Inhibitors Of Human Leukocyte Elastase Research Articles

Enantioselective Synthesis of Pharmaceutically Relevant Bulky Arylbutylamines Using Engineered Transaminases

AbstractATAs engineered for having an enlarged small binding pocket were applied for the synthesis of enantiomerically pure (R)‐benzo[1,3]dioxol‐5‐yl‐butylamine, a chiral component of human leukocyte elastase inhibitor DMP 777 (L‐694,458). Kinetic resolution of the racemic amine was performed by using the L59A variant of the (S)‐selective ATA from Chromobacterium violaceum (Cv‐ATA), providing the residual (R)‐enantiomer in excellent yield and >99% ee. At moderate enzyme loading and absence of co‐solvent, high volumetric productivity of 0.22 mol L−1 h−1 (42.5 g L−1 h−1) was achieved. Complementarily, the (S)‐enantiomer was generated via kinetic resolution using the (R)‐selective ATA‐117‐Rd11 from Arthrobacter sp. with acetone as the amino acceptor. In an alternative approach, we employed ATA‐117‐Rd11 for the asymmetric amination of the prochiral ketone precursor, which at 86% conversion gave the (R)‐benzo[1,3]dioxol‐5‐yl‐butylamine with excellent >99% ee. We further evaluated the utility of Cv‐ATA L59A for the asymmetric synthesis of pharmaceutically relevant (S)‐1‐phenylbutan‐1‐amine, a chiral component of the deubiquitinase inhibitor degrasyn (WP1130). The enzyme showed good tolerance to high concentrations of isopropylamine, producing (S)‐1‐phenylbutan‐1‐amine in enantiomerically pure form (>99% ee).magnified image

Crystal structure of highly glycosylated human leukocyte elastase in complex with an S2' site binding inhibitor.

Glycosylated human leukocyte elastase (HLE) was crystallized and structurally analysed in complex with a 1,3-thiazolidine-2,4-dione derivative that had been identified as an HLE inhibitor in preliminary studies. In contrast to previously described HLE structures with small-molecule inhibitors, in this structure the inhibitor does not bind to the S1 and S2 substrate-recognition sites; rather, this is the first HLE structure with a synthetic inhibitor in which the S2' site is blocked that normally binds the second side chain at the C-terminal side of the scissile peptide bond in a substrate protein. The inhibitor also induces the formation of crystalline HLE dimers that block access to the active sites and that are also predicted to be stable in solution. Neither such HLE dimers nor the corresponding crystal packing have been observed in previous HLE crystal structures. This novel crystalline environment contributes to the observation that comparatively large parts of the N-glycan chains of HLE are defined by electron density. The final HLE structure contains the largest structurally defined carbohydrate trees among currently available HLE structures.

Total Synthesis of Leupyrrin B1: A Potent Inhibitor of Human Leukocyte Elastase.

The total synthesis of leupyrrin B1 was accomplished by an expedient strategy that involves an optimized HATU-mediated amide coupling protocol of elaborate substrates. The generally useful procedure was also successfully applied in an improved total synthesis of leupyrrin A1. Finally, leupyrrins A1 and B1 were evaluated toward a panel of proteases, and human leukocyte elastase was discovered as a molecular target of the leupyrrins.

Recent Trends in the Design, Synthesis and Biological Exploration of β-Lactams

Since the discovery of penicillin, natural and synthetic β-lactams have aroused great interest not only as sources of effective antibacterial agents but also as specific inhibitors of proteases responsible for various non-bacterial pathological processes. This interest was reflected in our review published in Current Medicinal Chemistry in 2003. The present article summarises new data published during the last decade dedicated to the design, synthesis and biological exploration of new β-lactams with anti-inflammatory, antiviral, anticancer and other activities based on the inhibition of human leukocyte elastase, porcine pancreatic elastase, tryptase, chymase, human cytomegalovirus protease, fatty acid amide hydrolase, protein phosphatase methylesterase-1, serine protease responsible for tumor proliferation, cysteine proteases, matrix metalloproteinases, human 20s proteasome, human immunodeficiency virus, cholesterol absorption, human fatty acid synthase, bacterial RNase A and Leishmania D-mannosyl phosphate transferase. Antitumor effect was achieved also by new β-lactams activating apoptosis-specific poly(ADP-ribose) polymerase or participating in DNA intercalation.

