Collagenases, synthetic inhibitors

Synthetic Inhibitors of Bacterial and Mammalian Interstitial Collagenases... 

Figure 13. A stereo view showing the details of enzyme inhibitor interactions between fibroblast collagenase (MMPl)and the synthetic inhibitor RO32-0554 (5). The color code is as given for Fig. 6, with additional enzyme side chains discussed in the text coloured magenta.

In an analogous manner, inhibitors bearing substituents at the carbon spacer between the zinc ligand and the alpha centre of the PI subsite have different enzyme-inhibitor interactions with separate members of the MMP family. The crystal structure of the synthetic inhibitor RO32-0554 (5) (Fig. 13) complexed with fibroblast collagenase indicates a favorable interaction between the imide oxygen of the naphthalimide group of the inhibitor and an... 

Finally, collagenase inhibitors could also play a future role in the therapy of tumor invasicxi. Natural collagenase inhibitors have been shown to inhibit tumor invasicxi vitro. Synthetic inhibitors may also be developed vhich block the sulbstrate binding domain, conpetitively, or irreversibly inhibit the enzyme itself. 

Substrate analogues containing the mercaptan functionaUty have been extensively investigated as collagenase inhibitors, and some other sulphur-based functionalities have also been explored [1,161,172-185]. The mercap-tans tend to be very potent inhibitors of all of the MMP, presumably due to the strong interaction between the active site Zn(II) and the mercaptide anion. Unfortunately, these compounds tend to undergo inactivation by oxidative disulphide formation. However, the rate at which this occurs varies widely and depends on the structure of the inhibitor. The most common synthetic route to these derivatives again leads to a diastereomeric mixture. 

A number of studies have used synthetic collagenase inhibitors in physiological assays with live tissue or whole animals for the purposes of either establishing the role of a collagenase in a physiological event, or as a test of the efficacy of the inhibitor. Since these represent two of the most important... 

A role for a collagenase, presumably fibroblast-type collagenase, in bone resorption has been indicated by studies employing the Searle A-carboxyl alkyl synthetic collagenase inhibitor CI-1 (compound (197) in Table 8.18) and its less potent stereoisomer CI-2 (compound (198) in Table 8.18) [207]. Cultured embryonic mouse calvaria treated with parathyroid hormone exhibit loss of calcium and show pronounced collagen resorption. CI-1 inhibited the collagen resorption in a dose-dependent manner at significantly lower concentrations than CI-2, but had only a small effect on calcium loss. This inhibitory effect was reversible and not due to inhibitor cytotoxicity. 

INHIBITORS - The search for new agents which modify the rheumatic process has recently been oriented toward finding inhibitors of the enzymes directly involved in joint destruction. These Include inhibitors of the serine (elastase, cathepsin G, plasminogen activator) and metallo (collagenase, non-collagenolytic) proteinases. These compounds have been derived from both natural and synthetic sources. 

By retro synthetic analysis collagenase inhibitor RO0319790 (1) can be assembled from two chiral building blocks, (R) -succinate 2 and (S)-tert-leucine N-methyla-mide 13. As the latter can be prepared from commercially available (S)-tert-leucine 8 our work concentrated in particular on the construction of the first building block 2. In order to assemble the carbon skeleton of 2 in the most efficient way, extremely cheap maleic anhydride 4 was converted in a known ene reaction with isobutylene to provide the cyclic anhydride 6. Hydrogenation of the double bond followed by the addition of EtOH/p-TsOH yielded the racemic diethyl ester substrate 9 for the enzyme reaction. The enzymatic monohydrolysis of 9 afforded the monoacid (R)-2a. (R)-2 a was coupled via its acid chloride with leucine amide 13 to ester 14, which finally was converted into the hydroxamic acid 1. 

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