Synthetic inhibitors of bacterial and mammalian interstitial collagenases

Highly modular synthesis of C1-symmetric aminosulfoximines and their use as ligands in copper-catalyzed asymmetric Mukaiyama-aldol reactions

The development of C1-symmetric aminosulfoximines, their highly modular synthesis, and their application in enantioselective copper-catalyzed Mukaiyama-type aldol reactions between pyruvates and enolsilanes is described. In this context, the influence of the ligand architecture as well as the optimization of the reaction conditions are discussed. In detail, the dependence of the catalyst efficiency on the solvent, the metal source and the temperature are reported, and an interesting additive effect is highlighted. Furthermore, the substrate scope will be presented. With the optimized catalyst system, a number of aldol products with quaternary stereogenic centers have been obtained in high yields and with enantiomeric excesses up to 99 %.

The cell envelope-bound metalloprotease (camelysin) from Bacillus cereus is a possible pathogenic factor

A novel membrane proteinase of the nosocomial important bacteria species Bacillus cereus (synonyms: camelysin, CCMP) was purified up to homogeneity as was shown by mass spectrometry in its amphiphilic form. Camelysin is a neutral metalloprotease with a molecular mass of 19 kDa. Its unique N-terminus Phe-Phe-Ser-Asp-Lys-Glu-Val-Ser-Asn-Asn-Thr-Phe-Ala-Ala-Gly-Thr-Leu-Asp-Leu-Thr-Leu-Asn-Pro-Lys-Thr-Leu-Val-Asp-(Ile-Lys-Asp)- was not detected in the protein data bases during BLAST searches, but in the partially sequenced genome of Bacillus anthracis, coding for an unknown protein. Cleavage sites of the membrane proteinase for the insulin A- and B-chains were determined by mass spectrometry and N-terminal sequencing. Camelysin prefers cleavage sites in front of aliphatic and hydrophilic amino acid residues (-OH, -SO3H, amido group), avoiding bulky aromatic residues. The internally quenched fluorogenic substrates of the matrix metalloproteases 2 and 7 were cleaved with the highest efficiency at the Leu-decrease-Gly or Leu-decrease-Ala bond with the smaller residue in the P1' position. The protein specificity is broad--all various kinds of casein were cleaved as well as acid-soluble collagen, globin and ovalbumin; intact insulin was destroyed only to a low extent. Actin, collagen type I, fibrinogen, fibrin, alpha2-antiplasmin and alpha1-antitrypsin were cleaved. The protease formed SDS-stable complexes with Glu-plasminogen and antithrombin III, visible after SDS electrophoresis by gold staining and Western blot. The CCMP-plasminogen complex caused a partial activation of plasminogen to plasmin. Camelysin interacts with proteins of the blood coagulation cascade and could facilitate the penetration of fibrin clots and of the extracellular matrix during bacterial invasion.

N-hydroxyformamide peptidomimetics as TACE/matrix metalloprotease inhibitors: oral activity via P1' isobutyl substitution

N-Hydroxyformamide-class metalloprotease inhibitors were designed and synthesized, which have potent broad-spectrum activity versus matrix metalloproteases and TNF-alpha converting enzyme (TACE). Compound 13c possesses good oral and intravenous pharmacokinetics in the rat and dog.

Fibroblast growth factor (FGF)-2 directly stimulates mature osteoclast function through activation of FGF receptor 1 and p42/p44 MAP kinase

We previously reported that fibroblast growth factor-2 (FGF-2) acts not only on osteoblasts to stimulate osteoclastic bone resorption indirectly but also on mature osteoclasts directly. In this study, we investigated the mechanism of this direct action of FGF-2 on mature osteoclasts using mouse and rabbit osteoclast culture systems. FGF-2 stimulated pit formation resorbed by isolated rabbit osteoclasts moderately from low concentrations (>/=10(-12) m), whereas at high concentrations (>/=10(-9) m) it showed stimulation on pit formation resorbed by unfractionated bone cells very potently. FGF-2 (>/=10(-12) m) also increased cathepsin K and MMP-9 mRNA levels in mouse and rabbit osteoclasts. Among FGF receptors (FGFR1 to 4) only FGFR1 was detected on isolated mouse osteoclasts, whereas all FGFRs were identified on mouse osteoblasts. FGF-2 (>/=10(-12) m) up-regulated the phosphorylation of cellular proteins, including p42/p44 mitogen-activated protein (MAP) kinase, and increased the kinase activity of immunoprecipitated FGFR1 in mouse osteoclasts. The stimulation of FGF-2 on mouse and rabbit osteoclast functions was abrogated by PD-98059, a specific inhibitor of p42/p44 MAP kinase. These results strongly suggest that FGF-2 acts directly on mature osteoclasts through activation of FGFR1 and p42/p44 MAP kinase, causing the stimulation of bone resorption at physiological or pathological concentrations.

