Antibacterial and antibiofilm screening of new platinum(IV) complexes with some s-alkyl derivatives of thiosalicylic acid

Abstract

The influence of 5 new Platinum(IV) (Pt(IV)) complexes with S-alkyl derivatives of thiosalicylic acid (C1-benzyl, C2-methyl, C3-ethyl, C4-propyl and C5- butyl) was studied on 16 strains of bacteria. Antibacterial activity was tested using microdilution method with resazurin while antibiofilm activity was observed by tissue culture plate method, using doxycycline as a positive control. The results were expressed as minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and biofilm inhibitory concentration (BIC). The best result on Gram positive bacteria exhibited C1 and MIC was <7.81μg/ml against Staphylococcus aureus ATCC 25923. Bifidobacterium animalis subsp. lactis (probiotic) was sensitive to C2 (MIC at 15.625 μg/ml). The highest sensitivity of Gram negative bacteria was observed in Escherichia coli ATCC 25922 treated with C1, C2, C3 and C4, in Proteus mirabilis ATCC 12453 treated with C1, and in Pseudomonas aeruginosa treated with C2, C3 and C5 (all MICs at 250 μg/ml). The C2 complex were more efficient as antibiofilm agents and the best results were obtained with C2 acting against S. aureus and S. aureus ATCC 25923 biofilms. In conclusion, we noticed that the tested compounds exhibited promising properties as antibacterial and antibiofilm agents.

Keywords

• platinum(IV) complex
• antibacterial activity
• antibiofilm