Two new alkaloids, isokomarovine and komarovidinine, have been isolated from the epigeal part of the plant Nitraria komarovii Iljin et Lava. The passage from isokomarovine to komarovidinine has been performed. Their structures have been established on the basis of spectra and experimental facts: 1-(quinolin-5′-yl)-9H-pyrido[3,4-b]indole and indolo[3,2,1-de]quinolino[4,5-gh][1,5]naphthyridine, respectively. Their synthesis has been performed. © 1983 Plenum Publishing Corporation.