Dihydrobenzo[<i>c</i>]phenanthridine Alkaloids from Stem Bark of <i>Zanthoxylum nitidum</i>

Five novel alkaloids, zanthomuurolanine (1), epi-zanthomuurolanine (2), zanthocadinanines A (3) and B (4), and epi-zanthocadinanine B (5), composed of dihydrochelerythrine and a cadinane-type sesquiterpene linked by a methylene bridge, have been isolated from stem bark of Zanthoxylum nitidum. These structures were elucidated by spectroscopic techniques (UV, IR, MS, CD, 1H NMR, 13C NMR, DEPT, COSY, NOESY, HSQC, and HMBC analyses). Single-crystal X-ray diffraction studies confirmed the relative configurations of 1 and 4 and provided additional support for the structures of 2, 3, and 5.