Synthesis of a Series of Stromelysin-Selective Thiadiazole Urea Matrix Metalloproteinase Inhibitors

Abstract

The synthesis and enzyme inhibition data for a series of thiadiazole urea matrix metalloproteinase (MMP) inhibitors are described. A broad screening effort was utilized to identify several thiadiazoles which were weak inhibitors of stromelysin. Optimization of the thiadiazole leads to include an alpha-amino acid side chain with variable terminal amide substituents provided a series of ureas which were moderately effective stromelysin inhibitors, with Ki's between 0.3 and 1.0 microM. The most effective analogues utilized an L-phenylalanine as the amino acid component. In particular, unsubstituted 46 had a Ki of 710 nM, while the p-fluoro analogue 52 displayed increased potency (100 nM). Stromelysin inhibition was further improved using a pentafluorophenylalanine substituent which resulted in 70, a 14 nM inhibitor. While gelatinase inhibition was generally poor, the use of 1-(2-pyridyl)piperazine as the amide component usually provided for enhanced activity, with 71 inhibiting gelatinase with a Ki of 770 nM. The combination of this heterocycle with a p-fluorophenylalanine substituent provided the only analogue, 69, with collagenase activity (13 microM). The SAR for analogues described within this series can be rationalized through consideration of the X-ray structure recently attained for70 complexed to stromelysin. Uniquely, this structure showed the inhibitor to be completely orientated on the left side of the enzyme cleft. These results suggest that thiadiazole urea heterocycles which incorporate a substituted phenylalanine can provide selective inhibitors of stromelysin. Careful selection of the amide substituent can also provide for analogues with modest gelatinase inhibition.

Specificity of Binding with Matrix Metalloproteinases

“…Among the known zinc-chelating moieties, the hydroxamate group has been correlated with unfavorable pharmacokinetics (Babine and Bender 1997) and chronic toxicity. Thus, alternate zinc-binding groups are needed (Puerta et al 2004;Schroeder et al 2001;Foley et al 2001;Jacobsen et al 1999). Some micromolar inhibitors occupying the S1 0 pocket of MMP-13 without interacting with the catalytic zinc are described by Chen et al However, optimization by introducing a zinc-binding moiety yielded a selectivity of >5,800-, 56-, and >500-fold against MMP-1, MMP-9, and TACE (Chen et al 2000).…”

The Design, Structure, and Therapeutic Application of Matrix Metalloproteinase Inhibitors

“…These compounds are selective for MMP-3. The most potent one is compound 90, which inhibits MMP-3 with a K i of 18 nM and MMP-2 with a K i of 3000 nM [210]. The compound does not inhibit any of the collagenases.…”

MMP-3 (5A/6A) Polymorphism Does Not Influence Human Smooth Muscle Cell Invasion

“…The effect of the MMP-3 Inhibitor III (20 mM; Calbiochem, Nottingham, UK) on IL-1/PDGF-mediated invasion was also investigated by pre-treating cells for 1 h prior to loading them into the upper chamber. The K i for this inhibitor is 3.2 mM for MMP-3, with inhibition of MMP-2 observed only at substantially higher concentrations (K i > 200 mM) [25]. After incubation for 24 h at 37 C in a tissue culture incubator, duplicate membranes were processed and evaluated by counting cells in 10 random fields under high power (3400) light microscopy [23].…”