Photodynamic action

Photooxidation and photodynamic action. To convert kj to kcal/mol, divide by 4.184. 

Flavins (152), benzoamielated derivatives of lumazine (145), are implicated in a variety of photobiological processes such as photodynamic action, phototropism, phototaxis, and photosynthesis. The biologically active H form 152a of alloxazine (R = R = R = = H) is less stable in... 

CHL + —> photosynthesis or CHL triplet-excited state intersystem crossing 3CHL + 3O2 CHL -F Ozor 3CHL + CAR CHL -F CAR CAR iCAR —F harmless decay O2 -F CAR CARO2 CAR can be regenerated or O2 + AA O2 photodynamic action... 

Anwar, M., T. H. Khan, J. Prebble, and R F. Zagalsky. 1977. Membrane-bound carotenoid in Micrococcus luteus protects naphthoquinone from photodynamic action. Nature 270 538-540. 

Photodynamic therapy is based on a phenomenon known as photodynamic action, or the photodynamic effect, which are terms used to describe the damage to living tissue caused by certain photosensitizers in the presence of visible light and oxygen. Again, there is an extensive historical record, which has been reviewed several times during the 1990s.4,9-15... 

Blum, H. F. Photodynamic Action and Diseases Caused by Light, American Chemical Society Monograph Series No. 85 Reinhold New York, 1941. 

In other cases fullerene antibacterial action takes place after photoirradiation of fulleropyrrolidinium salts. It is not yet clear if the photodynamic action implies the participation of superoxide and hydroxyl radicals (type I mechanism) or singlet oxygen (type II mechanism) but the efficacy is really interesting with the death of more than 99.9% of bacterial and fungal cells and a special selectivity for microbes over mammalian cells (Tegos et al., 2005). Also a sulfobutyl fullerene derivative is able to inhibit environmental bacteria after photoirradiation and it exerts its action on E. coli even if incorporated in coated polymer (Yu et al., 2005). 

Fig. 7.3 Photodynamic action of fullerene C60 on cells MA-104, grown on fullerene on the surfaces (FoS) (10 ig/cm2 C60). Black columns - in the darkness grey - under illumination...

KeUey, E. E., Buettner, G. R., and Bums, C. P., 1997, Production ofhpid-derived free radicals in L1210 murine leukemia cells is an early oxidative event in the photodynamic action of Hiotofrin, Photochem. Photobiol. 65 576-580. 

Gerba, C. P., Wallis, C., and Melnick, J. L. (1977b). Disinfection of waste water by photodynamic action. J. Water Pollut. Control Fed. 49,575-583. 

Martin, D. F. and Perez-Cruet, M. 1. (1987). Preparation of sterile seawater through photodynamic action Preliminary screening studies. Fla. Sci. 50,168-176. 

The experiment thus described is an illustration of a very general phenomenon called photodynamic action.121 Photodynamic action is the photosensitized oxidation of a substrate. The substrate is usually an organic molecule, although not necessarily, and the sensitizer is usually a common dye absorbing in the visible region. Air or oxygen are usually, but not always,122 required. Photodynamic responses are found for substrates from the level of mammals to that of small molecules like... 

These reactions are clearly different from air-free photosensitization involving energy-transfer processes123 or electron-transfer processes (many of the dyes effective in photodynamic action can be photoreduced in air-free solution by inorganic reducing agents122). 

The photodynamic action of these dyes was first observed in terms of inactivation of biological activity, and of changes in the physical properties of polynucleotides. For example, the infectivity of viral RNA is destroyed by the photodynamic action of acridine orange129 and the transforming ability of DNA (see Glossary) is similarly destroyed by the similar action of a variety of dyes.130... 

The physical properties of DNA which are changed by photodynamic action are the melting point (Tm) (see Glossary) and the viscosity of the aqueous solution. The change in the melting point for irradiated DNA of various G + C contents can be correlated with the G + C content131 (Fig. 39) the slope of the line is about the same as... 

There is still much to be learned about photodynamic action. One of the most curious aspects is the photosensitized oxidation of DNA by various polynuclear hydrocarbons.128 Irradiation with visible light (108 ergs/mm2) of solutions of 6 mg of DNA, 2.5 mg of hydrocarbon, 3 ml of water, and 1 ml of acetone leads to a 70% preferential loss of guanine if the hydrocarbon is dibenzanthracene or 3-methylchol-anthrene, and of 40% of the adenine if the hydrocarbon is 3,4-benzpyrene. 

Besides DNA strand breaks, DNA-protein cross-links are also formed upon photodynamic action of chloroalbumine phthalocyanine (Ramakrishnan et al. 1988) and by a large variety of other photosensitizers (Villanueva et al. 1993). 

Rabow LE, Stubbe J, Kozarich JW (1990) Identification and quantitation of the lesion accompanying base release in bleomycin-mediated DNA degradation. J Am Chem Soc 112 3196-3203 Raleigh JA, Blackburn BJ (1978) Substrate conformation in 5 -AMP-utilizing enzymes 8,5 -cycloadenosine 5 -monophosphate. Biochem Biophys Res Commun 83 1061-1066 Ramakrishnan N, Clay ME, Xue L-Y, Evans El El, Rodriguez-Antunez A, Oleinick NL (1988) Induction of DNA-protein cross-links in Chinese hamster cells by photodynamic action of chloroaluminium phthalocyanine and visible light. Photochem Photobiol 48 297-303 Ramakrishnan N, Chiu S-M, Oleinick NL (2003) Yield of DNA-protein cross-links in y-irradiated Chinese hamster cells. Cancer Res 47 2032-2035... 

J.D. Spikes and R. Livingston, The molecular biology of photodynamic action sensitized photoautoxidations in biological systems, in L.G. Augenstein, R. Mason and M. Zelle (Eds.), Advances in Radiation Biology, Vol. 3, Academic Press, New York, 1969, pp. 29-110. 

Singlet-oxygen studies have being reported to such diverse areas as chemiluminescence [14], photocarcinogenity [15], ozonolysis [16], photodynamic action [17], peroxide decomposition [7], photosynthesis [14], air pollution [18], metallocatalyzed oxygenation reactions [19,20], synthetic applications [21], and polymer degradation [10]. 

Therrien et al. have developed organometallic ruthenium porphyrin compounds for anticancer photodynamic therapy. These combine synergistically the photodynamic action of porphyrins with the DNA damage-related cytotoxicity of Run-arene... 

Microbial cells exhibit a large variety of size, subcellular architecture, biochemical composition, and therefore also susceptibility to externally added chemical agents. Despite such a great diversity all types of microorganisms have been shown to be susceptible to photodynamic action, although specific demands on both photosensitizers and light characteristics have to be expected. 

Spikes, J.D., Livingstone, R. 1969. The molecular biology of photodynamic action sensitized photooxidations in biological systems. Adv. Radiat. Biol. 3, 28-121. 

T13. Timmins, G. S., and Davies, M. J., Conformational changes induced in bovine serum albumin by the photodynamic action of haematoporphyrin. J. Photochem. Photobiol. B 24, 117-122 (1994). 

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