Alliuocide A: a new antioxidant flavonoid from Allium cepa L

Re-investigation of the EtOAc fraction of the dried outer scales ofAllium cepa L. afforded one new flavonoid; alliuocide A (6), together with five known compoundds. Their structures were established by UV, IR, 1D (1H and 13 C), and 2D (1H-1H COSY, HMQC and HMBC) NMR, in additio n to mass spectroscopy and comparison with literature data. All the isolated compounds were tested for their antioxidant activity using DPPH assay. Compounds 3,5 and 6 showed high antioxidant activeity, while 1,2, and 4 had moderate activity.