Introduction. Flavanonol dihydroquercetin (DHQ) is known for its pronounced antioxidant properties, which are associated with a wide range of biological activity of this compound. Due to the presence of two chiral centers at positions 2 and 3 of the benzopyranone ring, this flavonoid is characterized by the phenomenon of cis-trans isomerism. However, a comparative analysis of the antioxidant properties of DHQ diastereomers has not been performed before. Aim. To evaluate the effect of diastereomeric composition on the reducing and radical scavenging properties of DHQ samples. Materials and methods. The diastereomeric composition of the DHQ samples was controlled under reverse phase chromatography with UV detection. The antioxidant capacity was studied using a model of inhibition of radical cations of 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS ^+• ). The reducing ability of the DHQ samples was evaluated using a 5-(2,4-disulfophenyl)-3-(2-methoxy-4-nitrophenyl)-2-(4-nitrophenyl)-2 H -tetrazolium monosodium salt (WST-8) model. Both tests were performed under the control of UV spectrophotometry. Results and discussion. The chromatograms of the samples obtained at 288 nm are characterized by two peaks with retention times of 18.79 ± 0.08 and 19.87 ± 0.08 min, which correspond to trans - and cis -diastereomers of DHQ. After 6 minutes of DHQ samples containing 0.8, 3.7, and 9.5 % of the cis-isomer adding to the ABTS ^•+ solution, the optical density at 730 nm decreased by 0.588 ± 0.008, 0.581 ± 0.017, and 0.602 ± 0.012, respectively (α 0.05, p 0.2196, r 0.7857), while in WST-8 solutions at 450 nm for similar samples, an increase in optical density was observed by 0.178 ± 0.030, 0.222 ± 0.026, and 0.188 ± 0.036, respectively (α 0.05, p 0.5157, r 0.0284). Conclusion. These results indicate that there is no significant effect of the diastereomeric composition on the antioxidant properties of the DHQ samples. Thus, the observed differences in the pharmacology of cis - and trans -DHQ should be explained by the selectivity of interaction with biological targets, rather than the free radicals scavenging activity.

Herein, an automated, parameter-based workflow is introduced for processing time-resolved high-resolution mass spectrometry (HRMS) data. Its utility is demonstrated using the reaction between the ABTS^•+ radical cation and the polyphenolic antioxidant naringenin. Data were collected using HRMS coupled to high-performance liquid chromatography (HPLC) in negative ion mode. The algorithm compares sequential time-resolved HRMS measurements to generate kinetic curves and calculate parameters for every detected species. Based on these curves and parameters, we can tentatively classify each species as a reagent, intermediate, or product. The algorithm was implemented as Java-based software. As a result, extensive data arrays of 1.3 million m/z-intensity pairs per experimental series were processed automatically. The workflow generated manageable candidate sets in each replicate series. Cross-replicate matching using a 5 ppm mass tolerance retained 29 ion tracks consistently detected in all three reaction runs for subsequent analysis. These ions can then be examined manually to identify compound structures. Overall, the approach provides a screening tool for untargeted reaction monitoring and supports subsequent structural annotation in complex chemical systems.