A new EGF-active polymeric pyridinium alkaloid from the sponge Callyspongia fibrosa

An inhibitor of the epidermal growth factor (EGF) receptor was isolated from an extract of the Micronesian sponge Callyspongia fibrosa. The structure of the EGF-active compound was first proposed, on the basis of ion-spray mass spectrometry, to be the cyclic dimer 1 (n= 2) but comparison of a sample produced by an efficient synthetic route revealed that hypothesis to be incorrect. The EGF-active constituent must therefore be a large oligomer or a polymer of the same repeating subunit 1