Methyl 3-[(1,1-dioxo-1λ6,2-benzothiazol-3-yl)amino]-5-nitrothiophene-2-carboxylate

The title nitro­thio­phene compound, C13H9N3O6S2, crystallizes with two independent mol­ecules in the asymmetric unit; the mol­ecular structure of each is stabilized by an intra­molecular N—H⋯O hydrogen bond. The two mol­ecules adopt flattened but slightly different conformations, viz. the dihedral angle between the thio­phene ring and the essentailly planar 1,2-benzisothia­zole fragment (r.m.s. deviations = 0.0227 and 0.0108 Å, respectively) is 15.62 (11)° in one mol­ecule and 5.46 (11)° in the other. In the crystal, mol­ecules are arranged into layers parallel to (-111) with weak Car—H⋯O inter­actions formed within the layer. N—H⋯O hydrogen bonds also occur. There are π–π stacking inter­actions between the mol­ecules in neighbouring layers, the distance between the centroids of the 1,2-benzisothia­zole benzene rings being 3.8660 (16) Å. Moreover, dipolar S=O⋯C=O inter­actions with an O⋯C distance of 2.893 (3) Å are observed between the symmetry-independent mol­ecules in different layers. The title compound showed weak inhibition of HLE (human leukocyte elastase).

In vitro evaluation of the antielastase activity of polycyclic β-lactams

A series of bi- and tricyclic β-lactam compounds was synthesized and evaluated as inhibitors of cleavage of synthetic substrates in vitro by the serine proteases Human Leukocyte Elastase (HLE), Human Leukocyte Proteinase 3 (HLPR3) and Porcine Pancreatic Elastase (PPE). The obtained results have permitted us to describe a homobenzocarbacephem compound as HLE and HLPR3 inhibitor, to observe the positive effect that the styryl group exerts on the HLE inhibitory activity in polycyclic β-lactam compounds and to conclude that the hydroxyl function decreases the HLE inhibitory activity or rules it out completely.

Trivaric Acid, a Potent Depside Human Leukocyte Elastase Inhibitor

Human leukocyte elastase (HLE) is a serine protease implicated in several inflammatory diseases, and represents a major target for anti-inflammatory drug development. In the present study, nordivaricatic acid (1), divarinyl divarate (2), and trivaric acid (3), three depsides isolated from the culture of a soil derived fungal strain were identified as inhibitors of HLE. Two didepsides 1 and 2 showed low inhibitory activity. In contrast, trivaric acid, a para-tridepside, exhibited highly potent inhibitory activity with an IC(50) value of 1.8 µM and a K(i) of 0.6 µM. Kinetic investigations with trivaric acid showed that this inhibition is reversible, competitive pattern. Further studies on the selectivity of three depsides toward serine proteases showed that they did not inhibit chymotrypsin, trypsin and thrombin even at 150 µM.

Enantioselective allylation of imines catalyzed by newly developed (−)-β-pinene-based π-allylpalladium catalyst: an efficient synthesis of (R)-α-propylpiperonylamine and (R)-pipecolic acid

A newly developed π-allylpalladium with a (-)-β-pinene framework and an isobutyl side chain catalyzed the enantioselective allylation of imines in good yields and enantioselectivities (20 examples, up to 98% ee). An efficient enantioselective synthesis of the (R)-α-propyl piperonylamine part of DMP 777, a human leukocyte elastase inhibitor and (R)-pipecolic acid have been achieved as a useful application of this methodology.

1H-pyrazolo[2,3-d][1,2,4]triazine-3,7-diones as a new class of human leukocyte elastase inhibitors.

A novel series of 1H-2-phenyl-substituted-pyrazolo[2,3-d][1,2,4]triazine-3,7-diones (3a-g) as potential inhibitors of Human Leukocyte Elastase (HLE) are reported, the acyl-pyrazole being probably involved in the inhibition mechanism of the serino-protease enzymes. The most potent inhibitor both in vivo and in vitro was 2-o-methoxyphenyl-5-methyl-6-nitro-pyrazolo[2,3-d][1,2,4]triazine-3,7-di one (3e), which significantly suppressed the HLE-induced pulmonary injury in rats when administered orally (100 mg/kg, 3 h prior to HLE administration.

Automated Prediction of Protein Association Rate Constants

The association rate constants (k(a)) of proteins with other proteins or other macromolecular targets are a fundamental biophysical property. Observed rate constants span over ten orders of magnitude, from 1 to 10(10) M(-1)s(-1). Protein association can be rate limited either by the diffusional approach of the subunits to form a transient complex, with near-native separation and orientation but without short-range native interactions, or by the subsequent conformational rearrangement to form the native complex. Our transient-complex theory showed promise in predicting k(a) in the diffusion-limited regime. Here, we develop it into a web server called TransComp (http://pipe.sc.fsu.edu/transcomp/) and report on the server's accuracy and robustness based on applications to over 100 protein complexes. We expect this server to be a valuable tool for systems biology applications and for kinetic characterization of protein-protein and protein-nucleic acid association in general.

