A new family of macrocyclic antibiotics based-on Pillar[5]arene concluding multi quinoline moieties

Due to the many negative effects of increasing resistance to traditional antibiotics on living organisms, the development of new antibiotic classes has become imperative and macrocyclic compounds come to the fore for the solution of this problem. In this paper, the Pillar [5]arenes including ten and five quinoline units were synthesized and characterized by some procedures such as magnetic susceptibility, FT-IR, elemental analyses, 1H NMR, 13C NMR, melting point. Moreover, zinc(II) and copper (II) complexes were prepared to compare the antimicrobial effects with macrocyclic ligands. In the complex compounds, the metal:ligand ratios were determined with Job method as 1:2 and 1:1 for deca and penta units, respectively. The magnetic properties of the copper (II) complexes are 1.83 BM and 1.87 BM while zinc complexes have a diamagnetic character. The target macrocyclic ligands (Compound 7 and 8) and their metal complexes (Cu(II) and Zn(II)) were screened for the antimicrobial properties against the bacterial strains of Escherichia coli ATCC 25922, Staphylococcus aureus (MRSA) ATCC 43300, Klebsiella pneumoniae. ATCC 70603, Salmonella enteritidis ATTC 13076, Pseudomonas aeruginosa ATCC 27853, Bacillus cereus ATTC 11778, Sarcina lutea ATCC 9341, and yeast Candida albicans NRRL Y-417 by using broth microdilution method. Compound 7 has the optimum MIC values for S. aureus (MRSA), B. cereus, C. albicans and P. aeruginosa microorganisms that they were determined as 23.43, 46.87, 93.75 and 187 μg/mL, respectively. Moreover, Compound 8-Cu(II) complex was defined as an excellent antimicrobial agent against MRSA, B. cereus and C. albicans strains that the MIC values were determined as 3.9 μg/mL for both bacteria. The metal complexes of the target macrocyclic ligands have a more antimicrobial effect than the reactants and the target macrorings. Moreover, they have more successful results for Gram positive derivatives rather than Gram negative microorganisms.