Trimeric Hemibastadin Congener from the Marine Sponge Ianthella basta

The first naturally occurring trimeric hemibastadin congener, sesquibastadin 1 (1), and the previously reported bastadins 3, 6, 7, 11, and 16 (2–6) were isolated from the marine sponge Ianthella basta, collected in Indonesia. The structure of 1 was elucidated on the basis of 1D and 2D NMR measurements and by HRMS. Among all the isolated compounds, the linear sesquibastadin 1 (1) and bastadin 3 (2) showed the strongest inhibition rates for at least 22 protein kinases (IC50 = 0.1–6.5 μM), while the macrocyclic bastadins (3–6) demonstrated a strong cytotoxic potential against the murine lymphoma cell line L5178Y (IC50 = 1.5–5.3 μM).