SYNTHESIS, STRUCTURAL, PHISICO-CHEMICAL CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY SCREENING OF NEW THIOUREA DERIVATIVES

A number of seven new thiourea derivatives having thiophene skeleton, obtained from 2-thiopheneacetic acid, have been synthesized, characterized by their physical properties (melting point, solubility), FT-IR, NMR spectroscopy and tested by qualitative and quantitative microbiological methods on various bacterial and fungal strains in order to identify their antimicrobial and antibiofilm activities, planktonic and biofilm growth state. The new compounds were prepared by the reaction of 2-thienyl-isothiocyanate with various primary aromatic amines. The antimicrobial activity of the obtained thiourea derivatives was evaluated by using both qualitative and quantitative assays, allowing to establish the Minimal Inhibitory Concentration (MIC) as well as the spectrum of antimicrobial and anti-biofilm activities. The compounds N-(2-trifluoromethylphenyl)-N'-(2-thienyl)-thiourea (4a) and N-(4-trifluoromethylphenyl)-N'-(2-thienyl)-thiourea (4c), proved to be the most efficient, showing antimicrobial activity on the majority of the tested strains in planktonic growth state. The compounds N-(3,5-dimethoxyphenyl)-N'-(2-thienyl)-thiourea (4d) and N-(3-trifluoromethylphenyl)-N-(2-thienyl)-thiourea (4b) had the broadest spectrum of anti-biofilm activity, which included the most clinically relevant biofilm forming microorganisms, i.e. Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans.