Abstract
Three series of 5-thio-1,3,4-thiadiazole carbamates containing alkynyl, aminoalkynyl, alkenyl or alkyl thio substituents have been synthesized as potential antimicrobial agents. The influence of both the alkynyl linkage and the various terminal nitrogen heterocyclic moieties on antimicrobial activity was assessed utilizing representative Gram-positive, Gram-negative and fungal species. Mannich base analogs containing a 2-ethyl carbamate group and a nitrogen heterocyclic of limited bulk provided the broadest spectrum of antimicrobial activity. The thiadiazole carbamates containing a 5-alkylthio substituent were consistently active against the Pseudomonas and Candida organisms studied. It is concluded that an acetylenic linkage is not an absolute requirement for potent antimicrobial activity in this molecular series, and that the binding sites of the organisms tested exhibit a steric requirement for lipophilic, but non-bulky, amine-containing heterocycles on Mannich base analogs.