Protease inhibitors. Part 8: synthesis of potent Clostridium histolyticum collagenase inhibitors incorporating sulfonylated L-alanine hydroxamate moieties

A series of hydroxamates was prepared by reaction of alkyl/arylsulfonyl halides with N-2-chlorobenzyl-L-alanine, followed by conversion of the COOH moiety to the CONHOH group, with hydroxylamine in the presence of carbodiimides. Other structurally related compounds were obtained by reaction of N-2-chlorobenzyl-L-alanine with aryl isocyanates, arylsulfonyl isocyanates or benzoyl isothiocyanate, followed by the similar conversion of the COOH into the CONHOH moiety. The new compounds were assayed as inhibitors of the Clostridium histolyticum collagenase, ChC (EC 3.4.24.3), a bacterial zinc metallo-peptidase which degrades triple helical collagen as well as a large number of synthetic peptides. The prepared hydroxamate derivatives proved to be 100-500 times more active collagenase inhibitors than the corresponding carboxylates. Substitution patterns leading to best ChC inhibitors (both for carboxylates as well as for the hydroxamates) were those involving perfluoroalkylsulfonyl- and substituted-arylsulfonyl moieties, such as pentafluorophenylsulfonyl; 3- and 4-protected-aminophenylsulfonyl-; 3- and 4-carboxyphenylsulfonyl-; 3-trifluoromethyl-phenylsulfonyl; as well as 1- and 2-naphthyl-, quinoline-8-yl- or substituted-arylsulfonylamidocarboxyl moieties among others. Similarly to the matrix metalloproteinase (MMP) hydroxamate inhibitors, ChC inhibitors of the type reported here must incorporate hydrophobic moieties at the P2' and P3' sites, in order to achieve tight binding to the enzyme. This study also proves that the 2-chlorobenzyl moiety, investigated here for the first time, is an efficient P2' anchoring moiety for obtaining potent ChC inhibitors.

Design and synthetic considerations of matrix metalloproteinase inhibitors

Experimental evidence confirms that the matrix metalloproteinases (MMPs) play a fundamental role in a wide variety of pathologic conditions that involve connective tissue destruction including osteoarthritis and rheumatoid arthritis, tumor metastasis and angiogenesis, corneal ulceration, multiple sclerosis, periodontal disease, and atherosclerosis. Modulation of MMP regulation is possible at several biochemical sites, but direct inhibition of enzyme action provides a particularly attractive target for therapeutic intervention. Hypotheses concerning inhibition of specific MMP(s) with respect to disease target and/or side-effect profile have emerged. Examples are presented of recent advances in medicinal chemistry approaches to the design of matrix metalloproteinase inhibitors (MMPIs), approaches that address structural requirements and that influence potency, selectivity, and bioavailability. Two important approaches to the design, synthesis, and biological evaluation of MMPIs are highlighted: (1) the invention of alternatives to hydroxamic acid zinc chelators and (2) the construction of nonpeptide scaffolds. One current example in each of these two approaches from our own work is described.

Hydroxamate derivatives of substrate-analogous peptides containing aminomalonic acid are potent inhibitors of matrix metalloproteinases

Novel peptides containing the sequence -Pro-Leu-Ama(NHOH)- were synthesized and characterized by spectroscopic techniques. Their inhibitory properties towards the activated form of native human gelatinase B (MMP-9) and the catalytic domain of neutrophil collagenase (cdMMP-8) were determined. The most effective inhibitor synthesized exhibits Ki values of 2 x 10(-6) M (cdMMP-8) and 5 x 10(-9) M (MMP-9) thus attaining interesting discrimination between the tested metalloproteinases. A most important feature of this type of inhibitor is its peptide nature making the compounds similar to natural substrates. In spite of the peptide character of the inhibitors synthesized, the P1-P1'-peptide bond shows a high resistance to cleavage by the proteinases.

