Paulina Kosikowska

Urease inhibitors as potential drugs for gastric and urinary tract infections: a patent review

Introduction: Urease is the enzyme that catalyzes the hydrolysis of urea, which is involved in serious infections caused by Helicobacter pylori in the gastric tract, as well as Proteus and related species in the urinary tract. The necessity to treat such infections has stimulated intensive studies on various groups of urease inhibitors. Areas covered: Patent literature on urease inhibitors with possible applications in medicine is reviewed in this paper. Hydroxamic acids, phosphoramidates, urea derivatives, quinones and heterocyclic compounds constitute the major classes of structures with such activity. Expert opinion: Until now, only one compound, acetohydroxamic acid, has been clinically used for the treatment of urinary tract infections by urease inhibition. Unfortunately, it exhibits severe side effects. Thus, it seems that the full potential of urease inhibition has not yet been fully explored. Several Japanese patents related to the use of herbal extracts as sources of polyphenolic urease inhibitors have been considered as complementary or alternative therapy; however, their accessibility is quite possibly due to reduced restrictions for the introduction of natural products to the market.

Computer-aided optimization of phosphinic inhibitors of bacterial ureases.

Urease inhibitors can be considered as a tool to control the damaging effect of ureolytic bacteria infections in humans which occur commonly in the developed countries. Computer-aided optimization of the aminomethylphosphinate structures by modifying both their N- and P-termini led to the invention of a novel group of inhibitors of bacterial ureases. Introduction of P-hydroxymethyl group into the molecule resulted in considerable increase of the inhibitory activity against enzymes purified from Bacillus pasteurii and Proteus vulgaris as compared with their P-methyl counterparts described previously. The designed compounds represent a competitive reversible class of urease inhibitors. The most potent, N-methyl-aminomethyl-P-hydroxymethylphosphinic acid, displayed K(i) = 360 nM against P. vulgaris enzyme.

Antimicrobial peptides (AMPs) as drug candidates : a patent review (2003-2015)

ABSTRACT Introduction: Antimicrobial peptides (AMPs) represent the large group of endogenous compounds widely distributed in nature. Due to their broad spectrum of antibiotic activity, as well as anti-inflammatory and immunomodulatory properties, AMPs became a model for the discovery of novel antimicrobial drugs that could answer the problem of the increasing antibiotic resistance of pathogenic microorganisms. Areas covered: The review represents a comprehensive analysis of patents and patent applications from the year 2003 to 2015 referring to the therapeutic use of AMPs. The article highlights the general trends in the design, potential mode of action, and methods of biological evaluation of AMPs. Expert opinion: The existing discord between the upcoming list of antimicrobial peptides claimed in the patents or related scientific articles as the potent drug candidates and the frequent failures of AMPs in clinical trials emphasize the need of a better understanding of their pleiotropic nature and mechanisms of host defense in general. Nevertheless, the encouraging examples of AMPs already introduced into the market, like Polymyxin or Fuzeon®, give some reason for optimism that development of AMPs as a novel class of antibiotics is still considered viable.

The crystal structure of Sporosarcina pasteurii urease in a complex with citrate provides new hints for inhibitor design

Urease, the enzyme that catalyses the hydrolysis of urea, is a virulence factor for a large number of ureolytic bacterial human pathogens. The increasing resistance of these pathogens to common antibiotics as well as the need to control urease activity to improve the yield of soil nitrogen fertilization in agricultural applications has stimulated the development of novel classes of molecules that target urease as enzyme inhibitors. We report on the crystal structure at 1.50-Å resolution of a complex formed between citrate and urease from Sporosarcina pasteurii, a widespread and highly ureolytic soil bacterium. The fit of the ligand to the active site involves stabilizing interactions, such as a carboxylate group that binds the nickel ions at the active site and several hydrogen bonds with the surrounding residues. The citrate ligand has a significantly extended structure compared with previously reported ligands co-crystallized with urease and thus represents a unique and promising scaffold for the design of new, highly active, stable, selective inhibitors.

