Comparison of the chemical-antioxidant profiles of different parts of Citrus reticulata Blanco (Rutaceae) based on OLE-HPLC-DAD-MS/MS-ABTS assay

Given the safety of synthetic antioxidants, people are increasingly inclined to develop and use natural antioxidants. However, rapid screening and identification of active ingredients from the complex systems of natural products is one of the major challenges for the modernization of traditional Chinese medicine. In this study, online extraction-high performance liquid chromatography-diode array detection-quadrupole time-of-flight mass spectrometry coupled with ABTS antioxidant assay (OLE-HPLC-DAD-QTOF-MS/MS-ABTS), in which sample preparation, separation, detection and antioxidant assay were integrated in a single step, was used to rapidly identify antioxidant components from the different parts of Citrus reticulata, including its peels, leaves, vascular bundies and seeds. After method validation (system adaptability, extraction yield and repeatability), the four samples of different botanical parts were analyzed. As a result, among 49 found chromatographic peaks, 33 peaks displayed varying degrees of antioxidant activity and 39 peaks were tentatively or unambiguously identified based on their retention time, UV spectrum and mass spectrometry information and the comparison with reference substance and data in literature, including 10 phenolic acids, 9 polymethoxy flavonoids, 7 flavonoid-O-glycosides and 13 other ingredients. It is concluded that the established method is simple, fast, and reliable, which not only saves the materials and solvents as well as time, but also reduces the risk of degradation of chemical components during the extraction process, suitable for rapid screening and identification of antioxidant components of complex mixture.