1,3-Dimethylisoguanine, a New Purine from the Marine Sponge Amphimedon viridis

Abstract
A new purine, 1,3-dimethylisoguanine (1), has been isolated from the marine sponge Amphimedon viridis and identified by analysis of spectroscopic data. Compound 1 increased the contractions obtained by transmural electrical stimulation in the guinea pig longitudinal muscle/myenteric plexus in a dose-dependent manner.