Scavenging of reactive oxygen species by chlorophyllin: An ESR study

The antioxidant effects of chlorophyllin (CHL), a water-soluble analog of t he green plant pigment chlorophyll, on different reactive oxygen species (R OS) were investigated by electron spin resonance (ESR) spectroscopy As a st andard, we have used the ability of CHL to scavenge the stable 1,1-diphenyl -2-picrythydrazyl (DPPH) radical. CHL inhibits the formation of 5,5-dimethy l-1-pyrroline-N-oxide add act with hydroxyl radical (DMPO-(OH)-O-. adduct) generated by gamma -radiation in a dose-dependent manner. At a concentratio n of 1 mM, CHL caused more than 90% inhibition of ESR signal intensity of t his adduct. However, the results obtained with the Fenton reaction were dif ferent. We also found evidence for the inhibition of O-1(2)-dependent forma tion of the 2,2,6,6-tetramethyl-piperidine oxide (TEMPO) radical during pho tosensitization of methylene blue with visible light. CHL was also able to inhibit hydrogen peroxide induced oxidation of phenol red. The rate constan t of the reaction of CHL with H2O2 was found to be 2.7 x 10(6) M-1 s(-1). I n conclusion, CHL has potent antioxidant ability involving scavenging of va rious physiologically important ROS.