PRODUCTION AND ACCUMULATION OF CHROMENES IN TISSUE-CULTURES OF AGERATINA-RIPARIA (ASTERACEAE)

Root cultures of Ageratina riparia were initiated from roots or from l eaves of differentiated plants and were grown on MS or AM solid media or in liquid growth media, respectively, for more than five years. Phy tochemical investigation of the root cultures afforded similar chromen e derivatives as found in roots of differentiated plants with esterifi ed chromenes such as ripariochromene B and C being the major constitue nts. Whereas the overall concentration of chromenes in plant roots amo unted to ca. 0.70 mg/g dry wt. the chromene concentrations in root cul tures were found to vary from 0.16-0.66 mg/dry wt. depending on the ty pe of media used. Only trace amounts of chromene derivatives were foun d in comparison when cell suspension cultures of A. riparia were analy sed which is thought to be due to the lack of secretory ducts in the l atter that are known to be favoured sites of chromene accumulation in differentiated plants. Aseptically grown plants of A. riparia as well as root or cell suspension cultures proved capable of hydroxylating th e chromene demethoxyencecalin that was added to liquid growth media. T he resulting 8-hydroxy derivative appears to be a biogenetic intermedi ate leading to methyripariochromene A which is the major chromene in a bove ground parts of A. riparia.