Jean-Louis Kraus

New protease inhibitors prevent γ-secretase-mediated production of Aβ40/42 without affecting Notch cleavage

We have designed new non-peptidic potential inhibitors of γ-secretase and examined their ability to prevent production of amyloid-β 40 (Aβ40) and Aβ42 by human cells expressing wild-type and Swedish-mutant β-amyloid precursor protein (βAPP). Here we identify three such agents that markedly reduce recovery of both Aβ40 and Aβ42 produced by both cell lines, and increase that of C99 and C83, the carboxy-terminal fragments of βAPP that are derived from β-and α-secretase, respectively. Furthermore, we show that these inhibitors do not affect endoproteolysis of endogenous or overexpressed presenilins. These inhibitors are totally unable to affect the mΔEnotch-1 cleavage that leads to generation of the Notch intracellular domain (NICD). These represent the first non-peptidic inhibitors that are able to prevent γ-secretase cleavage of βAPP without affecting processing of mΔEnotch-1 or endoproteolysis of presenilins. The distinction between these two proteolytic events, which are both prevented by disruption of presenilin genes, indicates that although they are intimately linked with βAPP and Notch maturation, presenilins are probably involved in the control of maturation processes upstream of enzymes that cleave γ-secretase and Notch.

Synthesis and Biological Activity of Phosphonate Analogues and Geometric Isomers of the Highly Potent Phosphoantigen (E)-1-Hydroxy-2-methylbut-2-enyl 4-Diphosphate

Gammadelta-T-lymphocytes contribute to innate immunity and are selectively activated by nonpeptide phosphorylated molecules (so-called phosphoantigens) produced by organisms responsible for causing a broad range of infectious diseases. gammadelta-T-cells are also activated by synthetic phosphoantigens and are cytotoxic to tumor cells. Here we report the synthesis, NMR characterization, and comparative biological evaluation of new pyrophosphate, phosphonate, and pyrophosphonate monoesters whose structures correspond to isosteric analogues and stereoisomers of the highly potent isoprenoid metabolite ( E)-1-hydroxy-2-methylbut-2-enyl 4-diphosphate called HDMAPP (hydroxy-dimethyl-allyl pyrophosphate). Both pyrophosphate and pyrophosphonate series elicit promising gammadelta-T-cell stimulatory responses in vitro, the pyrophosphonate ester (C-HDMAPP) being by far more stable than its parent pyrophosphate ester (HDMAPP) with improved ADMET properties and a similar pharmacodynamic profile based on in vivo studies in nonhuman primate. In both series, we found that E-stereoisomers are the most active derivatives and that Z-stereoisomers show very marginal bioactivity levels. These results indicate that the use of bioisosteric analogues of HDMAPP may represent promising new leads for immunotherapy.

Synthesis of new 3-alkoxy-7-amino-4-chloro-isocoumarin derivatives as new β-amyloid peptide production inhibitors and their activities on various classes of protease

A series of new 7-substituted-4-chloro-3-alkoxy isocoumarin derivatives were synthesized and evaluated as inhibitors of representative classes of proteases: serine protease (alpha-chymotrypsin, trypsin), cysteine protease (Caspase-3), and aspartyl protease (HIV-protease), 20S proteasome and also as inhibitors of amyloid peptide gamma-secretase-mediated production. Protease inhibition selectivity is directly related to the structure of the substituent at the 7-position of the isocoumarin nucleus. 7-Nitro-isocoumarin derivatives (4c, 4d, 4f) are potent alpha-chymotrypsin inhibitors but slightly active or inactive on HIV-protease, as well as on cysteine protease. In contrast, only derivatives bearing a free amino (5d, 5f) or a substituted amino group (6f) at the 7-position of the isocoumarin nucleus, were found weakly active or inactive on alpha-chymotrypsin, trypsin, Caspase-3 and HIV-protease, but prevent gamma-secretase-mediated production of Abeta 40/42 amyloid peptides, which is known to be involved in Alzheimers disease. Moreover, the most active compounds on beta-amyloid peptide production [JLK6 (5d), JLK2 (5f) and JLK7 (6f)] show only weak or moderate inhibitory activity on the 20S proteasome. The obtained results suggest that the described new isocoumarin analogues could be of interest, since compounds like JLK6 (5d), JLK2 (5f) and JLK7 (6f) can be considered as possible hits for the development of new agents directed towards Alzheimers disease.

Novel synthesis of 3,4-dihydro-5-bromo[1,4]oxazin-2-one derivatives, new protease inhibitor scaffold

We designed and synthesized a new class of serine protease inhibitors based on the oxazinone core. To this end, we first developed a short and efficient route to synthesize a new 3,4-dihydro[1,4]oxazin-2-one ring. Then we successfully synthesised the corresponding 5-bromo derivatives which have never been reported before, and demonstrated their inhibitory activities on alpha-chymotrypsin.

