Biosynthese der Digitoxose in Digitalis lanata EHRH. (Vorversuch). Desoxyzucker, 39. Mitteilung

Abstract

AbstractStrongly radioactive digitoxin (6) could be isolated (without dilution) in crystalline form from young plants of Digitalis lanata after their inoculation with D‐Glucose‐[6‐14C] using the wick method. Hydrolytic cleavage of this digitoxin gave digitoxigenin (11) and D‐digitoxose (7), both being isolated in crystalline form (without dilution). The genin was found to be 4 times more active, pro mole, than the digitoxose. This can be best explained when one assumes that the plant converts 1 mole of D‐glucose into 3 moles of acetic acid. After degradation of the digitoxose using NaJO4, acetaldehyde (as the crystalline p‐nitrophenylhydrazone) and formic acid (as the Pb salt) could be isolated. The acetaldehyde carried 65% and the formic acid 8,45% of the activity of the digitoxose. This is compatible with the assumption that digitoxose is formed in the plant from D‐glucose without re‐arrangement of the carbon chain. The appreciable activity of the formic acid could be derived from the relatively large proportion of radioactivity lost (ca. 38,9%), partly in the form of C1‐subunits, in the transformation of the intermediary lanosterol into digitoxigenin. This lost activity may be incorporated in unspecifically labelled D‐glucose which then re‐enters the biosynthetic pathway.