title: Scavenging of peroxynitrite by phycocyanin and phycocyanobilin from Spirulina platensis: protection against oxidative damage to DNA.
abstract: 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.
authors.affiliation: Chemical Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India [corrected].
authors.forename: V B
authors.initials: VB
authors.lastname: Bhat
authors.forename: K M
authors.initials: KM
authors.lastname: Madyastha
mesh_terms: D000458:Cyanobacteria / Q000737:chemistry; D004249:DNA Damage; D004278:DNA, Superhelical / Q000737:chemistry* / Q000187:drug effects; D016166:Free Radical Scavengers / Q000737:chemistry* / Q000494:pharmacology; D007700:Kinetics; D009566:Nitrates / Q000737:chemistry* / Q000494:pharmacology; D052980:Phycobilins; D010798:Phycocyanin / Q000737:chemistry* / Q000494:pharmacology; D010957:Plasmids / Q000737:chemistry* / Q000187:drug effects; D011758:Pyrroles / Q000737:chemistry* / Q000494:pharmacology; D013053:Spectrophotometry; D045725:Tetrapyrroles
chemical_list: D004278:DNA, Superhelical; D016166:Free Radical Scavengers; D009566:Nitrates; D052980:Phycobilins; D011758:Pyrroles; D045725:Tetrapyrroles; D010798:Phycocyanin; C039642:peroxynitric acid; C011069:phycocyanobilin