3.7. In Silico Studies

The electronic properties of the synthesized derivatives that demonstrated the best biological activities in the in vitro XTT assay were investigated with density functional theory calculations. The calculations were carried out with the aid of Gaussian 09 [53]. The geometry of the studied molecules was fully optimized using B3LYP/6-311G functional and the obtained molecular orbitals were visualized.

Molecular docking was used to investigate the interaction of the best biologically active molecules with the microbial receptors. We selected the most probable bacterial/fungal proteins that can be affected by the synthesized thiazole ligands based on the results previously reported in the literature. Molecular docking was carried out with the aid of the Molecular Operating Environment (MOE) 2014 software [54]. The geometry-optimized compounds that demonstrated the lowest MIC values in the XTT assay were selected and docked with the corresponding receptors. High-resolution 3D molecular structures of the receptors Secreted Aspartic Proteinase (SAP2; C. albicans; PDB ID: 1EAG), Enoyl-acyl Carrier Protein Reductase (fabI; S. aureus; PDB ID: 3GR6) and Enoyl-acyl Carrier Protein Reductase (FabI; P. aerugiosa; PDB ID: 4NR0) were obtained from the Protein Data Bank (PDB).