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 A-E (1-5, 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.