Identification of radical scavenging ability and active ingredient of the hot water extract of Forsythia viridissima

Elimination of oxidizing agents is an effective way to reduce oxidative stress levels. 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay is generally used to determine antioxidant activity.

The aims of the present study were to evaluate the antioxidant activity of hot water extract of Forsythia viridissima dried fruit by DPPH assay and to identify the potential active antioxidant ingredient.

The DPPH radical scavenging activity of the extract was compared to that of L-ascorbic acid (standard). The RC₅₀ values (concentration required for a 50% reduction of radicals) of the water extract and ascorbic acid were 556.7±13.0 μg/mL and 103.4±2.6 μg/mL, respectively. The analysis of the extract using ultra-high–performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-ESI-Q-TOF/MS) revealed eight compounds. Among them, only the peak area of quercetin-3-O-rhamnoside was found to decrease in a concentration-dependent manner following the DPPP and FVe reaction. Mechanism has not been elucidated yet, but there are many reports that the reaction of DPPH with antioxidants leads to a decrease in the HPLC peak. In addition, we also confirmed the decrease in HPLC peak after reaction with DPPH using L-ascorbic acid and caffeic acid. Thus, accumulated evidence by in vitro test suggests that peak decrease is associated with radical scavenging activity in the presence of quercetin-3-O-rhamnoside.

In this study, the potential antioxidant activity of was confirmed by DPPH assay and quercetin-3-O-rhamnoside was found to be highly related to DPPH radical scavenging activity. An antioxidant study of quercetin-3-O-rhamnoside against oxidative damage of DNA, proteins, and lipids has been planned for the future.

• References

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