Phyllanacidins A–C, three new cleistanthane diterpenoids from Phyllanthus acidus and their cytotoxicities

Phytochemical investigation on the nonpolar extracts of P. acidus leaves afforded three new cleistanthane diterpenoids, named phyllanacidins A–C (1–3), in addition to three known ones (4–6). Among them, compounds 2 and 3 represent the first examples of 17-nor cleistanthane diterpenoids. Their structures including absolute configurations were elucidated on the basis of extensive spectroscopic data and single crystal X-ray diffraction analysis....