Serotonin and dopamine derivatives from the Papua New Guinea zoantharian Zoanthus cf. sansibaricus

In our continuous search for bioactive natural products from marine zoantharians, three serotonin derivatives 1-3 and one dopamine analogue 4 together with the known ecdysteroids ajugasterone C (5) and turkesterone (6) and zoanthoxanthin derivative 3-norpseudozoanthoxanthin (7) were isolated from Zoanthus cf. sansibaricus collected off the coast of Papua New Guinea. The structures of these alkaloids were elucidated through spectroscopic analyses including 1D and 2D NMR experiments and HRESIMS data. This is the first report of serotonin and dopamine derived alkaloids from species of the genus Zoanthus. Compounds 1-3 demonstrated moderate bactericidal activity against S. aureus NCTC 7447 with an IC50 value of 83.3, 41.9 and 37.4 μM.