Acanthocyclamine A From the Indonesian Marine Sponge Acanthostrongylophora ingens

A new 3-alkylpiperidine compound (-)-acanthocyclamine A (1) has been obtained from the methanolic extract of Acanthostrongylophora ingens (order Haplosclerida, family Petrosiidae) collected from Wakatobi Marine National Park in South East Sulawesi, Indonesia. The structure of 1 was investigated by extensive 1D- and 2D-NMR experiments. The absolute configuration of 1 was established by X-ray crystallography from anomalous dispersion effects using Cu radiation as C2 (R), C3 (R), C7 (R), and C9 (R). A plausible biosynthetic scheme leading to 1 is presented, and compared with the biosynthetic pathway proposed for the manzamine alkaloids.