Marine sponge bis(indole) alkaloids that displace ligand binding to alpha 1 adrenergic receptors

The alpha 1 adrenergic receptor assay guided fractionation of an extract from the marine sponge Spongosorites sp. led to the isolation of topsentin-B2 (bromotopsentin) as the active compound. Topsentin-B2 and five related bis(indole) marine sponge metabolites were shown to displace ligand binding to alpha 1a and alpha 1b adrenergic receptors with K-i values for the alpha 1b receptor ranging from 0.08 to 1.15 mu M. All six compounds show selectivity for crib relative to alpha 1a adrenergic receptors. Copyright (C) 1996 Elsevier Science Ltd