Anabaenopeptins G and H, Potent Carboxypeptidase A inhibitors from the cyanobacterium Oscillatoria agardhii (NIES-595)

Anabaenopeptins G (1) and H (2) were isolated from the cultured cyanobacterium Oscillatoria agardhii (NIES-595) as potent carboxypeptidase A (CPA) inhibitors. The gross structure of 1 and 2 were established by spectroscopic analysis including the 2D NMR technique and the absolute configurations of 1 and 2 were determined by the spectral and chemical methods. 1 and 2 inhibited CPA with IC50ʹs of 0.0018 and 3.4 μg/mL, respectively.