ANTIMUSCARINIC ACTIVITY OF A FAMILY OF C11N5 COMPOUNDS ISOLATED FROM AGELAS SPONGES

In a search for potential target sites for C11N5 compounds obtained from marine sponges of the genus Agelas we evaluated their interaction with muscarinic acetylcholine receptors from rat brain membranes. In competition experiments with H-3-QNB these compounds displayed the following rank order of potency: sceptrin > oroidin greater-than-or-equal-to dibromosceptrin greater-than-or-equal-to clathrodin. Sceptrin (50 muM) was shown to be a competitive inhibitor of H-3-QNB binding as revealed by Scatchard analysis. The results demonstrate the ability of these compounds to interact with multiple target molecules in the micromolar range.