Antioxidant activity of gamma-oryzanol: mechanism of action and its effect on oxidative stability of pharmaceutical oils

Int J Pharm. 2005 Aug 11;299(1-2):146-54. doi: 10.1016/j.ijpharm.2005.05.018.


Gamma-oryzanol, a phytosteryl ferulate mixture extracted from rice bran oil, has a wide spectrum of biological activities; in particular, it has antioxidant properties and is often used in cosmetic formulations as a sunscreen. The first objective of the present investigation was to elucidate the molecular mechanism(s) of the antioxidant activity of gamma-oryzanol by utilising different in vitro model systems, such as scavenging of stable DPPH radical, OH and O2- radicals scavenging, and azocompound AMVN-initiated lipid peroxidation. The effect of gamma-oryzanol on the oxidative stability of vegetable oils of pharmaceutical and cosmetic interest was then evaluated in a oxidation accelerate test and compared with the effect of the well-known antioxidants BHA and BHT. Our results demonstrate that gamma-oryzanol is an organic radical scavenger able to prevent AMVN-triggered lipoperoxidation. Moreover, when added to oils at concentrations ranging between 2.5 and 10 mmol/kg, gamma-oryzanol shows a dose-dependent increase of the induction times; in particular, it improved the oxidative stability of oils very prone to lipoperoxidation because of their high content of polyunsaturated fatty acids. On the ground of our results, we can conclude that gamma-oryzanol may have a potential application for the stabilization of lipidic raw materials.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antioxidants / chemistry*
  • Azo Compounds / chemistry
  • Biphenyl Compounds / chemistry
  • Drug Stability
  • Free Radical Scavengers / chemistry
  • Hydrazines / chemistry
  • Hydroxyl Radical / chemistry
  • Lipid Peroxidation
  • Liposomes / chemistry
  • Nitriles / chemistry
  • Oxidation-Reduction
  • Phenylpropionates / chemistry*
  • Picrates
  • Plant Oils*
  • Superoxides / chemistry


  • Antioxidants
  • Azo Compounds
  • Biphenyl Compounds
  • Free Radical Scavengers
  • Hydrazines
  • Liposomes
  • Nitriles
  • Phenylpropionates
  • Picrates
  • Plant Oils
  • 2,2'-azobis(2,4-dimethylvaleronitrile)
  • Superoxides
  • Hydroxyl Radical
  • 1,1-diphenyl-2-picrylhydrazyl
  • gamma-oryzanol