Synthesis, structure elucidation and antibacterial evaluation of new steroidal -5-en-7-thiazoloquinoxaline derivatives

Steroidal thiazolo[4,5-b]quinoxaline-2-yl-hydrazone derivatives, previously prepared from the reaction of cholest-5-en-7-one-thiosemicarbazones with 2,3-dichloroquinoxalines at 80 °C in high yield. The thiosemicarbazone derivatives were obtained by the condensation of the thiosemicarbazide with steroidal ketones. All the compounds have been characterized by means of elemental analyses, IR, 1H NMR and mass spectroscopic data. The antibacterial activity was first tested in vitro by the disk diffusion assay against Escherichia coli and then the minimum inhibitory concentration (MIC) of active compounds was determined. The results showed that steroidal thiazoloquinoxaline derivatives are better growth inhibitors as compared to steroidal thiosemicarbazone of both types of bacteria (Gram-positive and Gram-negative). Compounds 7 and 8 are better antibacterial agents as compared to chloramphenicol.