A Chemical Screening Procedure for Glucocorticoid Signaling with a Zebrafish Larva Luciferase Reporter System

Glucocorticoid stress hormones and their artificial derivatives are widely used drugs to treat inflammation, but long-term treatment with glucocorticoids ...

Karlsruhe Institute of Technology - Campus North

The creation of novel diverse heterocycle libraries is an indispensable requirement of modern drug discovery processes. Currently, library sizes of over 10,000 discrete compounds are viable using programmed synthesis on solid supports. This review discusses the recent advances in the automated solid-phase syntheses of heterocycles to generate libraries of bioactive products, and illustrates library sizes that have been obtained, robots used for production of libraries, points of diversity and number of steps on the resin.

Automated synthesis of heterocycles on solid supports.

The fate of acetaminophen after intravenous injection in whole bowel-irrigated rats (n = 40) and the influence of activated charcoal on the kinetics were investigated. After randomization to four groups (n = 10, each group), plasma concentration and the quantities of acetaminophen and metabolites excreted into bile, urine and intestine were determined using an in vivo model with or without orally administered activated charcoal and with or without bile duct cannulation. The cumulative amount of acetaminiphen and metabolites exsorbed into the small intestine within 3.5 hr after intravenous injection was about 20% of dose in the animals with bile duct cannulation and about 7% of dose in the animals without. Correspondingly, about 13% of dose was detected in the externalized bile. Activated charcoal did not influence the amount exsorbed into the small intestine. Terminal half-life in plasma ranged from 35 to 51 min. within the four treatment groups without statistically significant difference (P = 0.152). Correspondingly, the area under the curve did not vary much and ranged between 2.6 and 3.3 g/min./l (P = 0.392). Deposition of acetaminophen and metabolites in liver and kidney after 3.5 hr was marginal and ranged between 0.02% and 0.6% of the dose within all groups. The excretion of acetaminophen and metabolites into urine varied strikingly between 31% and 56% of the dose within all groups and correlated with diuresis. The lack of effect of activated charcoal on the elimination of acetaminophen and metabolites may be due to the small amount of the drug being exsorbed into the intestine or the reduced adsorbent capacity of activated charcoal to acetaminophen and metabolites, which also could be influenced by inadequate luminal stirring.

Enteral exsorption of acetaminophen after intravenous injection in rats: influence of activated charcoal on this clearance path.

The fate of carbamazepine after intravenous injection in rats (n = 24) and the influence of activated charcoal on the kinetics was investigated. After randomization to four groups (n = 6, each), plasma concentration and the quantities of carbamazepine and metabolites excreted into bile, urine and intestine were determined using an in situ perfusion model of the small intestine (Ringer's solution) with or without orally administered activated charcoal (AC+; AC-) and with or without bile duct cannulation (BD+; BD-). The cumulative amount of carbamazepine and metabolites exsorbed into the small intestine within 3.5 hr after intravenous injection was about 15% in BD- animals and about 3% in BD+ animals. About 20% of the dose was detected in the externalized bile. Activated charcoal did not influence the amount exsorbed into the small intestine. Terminal half-life in plasma ranged from 159 min. to 194 min. within the four treatment groups without statistical significant difference (P = 0.751). Correspondingly, the area under the curve did not vary significantly and ranged between 1.13 and 1.41 g/min./l (P = 0.378). Excretion of carbamazepine and metabolites into urine varied between 3% and 6% of dose within all groups and showed close correlation with diuresis. In an identical experimental approach using a 2-fold intestinal perfusion rate (50 ml/hr; n = 8), no fundamental changes compared to the main experiment regarding pharmacokinetics of carbamazepine were observed. The lack of effect of activated charcoal on the elimination of carbamazepine and metabolites must be contributed to the small amount of the drug being exsorbed into the intestine and may be further influenced by reduced intestinal permeability of carbamazepine and metabolites or inadequate luminal stirring.

Seromucosal transport of intravenously administered carbamazepine is not enhanced by oral doses of activated charcoal in rats.

An efficient method to synthesize diaryl ethers and thioethers on solid supports is described. Starting from immobilized phenols or arylhalides, coupling with an access of aryliodides/arylbromides or phenolic/thiophenolic substrates in solution was successful in the presence of CuCl and Cs(2)CO(3) as base. Coupling conditions known from solution-phase syntheses of diaryl ethers have been effectively modified and adapted to solid-phase synthesis. Optimized conditions enabled the coupling of sterically hindered and/or electronically deactivated aryl moieties. After coupling, a newly developed diversity-generating linker based on cinnamic acid allowed the diaryl ethers to be cleaved from the resin either via saponification/transesterification or via ozonolysis. Latter offers the possibility of generating several additional compounds by simple variation of the cleavage conditions. The target substances were generally isolated in good to excellent yields and high purities.

