Pate PG, Wolfson JS, McHugh GL, Pan SC, Swartz MN. Novobiocin antagonism of amastigotes of Trypanosoma cruzi growing in cell-free medium.
Antimicrob Agents Chemother 1986;
29:426-31. [PMID:
3521485 PMCID:
PMC180408 DOI:
10.1128/aac.29.3.426]
[Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Inhibitors of the enzyme bacterial topoisomerase II (DNA gyrase) were evaluated for activity against Trypanosoma cruzi (Brazil strain), based on the theoretical need for a topoisomerase II in the replication of the kinetoplast DNA network. Novobiocin (500 micrograms/ml) antagonized amastigotes of T. cruzi growing in a cell-free medium at 37 degrees C, as manifested by inhibition of multiplication, abnormal morphology of Giemsa-stained organisms, and delayed or absent growth of cells upon subculturing in a drug-free medium. In contrast, novobiocin (1,000 micrograms/ml) essentially had no effect on the multiplication and motility of epimastigotes growing in a cell-free medium at 27 degrees C. This resistance of epimastigotes represented a difference in the physiology of this morphologic stage and not in the temperature of experimentation, because novobiocin inhibited multiplication of amastigotes at 27 degrees C as well and accelerated transformation to epimastigotes. With T. cruzi growing within cultured human fibroblasts, novobiocin (200 micrograms/ml) markedly inhibited transformation of intracellular amastigotes to trypomastigotes. Clorobiocin, a structural analog of novobiocin and likewise an inhibitor of the B subunit of bacterial topoisomerase II, was five times more potent on a molar basis than novobiocin was in antagonism of amastigotes growing in a cell-free medium and did not antagonize epimastigotes. Coumermycin A1, another analog of novobiocin, and five 4-quinolone antibacterial agents, antagonists of the A subunit of bacterial topoisomerase II, inhibited neither amastigotes nor epimastigotes. These experiments indicate that novobiocin and clorobiocin represent a new structural class of drugs with activity against T. cruzi. Whether the mechanism of action of these drugs involves antagonism of a T. cruzi topoisomerase II or an unrelated target is yet to be determined.
Collapse