Synthesis and Biological Activity of Biuret and Dithobiuret Metal Complexes

Abstract

A variety of bis and tris thiobiureto and dithiobiureto Co(II), Ni(II), Cd(II), Cu(II), Zn(II) metal complexes were synthesized by reacting N,N-dialkylcarbamoyl or N,N-dialkylthiocarbamoyl with potassium thiocyanide and twelve different commercially available amines. These complexes were characterized by spectroanalytical (UV-Vis, FT-IR, 1H-NMR and 13C-NMR) and single crystal X-ray diffraction techniques. To find percentage composition of atoms i.e. C, H and N present in synthesized complexes were also determined by CHN analysis. The obtained data from UV-Visible, FT-IR, 1H NMR, 13C NMR and elemental analysis were compared with the reported values which satisfactorily justified the synthesis of thiobiuret and dithiobiuret metal complexes. The structure of five complexes such as bis(1,1,5,5-tetramethyl-2,4-dithiobiureto)nickel(II) 12, bis(1,1,5,5-tetramethyl-2-thiobiureto)copper (II) 24, bis (1,1,5,5-tetramethyl-2,4-dithiobiureto) cadmium (II) 36, bis[(Z)-3-(3,3-dimethylbutanyol)-1,1-diethyl-2-thiobiureto]nickel (II) 48 and tris[(Z)-3-(3,3-dimethylbutanyol)-1,1-diethyl-2-thiobiureto] cobalt(II) 54 was unambiguously confirmed with single crystal X-ray analysis, establishing that the geometry of Ni(II), Cd(II) complexes (12, 36) is tetrahedral, square planar for Cu(II) and Ni(II) (24, 48) and octahedral geometry for (54) Co(II) complexes. Synthesized complexes were considered to evaluate their conductance and results indicate that they possess differential levels of electrolytic characteristics, which indicates that complexes had positive electrolytic behavior, whereas few complexes showed suppressed electrolytic properties. Regarding the assessment of antibacterial, antifungal, protein kinase inhibition, total antioxidant capacity, reducing power, DPPH radical scavenging, xxi ABTS antioxidant potential and anticancer assay; fourteen synthesized complexes were used for antibacterial and antifungal activity, thirty two complexes were considered for rest of the abovementioned assays. Out of fourteen complexes 8, 12, 13, 14, 27, 32, 38 had significant activities against three bacterial strains i.e. Echerishia coli, Staphylococcus aureus and Pseudomonas aeruginosa due to NCS containing moieties and 2, 3, 4, 12, 14, 27, 38, 47 possess differential levels of inhibition against Aspergilus niger, Flavus solani, Mucor species and Aspergilus flavus microbes. Out of thirty two said complexes on the other hand, 3, 5, 7, 10, 13, 15, 17, 19, 28, 46 and 1-8, 10, 12, 13, 14, 16-19, 22, 28-31, 43, 46 complexes were found as potential agents for protein kinase inhibition and antioxidant activity, respectively. Furthermore, all said synthesized transition metal complexes possessed significant inhibition activity against the cancer cell line. In all, biological findings obtained through the present study indicate that almost all synthesized complexes are promising candidates to combat cancer effect by suppressing oxidative stresses, and as well as anti-microbial activity to control infections. However, further comprehensive animal based studies are warranted to confirm our results to be translated them as drugs/medicines in future.