4-(3-coumarinyl)-4-thiazolin-2-one benzylidenehydrazones with antituberculosis activity.

In this study a new series of 4-(3-coumarinyl)-4-thiazoline-2-one benzylidenehydrazones (3a-v) were synthesized by condensation of 3-(omega-bromoacetyl)coumarins (1a and 1b) with 1-substituted benzylidene-4-substituted thiosemicarbazides (2a-1). Structures of the title compounds were elucidated by elemental analyses and spectrometric data (UV, IR, 1H-NMR and EIMS). These new compounds and some previously reported compounds (1a-d) were evaluated for antituberculosis activity against Mycobacterium tuberculosis H37Rv. The compounds exhibited varying degrees of inhibition in the in vitro primary screening that was conducted at 12 micrograms/ml against M. tuberculosis H37Rv in BACTEC 12B medium using the BACTEC 460 radiometric system. 1b, 3b, 3e, 3h, 3o and 3p demonstrating activity in the primary screen were re-tested at lower concentrations against M. tuberculosis H37Rv to determine the actual minimum inhibitory concentration (MIC) in CABTEC 460 and Alamar Blue assay (MABA). The most active compound was found to be 1b. The structure-activity relationships of the derivatives were investigated.