Chemical investigation of an Australian marine sponge, Pseudoceratina sp., collected from Mooloolaba South-East Queensland has provided a series of bromotyrosine metabolites from a simple modified tyrosine to more elaborate linear compounds. Six known compounds, (+)-aeroplysinin-1 (1), a mixture of 19-deoxyfistularin-3 (2) and 11-deoxyfistularin-3 (3), 11,19- dideoxyfistularin-3 (4), aerothionin (5) and homoaerothionin (6) have been isolated together with a new fistularin-3 derivative, 11-deoxy-19-ketofistularin-3 (7). The structures of all compounds were characterised using 1D and 2D NMR techniques, MS and by comparison with literature data. Two selected fistularin-3 derivative metabolites 4 and 7 were screened for in vitro activity against chloroquine-sensitive (3D7) P. falciparum malaria parasites and showed antimalarial activity with IC50 values of 5.4 and 2.8 μM, respectively.