Structural chemistry and anticancer activity of new heteroleptic palladium(II) carbodithioates

Four new potent anticancer palladium(II) complexes containing PdClPS2 coordination sphere have been synthesized and characterized by different analytical techniques. Here, P is the donor atom from organophosphine (triphenylphosphine (1 and 3) and tris(p-chlorophenyl)phosphine (2 and 4)) and S 2 chelate is from carbodithioate (N,N'-dibenzyl-1-carbodithioate (1 and 2) and 4-(2hydroxyethyl)piperazine-1-carbodithioate (3 and 4)). All complexes exhibited distorted square planar geometry around Pd center owing to the chelate restriction of carbodithioate. The complexes are more potent anticancer (1-4) and antioxidant (3) agents than the standard drugs ((anticancer activity against HepG2: IC50 (mu M) = 23.39 (1) < 77.27 (3) < 82.62 (2) < 86.65 (4) 110 (doxorubicin) and (antioxidant activity against DPPH 65.6 (%) (3) and total antioxidant capacity expressed as equivalent of ascorbic acid (3) 51.4 mu g/mg, respectively)). Interestingly, the complexes demonstrated low lethal effects as determined by brine shrimp assay. The lethality sequence is opposite to that observed in anticancer (LD50 (ppm): 102.87 (1) 65.54 (3) > 62.50 (2) > 39.82 (4)) indicating high selectivity of 1 and 3 towards cancer cells. Anticancer activities were found to depend on the molecular stability and axial protection offered by organophosphine of the complexes. (c) 2020 Elsevier B.V. All rights reserved.

Automated summary

Four new potent anticancer palladium(II) complexes with PdClPS2 coordination sphere were synthesized and characterized, showing high selectivity towards cancer cells and strong antioxidant activity, as well as low lethality as determined by brine shrimp assay.