A new labdane-type diterpenoid from Leonurus japonicus

Five fractions prepared from the crude extract of Leonurus japonicus were examined in order to determine their cytotoxic potential. Under the bioassay guidance, a new labdane-type diterpenoid (1), and nine known ones (2-10) along with a seco-labdane (11) were isolated from the aerial parts of Leonurus japonicus. The structure elucidation was primarily based on comprehensive spectroscopic analyses, including HRESIMS, IR, and 1D and 2D NMR...