Synthesis and Biological Evaluation of Some Novel 2-Pyrazinoic Acid-derived Esters

Pyrazine, a kojic acid having hydroxypyrone, and hydroquinone are the head compounds of different categories possessing a broad range of biological activities including anticancer and antioxidant activities, thus are interested in evaluating the cytotoxicity on K562 human leukemia cells and radical scavenging activities of these compounds in bonding together as ester compounds. Four hydroxypyrone containing-2-pyrazinoic esters along with hydroquinone containing-one were synthesized and characterized by spectral data. The cytotoxicity of these compounds on K562 human leukemia cells and free Radical scavenging activities were evaluated. The K562 cells were treated with various concentrations of each compound for a different time and cell viabilities were determined by MTT viability assay. It was observed that all compounds decreased the viability of the human leukemia K562 cells in a dose- and time-dependent manner. Hydroquinone pyrazinoate 4a with an IC50 value of 50±8.0 μM was the most active compound against the K562 cells. The compounds 4b and 4e showed higher cytotoxicity on K562 cells respectively after 72 h. Antioxidant activities of the compounds were evaluated by DPPH free radical scavenging assay. Hydroquinone ester 4a showed higher activity with an IC50 value of 0.82 mM than those of hydroxypyrone derivatives of which maltol pyrazinoate 4e showed the highest inhibition with IC50 value of 4.7 mM. Although free hydroxyl group of kojic acid was masked by ester group, 4b and 4e showed significant scavenging activities, as the same result was observed in the case of hydroquinone ester.