Amino acid derived sulfonamide hydroxamates as inhibitors of procollagen C-proteinase: solid-phase synthesis of ornithine analogues

Enzymatic Synthesis of Ricinoleyl Hydroxamic Acid Based on Commercial Castor Oil, Cytotoxicity Properties and Application as a New Anticancer Agent

BACKGROUND

New anticancer agents that rely on natural/healthy, not synthetic/toxic, components are very much needed.

METHODS

Ricinoleyl hydroxamic acid (RHA) was synthesized from castor oil and hydroxylamine using Lipozyme TL IM as a catalyst. To optimize the conversion, the effects of the following parameters were investigated: type of organic solvent, period of reaction, amount of enzyme, the molar ratio of reactants and temperature. The highest conversion was obtained when the reaction was carried out under the following conditions: hexane as a solvent; reaction period of 48 hours; 120 mg of Lipozyme TL IM/3 mmol oil; HA-oil ratio of 19 mmol HA/3 mmol oil; and temperature of 40°C. The cytotoxicity of the synthesized RHA was assessed using human dermal fibroblasts (HDF), and its application towards fighting cancer was assessed using melanoma and glioblastoma cancer cells over a duration of 24 and 48 hours.

RESULTS

RHA was successfully synthesized  and it demonstrated strong anticancer activity against glioblastoma and melanoma cells at as low as a 1 µg/mL concentration while it did not demonstrate any toxicity against HDF cells.

CONCLUSION

This is the first report on the synthesis of RHA with great potential to be used as a new anticancer agent.

Reprint of "The complex dynamics of myocardial interstitial fibrosis in heart failure. Focus on collagen cross-linking"

Myocardial interstitial fibrosis (MIF) is a common finding in heart failure (HF) patients, both with preserved and reduced ejection fraction, as well as in HF animal models. MIF is associated with impaired cardiac function and worse clinical outcome. The impact of MIF is influenced not only by the quantity but also by changes in the quality of collagen fibers and in the extracellular matrix components, such as a shift in collagen types proportion, increased fibronectin polymerization and increased degree of collagen cross-linking (CCL). In particular, CCL, a process that renders collagen fibers stiffer and more resistant to degradation, is increased both in patients and animal models of HF. Importantly, in HF patients increased cardiac CCL is directly associated with increased left ventricular stiffness and a higher risk of hospitalization for HF. The aim of this review is to address the complexity of MIF in HF, focusing on CCL.

The complex dynamics of myocardial interstitial fibrosis in heart failure. Focus on collagen cross-linking

Myocardial interstitial fibrosis (MIF) is a common finding in heart failure (HF) patients, both with preserved and reduced ejection fraction, as well as in HF animal models. MIF is associated with impaired cardiac function and worse clinical outcome. The impact of MIF is influenced not only by the quantity but also by changes in the quality of collagen fibers and in the extracellular matrix components, such as a shift in collagen types proportion, increased fibronectin polymerization and increased degree of collagen cross-linking (CCL). In particular, CCL, a process that renders collagen fibers stiffer and more resistant to degradation, is increased both in patients and animal models of HF. Importantly, in HF patients increased cardiac CCL is directly associated with increased left ventricular stiffness and a higher risk of hospitalization for HF. The aim of this review is to address the complexity of MIF in HF, focusing on CCL.

Role of lysyl oxidase in myocardial fibrosis: from basic science to clinical aspects

Because of its dynamic nature, the composition and structure of the myocardial collagen network can be reversibly modified to adapt to transient cardiac injuries. In response to persistent injury, however, irreversible, maladaptive changes of the network occur leading to fibrosis, mostly characterized by the excessive interstitial and perivascular deposition of collagen types I and III fibers. It is now becoming apparent that myocardial fibrosis directly contributes to adverse myocardial remodeling and the resulting alterations of left ventricular (LV) anatomy and function present in the major types of cardiac diseases. The enzyme lysyl oxidase (LOX) is a copper-dependent extracellular enzyme that catalyzes lysine-derived cross-links in collagen and elastin. LOX-mediated cross-linking of collagen types I and III fibrils leads to the formation of stiff collagen types I and III fibers and their subsequent tissue deposition. Evidence from experimental and clinical studies shows that the excess of LOX is associated with an increased collagen cross-linking and stiffness. It is thus conceivable that LOX upregulation and/or overactivity could underlie myocardial fibrosis and altered LV mechanics and contribute to the compromise of LV function in cardiac diseases. This review will consider the molecular aspects related to the regulation and actions of LOX, namely, in the context of collagen synthesis. In addition, it will address the information related to the role of myocardial LOX in heart failure and the potential benefits of controlling its expression and function.

Identification of a potential cardiac antifibrotic mechanism of torasemide in patients with chronic heart failure

OBJECTIVES

This study sought to investigate whether torasemide inhibits the enzyme involved in the myocardial extracellular generation of collagen type I molecules (i.e., procollagen type I carboxy-terminal proteinase [PCP]).

BACKGROUND

Torasemide has been reported to reduce myocardial fibrosis in patients with chronic heart failure (HF).

