Identification of NQO1 and ferrochelatase as interaction partners for neuroprotective N-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-arylamides.

Affinity chromatography was used to identify potential cellular targets that are responsible for neuroprotective activity of N-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-arylamides. Active and inactive representatives of N-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-arylamides bearing an extended linker were synthesized and immobilized on an agarose-based matrix. This was followed by the identification of specifically bound proteins isolated out of the whole rat brain extract.

Synthesis, Biological, and Computational Evaluation of Substituted 1-(2-Methoxyphenyl)-4-(1-phenethylpiperidin-4-yl)piperazines and 1-(2-Methoxyphenyl)-4-[(1-phenethylpiperidin-4-yl)methyl]piperazines as Dopaminergic Ligands.

Sixteen new 1-(2-methoxyphenyl)-4-(1-phenethylpiperidin-4-yl)piperazines and 1-(2-methoxyphenyl)-4-[(1-phenethylpiperidin-4-yl)methyl]piperazines were synthesized to be used as probes for mapping the dopamine D2 receptor (D2 DAR) arylpiperazine binding site. All compounds were evaluated for their affinity toward D2 DAR in an in vitro competitive displacement assay. The most active one was 1-(2-methoxyphenyl)-4-{[1-(3-nitrophenethyl)piperidin-4-yl]methyl}piperazine (25) with an affinity of Ki  = 54 nM.

Modeling of Dopamine D2 Receptor - Overview of 35-Year Evolution.

Research on dopamine (DA) and its receptors, and in particular the D2 receptor subclass, has been an intriguing and fast developing scientific field in the past 35 years. Methods of medicinal chemistry, molecular and structural biology as well as computational chemistry were used in the studies of DA receptors (DRs). Early attempts to describe DRs were based on a small amount of experimental data available and produced crude models at best.

Exploration of N-arylpiperazine Binding Sites of D2 Dopaminergic Receptor.

The crystal structures of the D3 dopamine receptor and several other G-protein coupled receptors (GPCRs) were published in recent times. Those 3D structures are used by us and other scientists as a template for the homology modeling and ligand docking analysis of related GPCRs. Our main scientific interest lies in the field of pharmacologically active N-arylpiperazines that exhibit antipsychotic and/or antidepressant properties, and as such are dopaminergic and serotonergic receptor ligands.

Regenerative nanotechnology in oral and maxillofacial surgery.

Regenerative nanotechnology is at the forefront of medical research, and translational medicine is a challenge to both scientists and clinicians. Although there has been an exponential rise in the volume of research generated about it for both medical and surgical uses, key questions remain about its actual benefits. Nevertheless, some people think that therapeutics based on its principles may form the core of applied research for the future.

Molecular modeling of 5HT2A receptor - arylpiperazine ligands interactions.

In this paper, we report the molecular modeling of the 5HT2A receptor and the molecular docking of arylpiperazine-like ligands. The focus of the research was on explaining the effects the ligand structure has on the binding properties of the 5HT2A receptor and on the key interactions between the ligands and the receptor-binding site. To see what the receptor–ligand interactions were, various substituents were introduced in one part of the ligand, keeping the rest unchanged.

N-{[2-(4-Phenyl-piperazin-1-yl)-ethyl]-phenyl}-arylamides with dopamine D₂ and 5-Hydroxytryptamine 5HT(1A) activity: synthesis, testing, and molecular modeling.

The ratio of affinities toward the dopamine D₂ and the 5-hydroxytryptamine 5-HT(1A) receptors is one of the important parameters that determine the efficiency of antipsychotic drugs. Here, we present the synthesis of ortho-, meta-, and para-N-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-arylamides and their structure-activity relationship studies on dopamine D₂ and 5-hydroxytryptamine 5-HT(1A) receptors. It was shown that the biological activity of the described ligands strongly depends on their topology as well as on the nature of the heteroaryl group in the head of the molecules.

Arylpiperazine-mediated activation of Akt protects SH-SY5Y neuroblastoma cells from 6-hydroxydopamine-induced apoptotic and autophagic death.

We investigated the ability of 19 recently synthesized arylpiperazine compounds to protect human SH-SY5Y neuroblastoma cells from the neurotoxin 6-hydroxydopamine (6-OHDA). The compound with the most potent neuroprotective action was N-{3-[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-picolinamide (6b), which reduced 6-OHDA-induced apoptotic death through stabilization of mitochondrial membrane and subsequent prevention of superoxide production, caspase activation and DNA fragmentation. 6-OHDA-triggered autophagic response was also reduced by 6b, which prevented inactivation of the main autophagy repressor mTOR, upregulation of proautophagic beclin-1, conversion of microtubule-associated protein 1 light chain 3 (LC3)-I to autophagosome-associated LC3-II, as well as intracytoplasmic acidification induced by 6-OHDA.

