Assignment of 13C NMR spectrum for blepharismin C based on biosynthetic studies

Blepharismins, toxic pigments of the ciliate Blepharisma japonicum, are polycyclic ring-condensed compounds. Assignment of 13C NMR signals for blepharismin C, a major constituent of blepharismins, was achieved by analyses of the HMQC, HMBC, and INADEQUATE spectra of 13C-enriched samples obtained by feeding experiments using sodium [1-13C], [2-13C], and [1,2-13C2]acetates.