Influence of dichloroacetylation on the antimicrobial activity of chloramphenicol derivatives and of various amines.

The dichloroacetyl group, one of the functional groups responsible for the antibacterial activity of chloramphenicol, has been inserted into various amines, and the dichloroacetamido-derivatives obtained have been studied against E. histolytica EdM, Candida albicans ATCC 2091, Saccharomyces cerevisiae ATCC 7921, Aspergillus niger NRRL 3, Trichomonas vaginalis and Mycobacterium tuberculosis H(37)Rv and ATCC 607. Among the various chlorophenoxamide analogues, only N-(benzothiazol-2-ylmethyl)dichloro-N-2-hydroxyethylacetamide shows an activity, in vitro and in vivo, comparable with that of chlorophenoxamide. The dichloroacetyl group is essential for the high amoebicidal activity in vivo of chlorophenoxamide. The dichloroacetamidopropiophenones of known antifungal activity also show marked amoebicidal activity in vitro, but they appear to have a different mechanism of action from chlorophenoxamide since the dichloroacetyl group is not indispensable. The high antitubercular activity of some benzothiazole derivatives is not increased by dichloroacetylation.