Sorbus domestica L. leaf extracts as functional products: phytochemical profiling, cellular safety, pro-inflammatory enzymes inhibition and protective effects against oxidative stress in vitro

The work combines detailed chemical profiling (UHPLC-PDA-ESI-MS3, HPLC-PDA, UV-spectrophotometric) and in vitro activity testing to provide the first comprehensive characteristics of leaves of the fruit plant S. domestica as a source of bioactive extracts used for the treatment of oxidative stress/inflammation-related pathologies. Polyphenol-rich (44 analytes, total content up to 700.0 ± 19.7 mg/g) extracts, obtained by fractionated extraction, were highly-efficient antioxidants (tests: DPPH, FRAP, TBARS) and anti-inflammatory agents (lipoxygenase and hyaluronidase inhibitors). Moreover, at in vivo-relevant levels (1-5 µg/mL) they effectively protected human plasma components against peroxynitrite-induced oxidative damage (reduced the levels of 3-nitrotyrosine, lipid hydroperoxides and thiobarbituric acid-reactive substances) and normalised/enhanced the total antioxidant status of plasma. Concentration- and phenolic-dependence was clearly evidenced for all models. Furthermore, the extracts were found safe in cytotoxicity test on human PBMCs. The defatted methanol-water (7:3, v/v) extract and its organic solvents fractions were demonstrated as the most advantageous for future applications.