Aplyronine A, a potent antitumor macrolide of marine origin, and the congeners aplyronines B and C: isolation, structures, and bioactivities

Aplyronine A (2), a potent antitumor macrolide was isolated from the sea hare Aplysia kurodai together with the congeners aplyronines B (3) and C (4). The absolute stereostructure of aplyronine A (2) was determined by the instrumental analysis (mainly NMR and MS) and the enantioselective synthesis of the fragments obtained from chemical degradation of aplyronine A (2). The structures of aplyronines B (3) and C (4) were also elucidated. Cytotoxicity and antitumor activity of aplyronine A (2) were evaluated.