High-performance liquid chromatography-electrospray ionization mass spectrometry was applied to the detection of the iron(III) complexes of the hydroxamate siderophores rhodotoluric acid, deferrioxamine B, and deferrichrome. Separation of the iron(III) complexes was obtained using a polystyrene-divinylbenzene stationary phase. The retention and responses of ferrioxamine and ferrichrome were optimal when a gradient elution program with methanol and 0.1% (v/v) formic acid as the mobile phases was used. These conditions were also suitable for the retention and separation of the uncomplexed ligands. Retention of iron(III) rhodotoluate was improved when formic acid was replaced by the ion-pairing reagent heptafluorobutyric acid (0.1%). Detection limits for the ferric complexes, defined as 3 SD of the lowest determined standard, were 26 nM for iron(III) rhodotoluate, 0.23 nM for ferrioxamine, and 0.40 nM for ferrichrome. A protocol for the solid-phase extraction of these hydroxamate siderophores from seawater was developed and applied to the extraction of siderophores from enriched incubated seawater samples.

The Cu(II) and Ag(I) complexes, [Cu(phendio) 3 ](ClO 4 ) 2 ·4H 2 O and [Ag(phendio) 2 ]ClO 4 (phendio = 1,10-phenanthroline-5,6-dione), are prepared in good yield by reacting phendio with the appropriate metal perchlorate salt. The X-ray crystal structure of the Ag(I) complex shows it to have a pseudo tetrahedral structure. 'Metal-free' phendio and the Cu(II) and Ag(I) phendio complexes strongly inhibit the growth of the fungal pathogen Candida albicans, and are more active than their 1,10-phenanthroline analogues. The simple Ag(I) salts, AgCH 3 CO 2 , AgNO 3 and AgClO 4 .H 2 O display superior anti-fungal properties compared to analogous simple Cu(II) and Mn(II) salts, suggesting that the nature of the metal ion strongly influences activity. Exposing C. albicans to 'metal-free' phendio, simple Ag(I) salts and [Ag(phendio) 2 ]ClO 4 causes extensive, non-specific DNA cleavage. 'Metal-free' phendio and [Ag(phendio) 2 ]ClO 4 induce gross distortions in fungal cell morphology and there is evidence for disruption of cell division. Both drugs also exhibit high anti-cancer activity when tested against cultured mammalian cells.

Siderophore type chelates were isolated from nutrient enriched seawater collected from coastal and near shore environments and detected using a novel high performance liquid chromatography -electrospray ionisationmass spectrometric technique. Seawater was enriched with added glucose, ammonia and phosphate, and incubated for four days. Seven different siderophore type compounds were detected in the extracted supernatants and tentatively identified based on mass numbers and spectra. The compounds comprised two groups, the ferrioxamines and the amphibactins. They were produced at typical coastal iron concentrations (total dissolved iron = 2.9 ± 1.4 2 nM and 2.2 ± 0.1 nM) both in the presence and absence of the iron chelating ligand ethylene diamine-N,N′-diacetic acid.

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