Synthesis, characterization and antimicrobial activity of Cr (III), Co (II) and Ni (II) complexes with 2-thiazoline-2-tiol derivative ligands against bacteria and yeasts of clinical importance

Abstract: Four novel Cr (III), Co (II) and Ni (II) complexes with 2-thiazoline-2-tiol derivative ligands were synthesized and characterized using elemental, physiochemical, and spectroscopy analytical methods. The results showed the formation of ligands coordinated by sulfur atoms of the C = S bond to the L1 ligand and by the sulfur atom of the C-S bond and/or nitrogen of the intra C-ring bond of the L2 ligand. The activity of the complexes against Gram-negative, Gram-positive bacteria and yeasts of clinical importance was evaluated by broth microdilution method. The best result was obtained to L2-Ni compound against E. cloacae (Minimal Inhibitory Concentration (MIC) = 62.5 µg/mL). Additionally, the compounds showed anti-Candida activity (MIC values ranging from 250 to 500 µg/mL), except the L1-Cr that was not active against any tested microorganism.

摘要：本研究合成了4种含2-噻唑啉-2-硫醇衍生物配体的新型三价铬（Cr(III)）、二价钴（Co(II)）与二价镍（Ni(II)）配合物，并通过元素分析、物理化学表征及光谱学分析方法对其进行了结构鉴定。结果显示，配体L1通过C=S键的硫原子与金属中心配位；配体L2则通过C-S键的硫原子及/或环内C-N键的氮原子与金属配位。采用肉汤微量稀释法，评估了该系列配合物对具有临床意义的革兰氏阴性菌、革兰氏阳性菌及酵母菌的抗菌活性。其中，L2-Ni配合物对阴沟肠杆菌（E. cloacae）的抑制效果最佳，其最低抑菌浓度（Minimal Inhibitory Concentration, MIC）为62.5 µg/mL。此外，除L1-Cr配合物对所有受试微生物均无活性外，其余配合物均表现出抗念珠菌活性，MIC值介于250~500 µg/mL之间。