Current Medicinal Chemistry - Volume 21, Issue 3, 2014

Autoinflammatory diseases area group of clinical conditions other than autoimmune diseases, characterized by recurrent inflammatory episodes. From apathogenetic point of view they are determined by a dys regulation of innate immunity, without involvement of specific immunity (auto reactive T cells and auto antibodies). Recently, the increased knowledge in the field of auto inflammation highlighted shared immune mechanisms in the pathogenesis of both classical monogenetic and multifactorial auto inflammatory diseases and a broad spectrum of chronic age-related inflammatory pathologies. The current increase in the prevalence of chronic inflammatory diseases makes this subject of topical interest. In the light of these considerations, we propose an update of auto inflammatory diseases and a new interpretation of auto inflammation with both theoretical and clinical implications.

Natural polycationic membrane-active peptides typically lack disulfide bonds and exhibit fusion, cellpenetrating, antimicrobial activities. They are mostly unordered in solution, but adopt a helical structure, when bound to phospholipid membranes. Structurally different are cardiotoxins (or cytotoxins, CTs) from cobra venom. They are fully β- structured molecules, characterized by the three-finger fold (TFF). Affinity of CTs to lipid bilayer was shown to depend on amino acid sequence in the tips of the three loops. In the present review, CT-membrane interactions are analyzed through the prism of data on binding of the toxins to phospholipid liposomes and detergent micelles, as well as their structural and computational studies in membrane mimicking environments. We assess different hydrophobicity scales to compare membrane partitioning of various CTs and their membrane effects. A comparison of hydrophobic/hydrophilic properties of CTs and linear polycationic peptides provides a key to their biological activity and creates a fundamental basis for rational design of new membrane-interacting compounds, including new promising drugs. For instance, from the viewpoint of the data obtained on model lipid membranes, cytotoxic activity of CTs against cancer cells is discussed.

Carbohydrate arrays are used as high-throughput screening platforms to study the carbohydrate-mediated recognition events for glycobiology. The polysaccharide arrays are easy to fabricate by non-covalently or covalently immobilizing polysaccharides onto array surfaces because polysaccharides have hydrophobic interactions. Oligosaccharides must be derived and covalently or non-covalently immobilized onto array surfaces to fabricate oligosaccharide arrays because they have hydrophilic interactions. At the moment, carbohydrate arrays are mainly used to study the carbohydrate-protein interactions and carbohydrate-binding lectins or antibodies, which are possible to be applied to clinics and diagnoses. This review mainly summed up the new fabrication strategies of carbohydrate arrays and their applications in recent four years.

Clinically significant antibiotic resistance is one of the greatest challenges of the twenty-first century. Yet new antibiotics are currently being developed at a much slower pace than our growing need for such drugs. Instead of focusing on conventional therapeutics that target in vitro bacterial viability, an alternative therapy is to target virulence factors and biofilms. Such anti-virulence strategies have attracted more and more attention rencently, for it would add both supplement and diversity to our current antimicrobial library. This approach has several potential advantages including imposing less evolutionary pressure on the development of antibiotic resistance, increasing the antibacterial targets and preserving the host endogenous microbiome. Quorum sensing is an intercellular communication process in bacterial communities, which can regulate coordinated expression of virulence factors and biofilms. N-Acyl homoserine lactones (AHLs) are autoinducers generated by a variety of Gram-negative bacteria. These signals combining with their cognate LuxR-type receptors trigger the expression of virulence genes. In this critical review, we summarize various structual types of small molecules targeting AHL-based quorum sensing to attenuate bacteria virulence factors and biofilms.

The adenosine A2A receptor (A2AR) is highly concentrated in the striatum, and a therapeutic target for Parkinson’s disorder (PD) and Huntington’s disease. High affinity and selective radiolabeled A2AR antagonists can be important research and diagnostic tools for PD. Positron Emission Tomography (PET) can play an important role by measuring radiolabeled A2A antagonists non-invasively in the brain. However, till date no complete review on A2AR PET ligands is available. The present article has been therefore focused on available PET tracers for A2AR and their detailed biological evaluation in rodents, nonhuman primates and humans. Drug design and development by molecular modeling including new lead structures that are potential candidates for radiolabeling and mapping of cerebral A2ARs is discussed in the present article. A brief overview of functions of adenosine in health and disease, including the relevance of A2AR for PD has also been presented.

The long-term usage of HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) eventually leads to rapid emergence of drug-resistant viruses and severe side effect. Therefore, it is imperative to seek the additional NNRTIs with potent and broad spectrum anti-mutant activities, and excellent pharmacokinetic profiles. The discovery of etravirine, rilpivirine and other successful examples has influenced the NNRTIs design strategy profoundly. Sustained efforts in this area have led to the identification of many promising NNRTIs hits, leads and candidates for the last few years. Hence, this review aims to highlight recent prominent advances in this field as well as contributions from our laboratory toward the discovery of novel potent NNRTIs from 2009 to 2013 (by May).

