Anticancer activity of four trinuclear cobalt complexes bearing bis (salicylidene)-1,3-propanediamine derivatives

Schiff base and its complexes are being paid more and more interests for their great prospects in biological applications. We reported here four cobalt(II) complexes [Co-3(L-1)(2)(HCOO)(2)] (1), [Co-3(L-2)(2)(HCOO)(2)(CH3OH)(2)].2CH(3)OH (2), [Co-3(HL3)(2)(OAc)(2)(DMF)(2)] (3) and [Co-3(HL4)(2)(HCOO)(2)(DMF)(2)].2H(2)O (4) bearing the bis-Schiff base ligand of bis(5-bromosalicylidene)-1,3-propanediamine (H2L1), bis(5-bromosalicylidene)-2-methyl-1,3-propanediamine (H2L2), bis(5-chlorosalicylidene)-2-hydroxyl-1,3-propanediamine (H3L3) and bis(5-bromosalicylidene)-2-hydroxyl-1,3-propanediamine (H3L4), respectively. The anti-tumor activities of the four titled complexes were screened on a series of tumor cell lines. After an overall consideration of their cytotoxicity on cancer cells and normal cells in comparison to those for cisplatin, complex 3 shows the best anticancer effect among the four titled complexes. It revealed the influence of anti-cancer effects of the substitution groups of H, Me and OH, as well as Cl and Br. Anticancer selectivity was also found for complex 3 on different cancer cell lines with the lowest IC50 value on T-24 cells. Complex 3 induces cell apoptosis through mitochondrial pathway as demonstrated by increasing the level of reactive oxygen species, decreasing mitochondrial membrane potential, activating caspase 3/9 and arresting cell cycle in G1 phase.

Automated summary

Schiff base and its complexes have great prospects in biological applications. This study reported four cobalt(II) complexes with bis-Schiff base ligands and screened their anti-tumor activities. Complex 3 showed the best anti-cancer effect and exhibited selectivity against cancer cell lines.