Brominated cyclodipeptides from the marine sponge Geodia barretti as selective 5-HT ligands.

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Hedner E, Sjogren M, Frandberg PA, Johansson T, Goransson U, Dahlstrom M, Jonsson P, Nyberg F, Bohlin L

Brominated cyclodipeptides from the marine sponge Geodia barretti as selective 5-HT ligands.

J Nat Prod. 2006 Oct;69(10):1421-4.

PubMed ID

17067154 [ View in PubMed

]

Abstract

The brominated cyclodipeptides barettin (cyclo[(6-bromo-8-entryptophan)arginine]) and 8,9-dihydrobarettin (cyclo[(6-bromotryptophan)arginine]) isolated from the marine sponge Geodia barretti have previously been shown to inhibit settlement of barnacle larvae in a dose-dependent manner in concentrations ranging from 0.5 to 25 microM. To further establish the molecular target and mode of action of these compounds, we investigated their affinity to human serotonin receptors. The tryptophan residue in the barettins resembles that of endogenous serotonin [5-hydroxytryptamine]. A selection of human serotonin receptors, including representatives from all subfamilies (1-7), were transfected into HEK-293 cells. Barettin selectively interacted with the serotonin receptors 5-HT2A, 5-HT2C, and 5-HT4 at concentrations close to that of endogenous serotonin, with the corresponding Ki values being 1.93, 0.34, and 1.91 microM, respectively. 8,9-Dihydrobarettin interacted exclusively with the 5-HT2C receptor with a Ki value of 4.63 microM; it failed to show affinity to 5-HT2A and 5-HT4, indicating that the double bond between the tryptophan and arginine residue plays an important role in the interaction with the receptor proteins.

DrugBank Data that Cites this Article

Binding Properties

Drug	Target	Property	Measurement	pH	Temperature (°C)
Methysergide	5-hydroxytryptamine receptor 2A	Ki (nM)	10	N/A	N/A	Details
Methysergide	5-hydroxytryptamine receptor 2C	Ki (nM)	2.5	N/A	N/A	Details