Sesquiterpenoids from an edible plant Petasites japonicus and their promoting effects on neurite outgrowth

Petasites japonicus (Sieb. & Zucc.) Maxim., belonging to the Compositae family, is a perennial herb and has been consumed as a wild vegetable. Our survey on the chemical composition of P. japonicus resulted in the isolation of two new and seventeen known sesquiterpenoids. Their structures were elucidated on the basis of nuclear magnetic resonance (NMR) spectroscopic data analysis, and the absolute configurations of the new compounds were established by comparison of the calculated and experimental electronic circular dichroism (ECD) spectra. Among these isolates, compound 1 was a sesquiterpene carrying a chlorine atom, 2 processed a rare 7,9-secobakkenolide skeleton, and compounds 4, 11- 13, 15, 18, and 19 were obtained from this species for the first time. Most of these compounds showed promoting effects on neurite outgrowth from PC12 cells. These chemical and biological results provide a basis for further development and utilization of P. japonicus as a functional food.