Wilhelm Herdering

Transport and distribution of 3-hydroxyglutaric acid before and during induced encephalopathic crises in a mouse model of glutaric aciduria type 1

Glutaric aciduria type 1 (GA1) is caused by the deficiency of glutaryl-CoA dehydrogenase (GCDH). Affected patients are prone to the development of encephalopathic crises during an early time window with destruction of striatal neurons and a subsequent irreversible movement disorder. 3-Hydroxyglutaric acid (3OHGA) accumulates in tissues and body fluids of GA1 patients and has been shown to mediate toxic effects on neuronal as well as endothelial cells. Injection of (3H)-labeled into 6 week-old Gcdh(-/-) mice, a model of GA1, revealed a low recovery in kidney, liver, or brain tissue that did not differ from control mice. Significant amounts of 3OHGA were found to be excreted via the intestinal tract. Exposure of Gcdh(-/-) mice to a high protein diet led to an encephalopathic crisis, vacuolization in the brain, and death after 4-5 days. Under these conditions, high amounts of injected 3H-3OHGA were found in kidneys of Gcdh(-/-) mice, whereas the radioactivity recovered in brain and blood was reduced. The data demonstrate that under conditions mimicking encephalopathic crises the blood-brain barrier appears to remain intact.

Synthesis and Application of Isosteric Purine 2′-Deoxyribofuranosides

Abstract The diastereoselective synthesis of several pyrrolo[2,3-d]- and pyrazolo[3,4-d]pyrimidine 2′-deoxy-ribofuranosides employing l-chloro-2-deoxy-3,5-di-0-(p-tolu-oyl)-a-D-erythropentofuranose and the nucleobase anion, generated by liquid-liquid or solid-liquid phase-transfer catalysis, is described. Appropriately protected phosphoramidites of 8-aza-7-deaza-2′-deoxyadenosine and 2′-deoxytubercidin were prepared and employed in solid-phase synthesis of palindromic DNA-fragments. The replacement of dA residues by deoxytubercidin within the Eco RI recognition site d(GAATTC) of the dodecamer d(GTAGAATTCTAC) gave evidence for purine N-7 binding to the endodeoxyribonuclease. The interpretation of similar experiments carried out on d(CGCGAATTCGCG) was obscured because of hairpin formation.

Dodecanucleotides Containing (E)-5-(2-Bromovinyl)-2′-Deoxyuridine: Influence of a Bulky Major Groove Substituent on Duplex Stability and Endodeoxyribonuclease Eco Ri Recognition

Abstract Self-complementary dodecanucleotides containing BVDU (1) have been prepared by solid-phase synthesis employing the phosphoramidite technique. The phosphoramidite of BVDU was obtained after 4, 4′-dimethoxytritylation and subsequent phosphitylation of the nucleoside 1. Melting experiments of the dodecamers containing one BVDU residue showed that the stability of such duplexes is only slightly affected by the bulky bromovinyl residue. The dodecamers d(GTAGAAbv5UTCTAC) (9) and d(GTAGAATbv5UCTAC) (10) were subject to hydrolysis experiments with the endodeoxyribonuclease Eco RI under star activity conditions. Whereas regioselective hydrolysis was decreased in case of the oligomer 10, compared to the non-modified oligomer 8, the oligomer 9-was not hydrolyzed at all under these conditions. This can be explained by a steric interference of the bulky bromovinyl substituent with the nitrogen-7 of the adjacent adenine moiety being a proton acceptor site during endonuclease binding. A complete assignment of 1...

In vivo targeting of ERG potassium channels in mice and dogs by a positron-emitting analogue of fluoroclofilium

The antiarrhythmic clofilium is an efficient blocker of hERG1 potassium channels that are strongly expressed in the heart. Therefore, derivatives of clofilium that emit positrons might be useful tools for monitoring hERG1 channels in vivo. Fluoroclofilium (F-clofilium) was synthesized and its channel-blocking properties were determined for hERG1 and hEAG1 channels expressed in HEK 293 cells and in Xenopus oocytes. When applied extracellularly in the whole-cell patch-clamp configuration, F-cloflium exhibited a slower onset of block when compared with clofilium, presumably owing to its lower membrane permeability. When applied in the inside-out configuration at the intracellular membrane side, it blocked hEAG1 channels almost as efficiently as clofilium (IC50 1.37 nM and 0.83 nM, respectively). Similar results were obtained for hERG1, showing Fclofilium is a potent hERG1 and hEAG1 channel blocker once it has reached the intracellularly accessible target site at the channel. Using the 18F-labeled analog we studied the in vivo binding and distribution of F-clofilium in mice and a dog. Greatest activity was found in kidneys and bones. A small but significant enrichment of activity in the dog myocardium known for its expression of cERG1 channels allowed to depict the myocardium of a living dog by PET. Thus, F-clofilium is a useful tool for imaging hERG channels in living organisms.

Phosphoramidites of [180] Chiral (Rp)- and (Sp)-Configurated Dimer-Blocks and their Use in Automated Oligonucleotide Synthesis

Abstract The N,N-diisopropylphosphoramidites 1 and 2 of appropriately protected chiral diastereoisomers of d(T-[P-180]-A) (6a and 6o, resp.) have been synthesized. They were employed in solid-phase synthesis to yield the octamers d(GAGT-(Rp)-[P180]-ACTC) and d(GAGT-(Sp)-[P180]-ACTC).

Sauerstoff-insertion bei der umlagerung von 2-aza-bicyclo[2.2.1]hept-2-enderivaten

Abstract N-Acyclation of N-hydroxy-2-azabicyclo[2.2.1]hept-2-ene causes rearrangement to oxa-aza-bicycles ( 7 , 8 ) by insertion of the hydroxalamine oxygen into the heterocyclic system. The mechanism is elucidated.

Oxygen Chiral Phosphate in Ribo- and 2′-Deoxyribodinucleoside Monophosphates by Oxidation of Phosphite Intermediates

Abstract Oxidation of dinucleoside monophosphite triesters of ribo- and deoxyribonucleosides with iodine-[18O]H2O furnished diastereoisomeric phosphate triesters having the oxygen labels in the P=O group. Chromatographic separation of the isomers followed by deprotection yielded oxygen chiral dinucleoside monophosphates. The absolute configuration of [18O]UpA has been established.

Synthesis of the deuterated compounds diethyl‐4‐D‐pyridine‐2,6‐dicarboxylate and diethyl‐3,4,5‐D3‐pyridine‐2,6‐dicarboxylate by catalytic reductive debromination

The synthesis of the mono- and trideutero compounds diethyl-4-D-pyridine-2,6-dicarboxylate (4) and diethyl-3,4,5-D3-pyridine-2,6-dicarboxylate (5) was achieved under a deuterium gas atmosphere by reductive debromination of diethyl-4-bromopyridine-2,6-dicarboxylate (1) and diethyl-3,4,5-tribromopyridine-2,6-dicarboxylate (2), respectively, using palladium black as catalyst and dichloromethane as solvent. The deuterium incorporation at the specified positions exceeded 95%.