6-Hydroxymanzamine A and 3,4-Dihydromanzamine A, New Alkaloids from the Okinawan Marine Sponge Amphimedon sp.

: Two new beta-carboline alkaloids, 6-hydroxymanzamine A [1] and 3,4-dihydromanzamine A [2], have been isolated from the Okinawan marine sponge Amphimedon sp. and their structures elucidated on the basis of nmr spectral data.