We searched for bioactive substances involved in flower bud formation of Arabidopsis thaliana. some significantly decreasing HPLC peaks were detected in the extract of flower buds-forming A. thaliana compared with that of the non-flower bud-forming stage. Compound 1, which corresponded to the most decreased HPLC peak, was isolated from aerial parts of A. thaliana. From NmR and ms data, compound...