Marine invertebrate sponges are a rich source of new bioactive substances. The objective of this investigation was to isolate the anti-mycobacterium bioactive compounds from sponge Haliclona sp. A new alkaloid (1) was obtained through bioassay-guided purification together with eight previously known substances, including cyclostellettamines A (5), B (6), C (7), E (8), and F (9) and the haliclocyclamines A (2), B (3), and C. The structures of 1-9 were established applying spectroscopic analysis, including 1D NMR (1H and13C-NMR), 2D NMR (HMQC, HMBC, 1H-1H COSY), mass spectroscopy, IR, and UV. Furthermore, the findings revealed that the compounds exhibited inhibitory activity against Mycobacterium smegmatis at 10 µg/disc. © 2022 Maarisit et al and the authors. This work is licensed under the Creative Commons Attribution 4.0 International License.