Synthesis and characterization of novel bioactive 1,2,4-oxadiazole natural product analogs bearing the N-phenylmaleimide and N-phenylsuccinimide moieties.
Taking into consideration the biological activity of the only natural products containing a 1,2,4-oxadiazole ring in their structure (quisqualic acid and phidianidines A and B), the natural product analogs 1-(4-(3-tert-butyl-1,2,4-oxadiazol-5-yl)phenyl)pyrrolidine-2,5-dione (4) and 1-(4-(3-tert-butyl-1,2,4-oxadiazol-5-yl)phenyl)-1H-pyrrole-2,5-dione (7) were synthesized starting from 4-(3-tert-butyl-1,2,4-oxadiazol-5-yl)aniline (1) in two steps by isolating the intermediates 4-(4-(3-tert-butyl-1,2,4-oxadiazol-5-yl)phenylamino)-4-oxobutanoic acid (3) and (Z)-4-(4-(3-tert-butyl-1,2,4-oxadiazol-5-yl)phenylamino)-4-oxobut-2-enoic acid (6). The two natural product analogs 4 and 7 were then tested for antitumor activity toward a panel of 11 cell lines in vitro by using a monolayer cell-survival and proliferation assay. Compound 7 was the most potent and exhibited a mean IC50 value of approximately 9.4 µM. Aniline 1 was synthesized by two routes in one-pot reactions starting from tert-butylamidoxime and 4-aminobenzoic acid or 4-nitrobenzonitrile. The structures of compounds 1, 2, 4, 5 and 6 were confirmed by X-ray crystallography.
Institut für Anorganische und Analytische Chemie, Technische Universität Carola Wilhelmina, Hagenring 30, D-38106 Braunschweig, Germany.
Catalin V
CV
Maftei
Elena
E
Fodor
Peter G
PG
Jones
M Heiko
MH
Franz
Gerhard
G
Kelter
Heiner
H
Fiebig
Ion
I
Neda
1,2,4-oxadiazoles; antitumor activity; bioisosteres; maleimide; natural product analogs