Novel Indole Alkaloids from Nauclea latifolia and Their Renin-Inhibitory Activities

Chemical studies on the crude MeOH extract of stems and barks of Nauclea latifolia resulted in the isolation of five new indole alkaloids, latifoliamides AE (15, resp.), along with one known alkaloid, angustoline (6). The structures of these compounds were elucidated by means of extensive NMR spectral studies. Compound 1 has a 20-ethylidenetetrahydrofuran ring incorporated in its structure and represents the first example of this class of indole alkaloids. All of the isolates exhibited moderate in vitro renin inhibitory activities.