Highly pigmented vegetables: Anthocyanin compositions and their role in antioxidant activities

Abstract

Twelve highly pigmented (red or purple) vegetables (carrots, cabbage, cauliflower, potatoes, onions, asparagus and eggplant) were investigated for their total anthocyanin contents (TAC) and compositions of the individual anthocyanins and anthocyanidins by UPLC and LC–DAD–ESI–MS, and their antioxidant activities by DPPH, FRAP (ferric reducing antioxidant power) and ORAC (oxygen radical absorption capacity) assays. While a total of 26 anthocyanins were identified, the main aglycones were only found to be limited to 4 anthocyanidins (cyanidin, petunidin, pelargonidin and delphinidin). The TAC ranged from 0.08 to 2.01mg Cyanidin-3-glucoside (C3G)/g DW and the total phenolic contents (TPC) was from 1.30 to 2.19mg GAE/g DW suggesting that anthocyanins were the main phenolics in certain vegetables but not others. DPPH radical scavenging activities were 54.91–81.94%, FRAP values 10.00–70.07μmol AAE/g DW and ORAC values were 3.74–189.32μmol TE/g DW. The two cruciferous vegetables (purple cauliflower and cabbage) showed the highest TPC, TAC, DPPH and FRAP values, and the onions the lowest. The antioxidant activities in the DPPH and FRAP assays correlated well with the TPC and TAC, but ORAC did not. Results of this study are comparable and provide a rapid and effective method for the identification and quantification of all major anthocyanidins and their glycosides (anthocyanins), and how they might contribute to the antioxidant activity, therefore important information in developing anthocyanin-rich nutraceuticals and functional foods.