Isolation and Identification of bakkenolides and caffeoylquinic acids from the aerial parts of Petasites japonicus

The major aim of this work is the research of secondary metabolites isolated from the aerial parts of Petasites japonicus. The plant material is extracted with a polar solvent, which is 95% by volume methanol at room temperature. The concentrated extract was partitioned as EtOAc, n-BuOH, and $H_2O$ fractions. From the EtOAC and n-BuOH fraction, two bakkenolides and two caffoylquinic acid were isolated using the Diaion HP-20, silica gel, ODS-A, and Sephadex LH-20 column chromatographies. According to the results of the results of physico-chemical and spectroscopic data including NMR, MS and UV. The chemical structures of the compounds were respectively determined as bakkenolide B (1), bakkenolide D (2), 1,5-dicaffeoylquinic acid (3), and 5-O-caffeoylquinic acid (4). These results suggest that the compounds isolated from the aerial parts of this plant were almost identical with known components of Petasites japonicus. However, it is necessary to investigate more about the difference of amounts of constituents according to harvest area and time.