Optimization research on <I>in vitro</I> screening model for human leukocyte elastase inhibitor

Optimization research on <I>in vitro</I> screening model for human leukocyte elastase inhibitor

HLE-Inhibitory Alkaloids with a Polyketide Skeleton from the Marine-Derived Fungus Coniothyrium cereale

The marine endophytic fungus Coniothyrium cereale produces the structurally unusual polyketide-type alkaloids (-)-cereolactam (1) and (-)-cereoaldomine (3), incorporating a lactam and an imine functionality, respectively, as well as the related metabolite (-)-trypethelone (2). Compounds 1 and 3 showed selective inhibition of human leukocyte elastase with IC50 values of 9.28 and 3.01 μM, respectively. Compound 2 was found to be inhibitory toward Mycobacterium phlei, Staphylococcus aureus, and Escherichia coli and also cytotoxic against mouse fibroblast cells (IC50=7.5 μM).

Synthesis and inhibition of human leucocyte elastase by functionalized N-aryl azetidin-2-ones: effect of different substituents on the aromatic ring.

N-aryl-3,3-difluoroazetidin-2-ones featured by a latent electrophilic methylene quinoniminium function have been synthesized and evaluated as inhibitors of human leucocyte elastase. To promote hydrophobic interactions with the enzyme, to increase the rates of beta-lactam ring opening and of benzylic group departure, or to induce hydrosolubility, these compounds incorporate on their aromatic ring either an alkyl moiety, a methoxy substituent or a carboxylic group. Some of these beta-lactams proved to be good inactivators of human leucocyte elastase.

Antimicrobial phenalenone derivatives from the marine-derived fungus Coniothyrium cereale

The marine-derived fungus Coniothyrium cereale was isolated from the green alga Enteromorpha sp. and found to produce the new phenalenone derivatives 1-7 as well as the known compounds lactone 8, (-) sclerodin (9), lamellicolic anhydride (10), (-) scleroderolide (11), and (-) sclerodione (12). The structures of these closely related compounds were established from extensive spectroscopic investigations on the basis of one and two dimensional NMR spectroscopic studies ((1)H, (13)C, COSY, NOESY, HSQC and HMBC) as well as mass spectrometric analysis (LC/MS, HREIMS and HRESIMS), UV and IR spectra. Compounds 5 and 11 showed the same antimicrobial activity toward Staphylococcus aureus SG 511 with an MIC value of 24 μM. The presence of a diketo-lactone ring as in compounds 5 and 11 was found to be essential for this activity. In agar diffusion assays with Mycobacterium phlei considerable inhibition zones were observed for compounds 2, 4 and 7. Compounds 1, 5 and 9 showed potent inhibition of human leukocyte elastase (HLE) with IC(50) values of 7.2, 13.3 and 10.9 μM, respectively.

Inhibition of human leukocyte elastase, plasmin and matrix metalloproteinases by oleic acid and oleoyl-galardin derivative(s)

Molecular modeling was undertaken at aims to analyze the interactions between oleic acid and human leukocyte elastase (HLE), plasmin and matrix metalloproteinase-2 (MMP-2), involved in the inhibitory capacity of fatty acid towards those proteases. The carboxylic acid group of the fatty acid was found to form a salt bridge with Arg 217 of HLE while unsaturation interacted with Phe 192 and Val 216 at the S 3 subsite, and alkyl end group occupied S 1 subsite. In keeping with the main contribution of kringle 5 domain in plasmin–oleic acid interaction [Huet E et al. Biochem Pharmacol 2004;67(4):643–54], docking computations revealed that the long alkyl chain of fatty acid inserted within an hydrophobic groove of this domain with the carboxylate forming a salt bridge with Arg 512. Finally, blind docking revealed that oleic acid could occupy both S′ 1 subsite and Fn(II) 3 domain of MMP-2. Several residues involved in Fn(II) 3/oleic acid interaction were similarly implicated in binding of this domain to collagen. Oleic acid was covalently linked to galardin (at P′ 2 position): OL-GAL (CONHOH) or to its carboxylic acid counterpart: OL-GAL (COOH), with the idea to obtain potent MMP inhibitors able to also interfere with elastase and plasmin activity. OL-GALs were found less potent MMP inhibitors as compared to galardin and no selectivity for MMP-2 or MMP-9 could be demonstrated. Docking computations indicated that contrary to oleic acid, OL-GAL binds only to MMP-2 active site and surprisingly, hydroxamic acid was unable to chelate Zn, but instead forms a salt bridge with the N-terminal Tyr 110. Interestingly, oleic acid and particularly OL-GALs proved to potently inhibit MMP-13. OL-GAL was found as potent as galardin ( K i equal to 1.8 nM for OL-GAL and 1.45 nM for GAL) and selectivity for that MMP was attained (2–3 log orders of difference in inhibitory potency as compared to other MMPs). Molecular modeling studies indicated that oleic acid could be accommodated within S′ 1 pocket of MMP-13 with carboxylic acid chelating Zn ion. OL-GAL also occupied such pocket but hydroxamic acid did not interact with Zn but instead was located at 2.8 Å from Tyr 176. Since these derivatives retained, as their oleic acid original counterpart, the capacity to inhibit the amidolytic activity of HLE and plasmin as well as to decrease HLE- and plasmin-mediated pro MMP-3 activation, they might be of therapeutic value to control proteolytic cascades in chronic inflammatory disorders.

