Spectroscopic and dual activities as antioxidant and antimicrobial agents of n, n’ donor Schiff base metal complexes Ikechukwu P. Ejidike 1,2* , Racheal O. Awolope 1 , Hadley S. Clayton 2 1 Department of Chemical Sciences, Faculty of Natural, Applied and Health Sciences, Anchor University, Nigeria, 2 Department of Chemistry, College of Science, Engineering and Technology, University of South Africa, South Africa Schiff base ligands bearing azomethine (>C=N–) functional group, possessing N, O, and S-donor atoms have been established as versatile pharmacophores for the design and development of various biologically active compounds. Infectious diseases that are directly related to bacteria exhibiting multiple resistance to antibiotics have increased the world’s mortality rate. Therefore, the need to develop novel antibacterial drugs with excellent mechanisms of action and the structural-activity relationship has become an urgent biomedical necessity. In effort geared towards the development of chemotherapeutic agents we report the antimicrobial and antioxidant activities of 4,4'-{ethane-1,2-diylbis[nitrilo( Z )methylylidene]}bis(2-methoxyphenol) ligand (SV) and its metal complexes represented as CoSV, CuSV, NiSV, ZrSV, VoSV, and UO 2 SV, their biological activities. The compounds were characterized by elemental analyses, molar conductance, UV-Vis, FTIR, and TGA. The IR spectral data suggest that the ligand behaves as a dibasic bidentate ligand with a dinitrogen donor atoms system towards central metal ions. The antibacterial properties of the complexes evaluated using standard methods to determine the zones of inhibition showed that all the complexes exhibited strong to moderate activities against S. aureus , E. faecalis, K. pneumonia , and P. aeruginosa bacteria compared to the parent ligand. Increased antibacterial properties of the complexes were attributed to the increased lipophilic nature of the ligand upon coordination with metal. The IC 50 (μM) value of the 2,2-Diphenyl-1-picrylhydrazyl radical scavenging activities of the Schiff base metal complexes ranged from 3.24 to 6.44 which were higher than that of standard ascorbic (IC 50 (μM) = 1.22) or Gallic acid (IC 50 (μM) = 2.02) used. Therefore, their potential as precursors for developing chemotherapeutic drugs for the elimination of pathological radicals-related diseases from the living system. References 1. Ejidike, I.P., Ajibade, P.A. J. Pharm. Sci. Res. 2017, 9, 593-600.
2. Wang, W., Zeng, F.-L., Wang, X., Tan, M.-Y. Polyhedron, 1996, 15(10), 1699-1703. 3. Ejidike, I.P., Ajibade, P.A. Int. J. Mol. Sci. 2016, 17, 60; doi:10.3390/ijms17010060 4. Gaballa, A.S., Asker, M.S., Barakat, A.S., Teleb, S.M. Spectrochimica Acta Part A, 2007, 67, 114-121.
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