Three New Isomeric Indole Alkaloids from Nauclea officinalis.

Three new isomeric monoterpene indole alkaloids, naucleofficines I-III (1-3, resp.) were isolated from the stems (with bark) of Nauclea officinalis. Their structures were elucidated on the basis of spectroscopic methods and single-crystal diffraction analyses. The cytotoxic activities of 1-3 against human colon cancer, human gastric cancer, and human hepatoma cells were also investigated.