Preclinical Characterization of BI 201335, a C-Terminal Carboxylic Acid Inhibitor of the Hepatitis C Virus NS3-NS4A Protease

BI 201335 is a hepatitis C virus (HCV) NS3-NS4A (NS3 coexpressed with NS4A) protease inhibitor that has been shown to have potent clinical antiviral activity. It is a highly optimized noncovalent competitive inhibitor of full-length NS3-NS4A proteases of HCV genotypes 1a and 1b with K(i) values of 2.6 and 2.0 nM, respectively. K(i) values of 2 to 230 nM were measured against the NS3-NS4A proteases of HCV genotypes 2 to 6, whereas it was a very weak inhibitor of cathepsin B and showed no measurable inhibition of human leukocyte elastase. BI 201335 was also shown to be a potent inhibitor of HCV RNA replication in vitro with 50% effective concentrations (EC(50)s) of 6.5 and 3.1 nM obtained in genotype 1a and 1b replicon assays. Combinations of BI 201335 with either interferon or ribavirin had additive effects in replicon assays. BI 201335 had good permeability in Caco-2 cell assays and high metabolic stability after incubation with human, rat, monkey, and dog liver microsomes. Its good absorption, distribution, metabolism, and excretion (ADME) profile in vitro, as well as in rat, monkey, and dog, predicted good pharmacokinetics (PK) in humans. Furthermore, drug levels were significantly higher in rat liver than in plasma, suggesting that distribution to the target organ may be especially favorable. BI 201335 is a highly potent and selective NS3-NS4A protease inhibitor with good in vitro and animal ADME properties, consistent with its good human PK profile, and shows great promise as a treatment for HCV infection.

Novel phenalenone derivatives

Marine-derived fungi are an important source of pharmacologically active natural products. Investigation of the crude extract of the fungus Coniothyrium cereale provided a new series of phenalenone derivatives, obtained by HPLC separations. The structures of the compounds were established on the basis of extensive spectroscopic studies (1H; 13C; HSQC, COSY, NOESY and HMBC), mass spectral analysis (LC/MS and HRESIMS), UV and IR. The absolute stereochemistry is based on the specific optical rotation and CD spectra which were compared with published data. Structurally most unusual and unprecedented is the lactame-containing compound 7. The compounds are subjected to cytotoxicity and antimicrobial evaluation and also towards the the enzymes human leukocyte elastase (HLE), trypsin, chymotrypsin, acetylcholinesterase, papain, cholesterolesterase and thrombin. Compounds 6 and 7 showed good in vitro cytotoxicity of IC50=41 and 27µM respectively. Compounds 6 and 8 showed antimicrobial activity of MIC=7.8 and 15.6µg/mL respectively. Compounds 1, 2 and 7 showed potent inhibition of HLE with IC50 values of 7.16, 10.9 and 13.3µM, respectively.

ChemInform Abstract: Inhibition of Human Leukocyte Elastase. Part 2. Inhibition by Substituted Cephalosporin Esters and Amides.

ChemInform Abstract: Inhibition of Human Leukocyte Elastase. Part 2. Inhibition by Substituted Cephalosporin Esters and Amides.

ChemInform Abstract: Inhibition of Human Leukocyte Elastase. Part 3. Synthesis and Activity of 3′-Substituted Cephalosporins.

ChemInform Abstract: Inhibition of Human Leukocyte Elastase. Part 3. Synthesis and Activity of 3′-Substituted Cephalosporins.

ChemInform Abstract: Inhibition of Human Leukocyte Elastase. Part 1. Inhibition by C-7-Substituted Cephalosporin tert-Butyl Esters.

ChemInform Abstract: Inhibition of Human Leukocyte Elastase. Part 1. Inhibition by C-7-Substituted Cephalosporin tert-Butyl Esters.