Determination of key receptor-ligand interactions of dopaminergic arylpiperazines and the dopamine D2 receptor homology model.

Interest in structure-based G-protein-coupled receptor (GPCR) ligand discovery is huge, given that almost 30 % of all approved drugs belong to this category of active compounds. The GPCR family includes the dopamine receptor subtype D2 (D2DR), but unfortunately--as is true of most GPCRs--no experimental structures are available for these receptors. In this publication, we present the molecular model of D2DR based on the previously published crystal structure of the dopamine D3 receptor (D3DR).

Interactions of N-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-2-aryl-2-yl-acetamides and 1-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-3-aryl-2-yl-ureas with dopamine D2 and 5-hydroxytryptamine 5HT(1A) receptors.

It is suggested that the ratio of dopamine D(2) to 5-hydroxytryptamine 5-HT(1A) activity is an important parameter that determines the efficiency of antipsychotic drugs. Here we present the synthesis of N-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-2-aryl-2-yl-acetamides and 1-{[2-(4-phenyl-piperazin-1-yl)-ethyl]-phenyl}-3-aryl-2-yl-ureas and their structure-activity relationship studies on dopamine D(2) and 5-hydrohytryptamine 5-HT(1A) receptors. It was shown that ligand selectivity and affinity strongly depends on their topology and the presence of a pyridyl group in the head of molecules.

Protein biomarkers for in vitro testing of toxicology.

The vision of the toxicology in the 21st century movement is to overcome the currently used animal tests and identify molecular pathways of toxicity, using human in vitro systems with the aim to provide the most relevant mechanistic information for human risk assessment. It is expected to translate key surrogate biomarkers to novel types of toxicity-related high throughput screening of the many thousands of compounds which need to be tested during development phases of the pharmaceutical industry and with regard to the REACH legislation in Europe. Systems biology, an emerging and increasingly popular field of research, appears to be the discipline of choice to integrate results from transcriptomics, proteomics, epigenomics and metabonomics technologies used to analyze samples from toxicological models.

Arylpiperazine dopamineric ligands protect neuroblastoma cells from nitric oxide (NO)-induced mitochondrial damage and apoptosis.

The protective ability of novel arylpiperazine-based dopaminergic ligands against nitric oxide (NO)-mediated neurotoxicity is investigated. The most potent neuroprotective arylpiperazine identified during the study was N-{4-[2-(4-phenyl-piperazin-1-yl)ethyl]-phenyl}picolinamide, which protected SH-SY5Y human neuron-like cells from the proapoptotic effect of NO donor sodium nitroprusside (SNP) by decreasing oxidative stress, mitochondrial membrane depolarization, caspase activation and subsequent phosphatydilserine externalization/DNA fragmentation. The protective effect was associated with the inhibition of proapoptotic (JNK, ERK, AMPK) and activation of antiapoptotic (Akt) signaling pathways, in the absence of interference with intracellular NO accumulation.

Stem cells in head and neck squamous cell carcinoma.

The existence of a small subpopulation of tumourigenic cancer stem cells in the bulk of human head and neck squamous cancers (SCC) has been recognised in recent reports. This subpopulation has self-renewal properties and is responsible for the production of differentiated daughter cells that form the bulk of the tumour. Stem cells in head and neck SCC can be identified functionally using their self-renewal properties, or by their characteristic surface markers.

Systems biology approaches and tools for analysis of interactomes and multi-target drugs.

Systems biology is essentially a proteomic and epigenetic exercise because the relatively condensed information of genomes unfolds on the level of proteins. The flexibility of cellular architectures is not only mediated by a dazzling number of proteinaceous species but moreover by the kinetics of their molecular changes: The time scales of posttranslational modifications range from milliseconds to years. The genetic framework of an organism only provides the blue print of protein embodiments which are constantly shaped by external input.

Synchronization of posttranslational modifications during aging: Time is a crucial biological dimension.

There is an urgent need for surrogate biomarkers in clinical diagnostics but also preclinical in toxicology of chemicals and efficacy testing of pharmaceuticals. On the background of the emerging fields of systems biology and theranostics, the importance of time scales and the synchronization of complex biological readouts become increasingly obvious. Systemic effects such as responses to stimuli, medical intervention, cellular stress, or toxicity elicit immediate molecular changes on the protein level.

What does systems biology mean for drug development?

The complexity and flexibility of cellular architectures is increasingly recognized by impressive progress on the side of molecular analytics, i.e. proteomics, genomics and metabolomics.

