Quantification and analysis of anthocyanin and flavonoids compositions, and antioxidant activities in onions with three different colors

摘要

Onion(Allium cepa L.) is a very important vegetable crop widely cultivated throughout the world. In this study, we measured total anthocyanins and flavonols of onions of three colors. The fresh weight(FW) of total anthocyanins were(29.99±1.19),(9.64±1.30) and(0.75±0.40) mg 100 g^(–1) fruit in red, yellow and white onions, respectively. Likewise, the FW of total flavonoids were(111.10±5.98),(36.64±3.59), and 0 mg 100 g^(–1) in red, yellow and white, respectively. Four types of anthocyanins(delphinidin 3,5-diglycosides, cyanidin 3,5-diglycosides, cyanidin 3-glycosides and cyanidin 3-(6′′-malonyl)-glucopyranoside) and two kinds of flavonoids(quercetin and quercetin 3-glycosides) were identified in two varieties(red and yellow bulb) of onions by HPLC/DAD-ESI/MS. The total polyphenol contents were also measured by means of Folin-Ciocalteu method. Moreover, all the concentrations of anthocyanins, flavonoids and polyphenols showed significantly positive correlations with antioxidant activities measured by DPPH˙, ABTS˙+ and FRAP assays. This study provided information on anthocyanin and flavonoids compositions that will be useful for onion breeding.