A new prenylated 3-benzoxepin derivative, elsholtzioxin (1), together with fifteen known compounds (2-16) were isolated from the whole parts of Elsholtzia penduliflora. Their structures were elucidated on the basis of various spectroscopic techniques and chemical evidences. The antiviral activities of these compounds were evaluated in vitro. The new compound (1) exhibited potential anti-influenza virus activity against strain A/WSN/33/2009 (H1N1) with inhibition rate of 47.19%. Compounds 2, 9 and 12 exhibited significant inhibitory activities with IC50 value of 26.16, 34.66 and 20.81 μM, respectively.
Keywords: Elsholtzia penduliflora; anti-IAV activity; benzoxepin derivative; labiatae.