Heteroaromatic Hybrid Benzimidazole/Oxadiazole (BZ/OZ) Ligand and Its Sm(III) Complex: Study of Their Antibacterial Activity, Toxicological Prediction and Interaction with Different Model Membranes

Two heteroaromatic hybrid compounds were synthesized and characterized using various analytical techniques. The results indicate that the benzimidazole/oxadiazole (BZ/OZ) metal derivative exhibits a tridentate coordination mode, where the carbonyl, imidazole and oxadiazole groups participate in coordination with the metal, in a ratio of 2:1 of the ligand to the metal. The antibacterial activities of the organic ligand and its metal complex were determined by in vitro tests against both Gram-positive bacterial strains and Gram-negative bacterial strains using the broth microdilution method. The metal complex showed greater antibacterial activities compared to the precursor ligand against all evaluated microorganisms. The results obtained through in silico predictions revealed significant toxicological differences among the analyzed molecules, suggesting special attention in the use of the ligand due to its possible carcinogenicity in mice and a need for structural modifications in the complex to reduce its carcinogenicity and toxicity. Furthermore, a biophysical study of the interaction of the BZ/OZ derivatives with different model membranes was explored through differential scanning calorimetry (DSC), simultaneous small- and wide-angle X-ray diffraction (SAXD and WAXD) and infrared spectroscopy (FT-IR). The results indicate that the compounds influenced membrane properties without significantly altering the lamellar organization. The findings suggest potential applications in understanding lipid interactions, elucidating toxicology and developing antibacterial agents.