Purification and characterization of an antioxidant peptide (GSQ) from Chinese leek (Allium tuberosum Rottler) seeds

A peptide with antioxidant activity was purified from Chinese leek seeds by successive chromatographic methods. The sequence was determined as Gly-Ser-Gln (290.10 Da) by LC-MS/MS. This purified peptide, discovered for the first time from Chinese leek seeds and designated as CLP-2, could efficiently quench free radicals and exhibit moderate reducing power. The concentrations for 50% activities for its radical scavenging effect against DPPH, ABTS+ and O2− were 0.61, 0.04 and 0.70 mg/mL, respectively. In addition, the peptide protected LO2 cells against hydrogen peroxide-induced damage at a concentration of 10 µg/mL. Furthermore, CLP-2 inhibited growth of Gram-negative and Gram-positive bacteria.