Compounds

This study evaluated the effects of incorporating silk fibroin nanoparticles into self-curing polymethyl methacrylate (PMMA) on the mechanical and Candida albicans responses of provisional dental prostheses. Rectangular specimens (64 × 10 × 3 mm) were fabricated and assigned to three groups (n = 10): G1 (control), PMMA without reinforcement; G2, PMMA with 0.5% silk nanoparticles; and G3, PMMA with 1% silk nanoparticleScheme4. 4 × 6 mm) were prepared. Scanning electron microscopy (SEM) was used to assess nanoparticle incorporation within the polymer matrix. No significant differences were observed in surface roughness (G1 = 0.4118 ± 0.100; G2 = 0.3245 ± 0.072; G3 = 0.3269 ± 0.076) or microhardness (G1 = 12.21 ± 0.351; G2 = 12.72 ± 0.213; G3 = 12.53 ± 0.177). Flexural strength differed significantly among the groups (p = 0.009), with higher values in nanoparticle-reinforced specimens (G1 = 79.142 ± 3.202; G2 = 87.089 ± 2.756; G3 = 92.412 ± 1.963). None of the tested concentrations exhibited antifungal activity against C. albicans. In conclusion, the incorporation of silk fibroin nanoparticles enhanced the flexural strength of self-curing PMMA without adversely affecting surface roughness or microhardness, although no antifungal effect was detected at the evaluated concentrations. Full article

The aim of this study was to evaluate, on a preliminary basis, the ability of multivariate techniques to predict the antioxidant activity of selected Stachys and Betonica species, based on chromatographic data. The methanol extracts of six Stachys species and ten Betonica species were analyzed using reversed-phase high-performance liquid chromatography (RP-HPLC) to obtain their chromatographic profiles. The phytochemical similarity of the samples was assessed using a selected chemometric method (principal component analysis (PCA) and hierarchical cluster analysis (HCA)). The antioxidant activity of the studied extracts (DPPH with 2,2-diphenyl-1-picrylhydrazyl reagent and FRAP—ferric reducing antioxidant power) was determined using a spectrophotometric technique. A multivariate PLS model was then used to predict the antioxidant activity of the methanolic extracts of Stachys and Betonica species based on their RP-HPLC fingerprints. The two obtained PLS models proved useful for predicting the biological activity of the tested extracts. High correlation coefficients (DPPH: R² = 0.9963; FRAP: R² = 0.9895) confirmed the reliability of the PLS prediction model. The results confirmed the effectiveness of combining qualitative and quantitative chromatographic fingerprinting methods with antioxidant activity testing and chemometric analysis, demonstrating that extracts from Stachys and Betonica are a rich source of bioactive substances with antioxidant properties. Full article

The natural durability of wood, determined primarily by its chemistry, meets the growing demand for environmentally sustainable alternatives to toxic wood preservatives. This study assessed the relationship between the fungitoxic acetone extractive content, in particular resin acids and stilbenes, and heartwood decay resistance among fifty-two Pinus nigra J. F. Arnold clones from a clonal seed orchard in Greece. Quantitative ¹H-NMR spectroscopy was employed to determine total stilbenes (TSs) and total resin acids (TRAs) in heartwood samples, while decay resistance was evaluated through standardized weight loss tests using the brown-rot fungus Coniophora puteana (Schumach.) P. Karst. (1865) and the white-rot fungus Porodaedalea pini (Brot.) Murrill (1905). The heartwood exhibited exceptionally high extractive content (mean TAE = 304.15 mg g_dhw⁻¹), with resin acids (68.26%) predominating over stilbenes (22.31%). Regression analysis showed that the TAE and TRAs were the strongest predictors of decay resistance, explaining 33% of the variance, while stilbenes exhibited weaker and more variable associations. P. pini caused significantly higher mean weight loss (11.43%) than C. puteana (3.55%), indicating species-specific fungal aggressiveness. Among individual resin acids, abietic acids were the most influential contributors to decay resistance. The results demonstrate that resin acids have a dominant role over stilbenes in determining the natural durability of P. nigra (Black pine) heartwood and could serve as effective biochemical markers for selective breeding. Full article

