Abstract:

Kidney bean peptides (KBP) were fractionated by gel filtration on SephadexG-50.The antioxidant and free radicalscavenging activities of three KBP fractions (Fra-A, Fra-B, Fra-C) were investigated using reducing power and 1,1-diphenyl- 2-pycrylhydrazyl (DPPH)/superoxide/hydroxyl radical-scavenging assay. The reducing power activity of Fra-C (RP50 2.263 mg/mL) was lower than that of ascorbic acid (RP50 0.828 mg/mL). Fra-C showed the strongest scavenging activity against DPPH, superoxideanion and hydroxyl radicals. The radical-scavenging effect was in a dose-dependent manner and the EC50 values for DPPH, superoxide and hydroxyl radicals were found to be 2.301, 2.553 mg/mL and 1.386 mg/mL, respectively. The amino acid analysis showed that Fra-C had a hydrophobic amino acid content of 36.78% and a hydrophobicity of 364.73 kcal/mol.The molecular weight distribution of Fra-C was found to mainly vary from 100 to 1000. The antioxidant activity of Fra-C is clearly related to the amino acid composition, the content of THAA and the molecular mass.

Key words: kidney bean peptides (KBP), antioxidant activity, free radical-scavenging activity, amino acid composition, molecular weight distribution