Notizen: Einbau von p-Hydroxybenzoesäure in die Hydrochinonkomponente des Arbutins in Bergenia crassifolia

Abstract

Feeding experiments showed that ortho- and meta-hydroxybenzoic acids and gentisinic acid were absorbed by the plants but were not incorporated into arbutin; all the radioactivity was found in the glucosides of these acids. p-Hydroxybenzoic acid, however, was incorporated into arbutin to the amount of 10%, whereas the remaining 90% of the acid likewise was found in the glucosides. In the purified crystallized arbutin from the feeding experiment with gentisinic acid no radioactivity was found in the glucoside. According to these results the biosynthesis of arbutin in higher plants follows this equence: phenylalanine is deaminated by phenylalanase to cinnamic acid which is hydroxylated to p-cumaric acid. p-Cumaric acid is further degraded to p-hydroxybenzoic acid and by oxidative decarboxylation is transformed to p-hydroquinone which in turn through uridindiphosphoglucose is glycolyzed to arbutia.