, Photocatalysis

In the construction of high-speed railway tunnels, when passing through different geological areas, the groundwater flowing through the drainage blind pipe is easy to produce crystals to block the drainage pipe. These crystal blockages are mainly produced by the dissolution of the concrete material of the initial support of the tunnel, which leads to the accumulation of precipitates in the drainage system and affects the tunnel structure safety. Based on the study of crystals and water samples in the blind pipe of Wujiayuan Tunnel, this paper discusses the relationship between the crystals in the blind pipe and the ion concentration, pH value, carbon dioxide concentration and partial pressure and temperature in groundwater. Combined with the environmental water chemical equilibrium software Visual MINTEQ 3.1, the influence of the above conditions on the formation of crystallization was simulated and the formation mechanism of Wujiayuan tunnel blind tube crystallization was proposed.

Keywords: tunnel blind pipe, crystals, water samples, Visual MINTEQ 3.1, precipitation formation mechanism

The present study investigates the behavior of Newtonian and non-Newtonian fluids in pumping and transport processes, using a laboratory facility. The rheological behavior of the selected fluids were determined by a rotational viscometer with concentric cylinders. The effect of pressure difference on pumping of selected fluids in the laboratory circuit showed a linear decrease of effective/delivered volumetric flow rate for the Newtonian fluid, glycerin/water 80%, and a non-linear decrease for non-Newtonian fluid, Separan AP 30E, 2g/l.

Keywords: Newtonian, non-Newtonian fluids, apparent viscosity, material consistency, flow behavior index, volumetric flow rate, pressure difference, pumping and transport.