Cyclodopa glucoside ( = (2<i>S</i>)‐5‐(β‐<scp>D</scp>‐glocopyranosyloxy)‐6‐hydroxyindoline‐2‐carboxylic acid) and its occurrence in red beet (<i>beta vulgaris</i> var. <i>rubra</i> L.)

Abstract

Abstract Cyclodopa glucoside ( = (2 S )‐5‐(β‐ D ‐glucopyranosyloxy)‐6‐hydroxyindoline‐2‐carboxylicacid; 1a ) is prepared from betainin ( 2a ) via a base exchange reaction. Its purification and physical properties are described. The compound is N ‐formylated in dilute HCOOH solution. Cyclodopa glucoside is contained in considerable amount in redbeet juice varying from 0.07 to 1.9 mmol/kg or from 12 to 46% relative to teh content of betanin. Teh occurrence of free cyclodopa glucoside supports its role as intermediate in betanin biosynthesis.