Dibromotyrosine derivatives, a maleimide, aplysamine-2 and other constituents of the marine sponge Pseudoceratina purpurea

A collection of the marine sponge Pseudoceratina purpurea from the Gulf of Thailand furnished aplysamine-2, two new bromotyrosine derivatives purpuroceratic acids A and B, two known bromotyrosine derivatives, 3-maleimide-5-oxime and common sponge constituents. Aplysamine-2, purpuroceratic acid A and 3-maleimide oxime were evaluated for their in vitro anticancer activity against three cancer cell lines, but only aplysamine-2 exhibited moderate dose dependent growth inhibitory effects.