1921
Volume 48, Issue 1
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645
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Abstract

Abstract

Sinefungin and its cyclic analog were evaluated in vitro for activity against the multiplication of . When either drug was tested for eight days on twelve epimastigote isolates, an 800-fold difference in drug sensitivity was found. Both drugs were trypanostatics at a concentration range from 0.1 µg/ml to 300 µg/ml. The 50% effective concentration (EC) of sinefungin and its cyclic analog at which the growth of a given isolate was inhibited was 0.38 µg/ml for sinefungin and 0.31 µg/ml for the cyclic analog against the Ma, Marin, OPS-86, Y, and Ya isolates, and > 300 µg/ml for sinefungin and 217 µg/ml for the cyclic analog against the A-35, Bertoldo, DS, EP, ES, OPS-58, and FL isolates. Incubation of drug-sensitive isolates for more than 10 days in glucose-saline (GS) medium, but not in minimal essential medium, in the presence of a 30-fold EC concentration of the drug induced an increase in the drug-resistant population, which maintained this phenotype for several passages in drug-free culture medium. Growth curves were analyzed as a function of parasite inoculum; it was observed that with sinefunginsensitive epimastigote isolates grown in GS medium in the presence of 10 µg/ml of the drug, the inhibitory effects of the drug were dependent on the initial inoculum: 1 × 10-1 × 10 parasites/ml were strongly inhibited even after 16 days. Significant impairment of thymidine incorporation into the DNA of parasites by both drugs was observed only in drug-sensitive epimastigote isolates. Vero cell-derived trypomastigotes of the twelve isolates studied grew in the presence of 50 µg/ml of sinefungin or the cyclic analog in culture medium, which suggests a stage-specific inhibitory effect.

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/content/journals/10.4269/ajtmh.1993.48.112
1993-01-01
2017-11-23
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