63365-11-7

A series of 5-substituted 2,4-diaminoquinazolines (3) has been synthesized and evaluated as inhibitors of the enzyme dihydrofolate reductase (DHFR) from both bacterial and mammalian sources.The best compounds (e.g. 53) show good activity against Escherichia coli DHFR, but there is no significant selectivity for the bacterial over the mammalian enzyme.The structure-activity relationships for enzyme inhibition appear to be complex and not amenable to simple analysis; a hypotesis to explain the observed qualitative structure-activity relationships is proposed.The inhibitory activities of the compounds against the growth of intact bacterial cells in vitro closely parallel those for the inhibition of the isolated bacterial enzymes, suggesting that their antifolate action is responsible for their antibacterial effects.Five of the compounds were tested for their ability to cure a systemic E. coli infection in the mouse, but they showed no therapeutic effects at their maximum tolerated doses.

A series of novel 1,2,3,5-tetrahydroimidazo[2,1-b]quinazolin-2-one derivatives substituted with a secondary amino group has been prepared and tested for the activities of inhibiting platelet aggregation in rats in vitro and ex vivo. Most of the compounds

A series of N-(2-cyano-substituted-phenyl)oxamates was prepared by acylation of the appropriate anthranilonitrile with ethyloxalyl chloride.Hydrolysis with sodium hydroxide gave the corresponding oxamic acid sodium salts.These compounds were extremely potent when tested in the rat passive cutaneous anaphylaxis (PCA assay either by the ip or the po route of administration).One of the sodium salts, oxoacetic acid sodium salt (11a, Wy-41 195), has ED50 value of 0.07 mg/kg po and has been selected for further evaluation.