Objective  Anti-peroxidation effect of the flavonoids extracted from fruits of Ligustrum obtusifolium on lipids was investigated.

  Method  Scavenging capacities of the crude extract on DPPH· and hydroxyl (·OH) free radicals were tested using spectrophotometry. Effects of the flavonoids on the malondialdehyde (MDA) content in rat liver homogenate upon spontaneous oxidation or peroxidation by either FeSO₄ or H₂O₂ induction and the mitochondrial swelling on rat liver induced by Fe²⁺ and ascorbic acid (Vc) as well as the hemolysis of red blood cells (RBCs) induced by H₂O₂ were assessed in vitro. And the activity of the catalase (CAT) and glutathione peroxidase (GSH-Px) and the level of the glutathione (GSH) were tested in vivo.

  Result  The flavonoid extract exhibited abilities in scavenging DPPH· and ·OH free radicals with IC₅₀ of (0.45±0.01) g·L⁻¹ and (1.57±0.12) g·L⁻¹, respectively. From the concentration of 1.0 g·L⁻¹ to 6.0 g·L⁻¹, the extract significantly reduced the in vitro MDA in rat liver homogenate under spontaneous oxidation; from 0.5 g·L⁻¹ to 6.0 g·L⁻¹, under FeSO₄ induction; and, from 2.0 g·L⁻¹ to 6.0 g·L⁻¹ under H₂O₂ induction. From 0.5 g·L⁻¹ to 10.0 g·L⁻¹, the flavonoids also suppressed the liver mitochondrial swelling induced by Fe²⁺ and Vc; while, from 2.0 g·L⁻¹ to 10.0 g·L⁻¹, the RBC hemolysis induced by H₂O₂, and those from 0.6 g·L⁻¹ to 4.0 g·L⁻¹ could enhance the level of CAT, GSH, and GSH-Px.

  Conclusion  The crude flavonoid extract from the fruits of L. obtusifolium significantly inhibited in vitro on both spontaneous and induced lipid peroxidation reducing the oxidative damage on the mitochondria and RBCs of rat liver, and enhance the acitivity of antioxidant enzymes and the content of non-enzyme antioxidants. The results suggested a promising potential in developing a natural antioxidant from the fruits.