Metabolism and bioconversion of chromene derivatives inAgeratina adenophora (Asteraceae)

Abstract

Seedlings ofAgeratina adenophora accumulate the chromenes demethoxyencecalin, encecalin and demethylencecalin. More than 80% of the total chromenes within the seedling are confined to the leaves where they are stored within the mesophyll. Metabolism of the chromenes during development of the seedlings was subjected to analysis by high-performance liquid chromatography. The accumulation kinetics obtained, as well as feeding experiments with non-radioactive chromenes, showed the bioconversion of these compounds to proceed from demethoxyencecalin via hydroxylation yielding demethylencecalin, followed by methylation yielding encecalin. Inhibitor studies with glyphosate indicate that the chromenes arise from precursors derived from the shikimic-acid pathway.