Photosensitiser

Trioxsalen (2,5,9-trimethyl-7H-furo[3,2-g]benzopyran-7-one) [3902-71-4] M 228.3, m 233-235 , 234.5-235 . Purified by recrystn from CHCI3. If too impure it is fractionally crystd from CHCl3-pet ether (b 30-60°) using Norit and finally crystd from CHCI3 alone to give colourless prisms, m 234.5-235°. It is a photosensitiser so it should be stored in the dark. [UV Kaufmann J Org Chem 26 117 1961-, Baeme et al. J Chem Soc 2976 1949.]... 

Kanofsky, JR and Sima, PD, 2006. Synthetic carotenoid derivatives prevent photosensitised killing of retinal pigment epithelial cells more effectively than lutein. Exp Eye Res 82, 907-914. 

Distillation to small volume of a small sample of a 4-year-old mixture of the alcohol with 0.5% of the ketone led to a violent explosion, and the presence of peroxides was subsequently confirmed [1]. Pure alcohols which can form stable radicals (secondary branched structures) may slowly peroxidise to a limited extent under normal storage conditions (isopropanol to 0.0015 M in brown bottle, subdued light during 6 months to 0.0009 M in dark during 5 years) [2], The presence of ketones markedly increases the possibility of peroxidation by sensitising photochemical oxidation of the alcohol. Acetone (produced during autoxidation of isopropanol) is not a good sensitiser, but the presence of even traces of 2-butanone in isopropanol would be expected to accelerate markedly peroxidation of the latter. Treatment of any mixture or old sample of a secondary alcohol with tin(II) chloride and then lime before distillation is recommended [3], The product of photosensitised oxidation is 2-hydroperoxy-2-propanol [4]. 

Otherwise there are sporadic references to bioactive compounds with potential value as therapeutic agents, but any systematic study of the latter property appears in most cases to be lacking and certain other individual compounds have been noted as having possible uses, for example, as photosensitisers (compound 145), photochromic materials (compound 63), or as chemiluminescent agents (compound 360). 

Suggested Alternatives for Differential Diagnosis Foot-and-mouth disease, vesicular stomatitis, peste des petits ruminants, photosensitisation, nasal botfly infestation, pneumonia, akabane infection, epizootic hemorrhagic disease of deer, contagious ecthyma, polyarthritis, footrot, foot abscesses, plant poisonings, and coenurosis. 

Porphyrin dimers were also considered as photosensitisers and evaluated for PDT cancer treatment.53,54 The corresponding preparation involves porphyrinic precursors which can be prepared by following the Lindsey methodology.27,28 Thus, once those precursors have been prepared, several O-glycosylporphyrin dimers were synthesised.55 58... 

Several research groups probably inspired by both the attractive features of PDT and the commercialization of Photofrin and Visudyne , have put considerable effort on the development and study of the so-called second generation photosensitisers. 

Based on biological results, a series of carbohydrate-photosensitiser conjugates in position 3 was prepared and biologically evaluated.68... 

The derivative 90 was obtained by condensation of the purpurin-18-A-hexylimide-17-propionic acid with aminolactose heptaacetate in the presence of benzotriazol-l-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) followed by the deacetylation procedure. The lactose-photosensitiser conjugate linked by an ethylene moiety was also prepared by following a similar approach. The purpurin-18-methyl ester 81 was converted into /V-(3-iodobenzyl)/ /evo-purpurin-18-7V-hexylimide-17-propionic ester by hydrogenation over Pd/C followed by reaction with 3-iodo-benzylamine. Afterwards, the propargyllactose heptaacetate reacted with A-(3-iodobenzyl)rMeio-purpurin-18-A-hexylimide-l 7-propionic ester in the presence of tris(dibenzylidieneacetone)dipalladium(0) (Pd2-dba3) which, after deacetylation conditions, afforded the derivative 89 (Fig. 9).68... 

Since glycosylated derivatives of this porphyrin core have been shown to be effective photosensitisers, inducing necrosis and/or apoptosis in several cancer cell lines, Drain s group used TPPF20 as a core platform to efficiently generate a variety of solution-phase combinatorial libraries.83 This... 

The photodynamic effect on red blood cells of the /xara-tetraglucosyl-porphyrin 31a and its analogous with the sugar unit in orto position has also been analysed. Considering the possibility of the photosensitiser causing hemolysis, this study became crucial.29 The two symmetric derivatives have proved to be ineffective in these cells. However, the asymmetric derivatives 49B and 50B are phototoxic and changes in hematological parameters were observed.29... 

Blais et al. prepared tri- and tetra-meta-glucosylated chlorin derivatives.77 The aim was to assess how the sugar units linked to chlorin derivatives affect the photoactivity, cell internalization and subcellular localization in HT29 human adenocarcinoma cells. This was compared with the action due to meso-tetrakis(m-hydroxyphenyl)chlorin, a compound being formulated as photosensitiser (Foscan ) for palliative treatment of head and neck cancers. 

The tetrakis(thioglycosyl) 128a and 129a derivatives can act as potent photosensitisers in their potential medicinal applications, this being due to their important photophysical properties.80... 

The kinetics of neither the photochemical nor the thermal decomposition of this compound have received much attention. Bodenstein et al.53 in 1937 showed that the hydrogen and fluorine reaction could not be photosensitised by chlorine at room temperature. 

Understand the principles behind the use of photosensitised processes and relate these to the use of sensitised reactions in organic photochemistry and photodynamic therapy. 

Since the excited-state donor molecules are initially produced by photoexcitation and the energy is transferred to A, energy transfer is also referred to as the photosensitisation of A or the quenching of D. ... 

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