J Agric Food Chem. 2020 Jan 1. Epub 2020 Jan 1. PMID: 31893634
Health Benefit of the Flavonoids from Onion: Constituents and Their Pronounced Antioxidant and Anti-neuroinflammatory Capacities.
Onion is the most widely cultivated vegetables around the world. In this study, the isolation, concentration, quantification and bioactivity evaluation of the phenolics in onion peels were investigated. Thirty-four phenolics, including 17 flavonoids and 17 non-flavonoids phenolics, were purified and identified. Among them, there were 2 new unusual epoxyflavanones and a new phenolic, as well as 13 unreported constituents from the genus of Allium. The total flavonoids were concentrated and finally obtained 90.25% flavonoids content extract. Fifteen main flavonoids were quantified using UPLC-PDA, and quercetin (36.94%) and quercetin 4-O-β-D-glucopyranoside (15.81%) were the richest flavonoids in content. The antioxidant and anti-neuroinflammatory capacities were evaluated and the bioactive results indicated that the flavonoids in onion exhibited pronounced activities. The study suggested that the flavonoids in onion peels could be used in functional food.