Diaryl ether and diaryl thioether syntheses on solid supports via copper (I)-mediated coupling.

Synthesis of aryl fluorides on a solid support and in solution by utilizing a fluorinated solvent.

Bioconjugation techniques using organic azides are compared in this critical review. A particular focus is on chemical ligation reactions and their application to chemical biology (179 references).

Bioconjugation via azide-Staudinger ligation: an overview.

A novel access to deuterated and D(3)CO-substituted arenes has been developed using immobilized triazenes as precursors. The linker system and the deuterating cleavage methodology could be shown to be compatible with various functional groups and are therefore suitable for the synthesis of derivatives only hardly available via comparable protocols.

Solid phase synthesis of selectively deuterated arenes.

New catalysts for the transition-metal-catalyzed synthesis of aziridines.

Lipocalins tailored with high affinity for prescribed ligands, so-called anticalins, constitute promising candidates as antidotes. Here, we present an animal study to investigate both pharmacokinetic and clinical effects of an anticalin specific for the digitalis compound digoxin. Intravenous digoxin (2.5-50 Î¼g/kg/min) was administered to rats until first changes in the ECG occurred (dose finding study) or a priori for 30 min (kinetic study). The anticalin DigA16(H86N), dubbed DigiCal, was administered intravenously at absolute doses of 1, 5, 10 and 20 mg, while the control group received isotonic saline. Hemodynamic changes, several ECG parameters and digoxin concentration in plasma were monitored at given time intervals. After DigiCal administration free digoxin concentration in plasma ultrafiltrate declined dramatically within 1 min to the presumably non-toxic range. There was also a significant and DigiCal dose-dependent effect on longer survival, less ECG alterations, arrhythmia, and improved hemodynamics. Infusion of a lower digoxin dose (2.5 Î¼g/kg/min) resulted in a more sustained reduction of free digoxin in plasma after DigiCal administration compared to a higher digoxin dose (25 Î¼g/kg/min), whereas ECG and hemodynamic parameters did not markedly differ, reflecting the known relative insensitivity of rats towards digoxin toxicity. Notably, we observed a re-increase of free digoxin in plasma some time after bolus administration of DigiCal, which was presumably due to toxin redistribution from tissue in combination with the relatively fast renal clearance of the rather small protein antidote. We conclude that anticalins with appropriately engineered drug-binding activities and, possibly, prolonged plasma half-life offer prospects for next-generation antidotal therapy.

Intravenous application of an anticalin dramatically lowers plasma digoxin levels and reduces its toxic effects in rats.

Vinyl and alkynyl azides: well-known intermediates in the focus of modern synthetic methods.

We have recently demonstrated that the anthocyanidin delphinidin, one of the most abundant dietary flavonoids, inhibits activation of ErbB and VEGFR family members. These receptors play crucial roles in the context of tumor progression and the outgrowth of blood and lymphatic vessels. Here we have developed an improved chemical synthesis for delphinidin in order to study the effects of the aglycon and its degradation product gallic acid on endothelial and tumor cells in vitro and in vivo. We found that delphinidin blocked the proliferation in vitro of primary human blood and lymphatic endothelial cells as well as human HT29 colon and rat MT450 mammary carcinoma cells in a dose-dependent manner. In contrast, its degradation product gallic acid had little effect. At higher concentrations, delphinidin induced apoptosis of endothelial and tumor cells. Furthermore, delphinidin potently blocked the outgrowth of lymphatic capillaries in ex vivo lymphangiogenesis assays. In the MT-450 rat syngeneic breast tumor model, it also significantly reduced angiogenesis and tumor-induced lymphangiogenesis when administered in vivo. These data reveal delphinidin to be a novel anti-lymphangiogenesis reagent. Surprisingly, however, the application of delphinidin unexpectedly promoted tumor growth and metastasis in the MT-450 tumor model, suggesting that the anti-proliferative effect of delphinidin on cultured cells does not necessarily reflect the response of tumors to this anthocyanidin in vivo. Furthermore, while delphinidin may have utility as a cancer chemopreventative agent, its ability to promote tumor growth once a neoplasm develops also needs to be taken into consideration.

Nicole Jung

Institute of Organic Chemistry

Karlsruhe Institute of Technology - Campus North

A Chemical Screening Procedure for Glucocorticoid Signaling with a Zebrafish Larva Luciferase Reporter System

Nicole Jung

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Institute of Organic Chemistry

Karlsruhe Institute of Technology - Campus North

A Chemical Screening Procedure for Glucocorticoid Signaling with a Zebrafish Larva Luciferase Reporter System

Institute of Organic Chemistry