Effect of Interaction between Protocatechualdehyde Produced from Streptomyces lincolnensis M-20 and Copper Ions on Antioxidant and Pro-oxidant Activities

Protocatechualdehyde (PA) is phenolic compound having antioxidative and antitumor activities. PA waspurified from supernatant of Streptomyces lincolnensis M-20. In the presence of copper ion, PA actedas pro-oxidant. The antioxidant activity was assessed with the 1,1-diphenyl-2-picrylhydrazyl (DPPH)assay, and the pro-oxidant effect of PA on DNA damage as pBR322 plasmid DNA-cleaving agents inthe presence of Cu(II) ions was investigated. The involvement of reactive oxygen species (ROS) in theDNA damage was confirmed by the inhibition of the DNA breakage by using glutathione (GSH),specific scavenger of ROS. When the increase in ROS reaches a certain level (the toxic threshold), itmay trigger cell death. The formation of the PA/Cu(II) chelate complex was confirmed by reactionwith ethylenediamine-tetraacetic acid (EDTA), a well-known chelating agent for metal ions, by usingUV/Vis spectroscopic analysis.