Content Determination of Functional Composition and Antioxidant Activity from Six Purple Plants

Background: Nowadays, many purple vegetables are available in the market. These vegetables have rich content of anthocyanins, which gives them their characteristic purple color. A high intake of anthocyanin‑rich vegetables/plant parts imparts potential beneficial effects. Therefore, in this study, we investigated six purple plants (SPPs; purple cauliflower, purple potato, purple lettuce, purple carrot, purple beans, and purple tomato) for their content of functional composition and their antioxidant activity. Materials and Methods: Anthocyanins from SPPs were extracted and purified by an optimized process. Then, we determined the total anthocyanin (TA) and cyanidin‑3‑O‑glucoside (C‑3‑G) content in the anthocyanin purified extracts (APEs) from the SPPs through pH difference and high‑performance liquid chromatographic methods, respectively. 2,2‑diphenyl‑1‑picrylhydrazyl and ferric reducing antioxidant power methods were used to test the antioxidant activities of the APEs. In addition, the contents of the total flavonoids, total polyphenol, Vitamin C, and dietary fiber from the SPPs were determined. Results: SPPs are rich in anthocyanins, flavonoids, phenolic acids, and other compounds that show strong antioxidant activity. According to our results, anthocyanin content was the highest in purple cauliflower, which translated into the greatest antioxidant activity of the APEs of purple cauliflower. The content of total flavonoid, polyphenol, and Vitamin C in the purple lettuce was higher than that of the other plants. The highest content of dietary fiber was found in purple potato. Conclusion: According to our results, purple cauliflower is the most potential plants to the pharmaceutical industry. Our results provide a theoretical basis for further exploration of efficacy of the purple plants and exploitation.