(-)-Dibromophakellin: an alpha2B adrenoceptor agonist isolated from the Australian marine sponge, Acanthella costata.

Bioassay-guided fractionation of the organic extract from the marine sponge Acanthella costata resulted in the isolation of the known natural product, (-)-dibromophakellin (1). Using a fluorescence imaging plate reader (FLIPR) based assay, compound 1 was identified as displaying agonist activity against the alpha(2B) adrenoceptor, with an EC(50) of 4.2muM. Debromination and Suzuki-Miyaura coupling reactions were undertaken in order to provide structure activity data about the pyrrole ring of this marine metabolite. These synthetic studies generated the known natural product analogues, (-)-phakellin (2), and (-)-monobromophakellin (3), along with the new synthetic derivatives (-)-4-bromo-5-phenylphakellin (5) and (-)-4,5-diphenylphakellin (6). Substitution of the C-5 Br of 1 with H (2 and 3) or phenyl (5 and 6) resulted in loss of activity indicating that Br at C-5 is required for agonist activity.

Polydiscamides B-D from a marine sponge Ircinia sp. as potent human sensory neuron-specific G protein coupled receptor agonists.

Polydiscamides B, C, and D (1-3) were isolated from a sponge Ircinia sp. The structures of 1 to 3 were elucidated by the comparison of their NMR and HRESIMS spectroscopic data with that of a structurally related compound, polydiscamide A. All compounds showed potent agonist activity against human sensory neuron-specific G protein couple receptor (SNSR), a receptor involved in the modulation of pain, and they are the first examples of nonendogenous human SNSR agonists.