Terpyridines are well-known ligands in coordination chemistry, are valued for their conformational flexibility and strong metal-binding properties, and are also of interest as fluorophores. This study focused on the synthesis and comprehensive investigation of a new class of bis-oxazolo[5,4-b]pyridine derivatives, designed based on their structural similarity to terpyridines. Four novel compounds, 4a–d, were synthesized by cyclization of amide derivatives of 3-aminopyridin-2(1H)-ones using pyridine-2,6-dicarboxylic acid and its dichloride as key acidic components. Their structures and purity were confirmed by melting point analysis, high-resolution mass spectrometry, and ¹H, ¹³C NMR spectroscopy. Compounds 4a–c exhibit UV absorption at 323–357 nm and intense blue to deep-blue fluorescence (357–474 nm, цi ≈ 0.32–0.84) in chloroform, dichloromethane, and acetonitrile, attributed to p–p* transitions within the conjugated ring system. These findings suggest their potential as phosphors for organic electronics. Computational modeling of 4a–c molecules provided insight into their electronic structures, conformational stability, and predicted optical behavior. The most stable conformers (4a–II, 4b–II, 4c–II′) exhibited a progressive decrease in the HOMO–LUMO gap from 4a to 4c, correlated with the enhancement of photoactivity. Among them, compound 4a stands out as the most promising luminophore, displaying the most intense and narrow luminescence band, owing to its high molecular symmetry and stable emission characteristics. Overall, this study lays the foundation for future studies of bis(oxazolo[5,4-b]pyridine) derivatives in coordination chemistry and optoelectronic materials development. Full article

Two crystalline complexes, (2,2′-bipyridine)Cu(CH₃COO)₂·5H₂O (3) and (2,2′-bipyridine)Cu(CH₃COO)₂·CH₃CN (4), have been isolated and characterized by low-temperature single-crystal X-ray diffraction experiments. Crystals of phase 3 were studied previously at room temperature (296 K) under conditions leading to rapid desolvation and less distinct characterization of the waters of crystallization. With our redetermination of 3 at 100(2) K, we present a detailed description of ribbon-like structure formed by water molecules in crystals of (2,2′-bipyridine)Cu(CH₃COO)₂·5H₂O. Acetate oxygens are linked by hydrogen-bonding to two inequivalent waters separated by 4.72 Å; the other three water molecules are trapped in polymeric ribbons of anticooperative hydrogen-bonded six-membered rings fused with cooperative hydrogen-bonded four-rings. Water oxygens of the fused ring ribbons associate only with other water oxygens, and this water structure has a local density and pair distribution function which resembles that of liquid water. Crystals of 4 are monoclinic, with acetonitrile of solvation unassociated with the complex. In both 3 and 4, bipyridine planes interleave through π-aryl stacking. Full article

Propolis is a resinous material produced by honeybees characterized by a high phenolic compound and flavonoid content. To date, several studies have examined the chemical composition of Mexican propolis from the south and north of the country. However, limited information is available on the chemical profile of propolis from central Mexico. The present study isolated six known compounds from propolis from central Mexico: one diterpene (sugiol, found for the first time in Mexican propolis), three flavonoids (chrysin, galangin 3-methyl ether, and 3,7-dimethoxyquercetin), a fatty acid (cerotic acid), and an unusual glycerol derivative (batyl alcohol). Moreover, LC-ESI-MS analysis conducted on the ethanolic extract led to the identification of three phenolic compounds and fourteen flavonoids commonly found in propolis. Lastly, the cytotoxic activity evaluation carried out on the ethanolic extract showed a decrease in the cell viability of human leukemia (Jurkat) cells in a concentration-dependent manner. Full article

The discovery of antiviral agents is an important research area because the world is increasingly exposed to the risk of viral infectious diseases. Herpes simplex virus type 2 (HSV-2) causes globally prevalent sexually transmitted diseases, and numerous individuals are living with HSV-2. Influenza A virus (IAV) causes annual epidemics and occasional pandemics, attracting great concern in public health. In this study, antiviral activities against HSV-2 and IAV of 103 flavonoids were screened. The screening identified cirsilineol and apigenin as active against HSV-2, while cirsimaritin and hymenoxin displayed anti-IAV activity. These flavonoids have the potential to serve as therapeutic candidates for viral infectious diseases. Full article

