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.