DECOMPOSITION OF α-TOCOPHERYL SPIRODIMER BY ALKALINE SAPONIFICATION

An alkaline saponification method containing pyrogallol is usually applied for the determination of tocopherols. Although there are some metabolites of α-tocopherol in tissues, it is not yet clear whether they are true metabolites or degradation products from the alkaline saponi-fication. Since it was shown that α-tocopheryl spirodimer, a metabolite of α-tocopherol, was degraded mainly to a substance positive to Emmerie-Engel reagent, the identification of this substance was carried out. As the model compound of α-tocopherol (α-T), mainly 2, 2, 5, 7, 8-penta-methyl-6-hydroxy-chromane (M) was used. The results obtained showed that spirodimers of α-T and M were reduced to the corresponding di-hydroxydimers with pyrogallol during the saponification. Therefore, it was suggested that the alkaline saponification method could not be applied to detect the metabolites from α-T and related compounds.