Phloeodictiues Al-A7 (34 34 4a, 4b, 4c, 5n,Sb) aud phloeodictines Cl-C2 (6a, 6b), new antibacterial and cytotoxic guanidine alkaloids, have been isolated from the sponge Phfoeodic@on sp. Their strucmres were established essentially by mass spectrometry utilizing B/E linked scanning and by 2D NMR experiments. We have recently reported the structure elucidation of two antibacterial and cytotoxic guanidine derivatives containing an unprecedented 6-hydroxy-1,2,3,4-tetrahydropyrrolo[l,2-al pyrimidinum skeleton, phloeodictines A (1) and B (Z), isolated from the New-Caledonian deep water sponge Phloeodictyon sp.' (family Nepheliospongia, order Nepheliospongidae). Further search for bioactive agents from the same sponge resulted in the isolation of new structurally related pyrrolo[ 1,2_aIpyrimidines named phloeodictines Al-A7 (3a, 3b, 4a, 4b, k, Sa, 5b) and Cl-C2 (6a, 6b). The structures of these compounds were established essentially by comparison of their collisionally activated dissociation (CAD) mass spectra obtained using FAB ionisation and B/E linked scanning2 with those of 1. All compounds exhibited in vitro antibacterial activities and were moderately cytotoxic against KB cells. The lyophilized sponge was extracted with methanol. The antimicrobial methanolic extract was desalted over Amberlite XAD-7 and subsequently subjected to medium pressure reversed-phase liquid chromatography (H20-MeOH step gradient). Final purification using preparative and semi-preparative RP-HPLC [Delta-Pak Cl& MeOH-NaCl(0.2M) -THF, pH adjusted to 2.2 with HCl] yielded a ca 2.6: 1 mixture (3) of phloeodictines Al (3a) and A2 (3b), a ca 2.6:0.7:0.3 mixture 4 of phloeodictines A3 (4a), A4 (4b) and A5 (4c), a ca 1:1.4 mixture (5) of phloeodictines A6 (5a) and A7 (5b) and a ca 1:l mixture 6 of phloeodictines Cl (6a) and C2 (6b) as colorless amorphous solids. Typical yields were 0.55% for 3, 0.02% for 4, 0.02% for 5 and 0.54% for 6 (dry weight sponge). The UV absorption of mixture 3 was the same as that of the previously reported phloeodictine A (l), exhibiting maxima at 224 (E 6700) and 274 (E 2200) nm. The positive ion FAB mass spectrum of 3 revealed two M+ peaks at m/z 432 and 418 corresponding to phloeodictine Al (3a) and A2 (3b) respectively. The molecular formulas C25H46N50 (M+, m/z 432.3712, A -1.0 mmu) for 3a and C24H44NsO (M+, m/z