METHODS

Chronic HF patients received either 10 to 20 mg/day oral torasemide (n = 11) or 20 to 40 mg/day oral furosemide (n = 11) in addition to their standard HF therapy. At baseline and after 8 months from randomization, right septal endomyocardial biopsies were obtained to analyze the expression of PCP by Western blot and the deposition of collagen fibers (collagen volume fraction [CVF]) with an automated image analysis system. The carboxy-terminal propeptide of procollagen type I (PICP) released as a result of the action of PCP on procollagen type I was measured in serum by radioimmunoassay.

RESULTS

The ratio of PCP active form to PCP zymogen, an index of PCP activation, decreased (p < 0.05) in torasemide-treated patients and remained unchanged in furosemide-treated patients. A reduction (p < 0.01) in both CVF and PICP was observed in torasemide-treated but not in furosemide-treated patients. Changes in PCP activation were positively correlated (p < 0.001) with changes in CVF and changes in PICP in patients receiving torasemide.

CONCLUSIONS

These findings suggest the hypothesis that the ability of torasemide to reduce myocardial fibrosis in chronic HF patients is related to a decreased PCP activation. Further studies are required to ascertain whether PCP may represent a new target for antifibrotic strategies in chronic HF.

A procollagen C-proteinase inhibitor diminishes collagen and lysyl oxidase processing but not collagen cross-linking in osteoblastic cultures

The deposition of insoluble functional collagen occurs following extracellular proteolytic processing of procollagens by procollagen N- and C-proteinases, fibril formation, and lysyl oxidase dependent cross-linking. Procollagen C-proteinases in addition process and activate lysyl oxidase. The present study evaluates a possible role for procollagen C-proteinases in controlling different aspects of collagen deposition in vitro. Studies determine whether inhibition of procollagen C-proteinase activity with a specific BMP-1 inhibitor results in perturbations in lysyl oxidase activation, and in collagen processing, deposition, and cross-linking in phenotypically normal cultured murine MC3T3-E1 cells. Data show that BMP-1 Inhibitor dose dependently inhibits lysyl oxidase activation by up to 50% in undifferentiated proliferating cells. In differentiating cultures, BMP-1 inhibitor decreased collagen processing but did not inhibit the accumulation of mature collagen cross-links. Finally, electron microscopy studies show that collagen fibril diameter increased. Thus, inhibition of procollagen C-proteinases results in perturbed collagen deposition primarily via decreased collagen processing.

Protease inhibitors of the sulfonamide type: anticancer, antiinflammatory, and antiviral agents

The sulfonamides constitute an important class of drugs, with several types of pharmacological agents possessing antibacterial, anticarbonic anhydrase, diuretic, hypoglycemic, and antithyroid activity among others. A large number of structurally novel sulfonamide derivatives have ultimately been reported to show substantial protease inhibitory properties. Of particular interest are some metalloprotease inhibitors belonging to this class, which by inhibiting several matrix metalloproteases (MMPs) show interesting antitumor properties. Some of these compounds are currently being evaluated in clinical trials. The large number of sulfonamide MMP inhibitors ultimately reported also lead to the design of effective tumor necrosis factor-alpha converting enzyme (TACE) inhibitors, potentially useful in the treatment of inflammatory states of various types. Since both MMPs and TACE contribute synergistically to the pathophysiology of many diseases, such as arthritis, bacterial meningitis, tumor invasion; the dual inhibition of these enzymes emerged as an interesting target for the drug design of anticancer/antiinflammatory drugs, and many such sulfonamide derivatives were recently reported. Human neutrophyl elastase (HNE) inhibitors of the sulfonamide type may also be useful in the treatment of inflammatory conditions, such as emphysema, cystic fibrosis, chronic bronchitis, ischemia reperfusion injury, and acute respiratory distress syndrome. Inhibition of some cysteine proteases, such as several caspase and cathepsin isozymes, may lead to the development of pharmacological agents effective for the management of several diseases, such as rheumatoid arthritis, inflammatory bowel disease, brain damage, and stroke. Another research line that progressed much in the last time regards different sulfonamides with remarkable antiviral activity. Some clinically used HIV protease inhibitors (such as amprenavir) possess sulfonamide moieties in their molecules, which are critical for the potency of these drugs, as shown by means of X-ray crystallography, whereas a very large number of other derivatives are constantly being synthesized and evaluated in order to obtain compounds with lower toxicity or augmented activity against viruses resistant to the such first generation drugs. Other viral proteases, such as those isolated from several types of herpes viruses may be inhibited by sulfonamide derivatives, leading thus to more effective classes of antiviral drugs.

Novel inhibitors of procollagen C-proteinase. Part 2: glutamic acid hydroxamates

Glutamic acid derived hydroxamates were identified as potent and selective inhibitors of procollagen C-proteinase, an essential enzyme for the processing of procollagens to fibrillar collagens. Such compounds have potential therapeutic application in the treatment of fibrosis.

Amino acid derived sulfonamide hydroxamates as inhibitors of procollagen C-proteinase. Part 2: Solid-phase optimization of side chains

Optimization of the amino acid side chain and the N-alkyl group of the sulfonamide of amino acid derived sulfonamide hydroxamates is discussed. The solid-phase synthesis of these potent inhibitors of procollagen C-proteinase (PCP) is presented. In addition, novel carboxylic acid sulfonamides were discovered to be PCP inhibitors.