Synthesis and single cell pharmacology of potential heterocyclic bioisosteres of the excitatory amino acid antagonist glutamic acid diethyl ester.
A series of heterocyclic analogues of glutamic acid diethyl ester (GDEE), an antagonist at central excitatory amino acid receptors, have been synthesized and tested biologically. (RS)-Ethyl alpha-amino-alpha-(3-ethoxyisoxazol-5-yl)acetate (7), (RS)-ethyl 2-amino-3-(3-ethoxy-5-methylisoxazol-4-yl)propionate (16) and closely related analogues were synthesized. Compound 7, a diethyl derivative of the naturally occurring excitatory amino acid ibotenic acid (IBO), was synthesized from 3-hydroxy-5-methylisoxazole (1) via 3-ethoxyisoxazol-5-ylacetic acid (5) and its ethyl ester. Nitrosation of this ester followed by catalytic reduction gave 7. The ethyl ester of IBO, 9, was synthesized in a similar manner from 3-benzyloxyisoxazol-5-ylacetic acid (8). Ethyl derivatives of the synthetic excitatory amino acid 2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) were synthesized from 3-hydroxy-4,5-dimethylisoxazole (10) through a diethyl acetylaminomalonate derivative, which upon deprotection gave the 3-ethoxy derivative of AMPA (15). Esterification of 15 gave the diethyl derivative 16 and the ethyl ester of AMPA (18) as well as N-ethylated derivatives of AMPA, 21 and 22 were synthesized. The final products were tested microelectrophoretically. The derivatives 7, 9, 15, 16 and 18 were weak and non-selective excitatory amino acid antagonists, whereas 21 and 22 were found to be inactive.
Department of Organic Chemistry, Royal Danish School of Pharmacy, Copenhagen.
U
U
Madsen
E O
EO
Nielsen
D R
DR
Curtis
D T
DT
Beattie
P
P
Krogsgaard-Larsen
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002415:Cats; D055598:Chemical Phenomena; D002621:Chemistry; D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D006571:Heterocyclic Compounds; D007395:Interneurons / Q000187:drug effects / Q000502:physiology; D015394:Molecular Structure; D013116:Spinal Cord / Q000166:cytology
D018691:Excitatory Amino Acid Antagonists; D005971:Glutamates; D006571:Heterocyclic Compounds; C011829:glutamic acid diethyl ester