Denigrins and Dactylpyrroles, Arylpyrrole Alkaloids from a <i>Dactylia</i> sp. Marine Sponge

Abstract

Seven new arylpyrrole alkaloids (<b>1</b>-<b>7</b>), along with four known compounds, were isolated from an extract of a <i>Dactylia</i> sp. nov. marine sponge, and their structures were elucidated by interpretation of NMR and MS spectroscopic data. Denigrins D-G (<b>1</b>-<b>4</b>) have highly substituted pyrrole or pyrrolone rings in their core structures, while dactylpyrroles A-C (<b>5</b>-<b>7</b>) have tricyclic phenanthrene cores. Due to the proton-deficient nature of these scaffolds, key heteronuclear correlations from ¹H-¹⁵N HMBC and LR-HSQMBC NMR experiments were used in the structure assignment of denigrin D (<b>1</b>). Dictyodendrin F (<b>8</b>), a previously described co-metabolite, inhibited transcription driven by the oncogenic PAX3-FOXO1 fusion gene with an IC₅₀ value of 13 μM.