BROMINATED SECONDARY COMPOUNDS FROM THE MARINE SPONGE VERONGIA-AEROPHOBA AND THE SPONGE FEEDING GASTROPOD TYLODINA-PERVERSA

Analysis of the marine sponge Verongia aerophoba from the Canary islan ds afforded the brominated secondary constituents isofistularin-3, aer ophobin-1 and aerophobin-2 which are probably involved in the chemical defense of the sponge. In addition the yellow pigment uranidine and t he unusual sterol aplysterol were isolated. The patterns of brominated compounds were almost superimposable when samples of V. aerophoba fro m different islands were compared by HPLC indicating de novo synthesis by the sponge or by endosymbiotic microorganisms rather than uptake b y filter feeding. The only differences observed between the different samples analyzed were with regard to the total concentrations of bromi nated compounds which varied from 7.2- 12.3% of the dry weight depende nt on the different collection sites. The Opisthobranch gastropod Tylo dina perversa is specialized for feeding on V. aerophoba. Chemical ana lysis of the gastropod revealed the sponge constituents uranidine. iso fistularin-3, aerophobin-1 and aerophobin-2 as well as aerothionin, a further brominated compound which is apparently a biotransformation pr oduct of the brominated sponge constituents.