Zero Hunger (SDG 2), Good Health & Well-being (SDG 3)
Synthesis, characterisation, and antimicrobial activity studies of quercetin- 5-suphonic acid, and its mixed-ligands metal(ii) complexes. Idongesit Ufot 1* , Nzikakyel Simon 2 , Atim Johnson 3 , Ekarika Johnson 4 , Idongesit Anweting 5 and Victor Mkpenie 6 Department of Chemistry, University of Uyo. Nigeria 1, 2, 3, 5, 6 , Department of Pharmaceutical Chemistry, University of Uyo. Nigeria 4 E-mail: idongesitufot@ymail.com This study investigated the synthesis, characterization, and antimicrobial evaluation of Quercetin- 5-sulfonic acid (Q5SA) and its mixed-ligand metal(II) complexes. The complexation with Cu(II), Fe(II), Ni(II), Zn(II), Mn(II), and Co(II) resulted in significant physicochemical changes, including alterations in colour, melting points, and refractive indices. Elemental analysis confirmed the molecular compositions, while spectroscopic techniques such as UV-Vis, FTIR, and NMR provided evidence of successful metal coordination through oxygen and nitrogen donor sites. Studies on magnetic susceptibility and electrical conductivity revealed marked paramagnetism in Fe(II) complexes, whereas Zn(II) complexes demonstrated diamagnetism. Antimicrobial evaluations showed a substantial increase in antibacterial and antifungal activities following metal coordination, with Co(II) and Cu(II) complexes exhibiting the highest potency. Specifically, the Cu(II) complex achieved a minimum inhibitory concentration (MIC) of 12.5 µg/mL against Staphylococcus aureus, while the Co(II) complex demonstrated an MIC of 25 µg/ mL against Escherichia coli. In silico assessments of drug-likeness indicated favorable bioavailability properties for this derivative of quercetin suggesting potential pharmaceutical applications. These findings highlight the role of metal coordination in enhancing the antimicrobial efficacy of Quercetin derivatives, supporting their potential as promising candidates for antimicrobial drug development. Key words: Quercetin, Synthesis, Antibacterial, Antifungal, Complexation References 1. Anand-David, A. V., Arulmoli, R., and Parasuraman, S. (2016). Overviews of biological importance of quercetin: a bioactive flavonoid. Pharmacognosy Reviews, 10 (20): 84–89 2. Bentz, A. E. (2009). A review of quercetin: chemistry, antioxidant properties, and bioavailability. Journal of Young Investigators, 29:358-362. 3. Cai, X., Fang, Z., Dou, J., Yu, A., and Zhai, G. (2013). 4. Bioavailability of quercetin: problems and promises. Current medicinal chemistry, 20(20): 2572–2582 5. Godlenska, P., Hamza, J., Kucharska, E., Solarz, P. and Roszak, S. (2020). 6. Optical and magnetic properties of Lanthanide(III) complexes with quercetin-5-sulphonic acid in the solid state and silica glass. Journal of Molecular Structure. 1219: 128504 Kalinowska, M., Świderski, G., Matejczyk, M., Lewandowski, W. (2016). 7. Spectroscopic, thermogravimetric and biological studies of Na(I), Ni(II) and Zn(II) complexes of quercetin. Journal of Thermal Analysis and Calorimetry, 126: 141–148. Vimalraj, S., Rajalakshmi, S., Preeth, D. R., Kumar, S. V., Deepak, T., Gopinath, V., Murugan, K., and Chatterjee, S. (2018). 8. Mixed-ligand copper (II) complex of quercetin regulate osteogenesis and angiogenesis. Materials for Biological Applications, 83: 187–194.
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