Synthesis and anti-human immunodeficiency virus type 1 activities of new peptido-nucleoside analogues

Summary In order to investigate whether antiproteasic peptides coupled to anti-reverse transcriptase nucleosides can act as inhibitors at the different stages of the HIV life cycle, various peptido-nucleosides were synthesized using methodologies involving (benzotriazol-1-yloxy)-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) as a coupling reagent between the N 4 -cytosinyl moiety and the peptide carboxy terminus. The anti-HIV-1 activity in MT 4 cells of this new class of compounds and their anti-HIV protease activities were determined. Fourteen peptido-nucleosides have been synthesized and six act against both the HIV-protease and viral replication in vitro . Although the activity of the most potent compounds against HIV was found to be one order of magnitude lower than that of the parent nucleoside drug 2′,3′-dideoxy-3′-thiacytidine, this new class of compound could be of biological interest. Indeed, since the in vitro half-lives ( t 1/2 ) of the hydrolysis of the most potent compounds in human plasma were found to be longer than 2.5 h, these analogues could reach the infected cells in their structural integrity. This observation does not exclude that these compounds may exert their antiviral effects as combined prodrugs through extracellular or intracellular hydrolysis.

Potential Neuroprotective Drugs in Cerebral Ischemia: New Saturated and Polyunsaturated Lipids Coupled to Hydrophilic Moieties: Synthesis and Biological Activity

The ganglioside GM1 has neuroprotective effects but is not of therapeutic value because of its lack of bioavailability. Thus, molecules that mimic GM1 represent a novel approach to neuroprotection. We have synthesized 19 small GM1-like analogues whose simplified structure includes a hydrophobic saturated or unsaturated moiety linked to a hydrophilic moiety. We report their neuroprotective effects in two distinct models of nerve cell death using hippocampus-derived HT22 cells. We found that several analogues protected the HT22 cells from death at concentrations ranging from 2 to 5 microM. Additional neuroprotective assays using cortical slices injured by glutamate confirmed these results. Since members of the MAP kinase family are known to be key players in nerve cell survival and death, we characterized the role of these kinases in the neuroprotective mechanisms of the GM1-like analogues. Interestingly, the results indicate that the compounds provide neuroprotection through distinct mechanisms of action.

Substituted thiazolamide coupled to a redox delivery system: a new γ-secretase inhibitor with enhanced pharmacokinetic profile

Inhibition of gamma-secretase, one of the enzymes responsible for the cleavage of the amyloid precursor protein (APP) to produce pathogenic A beta peptides, is an attractive approach for the treatment of Alzheimers disease. We have designed a new gamma-secretase thiazolamide inhibitor bearing a dihydronicotinoyl moiety as Redox Delivery System which allows specific delivery of the drug to the brain. Through, on the one hand, A beta peptide production measurements by specific in vitro assays (gamma-secretase Cell Free assay and Cell Based assay on HEK 293 APP transfected cells) and, on the other hand, pharmacokinetic studies on animal models, the new inhibitor shows a good pharmacokinetic profile as well as a potent gamma-secretase inhibitory activity in vitro. From the obtained results, it is expected that drug will be mainly delivered to the CNS with low diffusion in the peripheral tissues. Consequently the side effects of this gamma-secretase inhibitor on the immune cells could be reduced.

Synthesis of new 7-membered α-phenylthio cyclic oxamides: HIV inhibitors

Abstract Based on the concept of bioisosterism, we report the computer design and the synthesis of original 7-membered α-phenylthio cyclic oxamides with potent anti HIV-1 properties.

New Phosphonate Analogues of 3′-Thia-2′,3′-dideoxycytidine(BCH-189) Synthesis and Anti-HIV Evaluation

Abstract New phosphonate analogues of 3′-thia-2′,3′-dideoxycytidine (BCH-189) were synthesized in 5 steps via cyclocondensation of 2-mercaptoacetaldehyde di[2-methoxyethyl]acetal with 3-diethylphosphonopropionaldehyde as a key step, followed by a Lewis acid catalyst addition of the appropriate nucleic base. Anti-HIV evaluation of these analogues showed that the α-form 3b of 3′-thia-2′,3′-dideoxycytidine-4′-ethylene phosphonic acid was inactive while the β-form 3a was found to be less potent than the parent compound (BCH-189), showing that the replacement of the oxygen in position 5′ by a methylene group in the monophosphorylated intermediate diminishes the antiviral activity.

Synthesis and antiviral activity of N-4′-dihydropyridinyl and dihydroquinolinylcarbonyl-2-hydroxymethyl-5-[cytosin-1′-yl]-1,3-oxathiolane derivatives against human immunodeficiency virus and duck hepatitis B virus

Summary Dihydropyridine and dihydroquinoline derivatives of 2-hydroxymethyl-5-[cytosin-1′-yl]- 1,3-oxathiolane ((±)-3TC) have been prepared. The N--4-nicotinate or the N--4-quinoline-carboxylate amides were obtained by reacting nicotinic or quinolinecarboxylic acids with (±)-3TC in the presence of DCC and HOBT. These derivatives were converted into their corresponding N--methylpyridinium and N--methyl quinolinium salts by treatment with MeI in acetone. Reduction of the latter with Na2SS2OO4 gave dihydropyridine and dihydroquinoline compounds. The N--4-trifluorotoluidinonicotinate derivative was obtained from the coupling of niflumic acid and (±)-3TC using BOP and DIEA. The anti-HIV-1 activities of seven derivatives were determined in MT-4 infected cell cultures. Of these compounds, the IC0 v values ranged from 0.1–100 μM, while the IC0 f for (±)-3TC was 0.1 μM. The anti-HBV activities were determined in infected duck hepatocytes. Anti-HBV activities of the (±)-3TC derivatives were half that of the parent drug (±)-3TC. The lipophilicity (partition coefficients) of these compounds were determined. The dihydroquinoline prodrugs had greater lipophilicity than the dihydropyridine analogues.