Novel substituted quinoxaline 1,4-dioxides with in vitro antimycobacterial and anticandida activity

Thirty-six 6(7)-substituted-3-methyl- or 3-halogenomethyl-2-phenylthio–phenylsulphonyl–chloro-quinoxaline 1,4-dioxides belonging to series 3–6 were synthesised and submitted to a preliminary in vitro evaluation for antimycobacterial, anticandida and antibacterial activities. Antitubercular screening showed a generally good activity of 3-methyl-2-phenylthioquinoxaline 1,4-dioxides (3d,e,h–j) against Mycobacterium tuberculosis, and exhibited MIC between 0.39 and 0.78 μg mL−1 (rifampicin MIC=0.25 μg mL−1), whereas in compounds 4d,e, 5a,b,d,e,l and 6b–e,j,l MIC ranged between 1.56 and 6.25 μg mL−1. Results of the antibacterial and anticandida screening showed that 6e and 6l exhibited MIC=0.4 and 1.9 μg mL−1, respectively, against Candida krusei (miconazole MIC=0.9 μg mL−1), and 4i, 5b,d, 6e, MIC=3.9 μg mL−1 against Candida glabrata (miconazole MIC=0.4 μg mL−1), while compounds 3d,l, 5e,l, and 6b,d,e,l showed MIC=15.6 μg mL−1 against Vibrio alginolyticus