Heterocyclic zinc-binding groups for use in next-generation matrix metalloproteinase inhibitors: potency, toxicity, and reactivity

Abstract

In an effort to improve the zinc-chelating portion of matrix metalloproteinase (MMP) inhibitors, we have developed a family of heterocyclic zinc-binding groups (ZBGs) as alternatives to the widely used hydroxamic acid moiety. Elaborating on findings from an earlier report, we performed in vitro inhibition assays with recombinant MMP-1, MMP-2, and in a cell culture assay using neonatal rat cardiac fibroblast cells. In both recombinant and cell culture assays, the new ZBGs were found to be effective inhibitors, typically 10-100-fold more potent than acetohydroxamic acid. The toxicity of these chelators was examined by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt cytotoxicity assays, which demonstrate that most of these compounds are nontoxic at concentrations of almost 100 microM. To address the possible interaction of sulfur-containing ZBGs with biological reductants, the reactivity of these chelators with 5,5'-dithiobis(2-nitrobenzoic acid) was examined. Finally, thione ZBGs were shown to be effective inhibitors of cell invasion through an extracellular matrix membrane. The data presented herein suggest these heterocyclic ZBGs are potent, nontoxic, and biocompatible compounds that show promise for incorporation into a new family of MMP inhibitors.

Zinc‐Binding Groups Modulate Selective Inhibition of MMPs

“…[40] IC 50 values were determined (Table 1) as previously described, [31,33,40] and enzyme kinetic experiments were performed to determine the K m value, K i value, and the mode of inhibition. As expected, MMPi 1-5 are poor inhibitors of shallow S1' pocket MMPs (that is, MMP-1 and MMP-7) with IC 50 values greater than 50 mm.…”

“…[22] Other efforts have been made toward the identification of alternative ZBGs using a novel bioinorganic approach. [18,[29][30][31][32][33] These studies have identified new ZBGs, that are more potent than hydroxamic acids, some of which have been developed into potent, nonhydroxamate inhibitors of MMPs. [32,34,35] In the present study, a series of hydroxypyrone and hydroxypyridinone inhibitors have been synthesized and evaluated to demonstrate that the isoform selectivity of an MMPi can be influenced by the choice of ZBG.…”

Biomimetic Applications of Metal Systems Supported by Scorpionates

“…In these binding studies the coordination properties of the zinc binding groups of MMP inhibitors are investigated. In particular the pioneering work of Cohen Puerta & Cohen, 2003;Jacobsen & Cohen, 2004;Puerta et al, 2004;Puerta et al, 2005;Puerta et al, 2006;Jacobsen et al, 2007) and Vahrenkamp in this field has to be highlighted. Common zinc binding groups applied successfully in peptidase inhibitors have been either a carboxylic acid, a hydroxamic acid or a thiol functionality.…”

“…They reported the binding of β-mercaptoketone and β-mercaptoamide drugs in a bidentate fashion, while β-mercaptothiols bound exclusively in a monodentate manner, contrary to prior expectations . A whole series of publications by the same authors extended this concept to four different groups of chelators: hydroxypyridinones, pyrones, hydroxypyridinethiones and thiopyrones (Puerta & Cohen, 2003;Puerta et al, 2004;Puerta et al, 2005;Puerta et al, 2006;Jacobsen et al, 2007). Each of the tested small molecules was able to displace the hydroxide ligand in the [HB(pz Ph,Me ) 3 ]ZnOH model complex of the active site and to coordinate the zinc(II) in a bidentate fashion (Puerta & Cohen, 2003;Puerta et al, 2004;Puerta et al, 2006;Jacobsen et al, 2007) (Fig.…”

“…The zinc binding groups (ZBGs) listed above were found to have a greater affinity than acetohydroxamic acid (AHA) for the zinc(II) ion the model complex. Furthermore, the inhibitory activity of these ZBGs was compared with that of AHA (Puerta et al, 2006). All the new compounds were found to be more potent inhibitors of MMP-3 than AHA (Puerta et al, 2004).…”