Pharmacological effect of tetracyclines on proteoglycanases from interleukin-1-treated articular cartilage

Based on previous in vivo and in situ studies showing that tetracyclines possess antidegenerative effects on cartilage in conjunction with a reduced proteoglycan (PG) loss from the extracellular matrix, we investigated the effects of doxycycline, minocycline and tetracycline on the degradation and biosynthesis of PGs by bovine articular cartilage explants, both in vitro and in situ. Doxycycline, minocycline and tetracycline dose dependently, although weakly, inhibited PG degrading matrix metalloproteinases (MMPs) in vitro, when tested at concentrations ranging from 1 to 100 microM. Ro 31-4724 proved to be a potent inhibitor of MMP proteoglycanases (IC50 value 1.5 nM). Only at a concentration of 100 microM did doxycycline and minocycline significantly inhibit the interleukin-1 (IL-1)-induced augmentation of PG loss from cartilage explants into the nutrient media. The tetracyclines did not modulate the IL-1-mediated reduced aggregability of PGs, whereas 10 microM Ro 31-4724 partially restored the aggregability of PGs ex vivo. Tetracycline even at this high concentration was ineffective. Compared to the effects of the MMP inhibitor Ro 31-4724, treatment with tetracyclines at therapeutic serum levels of 1 or 10 microM was minimal, with little or no effect on cartilage proteoglycanases and PG biosynthesis. In our experiments, tetracyclines and Ro 31-4724 at doses evaluated had no cytotoxic effects on chondrocytes.

Non-peptidic cysteine derivatives as inhibitors of matrix metalloproteinases

By exploiting the thiol function of L-cysteine as a chelating group of the active-site zinc atom of matrix metalloproteinases (MMPs), N- and C-terminal derivatization of this amino acid with aliphatic and aromatic groups allowed us to explore the selectivity of the S and/or S' binding subsites of human neutrophil collagenase (MMP8) and stromelysin (MMP3). With N-benzyloxycarbonyl-L-cysteine-(2-phenyl)ethylamide a submicromolar inhibitor of MMP8 was discovered.

Matrix metalloproteinases and coronary artery disease: a novel therapeutic target

Matrix metalloproteinases (MMP) are a family of enzymes that selectively digest individual components of the extracellular matrix. Their function has been studied in both normal physiologic processes and pathologic states. In the blood vessel, MMPs play an important role in maintaining the vessel's integrity by breaking down extracellular matrix while new matrix is being synthesized. This is necessary to avoid weakening from continuous mechanical stresses. However, in certain environments, these MMPs may contribute to cardiovascular pathologic processes. The purpose of this review is to first discuss the role of MMPs in coronary vascular disease. Evidence suggests that MMPs contribute to the development of de novo atherosclerotic plaques and postangioplasty restenotic plaques by allowing smooth muscle cells to migrate from the vascular media to the intima. Evidence also suggests that MMPs contribute to the rupture of these plaques by degrading the fibrous cap that surrounds them. With this increased molecular information that concerns the pathogenesis of coronary vascular disease, new molecular therapies aimed at altering these processes are being investigated. The rationale, mode of delivery, and prospects for success of these therapies will also be discussed here.

Angiotensin-converting enzyme secretase is inhibited by zinc metalloprotease inhibitors and requires its substrate to be inserted in a lipid bilayer

Mammalian angiotensin-converting enzyme (ACE; EC 3.4.15.1) is one of several proteins that exist in both membrane-bound and soluble forms as a result of a post-translational proteolytic processing event. For ACE we have previously identified a metalloprotease (secretase) responsible for this proteolytic cleavage. The effect of a range of structurally related zinc metalloprotease inhibitors on the activity of the secretase has been examined. Batimastat (BB94) was the most potent inhibitor of the secretase in pig kidney microvillar membranes, displaying an IC50 of 0.47 microM, whereas TAPI-2 was slightly less potent (IC50 18 microM). Removal of the thienothiomethyl substituent adjacent to the hydroxamic acid moiety or the substitution of the P2' substituent decreased the inhibitory potency of batimastat towards the secretase. Several other non-hydroxamate-based collagenase inhibitors were without inhibitory effect on the secretase, indicating that ACE secretase is a novel zinc metalloprotease that is realted to, but distinct from, the matrix metalloproteases. The full-length amphipathic form of ACE was labelled selectively with 3-trifluoromethyl-3-(m-[125I]iodophenyl)diazirine in the membrane-spanning hydrophobic region. Although trypsin was able to cleave the hydrophobic anchoring domain from the bulk of the protein, there was no cleavage of full-length ACE by a Triton X-100-solubilized pig kidney secretase preparation when the substrate was in detergent solution. In contrast, the Triton X-100-solubilized secretase preparation released ACE from pig intestinal microvillar membranes, which lack endogenous secretase activity, and cleaved the purified amphipathic form of ACE when it was incorporated into artificial lipid vesicles. Thus the secretase has an absolute requirement for its substrate to be inserted in a lipid bilayer, a factor that might have implications for the development of cell-free assays for other membrane protein secretases. ACE secretase could be solubilized from the membrane with Triton-X-100 and CHAPS, but not with n-octyl beta-D-glucopyranoside. Furthermore trypsin could release the secretase from the membrane, implying that like its substrate, ACE, it too is a stalked integral membrane protein.

