ONTOGENETIC VARIATION OF BIOLOGICALLY-ACTIVE NATURAL-PRODUCTS IN AGERATINA-ADENOPHORA

The accumulation of major natural products (chromenes, sesquiterpenes, chlorogenic acid) in different leaves of seedlings of Ageratina adenophora was analysed during the first three months of seedling development. Chromenes were found to be confined to leaves at nodes 1-8 (leaves at node 1 being the cotyledons) whereas they were lacking in all leaves analysed from higher nodes. The major sesquiterpene as well as chlorogenic acid were, in contrast to the chromenes, hardly detectable in cotyledons and in primary leaves but were increasingly accumulated in leaves at higher nodes resulting in a chemical dichotomy during seedling development. The latter compounds were also present in leaves from 10-month-old plants. The sesquiterpene derivative exhibited contact toxicity and growth retarding activity against larvae of a noctuid species. The physiological aspects of this dichotomy in natural product accumulation during seedling development as well as its possible implications for the chemical defence of A. adenophora are discussed. © 1990.