Three New Pteridines, Hirudinoidines A – C, from Hirudo nipponica Whitman

Three new pteridines, hirudinoidines A – C ( 1 – 3 , resp.), with novel structural features were isolated from Hirudo nipponica Whitman , and their structures were elucidated on the basis of extensive spectroscopic analyses and by comparison of their spectral data with those of related metabolites. The configuration of 1 was unequivocally confirmed by single‐crystal X‐ray diffraction ( Fig. 2 ).