Quantitative Interrelation between Atractylenolide I, II, and III in Koidzumi Rhizomes, and Evaluation of Their Oxidative Transformation Using a Biomimetic Kinetic Model.

Analytical methods based on ultraperformance liquid chromatography/ion-trap mass spectrometry (UPLC/ion-trap MS) were developed for quantification of atractylenolide I, II, and III in the methanol extract of rhizomes with a C column in an acidified water/acetonitrile gradient eluent in an LC system, and ion-trap MS coupled with electrospray ionization was employed under positive-ion mode. The three atractylenolides were quantified in all samples, and the content of atractylenolide I, II, and III showed a significant correlation to each other. Such high correlation was explained by the mechanistic insights into the biosynthetic pathway of atractylenoide III and I from atractylenoide II by using the biomimetic cytochrome P450 model, [Fe(tmp)](CFSO) (tmp = -tetramesitylporphyrin). Atractylenolides could be transformed by oxidation via the oxidative enzyme in the plant. The present study first reports the first oxidative transformation of atractylenolides using the heme iron model complex.