Superoxide- and 1,1-Diphenyl-2-picrylhydrazyl Radical-scavenging Activities of Soyasaponin β g Related to Gallic Acid

Abstract

Soyasaponin β g at 1 mM had 8% scavenging activity for O₂ ^-, and 25 μM β scavenged 20.9% for the DPPH radical (IC₅₀: 63.8 μM). In the soyasaponin β g-gallic acid system, synerigistic effects were observed at a low level of gallic acid concentration. The spin density distribution calculated by the MNDO/AM1 method showed unpaired electron localization on the carbons at C-4 and C-6, and on the ketone group at C-4 of the DDMP moiety. Furthermore, for soyasaponin β g, the MNDO/AM1 method gave an ionization potential of 8.38 eV, electron affinity of 1.16 eV and Mulliken electronegativity of 4.77 eV. Based on this evidence, the synergistic antiradical effects of the soyasaponin β g-gallic acid system are assumed to involve two-electron reduction from gallic acid.

• superoxide
• 1,1-diphenyl-2-picrylhydrazyl radical
• soyasaponin β g
• triterpenoid
• Leguminosae