Potent antioxidative and antigenotoxic activity in aqueous extract of Japanese rice bran--association with peroxidase activity.
To estimate the preventive potential of Japanese rice bran (Oryza sativa japonica) against the oxygen radical-related chronic diseases such as cardio-vascular diseases and cancer, antioxidative and antigenotoxic activities of the rice bran extracts were analyzed by using assay systems for lipid peroxidation and genotoxin-induced umu gene expression. When effects of the rice bran extracts under different extraction conditions on hydroperoxide generation from auto-oxidized linoleic acid were examined using aluminum chloride method, the water extract showed strong antioxidant activity, but the methanol and acetone extracts did not exhibit significant activity. The water extract of rice bran was divided into the ethanol-precipitable (EP) and supernatant fractions, and EP fraction showed the dominant antioxidant activity, but the supernatant fraction did not exhibit significant antioxidant activity. When the effect of EP fraction on umu C gene expression in SOS response associated with DNA damage in Salmonella typhimurium (TA 1535/pSK 1002) induced by 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) was analyzed, it showed a dose-dependent suppressive activity against Trp-P-1-induced umu C gene expression. The bio-chemical analysis of EP fraction indicates that the major antioxidative and antigenotoxic activity of EP fraction is associated with a proteinous component with the molecular weight of more than 30 KDa. As a possible active principle for the antioxidative and antigenotoxic activity in EP fraction, the strong activity of an oxygen radical-scavenging enzyme, peroxidase was detected, and the purified horseradish peroxidase also caused the similar antioxidative and antigenotoxic activities. The significance of this finding is discussed from the viewpoint of the preventive role of rice bran against oxygen radical-related chronic diseases.
Higashi-Okai
Kiyoka
K
Department of Food and Nutrition, Hiroshima Jogakuin University, Ushita-Higashi, Higashi-Ku, Hiroshima 732-0063, Japan.
Kanbara
Keiko
K
Amano
Kanako
K
Hagiwara
Akiko
A
Sugita
Chie
C
Matsumoto
Norie
N
Okai
Yasuji
Y
D016587:Antimutagenic Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D001426:Bacterial Proteins / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006735:Horseradish Peroxidase / Q000494:pharmacology; D006801:Humans; D012275:Oryza; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D013014:SOS Response, Genetics; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000235:genetics
D016587:Antimutagenic Agents; D000975:Antioxidants; D001426:Bacterial Proteins; D010936:Plant Extracts; D006735:Horseradish Peroxidase