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In this work, we review some physical methods of macroscopic experiments, which have been recently argued to be promising for the acquisition of valuable characteristics of biomolecular structures and interactions. The methods we focused on are electron paramagnetic resonance spectroscopy, Raman spectroscopy, and differential scanning calorimetry. They were chosen since it can be shown that they are able to provide a mutually complementary picture of the composition of cellular envelopes (with special attention paid to mycobacteria), transitions between their molecular patterning, and the response to biologically active substances (reactive oxygen species and their antagonists—antioxidants—as considered in our case study). [ABSTRACT FROM AUTHOR]

Seven commercial hop (Humulus lupulus L.) oils originating from a selection of North American hop varieties (Amarillo, Azacca, Cascade, Centennial, Chinook, Saaz, and Ahhhroma) and six homemade hop oils hydrodistilled from the same commercial hop pellets (except Ahhhroma) were compared. Seven terpenes regarded as hop oil markers (i.e., α-pinene, β-pinene, β-myrcene, β-ocimene, limonene, β-caryophyllene, and α-humulene) and methyl heptanoate were identified and quantified by GC–MS and GC-FID. The antioxidant potential of the commercial hop oil samples was evaluated using electron paramagnetic resonance (EPR) spectroscopy, while their components' antibacterial (against Aliivibrio fischeri) and enzyme (α-glucosidase and lipase) inhibition activities were screened using high-performance thin-layer chromatography (HPTLC)-based assays. A distinct feature of five of the commercial hop oils (except Saaz and Ahhhroma) was relatively high contents of β-myrcene (between 4.21 and 6.40 µg mg−1 hop oil). Azacca, Cascade, and Centennial hydrodistilled oils had perceptibly higher contents of β-caryophyllene than the rest, and most of them (except Chinook) contained relatively high amounts of α-humulene. Differences between the terpene profiles of the commercial and homemade hydrodistilled hop oils suggested that the commercial hop oils were derived from hop cones in a process different from hydrodistillation. The oils showed relatively low antioxidant potential, comparable to that of popular beers and white wines. The highest antioxidant potential was observed in Ahhhroma oil, while it was very low in Centennial oil, and no antioxidant potential was observed in Cascade and Saaz oils. The developed streamlined workflow, including parallel HPTLC-directed bioassays and HPTLC—TLC–MS Interface—SPME–GC–MS, enabled the identification of β-myrcene, dimyrcenes, β-farnesene, and 2-methylbutyl isobutyrate as anti-obesity compounds and β-farnesene, β-myrcene, and 2-methylbutyl isobutyrate as weak antibacterial hop oil components. [ABSTRACT FROM AUTHOR]

Recent interest in the antioxidant capacity of foods and beverages is based on the established medical knowledge that antioxidants play an essential role in counteracting the damaging effects of free radicals, preventing human neurodegenerative diseases, cardiovascular disorders, and even cancer. At the same time, there is no "the method" that uniquely defines the antioxidant capacity of substances; moreover, the question of interrelation between results obtained by different experimental techniques is still open. In this work, we consider the trolox equivalent antioxidant capacity (TEAC) values obtained by electron paramagnetic resonance (EPR) spectroscopy and ultraviolet–visible (UV–vis) spectroscopy using the classic objects for such studies as an example: red, rosé, and white wine samples. Based on entirely different physical principles, these two methods give values that are not so simply interrelated; this creates a demand for machine learning as a suitable tool for revealing quantitative correspondence between them. The consideration consists of an approximate correlation-based analytical model for the key argument (i.e., T E A C E P R ) with subsequent adjustment by machine learning-based processing utilizing the CatBoost algorithm with the usage of auxiliary chemical data, such as the total phenolic content and color index, which cannot be accurately described by analytical expressions. [ABSTRACT FROM AUTHOR]