Background: The incidence of dementia, especially Alzheimer’s disease (AD), is rising, with over 55 million affected globally. Therefore, this disease, for which there is no adequate treatment, is more frequent and prevalent in women. Royal jelly, a bee secretion, is known for its health benefits and contains proteins, carbohydrates, lipids, minerals, polyphenols, enzymes, and B vitamins, as well as anti-inflammatory and antioxidant properties relevant to AD. Thus, we aimed to investigate the chemical compounds in royal jelly extract and their effect on neurobehavioral changes in an AD female model. Methods: In vitro studies were used to investigate the chemical and physicochemical properties of the royal jelly extract. In vivo studies, we divided female mice into five groups (n = 25): Control (C), Alzheimer (ALZ), ALZ standard (ALZ-STD, rivastigmine 1 mg/Kg), ALZ-D1 (royal jelly 150 mg/kg), and ALZ-D2 (royal jelly 300 mg/kg). The mice received the treatments orally at 45 days. We induced the AD model by orally administering aluminum chloride at 100 mg/kg and intraperitoneally injecting D-galactose at 120 mg/kg for 45 consecutive days, after which we subjected the animals to the radial arm maze, Morris water maze, elevated plus maze, and forced swim tests. Results: Analyses showed moderate acidity and a rich bioactive profile, with flavonoids being more prevalent. Antioxidant activity tests indicated moderate efficacy, while FTIR-ATR analysis revealed the chemical complexity of royal jelly. The royal jelly extract used in the study did not induce toxicity in vivo. Notably, royal jelly improved cognitive deficits, neurodegeneration, and reduced anxiety in AD. Conclusions: The study suggests that royal jelly extract has promising neuroprotective properties and could be a viable natural therapeutic option for AD. Full article

Endoperoxides constitute a distinctive class of highly oxygenated terpenoids defined by the presence of a cyclic peroxide (–O–O–) bond, a structural motif responsible for their pronounced chemical reactivity and diverse biological effects. Naturally occurring endoperoxide-containing terpenoids are broadly distributed across terrestrial and marine taxa, including higher plants, algae, fungi, and bryophytes, where they are believed to participate in chemical defense and ecological interactions. This review provides a comprehensive overview of naturally occurring endoperoxide terpenoids, focusing on their natural sources, structural diversity, and reported biological activities. Particular emphasis is placed on compounds exhibiting antiprotozoal and antitumor activities, exemplified by artemisinin and its derivatives, which remain cornerstone agents in antimalarial therapy and continue to attract interest for their anticancer potential. Structure–activity relationship (SAR) analysis, supported by computational prediction using the PASS (Prediction of Activity Spectra for Substances) platform, is employed to examine correlations between peroxide-containing frameworks and biological function. Comparative assessment of experimental data and predicted activity profiles identifies key structural features associated with antiprotozoal, antineoplastic, and anti-inflammatory effects. Collectively, this review highlights endoperoxides as a valuable and chemically distinctive class of bioactive natural products and discusses their promise and limitations as leads for further pharmacological development, particularly in light of their intrinsic reactivity and stability challenges. Full article

This study investigates the activation mechanism of boron-doped carbon (BMC) catalysts for the degradation of the antibiotic sulfamethoxazole (SMX) via persulfate (PMS) activation. The catalysts were synthesized using a sequential double-melting calcination method, resulting in mesoporous carbon nanosheets characterized by hierarchical macro-mesopores and atomically dispersed dual active sites. Comprehensive characterization was performed using BET, SEM, TEM, FT-IR, XPS, XRD, and Raman techniques. The optimized BMC catalyst demonstrated excellent performance, achieving complete removal of sulfamethoxazole (100%) and a high mineralization rate (~90%) within 45 min. Mechanistic analysis, including electron paramagnetic resonance (EPR), revealed that the degradation predominantly follows a singlet oxygen (1O2)-dominated pathway. The system exhibited broad applicability to various pollutants, along with notable operational stability and robust resistance to common environmental interferents. Persulfate activation was primarily attributed to boron-active sites, while the hierarchical mesoporous structure facilitated both pollutant enrichment and catalytic efficiency. Full article

