Activity assays of thiadiazine derivatives on Trichomonas vaginalis and amastigote forms of Trypanosoma cruzi.

Eight thiadiazine 1,1-dioxide derivatives were evaluated for antitrichomonal and antitrypanosomal activities. In vivo tests were performed on a murine model for trichomoniasis standardized in our laboratory. The capacity of compounds to clear visceral lesions in experimentally infected animals as well as their effects on the mortality time of mice were used as criteria for activity. One of the thiadiazines (compound 7b) showed an efficacy similar to that obtained with the reference drug metronidazole, although higher doses were required. Its toxicity on cell proliferation in tissue culture was moderate. In vitro assays on amastigote forms of Trypanosoma cruzi were carried out using cultures of Vero cells infected with metacyclic trypomastigotes. For one compound (1) trypanocidal activity resembled that of nifurtimox as assessed by microscopic counts of infected and uninfected cells. Unfortunately, this compound showed a high degree of cytotoxicity on Vero cell cultures.