Synthesis, characterization and antitumor activity of a 2,5-diketopiperazine copper coordination compound

Many cations have biological activities recognized within the human body; however, the choice of the ligand is a determining factor in the pharmacological properties of a complex. 2,5-diketopiperazines are cyclic peptides found as byproducts of protein degradation, used as models for protein studies and applied as precursors to antitumor agents. In this work, we synthesize 2,5-piperazinedione-1,4-diacetic acid (H2PDA) and its copper complex. Ligand and complex were characterized by CHNS, TGA, FTIR, SEM, XRD and NMR. For the complex, spontaneous and antitumor activity assays were performed in vivo. The H2PDA was obtained using iminodiacetic acid via hydrothermal synthesis (Figure 1). The NMR and FTIR (Figure 2) analyzes are in agreement with the literature. The complex crystals were obtained crystals using open crystallization in water. CHNS and TGA analysis confirm the formula [Cu(PDA)(H2O)2,5]. The FTIR shows the carbonyl and C-O signals, displaced in relation to the ligand, indicating coordination. The stretch band O-H confirms the water in the structure. Eight Wistar rats received 66.66 mg/kg of the complex and presented a set of behavioural responses in characteristic periods of occurrence. Responses in the Central Nervous System (excitatory and depressants) and in the Autonomic Nervous System were observed. The tumor inhibition activity of the complex against the Ehrlich tumor was verified. A medium tumor volume of 7 mm3, against 19 mm3 for tumours of the control group (63% inhibition), were observed, however we noticed a slight increase in the rate of tumor growth.