A novel alkaloid, chartrenoline (1), featuring an unusual 6/6/5/5-tetracyclic nucleus, was isolated from a marine Streptomyces chartreusis NA02069. The structure of 1 including its absolute configurations was established by extensive analyses of its high resolution mass, NMR and single-crystal X-ray diffraction data. A plausible biosynthetic pathway for chartrenoline (1) is proposed. (C) 2018 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.