IMB-SD62, a triazolothiadiazoles derivative with promising action against tuberculosis

One lead 3,6-disubstituted 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole was identified as an inhibitor of shikimate dehydrogenase with antitubercular activity. Following up this compound, we optimized the lead through systematic modification of the 3 and 6 positions. The antitubercular activities in vitro, shikimate dehydrogenase inhibitory activities and cytotoxicity of derivatives were determined. We found IMB-SD62 with lower cytotoxicity and better activity. Thus, we studied the in vivo efficacy of IMB-SD62 against Mycobacterium tuberculosis and pharmacokinetics of IMB-SD62. In vivo acute M. tuberculosis H37Rv infection assay, IMB-SD62 showed antitubercular activity with the mean lung CFU counts decreasing 1.7 lg. The plasma pharmacokinetics study in rats showed that the oral bioavailability of IMB-SD62 was 14% and the half time was 1.05 h. The results of tissue distribution indicated that IMB-SD62 was mainly absorbed by liver and lung. In vitro metabolism study suggested that the metabolic ways of IMB-SD62 were dealkylated, oxidized and demethylated. CYP enzyme inhibition of IMB-SD62 in human liver microsomes was also evaluated. IMB-SD62 showed barely inhibition on CYP3A4 and CYP2D6. The excretion study manifested that IMB-SD62 was mainly eliminated by fecal excretion in rats. We concluded that based on these pharmaceutical properties, IMB-SD62 has the potential to be developed into new TB drug.