The antioxidant properties of different types of tea—green, black and earl grey—were investigated using the EPR spectroscopy method based on a new semi-empirical mathematical model and on a single EPR spectroscopy measurement. The obtained values of the antioxidant capacity were correlated with the bioactive ingredient content identified through the NMR spectroscopy. Moreover, an attempt was made to determine what impact on the antioxidant properties of tea does adding sugar, milk, lemon and honey have. All studied teas exhibited antioxidant properties. The best DPPH free radical scavengers were green teas. Adding sugar, milk and lemon juice to tea did not significantly impact the antioxidant properties of the infusion; adding honey, however, caused an increase in the total antioxidant capacity of the infusion. The aromatic proton content correlates positively with the antioxidant capacity value. [ABSTRACT FROM AUTHOR]

Abstract: The antioxidant properties of samples of different kinds of commercially available alcoholic beverages were investigated by electron paramagnetic resonance (EPR) spectroscopy. This analytical technique is chiefly designed to enable accurate detection of free radicals. The determination of antioxidant activity by the EPR method is conducted by measuring the changes of the intensity of the EPR spectrum of stable radicals, which results from their interaction with antioxidants. Antioxidant capacity of alcoholic beverages samples was assessed with the use of the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH ). The highest antioxidant activity was found in red wines, followed by a blend of wine and brandy and then by whiskies, whereas plain vodkas and gin showed negative values of antioxidant activity. From our studies it can be concluded that the value of antioxidant capacity depends on the polyphenolic content, the time and method of ageing, as well as on the flavour and colour additives. [Copyright &y& Elsevier]

Glasses containing two different network-forming components and doped with optically active ions exhibit interesting properties. In this work, glass systems based on germanium dioxide and boron trioxide singly doped with lanthanides (Eu3+) and transition metals (Cr3+) ions are research subjects. Optical spectroscopy was the major research tool used to record excitation and emission spectra in a wide spectral range for studied systems. The emitted radiation of glasses doped with Cr3+ ions is dominated by broadband luminescence centered at 770 nm and 1050 nm (4T2 → 4A2). Interestingly, the increase of concentration of one of the oxides contributed to the detectable changes of the R-line (2E → 4A2) of Cr3+ ions. Moreover, EPR spectroscopy confirmed the paramagnetic properties of the obtained glasses. The influence of molar ratio GeO2:B2O3 on spectroscopic properties for Eu3+ ions is discussed. The intensity of luminescence bands due to transitions of trivalent europium ions as well as the ratio R/O decrease with the increase of B2O3. On the other hand, the increase in concentration B2O3 influences the increasing tendency of luminescence lifetimes for the 5D0 state of Eu3+ ions. The results will contribute to a better understanding of the role of the glass host and thus the prospects for new optical materials. [ABSTRACT FROM AUTHOR]

The remarkable variety of glasses doped with transition metal ions is a major reason for the growing popularity of spectroscopic studies to identify their optical properties. This study presents interesting results of analyzing the relationship between structural and optical properties of multicomponent germanate glass systems doped with Cr3+ ions. The chemical composition of the developed glasses was changed as a function of boron oxide and titanium oxide. EPR studies showed that each glass system exhibits two resonance signals in the low and high magnetic fields, respectively. The optical properties of the fabricated glasses were analyzed by recording optical absorption, excitation, and emission spectra. The calculated spectroscopic parameters showed very well the changes of the crystal field strength around Cr3+ ions. The used approach perfectly demonstrates the changes in the profile of the recorded luminescence bands related to the 4T 2 → 4A 2 and 2E → 4A 2 transitions of trivalent chromium ions. These findings set a new direction in infrared photonics because show a way to effectively tune the unique optical properties of Cr3+ ions from the change of the chemical composition of the germanate glassy matrix. • Multicomponent germanate glasses containing titanium dioxide and boron oxide doped with Cr 2 O 3 were prepared. • The properties of Cr3+ ions were studied using EPR and optical spectroscopy. • Selected spectral parameters for Cr3+ were determined owing to the Tanabe-Sugano diagram. • The observed emission bands corresponding to 4T 2.→ 4A 2 and 2E → 4A 2 transition of Cr3+ are located in a broad near-infrared range. [ABSTRACT FROM AUTHOR]