DISTRIBUTION, BIOSYNTHESIS AND TURNOVER OF PYRROLIZIDINE ALKALOIDS IN CYNOGLOSSUM-OFFICINALE

The facultative biennial Cynoglossum officinale contains the N-oxides of the following pyrrolizidine alkaloids (PAs): trachelanthamine, viridiflorine, 7-angeloylheliotridine, rinderine, echinatine, 3'-acetylechinatine and heliosupine. The inflorescences contain the highest levels of PAs. At the vegetative rosette stage, the youngest leaves have higher PA levels than the older leaves. Both isolated roots and isolated shoots of rosette plants were able to produce PAs from C-14-labelled putrescine. PA production patterns differed between roots and shoots. In intact plants, there was no significant turnover of PAs within 32 days. Within the shoot, PAs were reallocated from the ageing leaves into the newly formed, youngest leaves. Shoot to root transport of PAs was observed, which indicated that PAs are transported via the phloem.