Localization of daphnetin and umbelliferone in different tissues of Daphne mezereum shoots

The coumarins daphnetin and umbelliferone were detected in isolated tissues of Daphne mezereum stems and leaves and on the surface by analysis of extracts from brief dipping in almost boiling water. The surface had only low concentrations of these compounds compared with those of the whole leaf (≤ 0.1%). Daphnetin was always in higher concentration than umbelliferone, both in the whole leaf and in the whole stem. In isolated tissues daphnetin predominated, its concentrations being between 1.5 and 11 times as high as umbelliferone, except in the stem, where the xylem contained over twice as much umbelliferone as daphnetin. The highest concentrations of daphnetin were in storage tissues. The covering tissues, in almost all cases, contained the lowest concentrations of both daphnetin and umbelliferone.