Onion Extract Other Name: Allium Cepa Extract Botanical Source: Allium Cepa L. Plant Part Used: Bulb Specifications: Spiraeoside 30%; Quercetin 2%~95%; Rutin 5%~30%. In onion, spiraeoside (quercetin-4′-O-β-D-glucoside), rutin and quercetin and 3 other not identified compounds were found as the major constituents. Significant cultivar differences were found in total polyphenol and main flavonoid antioxidants. And during storage, an increase in flavonoids could be observed, especially at a laboratory temperature (22°C) compared to storage at a lower temperature.