Donald John Wolanin

Proteoglycan degradation by a chondrocyte metalloprotease: Effects of synthetic protease inhibitors

Synthetic inhibitors of a chondrocyte metalloprotease (CMP) were assessed for potency. Proteoglycan core protein was used as substrate. The IC50 values were between 2 X 10(-6) and 7 X 10(-6) M for two types of inhibitors, thiol tripeptides and N-carboxyalkyl peptides. Hydroxamic acid peptides were more potent, with IC50 values of 3.2 X 10(-8) to 6.0 X 10(-8) M. These results confirm inhibitory concentrations reported using a proteoglycan-polyacrylamide bead assay. The slopes of the dose-response curves for the thiol compounds were steeper than the slopes for the other two types of compounds. All of the culture media tested inhibited CMP to some extent. Some media also interfered with inhibitor activity. In Hams F10 nutrient medium, minimum CMP inhibition occurred, and all four hydroxamic acid peptides retained their activity for 1-2 days at 37 degrees. One thiol peptide compound assayed lost activity in 1 hr in thiocyanate-treated serum. All four hydroxamic acid peptides assayed retained activity in thiocyanate-treated serum after 3 days at 37 degrees. The hydroxamic acid peptides may provide a way to block endogenous CMP activity in vivo and to assess the role of CMP in normal and experimentally altered cartilage. They are more potent than other known CMP inhibitors. They retain activity in culture media and serum conditions used for in vivo and in vitro tests of CMP activity and toxicity.

Chapter 12. Pulmonary and Anti-Allergy Agents

Publisher Summary Investigations of neuropeptide antagonists as an approach to the treatment of asthma have gained momentum with the discovery of non-peptidic tachykinin antagonists. The literature debate over the role of β-adrenergic agonists in the treatment of asthma has intensified. However, results from a new study suggest that inhaled β-agonists are indeed associated with higher mortality, and that is an effect common to all β-agonists. The current status of research on leukotriene antagonists and their role in asthma have been reviewed in this chapter. Clinical studies have showed that ICI 204,219, given orally, could reduce antigen-induced bronchoconstriction in asthmatic patients. Zileuton, dosed orally to atopic asthmatics, only partially inhibited allergen-induced 5-lipoxygenase (5-LO) activity in vivo , despite almost complete ex vivo 5-LO inhibition. The development of thromboxane receptor antagonists (TXRAs) has been reviewed. Oral administration of the TXRA AA-2414 to asthmatic subjects favorably attenuated their response to methacholine challenge. The potential effects of platelet-activating factor (PAF) on pulmonary function through activation of human eosinophils, neutrophils, and macrophages have been examined. In a separate trial, oral dosing of the hetrazepine PAF antagonist apafant (WEB-2086) in humans provided potent inhibition of in vivo cutaneous and ex vivo platelet responses to PAF. The basic pharmacology and clinical results from several important second-generation histamine antagonists are summarized in this chapter. Recent studies on some of these agents have shown that they may possess characteristics in addition to their ability to antagonize histamine receptors. The search for applications of potassium channel openers in asthma has continued. Bradykinin and bradykinin antagonists have received increased attention and been the subject of several recent reviews. The role of tachykinins in pulmonary diseases is also reviewed in the chapter.

Computer-aided design of novel inhibitors of human leukocyte elastase

Publisher Summary This chapter discusses computer-aided design of novel inhibitors of human leukocyte elastase (HLE). HLE is a member of the serine protease family of enzymes and is contained in the azurophilic granules of human neutrophils. It is released from neutrophils in response to inflammatory stimuli and has been implicated in the development of various diseases such as emphysema, cystic fibrosis, and chronic bronchitis. Under normal conditions the body protects itself from the potentially damaging effects of extracellular HLE with endogenous inhibitors such as alpha-1-proteinase inhibitor (α 1 -PI) and secretory leukocyte protease inhibitor (SLPI). A variety of HLE inhibitors have been reported, including the peptidyl trifluoromethyl (TFMKs), α-ketobenzoxazoles, β-lactams and others. TFMK inhibitors function by interacting with the active site serine 195 hydroxyl group to give a hemiketal which is an analogue of the tetrahedral intermediate formed in the normal HLE-catalyzed hydrolysis reaction of amide bonds. Examination of the pyridone derivative in the active site model indicates that the absence of the proline ring significantly reduces the hydrophobic interaction with the S2 pocket of HLE.