Poly(acrylic acid)/polyvinylpyrrolidone (PAA/PVP) hydrogen-bonded complexes are of growing interest as functional materials for biomedical applications. However, the influence of polyhydroxyl additives, such as polyols and sugars, on complex formation and material performance remains insufficiently understood. This study aimed to elucidate how polyhydroxyl compounds affect the physical properties of PAA/PVP complexes. Dried PAA films were brought into contact with aqueous PVP solutions containing various additives (glycerol, sugar alcohols, or sugars), and the resulting hydrogels were dried to form films. Their swelling behavior in water and PBS, thermal stability, and mechanical properties were comparatively evaluated. Sugar alcohols markedly improved swelling and flexibility, whereas sugars showed limited effects. Glucitol exhibited intermediate performance due to a high tendency toward intramolecular hydrogen bonding in aqueous media. Mechanistic analysis suggested that sugar alcohols act in a chaperone-like manner during complex formation, promoting microphase-separated structures composed of hydrogen-bonded domains and free segment regions. These findings provide new molecular insight into designing PAA/PVP-based materials with additives for biomedical applications. Full article

Humulus lupulus L. (hops) is essential in brewing due to its contributions to bitterness, flavor, and aroma. This study compared the volatile profiles of five commercially important hop varieties—Amarillo, Ariana, Cascade, Centennial, and El Dorado—grown in their main regions of origin (United States for Amarillo, Cascade, and El Dorado; Germany for Ariana; and Brazil for Centennial). Headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME/GC-MS) enabled the identification of 312 volatile compounds, including monoterpenes (e.g., myrcene, linalool, geraniol), sesquiterpenes (e.g., humulene, caryophyllene), esters, alcohols, aldehydes, and ketones. Amarillo showed the highest myrcene content (22.61% of the total volatile area), while Centennial was distinguished by elevated γ-muurolene (20.59%), and El Dorado by the highest level of undecan-2-one (10.47%), highlighting marked varietal differences in key aroma-active constituents. Multivariate, including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), clearly discriminated the five varieties: PC1 (41.04% of the variance) separated samples enriched in fruity/floral monoterpenes and esters from those dominated by woody/resinous sesquiterpenes, whereas PC2 (25.93% of the variance) reflected variation in medium-chain esters, ketones, and waxy compounds. These chemometric patterns demonstrate that both genetic background and growing region terroir strongly shape hop volatile composition and, consequently, aroma potential, providing brewers with objective criteria for selecting hop varieties to achieve specific sensory profiles in beer. Full article

Electrospinning has emerged as a powerful technique for fabricating customised nanofibrous materials with integrated functional nanostructures, offering significant advantages for electrochemical energy applications. This review highlights recent advances in using electrospun nanofibres directly as active components in devices such as batteries, supercapacitors, and fuel cells. The emphasis is on the role of composite design, fibre morphology and surface chemistry in enhancing charge transport, catalytic activity and structural stability. Integrating carbon-based frameworks, conductive polymers, and inorganic nanostructures into electrospun matrices enables multifunctional behaviour and improves device performance. The resulting nanofibrous composite materials, often after heat treatment, can be used directly as electrodes or self-supporting layers, eliminating the need for additional processing steps such as size reduction or preparation of slurries and inks for creating functional nanofibre-based deposits. The importance of composite nanofibres as an emerging strategy for overcoming challenges related to scalability, long-term durability, and interface optimisation is also discussed. This review summarises the key results obtained to date and highlights the potential of electrospun nanofibres as scalable, high-performance materials for next-generation energy technologies, outlining future directions for their rational design and integration. Full article

