Bernd Peschke

A novel B-domain O-glycoPEGylated FVIII (N8-GP) demonstrates full efficacy and prolonged effect in hemophilic mice models

Frequent infusions of intravenous factor VIII (FVIII) are required to prevent bleeding associated with hemophilia A. To reduce the treatment burden, recombinant FVIII with a longer half-life was developed without changing the protein structure. FVIII-polyethylene glycol (PEG) conjugates were prepared using an enzymatic process coupling PEG (ranging from 10 to 80 kDa) selectively to a unique O-linked glycan in the FVIII B-domain. Binding to von Willebrand factor (VWF) was maintained for all conjugates. Upon cleavage by thrombin, the B-domain and the associated PEG were released, generating activated FVIII (FVIIIa) with the same primary structure and specific activity as native FVIIIa. In both FVIII- and VWF-deficient mice, the half-life was found to increase with the size of PEG. In vivo potency and efficacy of FVIII conjugated with a 40-kDa PEG (N8-GP) and unmodified FVIII were not different. N8-GP had a longer duration of effect in FVIII-deficient mouse models, approximately a twofold prolonged half-life in mice, rabbits, and cynomolgus monkeys; however, the prolongation was less pronounced in rats. Binding capacity of N8-GP on human monocyte-derived dendritic cells was reduced compared with unmodified FVIII, resulting in several-fold reduced cellular uptake. In conclusion, N8-GP has the potential to offer efficacious prevention and treatment of bleeds in hemophilia A at reduced dosing frequency.

Investigation of bioisosters of the growth hormone secretagogue L-692,429

Abstract The synthesis and structure-activity relationships of several analogs of L-692,429 with modifications in the biaryl and tetrazole moieties are described and several derivatives were found to be equipotent or slightly more potent than L-692,429.

Increase of neuronal histamine in obese rats is associated with decreases in body weight and plasma triglycerides.

Objective: The purpose of the present study was to examine the metabolic effects of a specific histamine H3 receptor antagonist, the cinnamic amide NNC 0038‐0000‐1202 (NNC 38‐1202).

Palladium-Catalyzed α-Arylation of Tetramic Acids

A mild, racemization-free, palladium-catalyzed alpha-arylation of tetramic acids (2,4-pyrrolidinediones) has been developed. Various amino acid-derived tetramic acids were cleanly arylated by treatment with 2 mol % of Pd(OAc)(2), 4 mol % of a sterically demanding biaryl phosphine, 2.3 equiv of K(2)CO(3) or K(3)PO(4), and aryl chlorides, bromides, or triflates in THF. With conventional heating, conversions >95% could be attained after 1 h at 80 degrees C, whereas microwave-induced heating led to much shorter reaction times (5 min at 110 degrees C). The electron density of the aryl electrophile had no effect on their reactivity: both electron-rich and electron-poor aryl chlorides and bromides or triflates led to good yields. Ortho-substituted aryl halides and heteroaryl halides, however, did not undergo the title reaction.

New growth hormone secretagogues: C-terminal modified sulfonamide-analogues of NN703.

The C-terminal the orally active growth hormone secretagogue NN703 was changed to prepare analogues with inverse sulfonamides and inverse amides. The compounds showed high activity in a in vitro rat pituitary model.

New highly potent dipeptidic growth hormone secretagogues with low molecular weight

Based on NN703, low molecular weight growth hormone secretagouges (GHSs) with a reduced number of hydrogen binding sites were designed by removal of the C-terminal amide group. The compounds were highly potent in combination with high efficacy in a rat pituitary cell assay, being characterized with EC(50) values down to 0.8 nM. Selected compounds were tested in in vivo animal models. The oral bioavailability in dogs was 16-44%. Also, the ED(50) values of the compounds were determined both in dog and swine.

Aminomethylthiophene-2-carboxylic acids as dipeptide mimetic in new growth hormone secretagogues

Abstract 3-Aminomethylbenzoic acid is a well established dipeptide mimetic. Herein, aminomethylthiophene-2-carboxylic acids 1) have been synthesized as analogues of 3-aminomethylbenzoic acid. Their use as a dipeptide-mimetic at the N -terminal of novel growth hormone secretagogues is described.

Demonstration of the strength of focused combinatorial libraries in SAR optimisation of growth hormone secretagogues

Abstract Aseries of 96 growth hormone secretagogues, derived from ipamorelin are described. The compounds are prepared as a 6 × 4 × 4 member library on solid support using a PAL resin. The compounds are all acylated dipeptides, based on two aromatic amino acids and a free amino N-terminal. All compounds are characterised by HPLC, LC-MS and their ability to release GH in a pituitary cell based assay. The most potent compounds show EC50 values at 1 nM and are full agonists. We demonstrate the strength of focused combinatorial libraries and confirm the pitfall in broad SAR exploration by giving examples where selected fragments obviously show poor receptor interaction except in very defined structural arrangements.

Synthesis and in vitro characterization of new growth hormone secretagogues derived from ipamorelin with dipeptidomimetic N-terminals

The structural requirements for N-terminal features for the minimal structure of growth hormone secretagogues derived from ipamorelin are investigated. It is found, that incorporation of nonpolar peptidomimetic amino acids at the N-terminal can replace the Aib-His moiety and lead to compounds with high in vitro potency with respect to their growth hormone secretagogue properties. New unnatural amino acids with double bonds, ether-linkages, and 1,3-phenylene-moieties in the backbone proved to be valuable dipeptidomimetics. Using them, growth hormone secretagogues with high potencies were obtained.

The influence of conformational restriction in the C-terminus of growth hormone secretagogues on their potency

In order to obtain more potent growth hormone secretagogues, a comparison of ipamorelin and NN703 suggested the addition of a polar group at the C-terminus of NN703. A study was conducted using constrained amines for this purpose. Here, substituted 4-piperidinylamino- and 4-dimethylaminopiperidino-substituents were found to give the most active compounds. A replacement of the 4-dimethylaminopiperidino-substituent with 4-hydroxypiperidino resulted in a series of compounds, which showed in vitro activity with EC(50) values in the low nanomolar range, and favourable kinetic properties, such as 40% oral bioavailability. The most promising compound was also tested in a swine in vivo model, resulting in a growth hormone level with a C(max) of over 40 ng mL(-1).