Phenolics in Citrus aurantium fruit identified by UHPLC-MS/MS and their bioactivities

Sour orange ( Citrus aurantium ) is a popular fruit with health benefits. Phenolics are the dominant bioactive compounds in this fruit. However, the full phenolics composition remains unclear. In this work, UHPLC-MS/MS was used to qualify and quantify the phenolics in sour orange fruits of cv. Morocco (MSO) and United (USO). Fifty-eight phenolics, including 26 flavonoid glycosides , 22 polymethoxylated flavonoids, 8 coumarins and 2 phenolic acids , were identified. Four limonoids were characterized. Flavonoid glycosides were the leading phenolics in MSO, while polymethoxylated flavonoids (including nobiletin, tangeritin and sinensetin) were dominant in USO. The phenolic extracts showed good antioxidant activities . USO extract had a significantly ( p  < 0.05) stronger neuroprotective activity than MSO extract. Auraptene, nobiletin and tangeritin were highly responsible for the neuroprotective activity. The results were helpful for the development of functional foods with sour orange.