Current Medicinal Chemistry - Volume 19, Issue 2, 2012

Numerous structurally different non-nucleoside compounds have been evaluated for their inhibitory effects against HIV replication, in which DABO derivatives, bearing the dihydro-alkoxyl-benzyl-oxopyrimidine scaffold, have been identified as a particular class of non-nucleoside reverse transcriptase inhibitors (NNRTIs). The S-DABO, NH-DABO, -N-DABO, DATNO and DACO analogs represent various structural chemical modifications of the substituents on C2, C6 and C5 of the pyrimidine ring to obtain potentially higher potency and lower cytotoxicity. This review article describes the recent progress of the chemical modifications and structureactivity relationship studies of DABO derivatives and provides new clues for the design of new DABO congeners.

Mitogen-activated protein kinase phosphatases (MKPs) are dual specificity protein phosphatases (DUSPs) that dephosphorylate both phospho-tyrosine and phospho-threonine residues on mitogen-activated protein kinases (MAPKs). Because the MAPK family of signalling molecules (phospho-p38 MAPK, c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK)) play essential roles in cell signalling pathways that regulate cell growth and inflammation, controlling MAPK-mediated pathways is a therapeutically attractive strategy. While small molecule MAPK inhibitors have utility, in this review we will focus on exploring the potential of targeting the endogenous MAPK deactivator - MKP-1. Importantly, there is a strong justification for developing both inhibitors and upregulators of MKP-1 because of the diverse roles played by MAPKs in disease: for example, in cancer, MKP-1 inhibitors may prove beneficial, as MKP-1 is overexpressed and is considered responsible for the failure of JNK-driven apoptotic pathways induced by chemotherapeutics; conversely, in inflammatory diseases such as asthma and arthritis, MKP-1 reduces MAPKmediated signalling and developing novel ligands to upregulate MKP-1 levels would be a therapeutically attractive anti-inflammatory strategy. Thus, in this review we utilise MKP-1 homology modeling to highlight the structural features of MKP-1 inhibitors that permit potent and selective inhibition, and to provide insights into the structural requirements for selective MKP-1 upregulators.

Quorum sensing (QS) is a communication procedure that predominates gene expression in response to cell density and fluctuations in the neighboring environment as a result of discerning molecules termed autoinducers (AIs). It has been embroiled that QS can govern bacterial behaviors such as the secretion of virulence factors, biofilm formation, bioluminescence production, conjugation, sporulation and swarming motility. Autoinducer 2 (AI-2), a QS signaling molecule brought up to be involved in interspecies communication, exists in both gram-negative and -positive bacteria. Therefore, novel approaches to interrupt AI-2 quorum sensing are being recognized as next generation antimicrobials. In the present review article, we summarized recent progresses on AI-2 bacterial quorum sensing inhibitors and discussed their potential as the antibacterial agents.

Cigarette smoking is the most important risk factor for the development of chronic obstructive pulmonary disease (COPD) and lung cancer, but only a part of smoking subjects develop these respiratory pathologies. Therefore, it is necessary to find sensible parameters to detect early lung alterations due to chronic tobacco smoke exposure. Long-term cigarette smoking is associated with a persistent inflammatory response in the lung that leads to tissue injury and dysfunction. Bronchoscopy and bronchial biopsies are the gold standard techniques for assessing pulmonary inflammation, but are invasive and not routinely used. Cellular analysis of induced sputum and measurement of fraction of exhaled nitric oxide (FENO) are validated non-invasive techniques for assessing respiratory inflammation. Measurement of biomolecules in sputum supernatants and exhaled breath condensate (EBC) are used as a research tool, but require standardization of procedures and, generally, analytical validation. Electronic nose differentiates healthy smokers from healthy nonsmokers based on breath volatile organic compounds (VOC) patterns. These techniques are potentially useful for identifying biomarkers of pulmonary inflammation and oxidative stress. Induced sputum, FENO, EBC and electronic nose are suitable for longitudinal sampling, thereby facilitating monitoring of lung damage process. This approach could enable an early identification of subgroups of healthy smokers at higher risk for tobacco-induced lung damage and prompt planning of secondary prevention strategies.

Despite their relatively lower efficiency, nonviral approaches are emerging as safer alternatives in gene therapy to viral vectors. Delivery of nucleic acids to the target site is an important factor for effective gene expression (plasmid DNA) or knockdown (siRNA) with minimal side effects. Direct deposition at the target site by physical methods, including ultrasound, electroporation and gene gun, is one approach for local delivery. For less accessible sites, the development of carriers that can home into the target tissue is required. Cationic peptides, lipoplexes, polyplexes and nanoplexes have been used as carriers for delivery of nucleic acids. Targeting ligands, such as cell targeting peptides, have also been applied to decorate delivery vehicles in order to enhance their efficacy. This review focuses on delivery strategies and recent progress in non-viral carriers and their modifications to improve their performance in targeting and transfection.

