Structural analogues of isatin and their antimicrobial activity.

A series of 5-haloisatins were aminomethylated in position 1 and hydrazino groups were introduced in position 3. Synthesized N-Mannich bases and hydrazones were biologically tested against various kinds of bacteria and fungi. Results from these in vitro studies showed a considerable growth inhibition of some gram negative bacteria caused by chlorinated N-Mannich bases of isatin. Comparing the inhibition zones of the halogenated isatin N-Mannich bases with structural analogues of nonhalogenated ones as well as with isatin itself, an increase in antimicrobial activity was observed, thus, indicating the importance of both substituents, namely, halogen in position 5 and an amino moiety in position 1. The most biologically active compound was found to be diisopropylamino-N-Mannich base of 5-chloroisatin.