Abstract: The chlorogenic acids and isochlorogenic acid A,B and C from Gynura procumbens (Lour.) Merr.was extracted and its structural identification.The antioxidant activities of chlorogenic acids and isochlorogenic acid A,B and C were evaluated by spectrophotometry on its ability of scavenging DPPH·,·OH and O₂^-·.The result showed that the contents of prepared chlorogenic acids and isochlorogenic acids A,B and C were 96.8%、98.2%、97.6% and 98.7%,respectively.The chlorogenic acid and isochlorogenic acid A,B and C had well scavenging activity to DPPH· and ·OH in the range of experimental concentration,and with the concentration increases,it increases gradually.But when the concentration increased from 5 to 100 μg/mL,the ability of scavenging O₂^-· had no obvious dose dependence,and compared with the positive control group (V_C),the effect was significantly weaker.The chlorogenic acids and isochlorogenic acid A,B and C from Gynura procumbens (Lour.) Merr had different antioxidant activities.

Key words: Gynura procumbens (Lour.) Merr, chlorogenic acid, isochlorogenic acid, antioxidant activities