Chalcones (1,3-diaryl-2-propen-1-ones) and their heterocyclic analogues, belong to the flavonoid family, which possess a number of interesting biological properties such as antioxidant, cytotoxic, anticancer, antimicrobial, antiprotozoal, antiulcer, antihistaminic and anti-inflammatory activities. Several pure chalcones have been approved for clinical use or tested in humans. Clinical trials have shown that these compounds reached reasonable plasma concentration and are well-tolerated. For this reason they are an object of continuously growing interest amongst the scientists. However, much of the pharmacological potential of chalcones is still not utilized. The purpose of this review is to provide an overview of the pharmacological activity of naturally occurring and synthetic chalcones. This review highlights more recent pharmacological screening of these compounds, their mechanisms of action and relevant structure-activity relationships.

Specific noncovalent interactions that are indicative of attractive, directional intermolecular forces have always been of key interest to medicinal chemists in their search for the “glue” that holds drugs and their targets together. With the rapid increase in the number of solved biomolecular structures as well as the performance enhancement of computer hardware and software in recent years, it is now possible to give more comprehensive insight into the geometrical characteristics and energetic landscape of certain sophisticated noncovalent interactions present at the binding interface of protein receptors and small ligands based on accumulated knowledge gaining from the combination of two quite disparate but complementary approaches: crystallographic data analysis and quantum-mechanical ab initio calculation. In this perspective, we survey massive body of published works relating to structural characterization and theoretical investigation of three kinds of strong, specific, direct, enthalpy-driven intermolecular forces, including hydrogen bond, halogen bond and salt bridge, involved in the formation of protein-ligand complex architecture in order to characterize their biological functions in conferring affinity and specificity for ligand recognition by host protein. In particular, the biomedical implications of raised knowledge are discussed with respect to potential applications in rational drug design.

Triazole compounds containing three nitrogen atoms in the five-membered aromatic azole ring are readily able to bind with a variety of enzymes and receptors in biological system via diverse non-covalent interactions, and thus display versatile biological activities. The related researches in triazole-based derivatives as medicinal drugs have been an extremely active topic, and numerous excellent achievements have been acquired. Noticeably, a large number of triazole compounds as clinical drugs or candidates have been frequently employed for the treatment of various types of diseases, which have shown their large development value and wide potential as medicinal agents. This work systematically reviewed the recent researches and developments of the whole range of triazole compounds as medicinal drugs, including antifungal, anticancer, antibacterial, antitubercular, antiviral, anti-inflammatory and analgesic, anticonvulsant, antiparasitic, antidiabetic, anti-obesitic, antihistaminic, anti-neuropathic, antihypertensive as well as other biological activities. The perspectives of the foreseeable future in the research and development of triazole-based compounds as medicinal drugs are also presented. It is hoped that this review will serve as a stimulant for new thoughts in the quest for rational designs of more active and less toxic triazole medicinal drugs.

Gyroxin is a glycoprotein isolated from rattlesnake venom, with known thrombin-like serine protease properties and behavioral action in the CNS. The mechanism of the latter has eluded experimenters for three decades. In this paper about the in vitro chick retina we demonstrate an excitotoxic CNS action of Gyroxin by observing retinal Intrinsic Optical Signals (IOS). These show sudden dynamic changes in the intact tissue due to gyroxin action. The very fast kinetics of this response precludes deep tissue penetration by the protein, a mechanism of tissue response described here for the first time. At nanomolar concentrations, Gyroxin alters profoundly the optical profiles of retinal spreading depression waves (RSDs), suggesting modulation of ionic transport and metabolism. This effect is reversible in contrast with the acute cell lysis induced with gyroxin pulses at higher concentration. Because there may be more than one target of Gyroxine at the retinal inner limiting membrane, additional biochemical assays were performed to study a possible Na/K-ATPase blockade and PAR receptor activation. We conclude that the Gyroxin interaction with basement membranes of CNS and endothelium triggers conformational phase transitions at basement membranes, with multiple functional consequences.

Utilizing the intrinsic optical signal (IOS) of retinal Spreading Depression (rSD) waves and the concomitant transparency changes of the tissue, we show that nicotine, in an in vivo near tissue preparation, has neuroprotective effects against the excitotoxic cell death, mediated through the activation of glutamate-receptors. For this study the retinal tissue was treated with NMDA, an agonist for the NMDA-glutamate-receptor, being excitotoxic at higher concentrations, to induce tissue damage. The protective effects of nicotine against glutamate induced neurotoxicity are demonstrated, comparing the IOS with NMDA and NMDA + nicotine. We additionally present data about the decrease of the propagation velocity of rSD waves after nicotine application and show analogical effects obtained with epibatidine, a specific nicotinic acetylcholine receptor (nAChR) agonist.

Spreading Depression is the underlying patho physiological mechanism for the neurological symptoms of migraine aura and is thought to play a major role in triggering migraine. Therefore it seems reasonable to use the Spreading Depression as a pharmacological tool for anti migraine drugs. Drugs that are able to alter parameters of Spreading Depression should also influence appearance and course of migraine attacks. Concerning the classification on the different mechanisms of drug action, especially the retinal Spreading Depression is useful, due to the separation of vascular and neuronal effects. In this study we investigated substances from different classes of common anti migraine drugs on different parameters of the retinal spreading depression. The results are discussed according to the classification of the drug.