Abstract: The present invention provides inhibitors of kynureninase having the formula ##STR1## where X is CO or CHOH; R.sub.A and R.sub.B, independently of one another, are H, a halogen, a halovinyl group, or a small alkyl or haloalkyl group having one to three carbon atoms; A is a H or an acetyl group; R.sub.1 is H, NH.sub.2, NR.sub.6 R.sub.7, NO.sub.2, halogen, CF.sub.3 or a small alkyl group having from one to three carbon atoms, wherein: R.sub.6 and R.sub.7, independently of one another, are H, a formyl group or a small alkyl group having from one to three carbon atoms with the exception that only one of R.sub.6 or R.sub.7 can be a formyl group; R.sub.2 is OH, H, halogen, CF.sub.3 or a small alkyl group having from one to three carbon atoms; and R.sub.3, R.sub.4 and R.sub.5, independently of one another, are H, halogen, CF.sub.3, NO.sub.2, NH.sub.2, or small alkyl group having from one to three carbon atoms, and with the proviso that when X=CO, neither R.sub.A nor R.sub.B can be CF.sub.3.