Synthesis, characterization and biological studies of oxovanadium(IV) and zinc(II) complexes of mixed ligands of sulfadiazine and dithiocarbamate

Abstract

The research involves the synthesis, characterization and biological studies of oxovanadium(IV) and zinc(II) complexes of mixed sulfadiazine and dithiocarbamates ligands. Twenty-five dithiocarbamates ligands were synthesized and characterized with elemental analysis, FT-IR, UV-Vis, 1H NMR and 13C NMR spectroscopy. The dithiocarbamate ligands were used with the sulfadiazine to synthesize mixed ligands complexes of oxovanadium(IV) and zinc(II). The oxovanadium(IV) and zinc(II) complexes were characterized with analytical and spectroscopic techniques. Results from molar conductivity confirmed the non-electrolytic nature of both the oxovanadium(IV) and zinc(II) complexes. The FT-IR spectra studies of the complexes confirmed bidentate coordination of sulfonamide nitrogen and pyrimidinyl nitrogen atoms of sulfadiazine to the metal ions, and the dithiocarbamate ligands acted as bidentate chelating ligands through sulfur atoms. The coordination in both metal complexes was N2S2 modes. Studies from UV-Vis spectra for mixed oxovanadium(IV) and zinc(II) complexes gave blue shifts (hypsochromic shifts) in comparison with the respective ligands through N-C=S and S-C=S absorption bands. The conclusion drawn from the UV-Vis studies were proposed structures distorted octahedral geometries for the oxovanadium(IV) complexes and tetrahedral geometries for zinc(II) complexes. The presence of phenyl groups in chemical shifts’ results in aromatic zinc(II) complexes (7.78- 6.38), ppm, the absence in aliphatic zinc(II) complexes, pyrimidine C4H2N2-H (8.60-8.10 ppm), and =CHSO2NNa (11.81-11.19 ppm) in 1H NMR, presence of 13C-SO2NNa (164.39-130.41 ppm) and N13CS2(207.00-179.32 ppm) moieties indicated the presence of the functional group still present and the impact of coordination of ligands to zinc(II) ions. Zinc(II) complexes of [Zn(SFZ)(tu-DTC)] [Zn(SFZ)(ml-DTC)] had the least chemical shift at a resonance of (179.32 ppm), while [Zn(SFZ)(ml-DTC)] has the highest resonance value with a signal for N13CS2 moiety. Four ligands of dithiocarbamates, ten mixed ligands of oxovanadium(IV) and eleven zinc(II) complexes were screened for cytotoxicity and anticancer activities. They were evaluated for in vitro cancer activities against six cancer cell lines; KMST-6 (a non-cancerous cell line), HT-29 (colon), W1-38 (fibroblast cell), TK-10 (renal), UACC-62 (melanoma) and MCF-7 (breast). The four ligands and four zinc(II) complexes showed potentials and potencies for cytotoxicity activities against KMST-6 and HT-29, except [Zn(SFZ)(me-DTC)]. Inactive or slightly active oxovanadium(IV) and zinc(II) complexes screened against W1-38, TK-10 UACC-62 and MCF-7 had inhibition concentration 50, IC50, of greater than 50 greater than 100. Six oxovanadium(IV) and three zinc(II) complexes showed potentials and potencies for cytotoxicity activities against W1-38. Four oxovanadium(IV) and two zinc(II) complexes showed potentials and potencies for cytotoxicity activities against TK-10. Eight oxovanadium(IV) and three zinc(II) complexes showed potentials and potencies for cytotoxicity activities against UACC-62. Eight oxovanadium(IV) and three zinc(II) complexes showed potentials and potencies for cytotoxicity activities against MCF-7. Results from studies showed that [VO(SFZ)(hx-DTC)] and [VO(SFZ)(cl-DTC)] as potent cytotoxicity and anticancer chemotherapeutic agents. Cisplatin, Emetine and Parthenolide were used as standard drugs and dimethylsulfoxide as negative control. Sodium sulfadiazine, derivatives of dithiocarbamates and both complexes of oxovanadium(IV) and zinc(II) were screened for their in vitro antibacterial potencies against two Gram positive (Staphylococcus aureus (MRSA252))and Enterococcus faecalis (BS385)) and Gram negative (Escherichia coli (MC4100))and Pseudomonas aeruginosa (PA01)) bacterial strains. Sodium sulfadiazine was found to have good activity against Staphylococcus aureus and Escherichia coli but most of the dithiocarbamates ligands were not active before coordination but some became more inactive or more active in various complexes of oxovanadium(IV) and zinc(II) ions. Meropenem, Tetracycline and Vancomycin were used as standard drugs and dimethylsulfoxide as negative control. The minimal inhibitory concentration (MIC) results proved that oxovanadium(IV) complexes had higher antibacterial activities than zinc(II) complexes. The oxovanadium(IV) complexes with MIC of high activities (32 μg/ml) are [VO(SFZ)(bt-DTC)],[VO(SFZ)(hx-DTC)], [VO(SFZ)(ch-DTC)] and [VO(SFZ)(hh-DTC)]. The results showed that oxovanadium(IV) complexes are better than their zinc(II) counterparts. These dual anticancer and antibacterial potentials and potencies of oxovanadium(IV) complexes can be further evaluated as potential chemotherapeutic agents.