**Kirsten Benkendorff**

Marine Ecology Research Center, School of Environment, Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia; Kirsten.benkendorff@scu.edu.au; Tel.: +61-2-66203755; Fax: +61-2-66212669

Received: 14 January 2013; in revised form: 4 March 2013; Accepted: 8 March 2013; Published: 23 April 2013

**Abstract:** The predatory marine gastropod *Dicathais orbita* has been the subject of a significant amount of biological and chemical research over the past five decades. Natural products research on *D. orbita* includes the isolation and identification of brominated indoles and choline esters as precursors of Tyrian purple, as well as the synthesis of structural analogues, bioactivity testing, biodistributional and biosynthetic studies. Here I also report on how well these compounds conform to Lipinski's rule of five for druglikeness and their predicted receptor binding and enzyme inhibitor activity. The composition of mycosporine-like amino acids, fatty acids and sterols has also been described in the egg masses of *D. orbita*. The combination of bioactive compounds produced by *D. orbita* is of interest for further studies in chemical ecology, as well as for future nutraceutical development. Biological insights into the life history of this species, as well as ongoing research on the gene expression, microbial symbionts and biosynthetic capabilities, should facilitate sustainable production of the bioactive compounds. Knowledge of the phylogeny of *D. orbita* provides an excellent platform for novel research into the evolution of brominated secondary metabolites in marine molluscs. The range of polarities in the brominated indoles produced by *D. orbita* has also provided an effective model system used to develop a new method for biodistributional studies. The well characterized suite of chemical reactions that generate Tyrian purple, coupled with an in depth knowledge of the ecology, anatomy and genetics of *D. orbita* provide a good foundation for ongoing natural products research.

**Keywords:** bioactivity; biosynthesis; brominated secondary metabolites; choline ester; indole
