Antibacterial, antioxidant and cytotoxicity evaluation of selected schiff base ligands and their corresponding metal complexes
| dc.contributor.author | Nawinda, Teopolina N. | |
| dc.date.accessioned | 2026-09-21T14:13:47Z | |
| dc.date.available | 2026-09-21T14:13:47Z | |
| dc.date.issued | 2025 | |
| dc.description | A Dissertation submitted in fulfilment of the requirement for the Degree of Doctor of Philosophy in Science in Biochemistry | |
| dc.description.abstract | Schiff bases are compounds that possess an azomethine group and are considered as aldehyde and ketone derivatives. Schiff bases have diverse pharmacological properties and constitute an important class of compounds for new drug development hence researchers are investigating these compounds for different biological activities. The present study was designed to synthesize Schiff base ligands and their metal complexes which were then screened for antibacterial and antioxidant activity as well as cytotoxicity against a cervical cancer cell line. Schiff base ligands were synthesized by means of the Schiff’s base reaction, and for each ligand, metal complexes of copper II (Cu2+) and nickel II (Ni2+) were synthesized. The structural confirmation of the synthesized compounds was done by Proton Nuclear Magnetic Resonance (1H NMR) and Fourier Transform Infrared (FTIR) spectroscopies. The antibacterial activity of the ligands and metal complexes was assayed by means of the agar disc diffusion method while the antioxidant activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and reducing power assays. Cytotoxicity studies were conducted against Henrietta Lacks (HeLa) cells using the 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Both ligands and metal complexes displayed antibacterial activity against strains of Staphylococcus aureus, Streptococcus mutans, Neisseria gonorrhoea, and Escherichia coli with minimum inhibitory concentration (MIC) values ranging from 2.5 – 10 mg/mL. All tested compounds demonstrated a concentration-dependent antioxidant activity, with half maximal inhibitory concentration (IC50) values in the range of 1.33 – 85.81 µg/mL. Selected ligands and metal complexes exhibited cytotoxic activity against HeLa cells, having IC50 values in the range of 4.12 – 16.80 µg/mL. Copper metal complexes exhibited the best antibacterial activity with iv recorded MIC of 2.5 mg/mL against most tested bacteria species. On the other hand, nickel metal complexes had the best antioxidant activity with IC50 values of 1.33 – 33.92 µg/mL. Most ligands and metal complexes exhibited moderate cytotoxicity against HeLa cells. However, L6 was the most toxic to HeLa cells as indicated by a lower IC50 (4.12 ± 0.6 µg/mL), compared to other compounds tested for cytotoxicity in the present study. There are no literature reports on the antibacterial, antioxidant and cytotoxic activities of the compounds analysed in this study. The results generated from this study showed that the biologically active ligands and metal complexes could be used as compounds of interest in the drug discovery process | |
| dc.identifier.uri | http://hdl.handle.net/11070/4293 | |
| dc.language.iso | en | |
| dc.publisher | University of Namibia | |
| dc.subject | Antioxidant | |
| dc.subject | Antibacteriel | |
| dc.subject | Cytotoxicity | |
| dc.subject | Metal complexes | |
| dc.subject | Namibia | |
| dc.subject | University of Namibia | |
| dc.title | Antibacterial, antioxidant and cytotoxicity evaluation of selected schiff base ligands and their corresponding metal complexes | |
| dc.type | Thesis |