Synthesis and biological evaluation of orally active matrix metalloproteinase inhibitors

The synthesis and biological evaluation of orally active inhibitors of matrix metalloproteinase are reported. Modifications of the P2' position and the alpha-substituent of hydroxamic acid derivatives were carried out, and revealed that the P2' substituent influenced the MMP inhibitory activities in vitro and in plasma after oral administration. The hydroxamates with phenylglycine at the P2' position were absorbed well orally. Compound 15e, which exhibited the longest duration of inhibitory activity in plasma after oral administration among the phenylglycine derivatives (5a-5d, 15a, 15c, 15e), was evaluated in a rat adjuvant arthritis model. A reduction in hind foot pad swelling and improvements of some inflammatory parameters were demonstrated when the compound was administered orally. These results indicate the potential of MMP inhibitors for rheumatoid arthritis.

Suppression of polarity, locomotion and F-actin levels of Walker carcinosarcoma cells by the inhibitor CI-959

Locomotor activity of tumor cells is an important factor for the capacity for invasion and metastasis. Therefore, inhibitors interfering with cellular mechanisms regulating spontaneous cell locomotion are of particular interest for cancer therapy. CI-959, a new benzothiophene cell activation inhibitor, has the capacity to suppress spontaneous polarity and locomotion of Walker carcinosarcoma cells. Suppression of polarity and locomotion was closely associated with a reduction in the relative amount of F-actin. The mechanisms involved in suppression of motility are Ca2(+)-independent and not related to cell-substratum adhesion. Walker carcinosarcoma cells appear to be able to locomote at very low (nM) levels of free [Ca2+]i.

Wound fluids from human pressure ulcers contain elevated matrix metalloproteinase levels and activity compared to surgical wound fluids

Fluid from acute surgical wounds and from nonhealing pressure ulcers was examined for the presence of several matrix metalloproteinases. Gelatin zymography demonstrated the presence of two major gelatinases with apparent molecular masses of 72 kDa and 92 kDa and two minor gelatinases with apparent mobilities of 68 kDa and 125 kDa. Antigen-specific sera identified the 72-kDa protein as matrix melloproteinase-2. The same sera also reacted with the 68-kDa protein, which is consistent with it being an activated form of matrix metalloproteinase-2. Antigen-specific sera identified the 92-kDa and 125-kDa proteins as matrix metalloproteinase-9. Levels of matrix metalloproteinase-2 and matrix metalloproteinase-9 were elevated more than 10-fold and 25-fold, respectively, in fluids from pressure ulcers compared with fluids from healing wounds. Examination of total potential and actual collagenolytic activity revealed that fluid from pressure ulcers contained significantly greater levels of both total and active collagenase compared with that of acute surgical wounds. In addition, an enzyme-linked immunosorbent assay demonstrated that fluids from pressure ulcers contained significantly more collagenase complexed with the inhibitor, tissue inhibitor of metalloproteinases. Together, these observations suggest that an imbalance exists between levels of matrix metalloproteinases and their inhibitors in the fluids of pressure ulcers and that this is primarily the result of elevated levels of the matrix metalloproteinases. The presence of excessive levels of activated forms of matrix-degrading enzymes at the wound surface of pressure ulcers may impede the healing of these wounds and may be relevant to the development of new rationales for treatment.

Isothiazolones interfere with normal matrix metalloproteinase activation and inhibit cartilage proteoglycan degradation

A series of isothiazolones that inhibit pro-(matrix metallo-proteinase) (proMMP) activation but do not inhibit the active enzyme are effective as cartilage protectants in bovine nasal cartilage organ culture, preventing interleukin-1 (IL-1)-induced proteoglycan (aggrecan) degradation without affecting its synthesis. These compounds were found to bind to prostromelysin (proMMP-3) in a non-dialysable and stoichiometric manner. Preincubation with cartilage-protectant isothiazolones prevented the binding of [14C]iodoacetamide to Cys75 of the MMP-3 propeptide, suggesting that the activity of these compounds involves their binding to the Cys75 of the MMP zymogen. Studies following chymotrypsin activation of proMMP-3 by SDS/PAGE indicated that altered processing of the 57 kDa zymogen to the active form occurred in the presence of compound. The 53 kDa intermediate seen on normal activation was not formed; instead a different intermediate appeared with a molecular mass of approx. 46 kDa. N-terminal sequence analysis indicated that this intermediate was formed by cleavage at the putative 4-aminophenylmercuric acid cleavage site. Importantly the 45 kDa active MMP-3 species formed in the presence of compound was one amino acid residue shorter than the native MMP-3. These results suggest that the inhibition of cartilage proteoglycan degradation by isothiazolones might be due to their ability to bind to the Cys75 in the propeptide region of the MMP zymogen and interfere with its normal activation process.