Chiral discrimination asserted by enantiomers of Ni (II), Cu (II) and Zn (II) Schiff base complexes in DNA binding, antioxidant and antibacterial activities

Chiral Schiff base ligands (S)-H2L and (R)-H2L and their complexes (S-Ni-L, R-Ni-L, S-Cu-L, R-Cu-L, S-Zn-L and R-Zn-L) were synthesized, characterized and examined for their DNA binding, antioxidant and antibacterial activities. The complexes showed higher binding affinity to calf thymus DNA with binding constant ranging from 2.0 × 105 to 4.5 × 106 M−1. All the complexes also exhibited remarkable superoxide (56–99%) and hydroxyl scavenging (45–89%) activities as well as antibacterial activities against gram (+) and gram (−) bacteria. However, none of the complexes showed antifungal activity. Conclusively, S enantiomers of the complexes were found to be relatively more efficient for DNA interaction, antioxidant and antibacterial activities than their R enantiomers. This study reveals the possible utilization of chiral Schiff base complexes for pharmaceutical applications.

Graphical abstract. Chiral Schiff base Ni (II), Cu (II) and Zn (II) complexes have been synthesized and characterized by various physico-chemical methods. All the complexes were subjected to DNA binding, antioxidant and antibacterial activities.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Chirality in a molecules plays a significant role in medicinal chemistry. ► Where only one enantiomer shows desirable therapeutic effect. ► S enantiomer of complexes showed strong biological activity than R enantiomer. ► S enantiomer of Ni and Cu complexes bind with DNA through intercalation.