Studies on the Turnover of Cardenolides in Convallaria majalis

In leaves of CONVALLARIA MAJALIS L. the cardenolide content is known to decrease towards the end of the vegetation period. However, at this stage the rate of biosynthesis is even higher than at the onset of flowering. This has been revealed by photosynthesis experiments in the presence of (14)CO (2) and the subsequent isolation of 15 labelled cardenolides using PC, TLC and HPLC. IN VITRO and IN VIVO experiments showed that the first step in the degradative pathway of convalloside is deglucosidation yielding convallatoxin, followed by conversion into several yet unidentified degradation products other than known cardenolides of C. MAJALIS. This indicates that the cardenolides of C. MAJALIS are subjected to a turnover at least towards the end of the vegetation period.