Isolation and characterization of the new purine 1,3,7-trimethylisoguanine from the New Zealand ascidian Pseudodistoma cereum

The new purine 1,3,7-trimethylisoguanine (1) has been isolated from the ascidian Pseudodistoma cereum. The structure of 1 was elucidated by analysis of NMR spectroscopic and mass spectrometric data and by comparison with the regioisomeric purine 1,3,7-trimethylguanine (2).