Alzheimer´s disease (AD) is a neurodegenerative disorder with no known cure and rapid rise in incidence. The predominant cognitive impairment is currently treated using cognitive enhancers like cholinesterase inhibitors. The two molecular hallmarks of AD are amyloid plaques created from an amyloid precursor protein and hyperphosphorylated tau protein that is deposited as neurofibrillary tangles inside neurons. A number of pathological mechanisms follow or precede these formations. Alteration in mitochondrial function and deposition of heavy metals are reported. The disease progression is enhanced by oxidative stress. However, the role of oxidative stress is not universally accepted. The current review covers and discusses the basic evidence and role of oxidative stress in AD development.

NADPH oxidases (NOX), catalyzing the reduction of molecular oxygen to form the superoxide radical anion (•O2 -) and hydrogen peroxide (H2O2), are involved in several pathological conditions, such as stroke, diabetes, atherosclerosis, but also in chronic neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, or multiple sclerosis. GKT136901 is a novel NOX-1/4 inhibitor with potential application in the areas of diabetic nephropathy, stroke, or neurodegeneration. In the present study, we investigated additional pharmacological activities of the compound with respect to direct free radical scavenging. GKT136901 did not interact with nitric oxide (•NO), •O2 -, or hydroxyl radicals (•OH), but it acted as selective scavenger of peroxynitrite (PON) already in the submicromolar concentration range. Alpha synuclein (ASYN) is a protein involved in the pathogenesis of Parkinson’s disease and a known target for PON-dependent tyrosine nitration. Submicromolar concentrations of GKT136901 prevented tyrosine nitration and di-tyrosine-dependent dimer formation of ASYN by PON as indicated by Western blot and mass spectrometric analysis. GKT136901 itself was degraded when exposed to PON. In a human neuronal cell model, GKT136901 prevented both the depletion of reduced intracellular glutathione, and the degeneration of neurites when present during PON treatment of the cells. When GKT136901 was applied after PON treatment, no protective effect was observed, thus excluding an impact of GKT136901 on cellular death/survival pathways. In summary, selective scavenging of PON is an additional pharmacological property of the NOX-1/4 inhibitor GKT136901, and this may add to the efficiency of the drug in several disease models.

Background: Photodynamic therapy (PDT) has been successfully used to treat various solid tumors. However, some cancer types respond poorly to PDT, including urothelial carcinomas, nasopharyngeal carcinomas, and extrahepatic cholangiocarcinomas. The therapeutic recalcitrance is in part due to the use of photosensitizers with suboptimal optical/ photochemical properties and unfavorable pharmacokinetics. Objective: To circumvent these drawbacks, a secondgeneration photosensitizer with improved optical/photochemical properties, zinc phthalocyanine (ZnPC), was encapsulated in interstitially targeted, polyethylene glycol-coated liposomes (ITLs) intended for systemic administration. The ZnPC-ITLs were examined for reactive oxygen species (ROS) generation and oxidation capacity and validated for tumoricidal efficacy in human extrahepatic cholangiocarcinoma (Sk-Cha1) cells. ZnPC-ITL uptake and the mechanism and mode of PDT-induced cell death were studied. Methods: The ITL formulation was optimized on the basis of fluorescence spectroscopy and photon correlation spectroscopy. The extent of ROS generation, protein oxidation, and membrane oxidation were determined by the 2’,7’-dichlorodihydrofluorescein, tryptophan oxidation, and calcein leakage assays, respectively. PDT efficacy was evaluated by measuring mitochondrial activity and apoptosis-/necrosis-specific staining in combination with flow cytometry. The uptake of fluorescently labeled ITLs was assayed by confocal microscopy, flow cytometry, and fluorescence spectroscopy. Results: ZnPC-ITLs exhibited maximum ROS-generating and oxidation potential at a ZnPC:lipid molar ratio of 0.003. PDT of Sk-Cha1 cells incubated with ZnPC-ITLs induced cell death in a lipid concentration- dependent manner. The mode of PDT-induced cell death comprised both apoptosis and necrosis, with necrotic cell death predominating. Post-PDT cell death was attributable to pre-PDT ZnPC-ITL uptake by cancer cells, which was more efficient at smaller ITL diameters and a more positive surface charge. Conclusions: ZnPC-ITLs constitute a nanoparticulate photosensitizer delivery system capable of inducing apoptosis and necrosis in cultured extrahepatic cholangiocarcinoma cells by PDT-mediated oxidative processes. PDT-induced cell death is dependent on the extent of ITL uptake, which in turn relies on ITL size and zeta potential.