New diterpenoids with estrogen sulfotransferase inhibitory activity from Leonurus sibiricus L.

ABSTRACT

Four new diterpenoids (1-4), along with eight known diterpenoids (5-12) were isolated from the acetone extract of Leonurus herb (aerial parts of Leonurus sibiricus L.). The structures of the compounds were determined by spectroscopic methods. Among the isolated compounds, compounds 2, 3, 8, 9 and 10 showed inhibitory activity against human liver cytosol estrogen sulfotransferase (E-ST), which plays a key role in the maintenance of cellular estrogen levels. Compound 2 showed the strongest activity with an IC50 value of 7.9 µM, which is comparable to the activity of the positive control, meclofenamic acid (IC50 5.4 µM).