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 (CH 3 OH) 2 ]·2CH 3 OH ( 2 ), [Co 3 (HL 3 ) 2 (OAc) 2 (DMF) 2 ] (3) and [Co 3 (HL 4 ) 2 (HCOO) 2 (DMF) 2 ]·2H 2 O ( 4 ) bearing the bis-Schiff base ligand of bis(5-bromosalicylidene)-1,3-propanediamine (H 2 L 1 ), bis(5-bromosalicylidene)-2-methyl-1,3-propanediamine (H 2 L 2 ), bis(5-chlorosalicylidene)-2-hydroxyl-1,3-propanediamine (H 3 L 3 ) and bis(5-bromosalicylidene)-2-hydroxyl-1,3-propanediamine (H 3 L 4 ), 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 IC 50 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. We reported here the anti-cancer activities of four new linear trinuclear cobalt(II) complexes bearing the ligands of bis(salicylidene)-1,3-propanediamine derivatives, which are comparable to cisplatin and show significant influence of the substitution groups on anticancer effect. • Anti-tumor activities of four trinuclear cobalt complexes. • Best anti-tumor selectivity for complex with hydroxyl and chloro variable groups. • The anti-tumor mechanism of the complex was studied.