The antioxidant activities of two crude extracts ($CH_2Cl_2$ and MeOH) and their solvent fractions (n-hexane, 85% aq. MeOH, n-BuOH, and $H_2O$ fractions) from Corydalis heterocarpa were determined by evaluating authentic $ONOO^-$ and $ONOO^-$ generated from SIN-1 (3-morpholinsydnonimine) in vitro as well as by measuring the degree of occurrence of intracellular reactive oxygen species (ROS) and nitric oxide (NO). Scavenging activities of solvent fractions on authentic $ONOO^-$ increased in the order of n-BuOH > 85% aq. MeOH > $H_2O$ > n-hexane fractions, while those on $ONOO^-$ generated from SIN-1 increased in the order of n-BuOH > 85% aq. MeOH > $H_2O$ > n-hexane fractions. In addition, all solvent fractions effectively inhibited the intracellular ROS and NO levels. The n-BuOH fraction especially exhibited the strongest ROS scavenging effect. Further purification of n-BuOH fraction led to the isolation of cnidimoside A, which presented the potent ROS scavenging effect at $10\;{\mu}M$. From these results, extracts of C. heterocarpa and its component, cnidimoside A, were predicted to be potentially useful as ingredients for protecting against oxidation.

Keywords: Corydalis heterocarpa, cnidimoside A, nitric oxide, reactive oxygen species, peroxynitrite