Antioxidant activity of gamma-oryzanol: mechanism of action and its effect on oxidative stability of pharmaceutical oils.
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.
Juliano
Claudia
C
Dipartimento di Scienze del Farmaco, Via Muroni 23/A, University of Sassari, Sassari, Italy. julianoc@uniss.it
Cossu
Massimo
M
Alamanni
Maria Cristina
MC
Piu
Luisella
L
D000975:Antioxidants / Q000737:chemistry*; D001391:Azo Compounds / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry; D004355:Drug Stability; D016166:Free Radical Scavengers / Q000737:chemistry; D006834:Hydrazines / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D015227:Lipid Peroxidation; D008081:Liposomes / Q000737:chemistry; D009570:Nitriles / Q000737:chemistry; D010084:Oxidation-Reduction; D010666:Phenylpropionates / Q000737:chemistry*; D010851:Picrates; D010938:Plant Oils; D013481:Superoxides / Q000737:chemistry
D000975:Antioxidants; D001391:Azo Compounds; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D006834:Hydrazines; D008081:Liposomes; D009570:Nitriles; D010666:Phenylpropionates; D010851:Picrates; D010938:Plant Oils; C055792:2,2'-azobis(2,4-dimethylvaleronitrile); D013481:Superoxides; D017665:Hydroxyl Radical; C004931:1,1-diphenyl-2-picrylhydrazyl; C013172:gamma-oryzanol