title: 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.
authors.affiliation: Centre for Potential in Genomic Science, School of Biological Sciences, Madurai Kamaraj University, Madurai, Tamil Nadu, India.
authors.forename: Bibbin Tom
authors.initials: BT
authors.lastname: Paul
authors.forename: Anamika
authors.initials: A
authors.lastname: Patel
authors.forename: Govindan Sadasivam
authors.initials: GS
authors.lastname: Selvam
authors.forename: Sandhya
authors.initials: S
authors.lastname: Mishra
authors.forename: Pushpita Kumar
authors.initials: PK
authors.lastname: Ghosh
authors.forename: Ramachandran
authors.initials: R
authors.lastname: Murugesan
mesh_terms: D001671:Biochemistry / Q000379:methods; D000458:Cyanobacteria / Q000378:metabolism*; D003497:Cyclic N-Oxides / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation* / Q000379:methods; D005609:Free Radicals; D008027:Light; D008954:Models, Biological; D008956:Models, Chemical; D010798:Phycocyanin / Q000737:chemistry*; D010879:Piperazines / Q000494:pharmacology; D017382:Reactive Oxygen Species; D013113:Spin Labels; D019097:Spin Trapping / Q000379:methods*; D013481:Superoxides; D013997:Time Factors
chemical_list: D003497:Cyclic N-Oxides; D005609:Free Radicals; D010879:Piperazines; D017382:Reactive Oxygen Species; D013113:Spin Labels; D010798:Phycocyanin; D013481:Superoxides; C001803:tempol; C007306:triethylenediamine