Antifungal nickel(II) complexes derived from amino sugars against pathogenic yeast, Candida albicans

Nickel(II) complexes containing N-glycosides derived from D-glucosamine (D-GlcN) and ethylenediamine (en) and trimethylenediamine (tn), [Ni(D-GlcN-en)2]Cl2·H2O (1) (D-GlcN-en=1-{(2-aminoethyl)amino}-2-amino-1,2-dideoxy-D-glucose) and [Ni(D-GlcN-tn)2]Cl2·4H2O (2) (D-GlcN-tn=1-{(3-aminopropyl)amino}-2-amino-1,2-dideoxy-D-glucose), are fairly stable in water at room temperature and showed effective antifungal activity against pathogenic yeast, Candida albicans, with the MIC (minimal concentration of inhibition) values of the complexes being 0.25 mM. The results obtained enzyme assays by using preparations of C. albicans chitinase fraction suggested that the sugar complexes 1 and 2 played a role of novel chitinase (chitin-degradation enzyme) inhibitor, where the modes of inhibition were competitive (Ki=1.3 mM for 1, Ki=1.8 mM for 2). The newly prepared nickel(II) complex 2 was characterized by elemental analysis, magnetic susceptibility, electronic absorption and circular dichroism spectroscopies, and an X-ray crystallographic analysis.