Ianthesine E, a new bromotyrosine-derived metabolite from the Great Barrier Reef sponge Pseudoceratina sp.

Abstract

The new compound ianthesine E (1) was isolated from the Great Barrier Reef marine sponge Pseudoceratina sp. along with the known metabolites 11-hydroxyaerothionin (2), aerothionin (3) and 11,19-dideoxyfistularin 3 (4). Structures were determined on the basis of their spectroscopic data. The compounds were tested for inhibition of [³H] DPCPX binding to adenosine A₁ receptors in a whole cell binding assay. At 100µM, aerothionin was the most potent, inhibiting 67% of binding, followed by ianthesine E and 11-hydroxyaerothionin which inhibited 61% of binding, and 11,19-dideoxyfistularin which initiated 51% of binding Ianthesine E (EC₅₀ 60µM), aerothionin (EC₅₀ 42 µM) and 11,19-dideoxyfistularin-3 (EC₅₀ 2.6 µM) exhibited moderate cytotoxicity against the HeLa cell line.

Keywords:

• Ianthesine
• Marine sponge
• Pseudoceratina
• Adenosine receptors

Acknowledgement

We are indebted to Rick Willis, Australian Institute of Marine Science, Townsville, for the HRMS analysis and Ngoc Pham and Sonya Kaiser, NPD, for assistance with binding assays. CHO.K1 cells expressing the human adenosine A₁ receptor were a kind donation from Peter Schofield and Andrea Townsend-Nicholson, The Garvan Institute of Medical Research, Sydney. Support from the Australian Research Council is acknowledged. JAK acknowledges the receipt of a Griffith University Postgraduate Research Scholarship.