Stem cells and growth factors in wound healing

Wound healing is a complex process which depends on the presence of various types of cells, growth factors, cytokines and the elements of extracellular matrix. A wound is a portal of entry for numerous pathogens, therefore during the evolution wound healing process has formed very early, being critical for the survival of every individual. Stem cells, which give rise to their early descendants progenitor cells and subsequently differentiated cells, play a specific role in the process of wound healing. Among the most important cells which take part in wound healing the following cells need to be distinguished: epidermal stem cells, dermal precursor of fibroblasts, adipose-derived stem cells as well as bone marrow cells. The activity of these cells is strictly regulated by various growth factors, inter alia epidermal growth factor (EGF), fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), transforming growth factor (TGF), vascular endothelial growth factor (VEGF). Any disorders in functioning of stem cells and biological activity of growth factors may lead to the defects in wound healing, for instance delayed wound healing or creation of hypertrophic scars. Therefore, knowledge concerning the mechanisms of wound healing is extremely essential from clinical point of view. In this review the current state of the knowledge of the role of stem cells and growth factors in the process of wound healing has been presented. Moreover, some clinical aspects of wound healing as well as the possibility of the therapy based on stem cells and growth factors have included.

Inhibitors of cathepsin G: a patent review (2005 to present)

Introduction: Cathepsin G (CatG) is a neutral proteinase originating from human neutrophils. It displays a unique dual specificity (trypsin- and chymotrypsin-like); thus, its enzymatic activity is difficult to control. CatG is involved in the pathophysiology of several serious human diseases, such as chronic obstructive pulmonary disease (COPD), Crohns disease, rheumatoid arthritis, cystic fibrosis and other conditions clinically manifested by excessive inflammatory reactions. For mentioned reasons, CatG was considered as good molecular target for the development of novel drugs. However, none of them have yet entered the market as novel therapeutic agents. Areas covered: This article presents an in-depth and detailed analysis of the therapeutic potential of CatG inhibitors based on a review of patent applications and academic publishing disclosed in patents and patent applications (1991 – 2012), with several exceptions for inhibitors retrieved from academic articles. Expert opinion: Among the discussed inhibitors of CatG, examples corresponding to derivatives of β-ketophosphonic acids, aminoalkylphosphonic esters and boswellic acids (BAs) could be regarded as the most promising. The most promising one seems to be analogues of compounds of Natures origin (peptidic and BA derivates). Nevertheless, nothing is currently known about the clinical disposition of any of the CatG inhibitors discovered so far. This latter point suggests that there is still a lot of work to do in the design of stable, pharmacologically active compounds able to specifically regulate the in vivo activity of cathepsin G.

Synthesis and Evaluation of Biological Activity of Antimicrobial--Pro-Proliferative Peptide Conjugates.

Skin represents the largest organ of the human body and plays a crucial role in its protection from the negative impact of the outside environment, maintains its homeostasis, enables sensory interaction and thermoregulation. The traumatized skin tissue undergoes several phenotype switches due to progressive reoxygenation and release of cytokine and growth factors, that activate mechanisms of reparative processes. However, in case of wounds colonized with pathogenic microflora natural regenerative mechanisms become substantially impaired, that could lead to chronic inflammatory states with non-healing skin lesions. Herein, we present the initial results of our studies aimed at the design of bifunctional peptide-based compounds. The chemical approach, that was utilized in this work, was based on the conjugation of antimicrobial peptides with the peptides, that have potential pro-proliferative and/or cytoprotective activity towards human keratinocytes and fibroblasts, in order to obtain antimicrobials with reduced cytotoxicity or compounds that maintain both activities, i.e. inhibit bacterial or fungi growth and activate cell proliferation/migration in in vitro tests. As a result, we obtained a group of peptide conjugates that effectively inhibited the growth of selected bacterial and fungi strains and were able to stimulate proliferation and migration of keratinocytes and fibroblasts under their effective microbicidal concentrations.

Bisphosphonic acids as effective inhibitors of Mycobacterium tuberculosis glutamine synthetase

Abstract Inhibition of glutamine synthetase (GS) is one of the most promising strategies for the discovery of novel drugs against tuberculosis. Forty-three bisphosphonic and bis-H-phosphinic acids of various scaffolds, bearing aromatic substituents, were screened against recombinant GS from Mycobacterium tuberculosis. Most of the studied compounds exhibited activities in micromolar range, with N-(3,5-dichlorophenyl)-2-aminoethylidenebisphoshonic acid, N-(3,5-difluorophenyl)-2-aminoethylidene-bisphoshonic acid and N-(3,4-dichlorophenyl)-1-hydroxy-1,1-ethanebisphosphonic acid showing the highest potency with kinetic parameters similar to the reference compound – L-methionine-S-sulfoximine. Moreover, these inhibitors were found to be much more effective against pathogen enzyme than against the human ortholog. Thus, with the bone-targeting properties of the bisphosphonate compounds in mind, this activity/selectivity profile makes these compounds attractive agents for the treatment of bone tuberculosis.