A connection between the mitochondrial permeability transition pore, autophagy, and cerebral amyloidogenesis.

In a drug reprofiling attempt, we explored novel neuroprotective properties of 4-azasteroids by synthesizing chemical affinity tags capturing adenine nucleotide translocator-1, as a potential target. Dutasteride inhibits the mitochondrial transition pore and induces an increase of autophagosomal structures in human cell lines. In vivo, a surprising reduction of the beta-amyloid plaque load in a model for cerebral amyloidosis appears to connect release of neurotoxic peptides, mitochondrial apoptosis and autophagy.

Nonenzymatic posttranslational protein modifications in ageing.

One of the most fundamental molecular aspects of aging is accumulating oxidative damage caused by reactive oxygen species (ROS) as proposed by the free radical theory of aging. These unwanted chemical side products of normal metabolism lead to the formation of altered, less active and potentially toxic species of DNA, RNA, proteins, lipids, and small molecules. Due to gradually accumulating small contributions of irreversible reactions during ageing, uncatalyzed chemical side reactions occur with increasing frequencies and repair functions decline.

Synthesis, binding properties and receptor docking of 4-halo-6-[2-(4-arylpiperazin-1-yl)ethyl]-1H-benzimidazoles, mixed ligands of D2 and 5-HT1A receptors.

In this publication we are describing synthesis, binding properties, and receptor docking of 4-halo-6-[2-(4-arylpiperazin-1-yl)ethyl]-1H-benzimidazoles, a new compounds with potential antipsychotics properties. Affinity towards the dopamine D(1)-like and D(2)-like, and serotonin 5-HT(1A) receptors was evaluated using the radioligand binding assays. All compounds tested had affinity for the D(2)-like and 5-HT(1A) receptors, but were inactive towards the D(1)-like receptor.

1-cinnamyl-4-(2-methoxyphenyl)piperazines: synthesis, binding properties, and docking to dopamine (D(2)) and serotonin (5-HT(1A)) receptors.

Clinical properties of atypical antipsychotics are based on their interaction with D(2) dopamine receptor and serotonin 5-HT(1A) and 5-HT(2A) receptors. As a part of our research program on new antipsychotics, we synthesized various derivatives of 1-cinnamyl-4-(2-methoxyphenyl)piperazines, and evaluated their affinities for D(2), 5-HT(1A), 5-HT(2A), and adrenergic (alpha(1)) receptors using radioligand-binding assays. In addition, we performed docking analysis using models for the D(2) and 5-HT(1A) receptors.

Hexadecanedionic acid-sepharose 4B: A new tool for preparation of albumin-depleted plasma.

Serum and plasma are the major sources of human material for clinical molecular diagnostics and drug discovery. However, due to the high abundance of some proteins, of which serum albumin (SA) is most prominent, lower-abundance proteins often remain undetectable in proteomic analysis of these body fluids. We have used hexadecanedionic acid (HDA) immobilized to Sepharose 4B to develop an affinity resin that is effective in the removal of SA from plasma.

NMDA receptors are not alone: dynamic regulation of NMDA receptor structure and function by neuregulins and transient cholesterol-rich membrane domains leads to disease-specific nuances of glutamate-signalling.

Glutamate receptors of the N-methyl-D-asparate (NMDA-) subtype are tetrameric allosteric and ligand-gated calcium channels. They are modulated by a variety of endogenous ligands and ions and play a pivotal role in memory-related signal transduction due to a voltage-dependent block by magnesium, which makes them Hebbian coincidence detectors. On the structural level NMDA receptors have an enormous flexibility due to seven genes (NR1, NR2A-D and NR3A-B), alternative splicing, RNA-editing and extensive posttranslational modifications, like phosphorylation and glycosylation.

Enrichment of phosphoproteins for proteomic analysis using immobilized Fe(III)-affinity adsorption chromatography.

We described an efficient protocol to strongly enrich phosphoproteins from mixtures of total cellular proteins using homemade, recyclable Fe(III)-affinity columns. An integral feature of the method is the use of a detergent cocktail that allows use of different pHs for total protein extraction (pH 6.8) and for subsequent affinity capture of phosphoproteins (pH 3.

Interaction of arylpiperazines with the dopamine receptor D2 binding site.

The docking of several 1-benzyl-4-arylpiperazines to the dopamine receptor (DAR) D2 was examined. The results demonstrated that the interaction of protonated N1 of the piperazine ring with Asp 86 (III.32) and edge-to-face interactions of the aromatic ring of the arylpiperazine part of the ligand with Phe 178 (VI.