Pseudoceratina psammaplysin

Psammaplysin E (84), ceratinamine (85), and molokaiamine (86) from the sponge Pseudoceratina purpurea exhibit potent cytotoxicity against P-388 murine leukemia cells with IC50 values of 2.1, 3.4, and 2.1 pg/ml, respectively [74]. Recently, the related waianaeamines have been isolated from an undescribed verongid sponge from Molokai Island [75]. 

The bromotyramine derivatives ceratinamide A (136) and psammaplysin A (137) from the sponge Pseudoceratina purpurea inhibit the settlement and metamorphosis of cyprid larvae of the barnacle Balanus amphitrite (ED50 0.10 and 0.27 (Jg/ml). Interestingly, psammaplysin A induces larval metamorphosis of the ascidian Halocynthia roretzi (ED 0o 1.2 (Jg/ml) [74]. 

Bromotyrosine-derived metabolites are often encountered in marine sponges of the families Aplysinidae and Pseudocer-atidae, in particular Pseudoceratina (= Psammaplysilla) purpurea. They show a variety of biological activities, which include antimicrobial, enzyme inhibitory, and antifouling activities. Psammaplysin A (47) is antimicrobial, cytotoxic, and antifouling, whereas psammaplin A (48) is an inhibitor of histone deacetylase (2). The marine sponge lanthella basta synthesizes at least 25 bastadins that are linear or cyclic peptides composed of four bromotyrosine residues [bastadin 5 (49)] and show antimicrobial, cytotoxic, and enzyme inhibitory activities as well as interaction with Ca + channels (21). 

Ceratinamides A (68) and B (69), antifouling bromotyrosine derivatives, were isolated from marine sponge Pseudoceratina purpurea through a bioassay -guided isolation (Figure 4) [38]. Ceratinamide A (68) is structurally similar to psammaplysin A (27) and has one formyl group at the A-terminus. 

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