ANTIMICROBIAL ACTIVITY INVESTIGATION OF SOME THIOSEMICARBAZIDES AND THEIR CYCLIZATION PRODUCTS

The aim of the present study was the investigation of the potential antimicrobial activity of some thiosemicarbazides (C1 and C2) and their cyclization products from 1,2,4-triazole (C3 and C4) and 1,3,4-thiadiazole (C5 and C6) class. All these compounds contain in their molecule X-C6H4SO2C6H4- (X=H, Br) and 2-F-C6H4- radicals and their synthesis was recently reported. The compounds C1-C6 have been tested against 10 reference microbial strains and 30 clinical fungal isolates using the broth microdilution method, in order to determine their minimum inhibitory concentrations (MIC) and minimum bactericidal/fungicidal concentrations (MBC/MFC), respectively. The MIC values ranged between: 32-256 mu g/mL for thiosemicarbazide Cl and triazole C3, 128->512 mu g/mL for thiosemicarbazide C2 and triazole C4, and 256->512 mu g/mL for thiadiazoles C5 and C6. In all cases, the MBC/MIC or MFC/MIC ratio was less or equal to 4. As thiosemicarbazide C1 and triazole C3 presented the best antibacterial and antifungal activity from all studied compounds, it was considered that further investigations for these two compounds must be performed against more microbial strains.