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Photodynamic action of C-phycocyanins obtained from marine and fresh water cyanobacterial cultures: a comparative study using EPR spin trapping technique.

Abstract
C-phycocyanins, major biliproteins of blue green algae (cyanobacteria), widely used as colourants in food and cosmetics are known for their antioxidant as well as therapeutic potential. Recent claims indicating phycobiliproteins exert stronger photodynamic action on tumor cells than clinically approved hematoporphyrin derivatives motivate us to investigate the photodynamic action of two newly isolated C-phycocyanins from Phormidium [PHR] and Lyngbya [LY] spp, respectively in comparison with known C-phycocyanin from Spirulina sp. [SPI]. Photolysis of air saturated solutions of PHR, LY and SPI in the presence of 2,2,6,6-Tetramethyl piperidinol (TEMPL) generated three line EPR spectrum characteristic of 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxyl (TEMPOL). The increase in intensity of the EPR spectrum with time of irradiation and decrease in intensity, in the presence of 1O2 quencher DABCO confirm the formation of 1O2. Photoirradiation in the presence of spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) generated EPR signal characteristic of O2(-) adduct. Efficiency of 1O2 generation is of the order LY > PHR> SPI. The yield of reactive oxygen species (ROS) generation is found to be 1O2>O2(-) indicating type II mechanism to be the prominent pathway for photosensitation by phycocyanins.
AuthorsBibbin Tom Paul, Anamika Patel, Govindan Sadasivam Selvam, Sandhya Mishra, Pushpita Kumar Ghosh, Ramachandran Murugesan
JournalFree radical research (Free Radic Res) Vol. 40 Issue 8 Pg. 821-5 (Aug 2006) ISSN: 1071-5762 [Print] England
PMID17015260 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
Chemical References
  • Cyclic N-Oxides
  • Free Radicals
  • Piperazines
  • Reactive Oxygen Species
  • Spin Labels
  • Phycocyanin
  • Superoxides
  • tempol
  • triethylenediamine
Topics
  • Biochemistry (methods)
  • Cyanobacteria (metabolism)
  • Cyclic N-Oxides (chemistry)
  • Electron Spin Resonance Spectroscopy (instrumentation, methods)
  • Free Radicals
  • Light
  • Models, Biological
  • Models, Chemical
  • Phycocyanin (chemistry)
  • Piperazines (pharmacology)
  • Reactive Oxygen Species
  • Spin Labels
  • Spin Trapping (methods)
  • Superoxides
  • Time Factors

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