Denigrins H-L: Sulfated Derivatives of Denigrins D and E from a New Zealand Dictyodendrilla c.f. dendyi Marine Sponge

Abstract

Five new sulfated arylpyrrole and arylpyrrolone alkaloids, denigrins H-L (1-5), along with two known compounds, dictyodendrin B and denigrin G, were isolated from an extract of a New Zealand Dictyodendrilla c.f. dendyi marine sponge. Denigrins H-L represent the first examples of sulfated denigrins, with denigrins H and I (1-2), as derivatives of denigrin D, containing a pyrrolone core, and denigrins J-L (3-5), as derivatives of denigrin E (6), containing a pyrrole core. Their structures were elucidated by interpretation of 1D and 2D NMR spectroscopic data, ESI, and HR-ESI-MS spectrometric data, as well as comparison with literature data. Compounds 1-5, along with six known compounds previously isolated from the same extract, showed minimal cytotoxicity against the HeLa cervical cancer cell line.

Keywords: alkaloids; denigrin; pyrrole; pyrrolone; sodium sulfate; sponge.

Figure 1

Structures assigned to the previously reported denigrins with the general structure of denigrin type compounds displayed in blue.

Figure 2

Chemical structures of compounds 1–6.