Comparison of Chemical Profiling and Antioxidant Activities of Fruits, Leaves, Branches, and Flowers of <i>Citrus grandis</i> ‘Tomentosa’

<i>Citrus grandis</i> ‘Tomentosa’ (CGT) is particularly cultivated in China and widely used in health foods. In this study, the chemical profiles of different parts of CGT were comprehensively compared by rapid resolution liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry method. A total of 22 compounds were identified and two <i>C</i>-glucosyl flavones were found for the first time in CGT. Four main constituents (rhiofolin, naringin, meranzin hydrate, and isoimperatorin) in different parts of CGT were simultaneously determined. Overall, the contents of the four main compounds decreased with the ripening process. In parallel, the antioxidant activities of their extracts were also evaluated by three assays (2,2′-azinobis­(3-ethylbenzthiazolinesulfonic acid) diammonium salt, 2,2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power), and the results indicated a similar tendency: small fruit > flower ∼ medium fruit > large fruit > leaf ∼ branch. The results obtained in the present work may provide useful information for future utilization of CGT