Gastrointestinal disorders negatively affect populations worldwide. Considering the side effects of synthetic drugs, natural products can be a safe and effective alternative to help treat gastric ulcers and diarrhea. In this context, the present study reviewed the antiulcerogenic and antidiarrheal activities of species of the genus Croton (Euphorbiaceae). The scientific documents were retrieved from different databases, covering publications from the first report on the topic in 1998 to October 2025. Although the genus Croton comprises approximately 1200 species, only 11 have been evaluated for their antiulcerogenic and antidiarrheal potential in in vivo and in vitro studies. Among the identified bioactive constituents, the diterpenes trans-dehydrocrotonin and trans-crotonin, isolated from Croton cajucara, demonstrated significant antiulcerogenic activity in several experimental models in vivo. Similarly, the compound crofelemer, isolated from the latex of the bark of Croton lechleri, has shown promising results in several clinical trials for the treatment of diarrhea. Furthermore, flavonoids including rutin and quercitrin have been detected in Croton campestris. Regarding gastroprotective mechanisms, evidence suggests that extracts and essential oils obtained from Croton species may act through the nitric oxide pathway, promoting an antiulcerogenic effect. Additional studies are needed to investigate the gastroprotective and antiulcerogenic potential of at least 17 Croton species used empirically in traditional medicine for the treatment of gastrointestinal disorders but still without scientific validation. Full article

Background: Powdered mucilages are increasingly being used as natural excipients in pharmaceutical formulations, functioning as binders, disintegrants, thickeners, suspending agents, and film formers. Their swelling, viscosity-enhancing, and biocompatible properties also make them useful in controlled-release systems and tablet production. This study aimed to produce spray-dried Cydonia oblonga (CO) mucilage, examine how drying parameters influence yield, and determine its physicochemical and rheological characteristics to evaluate its suitability for pharmaceutical applications. Methods: Powdered CO mucilage was obtained by spray drying. The obtained powders were characterized on yield, particle size and morphology, moisture content, loss on drying, flow properties and swelling index. Results: The obtained powders show yields of 10.6–16.4%, particle sizes of 4.5–5.39 μm, and moisture contents of 2–3%. Their flowability is limited despite satisfactory angle of repose, Hausner ratio, and Carr index values, yet all powders exhibit excellent swelling properties. Conclusions: Model CM6 of the obtained powdered CO seeds hydrocolloid stands out as the best spray-dried hydrocolloid, combining high drying efficiency, low residual moisture, uniform particle formation, and excellent swelling capacity despite its limited flowability. These properties make it a strong candidate for use as a biopolymer or excipient in pharmaceuticals. Full article

For centuries, people have used herbs, plants, and spices as remedies for health problems or simply to ameliorate body energy or vitality because of the bioactive compounds they contain. The Capsicum genus, which includes the chili pepper, is one of the oldest crops to be domesticated and used. It is characterized by three qualities: pungency/flavor, color, and aroma. Capsaicinoids are responsible for the pungent flavor. Carotenoids and flavonoids determine the remarkable and colorful tones of chili peppers. Volatile compounds provide their characteristic aroma. This prompts consumers to purchase and utilize the numerous varieties of chili peppers, whether fresh or dried. The presence of these bioactive compounds gives chili peppers functional attributes that promote health. This paper reviews the scientific research carried out over the last 25 years on these attributes. This paper also looks at how Capsicum fruits could be used as a valuable source of nutrients from plants that have beneficial biological properties. Full article

Chamomile (Matricaria chamomilla L.) and feverfew (Tanacetum parthenium L. Sch. Bip.), both members of the Asteraceae family, are widely distributed in Serbia and traditionally used for their medicinal properties. Chamomile is primarily known for its gastrointestinal effects, while feverfew is noted for its antimigraine activity. Although the biological activity of each plant has been individually studied, there has been a lack of research related to their blends. So, the aim of this study was to prepare various chamomile/feverfew blends and their extracts with special focus on extraction temperature, to obtain superior herbal extract with the best functional characteristics. In order to characterize the obtained blend extracts this study included spectrophotometric and UHPLC Q-ToF MS analysis of prepared (selected) extracts, as well as evaluation of their antioxidant (ABTS, DPPH, FRAP, and CUPRAC) and antimicrobial properties. Antibacterial activity was evaluated against two Gram-positive and four Gram-negative bacterial strains using the broth microdilution method. Untargeted analysis showed the same phytochemical profile for both selected extracts (B3 and B9), as well as differences in distribution and abundance of identified compounds depending on applied extraction temperature (cold or heat-assisted). These differences in profile most probably contributed to variations in the antioxidant and antimicrobial properties of the extracts. The most potent antioxidant activity (123.04 µM TEAC/g) was observed for the 3:1 feverfew/chamomile blend (ABTS assay), while the highest metal-chelating capacity (1288.95 µM VCEAC/g) was recorded in extracts obtained by heat-assisted extraction (CUPRAC assay). Antibacterial activity of all blends ranged from 0.625 to 2.5 mg/mL, regardless of the extraction method. The findings indicate that combined extracts of chamomile and feverfew represent a promising source of bioactive compounds with potential applicability in both food science and pharmaceutical (biomedical) research. Full article

