Qualitative and quantitative analysis of phenolic compounds in blueberries and protective effects on hydrogen peroxide‐induced cell injury

This work was conducted to optimize an accelerated solvent extraction for ultra high performance liquid chromatography-mass spectrometry/mass spectrometry analysis of blueberry phenolic compounds. The conditions for accelerated solvent extraction were verified using response surface methodology to obtain the following optimized conditions: ethanol concentration (pH = 3), 48%; temperature, 50℃, and static cycle times, 3. Further, ultra high performance liquid chromatography with quadrupole Exactive Orbitrap mass spectrometry and ultra high performance liquid chromatography with triple-quadrupole tandem mass methods for determination of the detailed phenolic composition were developed and validated. Total of 81 phenolic compounds were identified by ultra high performance liquid chromatography with quadrupole Exactive Orbitrap mass spectrometry including 23 anthocyanins, 32 flavonols, 11 proanthocyanidins, 2 other flavonoids, and 13 phenolic acids. Fifty-one of these compounds have been simultaneously quantified by ultra high performance liquid chromatography with triple-quadrupole tandem mass including 31 anthocyanins, 8 flavonols, 6 proanthocyanidins, 2 other flavonoids, and 8 phenolic acids. Malvidin-dinhexoside has, for the first time, been detected in wild. Moreover, by verifying the protection on PC12 cells against oxidative damage, it was showed that the phenolic extracts (500 µg/mL) can improve significantly the viability (9.26-24.78%) of hydrogen peroxide-induced PC12 cells, activities of superoxide dismutase (34.59-37.90 U/mg) and glutathione peroxidase (6.87-14.42 mU/mg) and decrease the content of malonic dialdehyde (13.27-24.62 nmol/mg). Correlation analysis suggested that anthocyanins might contribute most to these activities.