Antioxidant mechanism studies on ferulic acid: identification of oxidative coupling products from methyl ferulate and linoleate.

In our studies of the chain-breaking antioxidant mechanism of natural phenols in food components, ferulic acid, a phenolic acid widely distributed in edible plants, especially grain, was investigated. The radical oxidation reaction of a large amount of ethyl linoleate in the presence of the methyl ester of ferulic acid produced four types of peroxides as radical termination products. The isolation and structure determination of the peroxides revealed that they had tricyclic structures which consisted of ethyl linoleate, methyl ferulate, and molecular oxygen.

[Utilization of school lunch dietary data to estimate theoretical maximum daily intake (TMDI) of selected pesticide residues].

Objectives: The theoretical maximum intake values of pesticides by body weight (TMI) were estimated for school children and the differences in district and age-group were compared. Furthermore TMI values for children (7-11 years old) were calculated from Japanese National Nutrition Survey (NNS) data. Our TMI values for school children were compared with those from NNS data and evaluated to assess whether our values were appropriate for use in the calculation of theoretical maximum of daily intake (TMDI) of the pesticides.

Simple detection method of powerful antiradical compounds in the raw extract of plants and its application for the identification of antiradical plant constituents.

A simple detection method for a powerful radical scavenging compound in a mixture containing a large variety of compounds, such as the raw extract of edible plants, was developed using 1,1-diphenyl-2-picrylhydrazyl (DPPH) as the radical reagent. The method was established on the basis of the features of the typical chain-breaking antioxidation reaction mechanism, which suggests that the radical scavenging antioxidant should be converted to other stable nonradical compounds during the reaction. This method requires only a simple HPLC instrument, and the disappearance or decrease in the peak intensity, which is induced by the addition of DPPH.

Recovery mechanism of the antioxidant activity from carnosic acid quinone, an oxidized sage and rosemary antioxidant.

A solution of carnosic acid quinone, which is a radical chain-termination product having no antioxidant activity in the antioxidant reaction of carnosic acid, recovers potent antioxidant activity upon standing. The HPLC analysis of an aged solution of carnosic acid quinone revealed that several antioxidants are produced in the solution. From the time-course and quantitative analyses of the formation of the products and their structural analysis, an antioxidant mechanism from carnosic acid quinone is proposed that includes a redox reaction of carnosic acid quinone in addition to the isomerization to lactone derivatives.

Structural identification of new curcumin dimers and their contribution to the antioxidant mechanism of curcumin.

As a part of the research project on the elucidation of the chain-breaking antioxidant mechanism of natural phenolics against the oxidation of food components, curcumin, a main turmeric pigment, was investigated. A relatively high concentration of curcumin gave three dimers as radical termination products in addition to the coupling products with curcumin and the lipid hydroperoxide. The structural analysis of these dimers and quantitative analysis of their production rates revealed that radical-radical termination mainly occurred at the 2-position of curcumin.