New Acorane-Type Sesquiterpene from Acorus calamus L.

A new sesquiterpene, named neo-acorane A (), and two known ones, acoric acid () and calamusin D (), were isolated from a 95% ethanol extract of the rhizome parts of L. Their structures were elucidated by spectroscopic methods, and the absolute configurations were determined by single-crystal X-ray diffraction analysis. Compounds and are nonisoprenoid sesquiterpenoids, likely biosynthesized from an acorane-type sesquiterpene by oxidative fission of the six- or five-membered ring. Moreover, compounds (10 μM), (5 μM and 10 μM) and (10 μM) showed cell proliferation activity on the SK-N-BE (2) cell line.