Scavenging of peroxynitrite by phycocyanin and phycocyanobilin from Spirulina platensis: protection against oxidative damage to DNA

Biochem Biophys Res Commun. 2001 Jul 13;285(2):262-6. doi: 10.1006/bbrc.2001.5195.


Peroxynitrite (ONOO(-)) is known to inactivate important cellular targets and also mediate oxidative damage in DNA. The present study has demonstrated that phycocyanin, a biliprotein from spirulina platensis and its chromophore, phycocyanobilin (PCB), efficiently scavenge ONOO(-), a potent physiological inorganic toxin. Scavenging of ONOO(-) by phycocyanin and PCB was established by studying their interaction with ONOO(-) and quantified by using competition kinetics of pyrogallol red bleaching assay. The relative antioxidant ratio and IC(50) value clearly indicate that phycocyanin is a more efficient ONOO(-) scavenger than PCB. The present study has also shown that PCB significantly inhibits the ONOO(-)-mediated single-strand breaks in supercoiled plasmid DNA in a dose-dependent manner with an IC(50) value of 2.9 +/- 0.6 microM. These results suggest that phycocyanin, has the ability to inhibit the ONOO(-)-mediated deleterious biological effects and hence has the potential to be used as a therapeutic agent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cyanobacteria / chemistry
  • DNA Damage*
  • DNA, Superhelical / chemistry*
  • DNA, Superhelical / drug effects
  • Free Radical Scavengers / chemistry*
  • Free Radical Scavengers / pharmacology
  • Kinetics
  • Nitrates / chemistry*
  • Nitrates / pharmacology
  • Phycobilins
  • Phycocyanin / chemistry*
  • Phycocyanin / pharmacology
  • Plasmids / chemistry*
  • Plasmids / drug effects
  • Pyrroles / chemistry*
  • Pyrroles / pharmacology
  • Spectrophotometry
  • Tetrapyrroles


  • DNA, Superhelical
  • Free Radical Scavengers
  • Nitrates
  • Phycobilins
  • Pyrroles
  • Tetrapyrroles
  • Phycocyanin
  • peroxynitric acid
  • phycocyanobilin