Cytotoxic triterpenoids from the leaves of Microtropis fokienensis.

Five new triterpenoids, microfokienoxanes A-D (1-4) and 3beta,28-dihydroxy-11alpha-methoxyurs-12-ene (5), were isolated and identified from the leaves of Microtropis fokienensis, along with nine known compounds. The structures of the new compounds were elucidated by spectroscopic methods. The compounds obtained in this investigation were evaluated against a small panel of human cancer cell lines for cytotoxicity. Only compounds 3 and 5 exhibited cytotoxicity (IC50 < or = 5 microg/mL) for one or more cell lines.