SOLUBLE PHENOLIC CONSTITUENTS FROM CUSCUTA-REFLEXA AND CUSCUTA-PLATYLOBA

Phytochemical analysis of the phanerogamic parasites C. reflexa and C. platyloba yielded characteristic patterns of soluble phenolic constituents. Whereas C. reflexa contained mainly caffeic acid depsides, C. platyloba was characterized by the accumulation of flavonoids of the flavonol-type. The phenolic patterns proved to be stable in both Cuscuta ssp. irrespective of different host plants employed in the experiments. Segmentation of growing Cuscuta shoots showed different concentrations of phenolic compounds. In contrast to the flavonoids that gradually declined from the meristematic apex towards the haustoria, the hydroxycinnamic acid derivatives were found to be enriched in the haustorial region in addition to their high concentration in the stem apex. The high concentration of phenylpropanoids in the apex, as well as the accumulation of caffeic acid depsides in the haustorial regions, were correlated to an enhanced activity of PAL in the respective segments.