The Protective Effect of Boschnikia rossica Extract on Free Radical-Induced Oxidative Damage of Biomolecules and Establishment of a Method for Determining the Content of Oleanolic Acid

Oxidative stress-induced damage to biomolecules such as proteins, lipids, and DNA is closely related to chronic diseases. Developing efficient, low-toxicity, and multi-target natural antioxidants has become an important research direction in food and medicine. This study established a detection method for oleanolic acid (OA) content in <i>Boschnikia rossica</i> extract (BRE). It systematically evaluated the in vitro antioxidant activity and protective effect of <i>Boschnikia rossica</i> extract on oxidative damage of biomolecules. Firstly, the detection method based on RP-HPLC has improved the problem of low separation efficiency and high interference in detecting OA in <i>Boschnikia rossica</i>. The optimal analysis conditions were obtained by optimizing the chromatographic conditions: the chromatographic column was Agilent TC-C₁₈ (250 mm × 4.6 mm, 5 μm); the mobile phase was methanol/0.4% phosphoric acid aqueous solution (85/15, <i>v</i>/<i>v</i>), pH 2.14; the column temperature was 20 °C; the flow rate was 1.2 mL/min; and the detection wavelength was 220 nm. Under these conditions, the linear relationship of OA was good within the concentration range of 100-800 mg/L, with a recovery rate of 98.88-101.46% and RSD less than 2%. The content of OA was 0.358 mg/g. Next, the in vitro antioxidant effect of BRE was tested, and it was found that BRE had reasonable scavenging rates against ABTS, DPPH, and hydroxyl radicals, with IC₅₀ values of 224.32 mg/L, 58.43 mg/L, and 432.21 mg/L, respectively. In addition, BRE had significant inhibitory effects on protein oxidative degradation, carbonylation modification, lipid oxidation, and DNA oxidative damage induced by different free radicals. Finally, BRE can be a natural alternative to synthetic antioxidants and has important application value in delaying food oxidation and developing anti-aging functional foods.