Photodynamic activity

Another approach aiming at the mechanism of the primary photoreaction was undertaken by Lang-Feulner and Rau107). They incubated mycelia of Fusarium in photodynamically active (methylene blue, toluidine blue, neutral red) or inactive... 

Scheme 2. Molecular structures of some photodynamically active and inactive dyes which have been employed as potential (artificial) bluelight photoreceptors...

A second example has been addressed in which the synthesis and potential application of a series of neutral O-glycosylated porphyrin dimers and two original O-glycosyl cationic dimers were examined in PDT. In order to understand the influence of the number of glycosyl moieties, the spatial geometry and the ionic character on their photodynamic activity was evaluated.144 The in vitro results... 

X. Chen, L. Hui, D. A. Foster, and C. M. Drain, Efficient synthesis and photodynamic activity of porphyrin-saccharide conjugates Targeting and incapacitating cancer cells, Biochemistry, 43 (2004) 10918-10929. 

Several other metal complexes have promising photodynamic activity and are currently under development (248). Metalloporphyrins inhibit the enzyme heme oxygenase for example, chromium porphyrin and mesoporphyrin are potent inhibitors of heme oxygenase both in vitro and in vivo (249, 250) and are being used for the treatment of the neonatal jaundice. 

Alvarez MG, Prucca C, Milanesio ME, Durantini EN, Rivarola V (2006) Photodynamic activity of a new sensitizer derived from porphyrin-C60 dyad and its biological consequences in a human carcinoma cell line. Int J Biochem Cell Biol 38 2092-2101. 

In particular for fullerenes, antioxidant properties and photodynamic activity are presented in detail, together with the analysis of gadolinium endohedrals as magnetic resonance imaging (MRI) contrast agents. Moreover, drag delivery based on carbon nanomaterials has been illustrated. 

Compared to other classes of dyes, few attempts have been made to establish photosensitizing dyes as pure diagnostic agents, as in this context two major drawbacks of these compounds appeared (i) the strong photodynamic activity and sometimes prolonged persistence of photosensitivity in several organs, particularly the skin, which is regarded as a potential safety concern, and (ii) the... 

The experiments presented above definitively established the fact the Lipson s HPD-forming procedure gives dimeric and trimeric porphyrin esters as the high-molecular weight component which is eminently better localized and retained in tumor cells and is responsible for most of the photodynamic activity associated with HPD. Mechanistically, the formation of ester linkage is not only understandable but expected as well. Under the alkaline condition employed in the synthesis of HPD, the nucleophilic substitution reaction illustrated in the following scheme is very similar to the... 

The localization of the sensitizer has a significant effect on the photodynamic activity. Eosin is scarcely taken up by cells, and Pooler and Girotti [131] report that Eosin isothiocyanate is 50-100 times more efficient for inducing photohemolysis of human erythrocytes. The spectral properties and quantum yields for singlet oxygen production are identical for both compounds. Therefore, they attribute the difference in photodynamic activity to the ability of the isothiocyanate derivative to bind covalently to band 3 protein. 

The pentacyclic thioxanthylium salt 624 absorbs at 582 nm (emax 105 000 M-1 cm-1) with a fluorescence emission maximum at 600 nm. The dye displays photodynamic activity in vitro against chemosensitive hamster ovary cell lines (Equation 207) <2006BMC8635>. 

Janczyk A, Wolnicka-Glubisz A, Urban ska K, Kisch H, Stochel G, Macyk W. Photodynamic activity of platinum(IV)-chloride surface modified Ti02 irradiated with visible light. Free Rad Biol Med 2008 44 1120-30. 

Sterilisation of blood products and other organ transplant tissues opens another area for photodynamic effect applications. Photodynamic activity of some inorganic sensitizers together with their photocatalytic activity can be very useful in water, air, and surface detoxification (see Chapter 21). APDT can be a new approach for safe food. The reduction of several Gram-positive bacteria and yeasts has been observed in tests with visible light and haematoporphyrin or chlorophylls (natural constituents of food) as photosensitizers [54],... 

Mantareva V, Kussovski V, Angelov I, et al. Photodynamic activity of water-soluble phthalocyanine zinc(II) complexes against pathogenic microorganisms. Bioorgan Med Chem 2007 15 4829-35. 

Fundamentals of heterogeneous photocatalysis have been described in Chapter 7. The photodynamic activity of Ti02 (based on its photocatalytic activity and high efficiency in ROS generation) can find applications in photodynamic therapy (PDT) and photodynamic inactivation of microorganisms (PDI), described in Chapters 17 and 18, respectively. Selected environmental aspects of heterogeneous photocatalysis are described below. 

Mucsi et al. [78] reported that trifluoperazine, chlorpromazine, and promethazine were effective against herpes simplex virus. Certain benzo[a]-phenothiazines also produced identical results against herpes virus [78]. Some structurally related phenothiazines exhibited photodynamic activity against the pseudorabies virus [33]. The inhibitory effect of the phenothiazines was investigated on the multiplication of several viruses. 

Related systems to the naphthazarines are perylenequinones 33, which are biologically active pigments obtainable from natural sources. These compounds are of interest not only because of their peculiar structure features, but also owing to their photodynamic activity. 

S.S. Epstein (1963). The photodynamic activity of polycyclic hydrocarbons carcinogens. Acta Unio Int. Cancrum, 19, 599-601. 

Rose bengal is not toxic to animals in doses of 5 mg/kg, which is 2-3 times the usual dose. Severe reactions have not been reported. However, rose bengal, like other triphenylmethane dyes, exhibits photodynamic activity (S9), so that patients receiving it may show photosensitivity and blood containing it may undergo some hemolysis when exposed to sunlight. 

Certain other porphyrins have shown improved in vivo photodynamic activity over Hpd and Photofrin, for example, the meso-tetra(hydroxyphenyl) porphyrin examined by Berenbaum et al. (Figure 19). The meta derivative was some 25-30 times more potent (in terms of comparative tumoricidal doses) than Hpd in an in vivo mouse tumor with apparently less skin photosensitivity [56]. 

Konig, K., Felsmann, A., Dietel, W., and Boschmann, M. (1990) Photodynamic activity of HPD-photoproducts, Studia Biophysica, 138 219-228. 

Hypocrellin A (75), dark red pigment with photodynamic activity toward microorganisms, was isolated from Hypocrella bambusae (Chen et al., 1981). Its analog hypocrellin B (76) was found later from the same species (Zhang et al., 1989). 

---