Synthesis of the constrained glutamate analogues (2S,1 ' R,2 ' R)- and (2S,1 ' S,2 ' S)-2- (2 'carboxycyclobutyl)glycines L-CBG-II and L-CBG-I by enzymatic transamination

Optically pure trans-cyclobutane analogues of glutamic acid are prepared by highly selective enzymatic transamination of a single racemic trans-cyclobutane α-ketoglutaric acid derivative 5, which is synthesized in five steps from maleic anhydride. (2S,1′R,2′R)- and (2S,1′S,2′S)-2-(2′-carboxycyclobutyl)glycines L-CBG-II and L-CBG-I are obtained using aspartate aminotransferase (AAT) and branched chain aminotransferase (BCAT), respectively

Chemo-enzymatic synthesis of a series of 2,4-syn-functionalized (S)-glutamate analogues: new insight into the structure-activity relation of ionotropic glutamate receptor subtypes 5, 6, and 7.

International audience(S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the central nervous system (CNS) activating the plethora of ionotropic Glu receptors (iGluRs) and metabotropic Glu receptors (mGluRs). In this paper, we present a chemo-enzymatic strategy for the enantioselective synthesis of five new Glu analogues 2a−f (2d is exempt) holding a functionalized substituent in the 4-position. Nine Glu analogues 2a−j are characterized pharmacologically at native 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA), kainic acid (KA), and N-methyl-D-aspartic acid (NMDA) receptors in rat synaptosomes as well as in binding assays at cloned rat iGluR5−7 subtypes. A detailed in silico study address as to why 2h is a high-affinity ligand at iGluR5−7 (Ki = 3.81, 123, 57.3 nM, respectively), while 2e is only a high affinity ligand at iGluR5 (Ki = 42.8 nM). Furthermore, a small series of commercially available iGluR ligands are characterized in iGluR5−7 bindin

Chronic exposure to glufosinate-ammonium induces spatial memory impairments, hippocampal MRI modifications and glutamine synthetase activation in mice

International audienceGlufosinate-ammonium (GLA), the active compound of a worldwide-used herbicide, acts by inhibiting the plant glutamine synthetase (GS) leading to a lethal accumulation of ammonia. GS plays a pivotal role in the mammalian brain where it allows neurotransmitter glutamate recycling within astroglia. Clinical studies report that an acute GLA ingestion induces convulsions and memory impairment in humans. Toxicological studies performed at doses used for herbicidal activity showed that GLA is probably harmless at short or medium range periods. However, effects of low doses of GLA on chronically exposed subjects are not known. In our study, C57BL/6J mice were treated during 10 weeks three times a week with 2.5, 5 and 10 mg/kg of GLA. Effects of this chronic treatment were assessed at behavioral, structural and metabolic levels by using tests of spatial memory, locomotor activity and anxiety, hippocampal magnetic resonance imaging (MRI) texture analysis, and hippocampal GS activity assay, respectively. Chronic GLA treatments have effects neither on anxiety nor on locomotor activity of mice but at 5 and 10 mg/kg induce (1) mild memory impairments, (2) a modification of hippocampal texture and (3) a significant increase in hippocampal GS activity. It is suggested that these modifications may be causally linked one to another. Since glutamate is the main neurotransmitter in hippocampus where it plays a crucial role in spatial memory, hippocampal MRI texture and spatial memory alterations might be the consequences of hippocampal glutamate homeostasis modification revealed by increased GS activity in hippocampus. The present study provides the first data that show cerebral alterations after chronic exposure to GLA

Euglenatides, potent antiproliferative cyclic peptides isolated from the freshwater photosynthetic microalga Euglena gracilis

By limiting the nitrogen source to glutamic acid, we isolated cyclic peptides from Euglena gracilis containing asparagine and non-proteinogenic amino acids. Structure elucidation was accomplished through spectroscopic methods, mass spectrometry and chemical degradation. The euglenatides potently inhibit pathogenic fungi and cancer cell lines e.g., euglenatide B exhibiting IC 50 values of 4.3 μM in Aspergillus fumigatus and 0.29 μM in MCF-7 breast cancer cells. In an unprecedented convergence of non-ribosomal peptide synthetase and polyketide synthase assembly-line biosynthesis between unicellular species and the metazoan kingdom, euglenatides bear resemblance to nemamides from Caenorhabditis elegans and inhibited both producing organisms E. gracilis and C. elegans. By molecular network analysis, we detected over forty euglenatide-like metabolites in E. gracilis, E. sanguinea and E. mutabilis, suggesting an important biological role for these natural products

Chemoenzymatic synthesis and pharmacology of glutamate analogues

National audienc

Recent progress in the synthesis of glutamic acid analogues by enzymatic transamination

Communication oral

Aminotransférases et analogues de l'acide glutamique

Poste

Synthèse chimioenzymatique d'analogues de l'acide glutamique potentiellement actifs dans le système nerveux central

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