Combinatorial Chemistry & High Throughput Screening - Volume 15, Issue 7, 2012

The zebrafish has emerged as an excellent transitional screening model system between cell-based assays, which are rapid and inexpensive but have limited physiological relevance, and higher vertebrate models, which have better physiological relevance, but are more time-consuming and expensive to deploy. As vertebrates, zebrafish maintain significant evolutionary proximity to humans and have been validated as robust models for drug research, studies of mechanism and behavioral genetics. Unlike higher vertebrate models, zebrafish are well-suited to high-throughput applications owing to their high fecundity, rapid extrauterine development and transparency during organogenesis enabling in vivo labeling and imaging. Recent advances have been made in automating high content and high-throughput zebrafish screens, with the goal of developing fully automated drug screening platforms. The application and continued development of these technologies holds potential clinical significance in drug discovery and elucidating disease mechanisms.

“Click” chemistry method was used to fabricate novel waterborne polyurethane (WPU)/montmorillonite (MMT) composites based on alkyne-containing WPU and azide-modified montmorillonite. The morphology of these composites was characterized by x-ray diffractometer, scanning electron microscope. The mechanical properties, thermal stability, and flame resistance of the composites were investigated by tensile, thermogravimetry and cone calorimetric experiments, etc. The experimental results show that the tensile strength, water resistance and flame retardancy of the WPU/MMT composites have been reinforced efficiently owing to the linking of MMT by click reaction.

microRNAs (miRNAs) are evolutionary conserved, small endogenous non-coding, RNA molecules. Although their mode of action has been extensively studied, little is known about their biogenesis. As their altered expression has been implicated in many diseases, small molecules that would modulate their expression are sought after. They are generated through the concerted action of several complexes which promote their transcription, maturation, export, trafficking, and loading of mature miRNA into silencing complexes. An increasing number of studies have suggested that each of these steps serves as a regulatory junction in the process, and therefore provides an intervention point. For this purpose, we have developed a simple image-based assay strategy to screen for such modulators. Here, we describe its successful implementation which combines the use of a microRNA 21 (miR-21) synthetic mimic together with an EGFP based reporter cell line, where its expression is under the control of miR-21, to monitor EGFP expression in a format suitable for HTS. The strategy was further validated using a small panel of known gene modulators of the miRNA pathway. A screen was performed in duplicate against a library of 6,912 compounds and identified 48 initial positives exhibiting enhanced EGFP fluorescence intensity. 42 compounds were found to be inherently fluorescent in the green channel leaving the remaining 6 as potential inhibitors and with a positive rate of 0.09%. Taken together, this validated strategy offers the opportunity to discover novel and specific inhibitors of the pathway through the screening of diverse chemical libraries.

Previous studies have demonstrated that Ganoderma lucidum polysaccharides (Gl-PS) exhibited potential antihyperglycemic effect in rats. The aim of the present study was to investigate the mechanism of the hypoglycemic effect of a low- molecular-weight Gl-PS in streptozotocin (STZ)-induced diabetic Sprague-Dawley (SD) rats. Gl-PS was extracted and purified from Ganodema lucidum fruiting body. 50 male SD rats were included in the study; 10 were taken as healthy controls; 40 were induced to diabetes by a single injection of 65 mg/kg STZ, of which 30 were selected as successful diabetic rat models. The 30 diabetic rats were divided into three groups: Gl-PS (200 mg/kg Gl-PS), metformin (100 mg/kg metformin) and diabetic control (n = 10 per group). After eight weeks’ oral administration, plasma concentrations of fasting glucose, triacylglyceride, total cholesterol and nitric oxide were significantly decreased in Gl-PS and metformin groups. Pancreatic superoxide dismutase, catalase and glutathione peroxidase were significantly increased in Gl-PS and metformin groups. Histopathological results showed that Gl-PS and metformin had protective effect on β-cells. The mRNA expressions of Bcl-2 and PDX-1 in pancreas were up-regulated, but Bax, iNOS and Casp-3 down-regulated in Gl- PS and metformin groups compared to diabetic control group. The present results suggested that Gl-PS had a hypoglycemic effect in STZ-induced diabetic rats through preventing apoptosis of pancreatic β-cells and enhancing β- cells regeneration.

We herein document the discovery of 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones as a novel family of platelet aggregation inhibitors. The preliminary optimization study enabled us to establish the most salient features of the structure-activity relationships in this series as well as to identify novel derivatives that are upto 60 times more potent than the hit structure 1 and slightly superior to the reference drug Milrinone.

The integrity of the vascular wall and its intrinsic basement membrane structures ensure that plasma and the corpuscular elements of the blood remain confined to the intravascular milieu and can enter into the extravascular compartment in a well controlled fashion in cases of tissue infection or inflammation. However, sometimes inflammatory stimuli act on blood leukocytes and on endothelial cells from within the blood vessels and in an overwhelming way, leading to inflammatory shock syndromes. These severe conditions with high mortality rates are characterized by intravascular neutrophil degranulation, permeability changes of endothelia and disintegration of basement membranes and lead to almost uncontrollable edema, coagulation changes and multi-organ failure. Matrix metalloproteinases (MMPs) have been functionally linked with septic and endotoxin shock, with cytokine release syndromes and with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Here we review a number of association studies, compare inflammatory shock data from gene knockout studies in mice and provide some insights from recent investigations with inhibitors of MMPs. This evaluation strengthens the expectation that MMP inhibitors, in particular those blocking neutrophil proteases, may become useful in the early phase of acute inflammatory shock syndromes.

Poly(ethylene glycol) (PEG) has been used as a sustainable, non-volatile, and environmentally friendly reaction solvent for synthesis of functionalized anilines and benzenes via the reaction of malononitrile and β-ketoester derivatives in the presence of activated acetylenes at 80o C. No additional solvent and catalyst are required.

A simple, inexpensive, environmentally friendly and efficient route for the acylation of a number of alcohols, phenols and amines using pentafluorophenylammonium triflate (PFPAT) as a catalyst is described. PFPAT organocatalyst is air-stable, cost-effective, easy to handle, and easily removed from the reaction mixtures.

Trivalent lanthanide ions (Ln3+) doped inorganic nanocrystals (NCs) have currently attracted reviving interest and come to the forefront in nanophotonics owing to their potential applications in diverse fields such as luminescent biodetection and bioimaging. As an alternative to conventional biolabels, Ln3+-doped NCs show superior features including large stokes shift, multicolor fine-tuning, narrow emission band widths, high photostability, and low toxicity. Particularly, the long-lived luminescence and distinct upconversion (UC) of Ln3+-doped NCs are desirable for various bioapplications. The long-lived luminescence of Ln3+ combined with time-resolved technique can efficiently suppress the interference from short-lived background, resulting in a high signal-to-noise ratio (S/N) and background-free measurements. Near-infrared excited UC emissions of Ln3+ can bring no autofluorescence and no photodamage to cells or tissues, and thus UC NCs have been regarded as one of the most useful in vivo optical contrast agents. In this review, we outline the most recent development of Ln3+-doped NCs as biolabels from the controlled synthesis and surface functionalization of NCs to their bioapplications in heterogeneous and homogeneous biodetection as well as in vitro and in vivo bioimaging.