Antioxidant, Cytotoxicity, and Anti-inflammation Activities of Phenanthroline Adducts of Zn(II) and Ni(II) bis(N-alkyl-N-phenyldithiocarbamate)

Abstract

In this study, 4,7-diphenyl-1,10-phenanthroline adducts of Ni(II) and Zn(II) of N-methyl or ethyl-N-phenyldithiocarbamate were synthesized and the final adducts were represented as [Zn(L1)2L3], [Zn(L2)2L3], [Ni(L1)2L3], [Ni(L2)2L3] (where L1 = methyl, L2 = ethyl, L3 = bathophenanthroline) and characterized using various spectroscopic techniques and elemental analysis. Both the FT-IR and NMR analysis suggest that all the adducts possessed six coordination geometry by the metal atom centres upon the emergence of a new M-N bond. This was shown by the changes observed in the peaks and chemical shifts of the adducts in comparison to the parent complexes. The cytotoxicity, antioxidant, and anti-inflammatory properties were evaluated using different assays to ascertain their biological properties. In all the assays, no noticeable trend was observed between the adducts of similar ligands and metals. Nevertheless, in the antioxidant assays, a good to moderate activity was observed, especially in the DPPH assay, which gave the best radical scavenging properties. Additionally, the estimated IC50 values of 0.011 and 14.76 µM were calculated for the cytotoxicity in the human cervical cancer (HeLa) cell line for both [Zn(L1)2L3] and [Ni(L2)2L3] adducts, respectively, in comparison to 5-Flurouracil (17.48 µM). On the other hand, very low cytotoxicity was found for most of the adducts in the embryonic kidney 293 (HEK 293) cell lines, especially for [Zn(L1)2L3], demonstrating its superior amongst the other adduct and the standard drug. Moreover, the adducts exhibited good to moderate anti-inflammatory properties compared to diclofenac, a controlled drug. These findings thus suggest that the adducts, particularly [Zn(L1)2L3], hold promise as potential anticancer agents and warrant further evaluation through clinical trials.