The levels of bioactive ingredients in Citrus aurantium L. at different harvest periods and antioxidant effects on H2O2‐induced RIN‐m5F cells

BACKGROUND Citrus aurantium L. (Aurantii fructus) is a multi-purpose citrus fruit with high medicinal and nutritional value, but currently there is no data that can be used to investigate its appropriate harvest time to obtain high-quality citrus bioactive ingredients. RESULTS Phytochemicals and levels of the main bioactive ingredients were investigated by UHPLC-ESI-Q-TOF/MS. The contents of flavanones, polymethoxyflavones, coumarins, synephrine, and limonin in citrus fruit were analyzed at different harvest periods, and significant differences ranging from 0.03 ± 0.01 to 116.26 ± 40.20 g kg-1 (DW) were shown. These compounds were present in higher amounts in June and then decreased gradually, while biomass accumulation of most of them showed an increasing tendency along the harvest times. The H2 O2 -induced RIN-m5F cells model was employed to evaluate their antioxidant capacity. Citrus fruit harvested from June 11 to July 7 possessed an excellent antioxidant capacity by inhibiting the intensity of intracellular reactive oxygen species (ROS) (p < 0.01) and improving superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH) activities (p < 0.01). In addition, chemical compositions and antioxidant capacities of citrus leaves, stems, and roots were evaluated, and these showed great variation compared with citrus fruits. Multivariate statistical analysis indicated that harvesting time was related closely to the phytochemical contents and antioxidant capacity. CONCLUSION Citrus fruit can be appropriately harvested from June to early July when the levels of bioactive ingredients and antioxidant activity reach higher values. This research provides practical information for producing high-quality citrus products. This article is protected by copyright. All rights reserved.