Denigrins and Dactylpyrroles, Arylpyrrole Alkaloids from a Dactylia sp. Marine Sponge.

Seven new arylpyrrole alkaloids ( 1 - 7 ), along with four known compounds, were isolated from an extract of a Dactylia sp. nov. marine sponge, and their structures were elucidated by interpretation of NMR and MS spectroscopic data. Denigrins D-G ( 1 - 4 ) have highly substituted pyrrole or pyrrolone rings in their core structures, while dactylpyrroles A-C ( 5 - 7 ) have tricyclic phenanthrene cores. Due to the proton-deficient nature of these scaffolds, key heteronuclear correlations from ¹ H- ¹⁵ N HMBC and LR-HSQMBC NMR experiments were used in the structure assignment of denigrin D ( 1 ). Dictyodendrin F ( 8 ), a previously described co-metabolite, inhibited transcription driven by the oncogenic PAX3-FOXO1 fusion gene with an IC ₅₀ value of 13 μM.