Thermally activated delayed fluorescence (TADF) often achieves high device efficiencies in organic light-emitting diodes. Here we develop TADF dyes, 1-H and 1-Me, based on an N,N-diphenylaminophenyl–phenylene–quinoxaline donor–π–acceptor system, which contains an unsubstituted 1,4-phenylene and a 2,5-dimethyl-1,4-phenylene π-spacer, respectively. In UV–vis absorption spectra in toluene at room temperature, 1-H showed a relatively intense shoulder band at 400 nm, whereas 1-Me had a weak, blue-shifted shoulder at 386 nm, indicating 1-Me adopts a more twisted π-conjugation system. On the other hand, the photoluminescence (PL) wavelength of 1-Me (λ_PL; 558 nm) under the same conditions was slightly red-shifted in comparison with that of 1-H (λ_PL; 552 nm), due to larger structural relaxation of 1-Me. From PL lifetime measurements, both the dyes showed TADF in 10 wt%-doped poly(methyl methacrylate) film, and their PL quantum yields were moderate (Φ_PL; ca. 0.5 at 300 K). As for the photokinetics, 1-Me exhibited larger rate constants for intersystem crossing and reverse intersystem crossing than 1-H due to the small excited-state singlet–triplet energy gap (ΔE_ST) of 1-Me. Furthermore, theoretical calculations indicated the triplet state of 1-Me is destabilized by localization of the spin density, resulting in the reduced ΔE_ST to facilitate TADF. Full article

Salvia dumetorum Andrz. ex Besser is a promising non-pharmacopoeial plant species with traditional medicinal potential. This study aimed to determine the optimal microwave-assisted extraction (MAE) conditions for obtaining a polyphenol-rich ethanolic extract from the S. dumetorum leaves. Dried and powdered leaves were extracted using 40% ethanol with different power of microwaves varying from 200 to 800 W and time of extraction 2–8 min. The extract was filtered, concentrated, and evaluated for yield, identification of phenolic compounds using high-performance liquid chromatography (HPLC), total phenolic content (TPC), and total flavonoid content (TFC). Extraction yields ranged from 2.20% to 25.80% based on dry weight. TPC and TFC were determined using Folin–Ciocalteu and aluminum chloride colorimetric assays, respectively, and are expressed as mg GAE/g and mg RUE/g of dry extract. The antioxidant activity of the extracts was evaluated using the DPPH (2,2-diphenyl-1-picrylhydrazyl radical) assay. According to HPLC analysis, the main phenolic components of the extracts were rosmarinic acid (1.78–2.95 mg/mL), chlorogenic acid (0.31–0.54 mg/mL), caffeic acid (0.11–0.20 mg/mL), rutin (up to 0.47 mg/mL) and ferulic acid (0.13–0.33 mg/mL); traces of myricetin were found only in isolated samples. The optimum extraction conditions were found to be 400 W microwave power, 8 min extraction time, one MAE cycle, and a 1:30 g/mL solvent-to-material loading ratio; TPC and TFC were evaluated as 35.23 ± 0.50 mg GAE/g DW and 19.94 ± 0.14 mg RuE/g DW, respectively, indicating the highest yield of polyphenolic compounds, antioxidant potential inhibiting 96.68% ± 0.27 of DPPH radicals, and IC₅₀ = 10.24 µg/mL. These findings highlight the efficiency of MAE in producing a bioactive ethanolic extract of S. dumetorum, which can be further explored for potential applications as a natural antioxidant in pharmaceutical or cosmetic formulations. Full article