Quinolinic acid, α-picolinic acid, fusaric acid, and 2,6-pyridinedicarboxylic acid enhance the Fenton reaction in phosphate buffer

Abstract

Quinolinic acid, α-picolinic acid, fusaric acid, and 2,6-pyridinedicarboxylic acid enhanced the Fenton reaction in phosphate buffer, respectively. The enhancement by quinolinic acid, α-picolinic acid, fusaric acid, and 2,6-pyridinedicarboxylic acid of the Fenton reaction may be partly related to their respective actions in the biological systems such as a neurotoxic effect (quinolinic acid), a marked growth-inhibitory action on rice seeding (α-picolinic acid and fusaric acid), and an antiseptic (2,6-pyridinedicarboxylic acid). The ultraviolet–visible absorption spectrum of the mixture of α-picolinic acid with ferrous ion showed a characteristic visible absorbance band with a λ max at 443 nm, suggesting that α-picolinic acid chelate of Fe 2+ ion forms in the solution. Similar characteristic visible absorbance band was also observed for the mixture of Fe 2+ ion with quinolinic acid (or fusaric acid, or 2,6-pyridinedicarboxylic acid). The chelation seems to be related to the enhancement by quinolinic acid, α-picolinic acid, fusaric acid, and 2,6-pyridinedicarboxylic acid of the Fenton reaction. α-Picolinic acid was reported to be a toxic substance isolated from the culture liquids of blast mould ( Piricularia oryzae CAVARA). On the other hand, it has also been known that chlorogenic acid protects rice plants from the blast disease. The chlorogenic acid inhibited the formation of the hydroxyl radical in the reaction mixture of α-picolinic acid, FeSO 4(NH 4) 2SO 4, and H 2O 2. Thus the inhibition may be a possible mechanism of the protective action of the chlorogenic acid against the blast disease.