The Antioxidant and Free Radical Scavenging Activities of Chlorophylls and Pheophytins

Abstract

Chlorophylls are important antioxidants found in foods. We explored the mechanisms through which the a and b forms of chlorophyll and of pheophytin (the Mg-chelated form of chlorophyll) reduce oxidation: we used comet assay to measure prevention of H2O2 DNA damage; we tested for quenching of 1,1-diphenyl-2-picrylhydrazyl (DPPH); we measured the ability to chelate Fe(II); and, we tested their ability to prevent formation of thiobarbituric acid reactive substances (TBARS) during Cu-mediated peroxidation of low density lipoprotein (LDL) in a chemical assay. All chlorophylls and pheophytins showed significant dose-dependent activity in the assays, with the pheophytins being the strongest antioxidants. Thus, these chemicals can prevent oxidative DNA damage and lipid peroxidation both by reduc- ing reactive oxygen species, such as DPPH, and by chelation of metal ions, such as Fe(II), which can form reactive oxy- gen species.