2003 年 52 巻 1 号 p. 15-23
Laccase, a kind of polyphenoloxidase, was found to oxidize unsaturated triacylglycerol under mild reaction conditions in the presence of mediators that generate relatively stable radicals or cation species. 2,2′-Azinobis(3-ethylbenzthiazoline-6-sulfonate), 1-hydroxybenzotriazole, syringaldehyde, 2,4-pentanedione and phenothiazine were used as mediators. The oxidized products were characterized by UV- and IR- spectroscopic analyses, ferric thiocyanate peroxide analysis and size exclusion chromatography. It was considered that conjugated diene peroxide units were formed in triacylglycerol without substantial polymerization or degradation reactions of the main chain in the fatty acid residual group. Under the same reaction conditions as for triacylglycerol, linolenic acid and linoleic acid, which constitute triacylglycerol, were also oxidized by the laccase/mediator system, but lower and higher molecular weight portions were formed. The former portion is considered as a degradation product of the corresponding peroxidized unsaturated fatty acid by fractionation followed by gas chromatography/mass spectrometry analysis.
