Sesterterpenoids isolated from the marine sponge Coscinoderma bakusi

Twelve neomanoalide derivatives (1–12) and two halisulfate derivatives (13 and 14), nine of which are unprecedented (4–9, 11, 12, and 14; coscilides A–H and halisulfate 11, respectively), were isolated from the sponge Coscinoderma bakusi. The previously unreported neomanoalide derivatives show distinct features in their 6,7-double bond geometry (4 and 9) or terpenoid moieties (5–8, 11, and 12) compared to the reported ones, as elucidated using NMR spectroscopy and HRMS analysis. Among these derivatives, compounds 11 and 12 contain terpenoid moieties that are rarely found in marine natural products. The isolated compounds showed low activity against hTRPA1, six pathogenic bacterial strains, 10 cancer cell lines, except in the case of 7, which exhibited activity against hTRPA1 (IC₅₀, 34.5 μM) and Staphylococcus aureus (MIC, 32.0 μg/mL). The halisulfate derivative 14 inhibited NO production in LPS-activated RAW 246.7 macrophage by 45% at a concentration of 10.0 μM. Although no significant activity was observed for the compounds in this study, the compounds reported herein would contribute to the chemical diversity of marine sesterterpenoids.