Quinolones from a bacterium and tyrosine metabolites from its host sponge, Suberea creba from the Coral Sea

A marine bacterium, identified as a pseudomonad, isolated from Suberea creba Bergquist, 1995 (Porifera, Dictyoceratida, Verongida, Aplysinellidae) collected along the eastern coast of New Caledonia, gave in culture phenazine-alpha-carboxamide, 2-n-heptylquinol-4-one, 2-n-nonylquinol-4-one, 2-n-(1'E-nonenyl)quinol-4-one, 3-n-heptyl-3-hydroxyquinolin-2,4-dione, a N-oxide-2-n-heptylquinoline derivative, and a benzyldiketopiperazine. None of these products could be detected, at the HPLC-UV sensitivity level, in the sponge extracts, which contained instead (+)-aerothionin, homoaerothionin, (+)-aeroplysinin-1, dibromo-, bromochloro-, and dichloroverongiaquinol. 2-n-Heptylquinol-4-one, (+)-aeroplysinin-1, and dibromoverongiaquinol showed strong antibacterial activity in vitro. The latter also proved promising for mariculture, rivaling chloramphenicol as an antibacterial agent in cultures of Pecten maximus larvae, while being nontoxic according to the Artemia salina test.