A nuclear magnetic resonance analysis has revealed that scytovirin has two domains and the first domain (1–48 amino acids) has similar anti-HIV activity to that of the full-length scytovirin. 44 In addition, two cyclic depsipeptides, ichthyopeptins A and B, were also isolated from Microcystis ichthyoblabe. They have shown antiviral activity against influenza A virus.