HPLC-UV-MS Profiles of Phenolic Compounds and Antioxidant Activity of Fruits from Three Citrus Species Consumed in Northern Chile

摘要

Peels and edible pulp from three species of citrus including Citrus aurantifolia (varieties pica and sutil) and Citrus x lemon var. Genova widely cultivated and consumed in Northern Chile (I and II region) were analyzed for phenolic compounds and antioxidant activity for the first time. A high performance electrospray ionization mass spectrometry (HPLC-UV-ESI-MS) method was developed for the rapid identification of phenolics in extracts from peels and juices of all species. Several flavonoids including one kaempferol-O-hexoside (peak >16) and one hesperidin derivative (peak >22) three quercetin derivatives (peaks >4, >19 and >36), five isorhamnetin derivatives (peaks >5, >23, >24, >26 and >29) four luteolin derivatives (peaks >14, >25, >27 and >40), seven apigenin derivatives (peaks >2, >3, >12, >20, >34, >35 and >39), seven diosmetin derivatives (peaks >7–>9, >17, >21, >31 and >37), three chrysoeriol derivatives (peaks >10, >18 and >30), and four eryodictiol derivatives (peaks >6, >13, >15 and >38) were identified in negative and positive mode using full scan mass measurements and MSⁿ fragmentations. Ascorbic acid content was higher in the pulps of the varieties Genova and Sutil (60.13 ± 1.28 and 56.53 ± 1.06 mg ascorbic acid per g dry weight, respectively) while total phenolic content was higher in Pica peels followed by Sutil peels (34.59 ± 0.81 and 25.58 ± 1.02 mg/g GAE dry weight, respectively). The antioxidant capacity was also higher for Pica peels (10.34 ± 1.23 µg/mL in the DPPH assay and 120.63 ± 2.45 µM trolox equivalents/g dry weight in the FRAP assay). The antioxidant features together with the high polyphenolic contents can support at least in part, the usage of the peel extracts as nutraceutical supplements, especially to be used as anti-ageing products.