Antimycoplasmal Compounds. II. : Antimycoplasmal Activity of Bis-thiosemicarbazones

Abstract

Bis-thiosemicarbazones (bis-TS) were synthesized and for their in vitro and in vivo antibacterial effect against Mycoplasma gallisepticum was examined. Among the tested compounds, α-ketoaldehyde bis-TS exhibited a strong in vitro activity, and minimal inhibitory concentration (MIC) of most active methylglyoxal bis-TS was 3.9-7.8×10^-3 μg/ml. α-Diketone bis-TS were inferior to α-ketoaldehyde bis-TS, but their toxicity to HeLa cells was extremely low. Eight compounds which have small MIC value or large ratio of toxic concentration to HeLa cells to MIC, were selected for examining their therapeutic effectiveness in Mycoplasma-infected chicken. When the compounds were added to feed, methylglyoxal bis (4-methyl-TS) showed 64% inhibition at a level of 25 ppm. In the case of intramuscular injection, 1-phenylpropane-1, 2-dione bis-TS exhibited 64% inhibition at a level of 20 mg/chicken administered twice daily on the day of infection and on 5th day after infection.