Porphyrins photodynamic therapy

LDMS is particularly well suited for the analysis of porphyrins.35-39 The heme molecule—a 22 rc-electron conjugated protoporphyrin system (Figure 8.1)—is an efficient photo-absorber in the visible and near UV (with an absorption maximum—the Soret band—near 400nm). This feature, concurrently with its low ionization potential, warrants that direct LDMS will possess extremely low limits for heme detection. The uses of IR or UV LDMS for structural characterization of natural porphyrins and their metabolites, synthetic monomeric porphyrins (e.g., used in photodynamic therapy), porphyrin polymers, and multimeric arrays, have been well documented.41148 In addition fast atom bombardment MS has been used to characterize purified hemozoin, isolated from the spleens and livers of Plasmodium yoelii infected mice.49... 

Given stringent requirements for effective sensitizers and the desire to use wavelengths further to the red for therapeutic appHcations, definition of newer sensitizers has been a principal area of research since about 1987. Expanded theoretical and experimental understanding of photophysics has been a key element in identifying new classes of potential sensitizers (93—98). Research has focused on cationic derivatives of Nile Blue (93), metaHo-phthalocyanines (94), naphthalocyanines (95), chlorin-type compounds (96), expanded ring porphyrinoids (97), as well as porphyrins other than hematoporphyrin and its derivatives (98). This work has also been reviewed (10,91). Instmmentation for photodynamic therapy has been reviewed (99). 

Porphyrin-based photosensitizers for use in photodynamic therapy 98T4151. 

Porphyrins, modified natural chlorophylls, chlorins, phthalocyanins, xanthenes, phenothiazine, and phenoxazine dyes as new sensitizers for photodynamic therapy 98MI50, 98MI51, 98MI52, 98MI53. 

Nitro ilkenes derived from galdctose or other carbohydrates are converted directly into pyrroles siibsdnited v/ith such carbohydrates at the fi-posidon. They are important precursors for water-soluble porphyrins fEq. 10.29. Such kmds of porphyrins are good candidates for photodynamic therapy of cancer and have been extensively snithed. 

Miller, JW, Walsh, AW, Kramer, M, Hasan, T, Michaud, N, Flotte, TJ, Haimovici, R, and Gragoudas, ES, 1995. Photodynamic therapy of experimental choroidal neovascularization using lipoprotein-delivered benzo-porphyrin. Arch Ophthalmol 113, 810-818. 

Over the past 20 years, the principal biomedical application for (free or metal-substituted) porphyrins has been Photodynamic Therapy (PDT), with extensive literature in the area including a number of comprehensive reviews (114-116). Porphyrins offer scope for optical imaging as they are potent fluorophores in the red region of the electromagnetic spectrum. Although, to date, the emphasis has been on their therapeutic effects, due to their... 

MRI contrast agents. Therefore the possibility of combined diagnostic imaging and photodynamic therapy arises (324). Lanthanide texaphy-rin complexes are more kinetically stable than the porphyrin analogs. 

R. K. Pandey and G. Zheng, Porphyrins as Photosensitizers in Photodynamic Therapy, Academic Press, San Diego, 2000. 

Porphyrins 21 are the backbone of major players in life cycles—cytochromes (Scheme 8). There are three types of cytochromes, classified by their color, or more precisely by their long-wavelength absorption band, as a (600 mn), b (563 nm), and c (550 nm). They are protein conjugates of a porphyrin complex with iron(II), which is a coenzyme called heme (22). In plants, porphyrins form a complex with magnesium-(II) chlorophylls a and b (23), vital in photosynthesis. Porphyrin derivatives are used in photodynamic therapy for dermatological diseases such as psoriasis, and for skin or subcutaneous cancer.5c-e... 

In the photodynamic therapy of cancer, for example, macrocyclic tetrapyrrholic compounds named porphyrins are used. Porphyrin-containing wastewaters can negatively affect the aquatic ecosystems (plants and fish population), even in very small concentrations. Recent studies present a method adequate for the advanced purification of medical wastewaters containing such porphyrins [94],... 

Porphyrins and related structures have long been used in photodynamic therapy (PDT). In PDT, the photo-induced production of singlet oxygen is the toxifying... 

Photodynamic therapy for the treatment of tumours involves the selective uptake and retention of a highly-coloured porphyrin sensitiser (Figure 6.17) in the tumour. Irradiation by a laser with a wavelength corresponding to the absorption maximum of the porphyrin (D) causes excitation of the porphyrin to the excited singlet state. 

Milanesio ME, Alvarez MG, Rivarola V, Silber JJ, Durantini EN (2005) Porphyrin-fullerene C60 dyads with high ability to form photoinduced charge-separated state as novel sensitizers for photodynamic therapy. Photochem Photobiol 81 891-897. 

Bonnett R (1995) Photosensitizers of the porphyrin and phthalocyanine series for photodynamic therapy. Chem Soc Rev 24 19... 

Tetrapyrroles contain an extended jt-conjugated system which is responsible for their use in a wide range of applications ranging from technical (pigments, catalysts, photoconductors) to medicinal (photodynamic therapy) uses. The electronic absorption spectra are governed by the aromatic 18 tt-electron system and typically consist of two main bands. In phthalocyanines the Q band around 660-680 nm is the most intense one accompanied by a weaker Soret band near 340 nm . In porphyrins the situation is reversed with an... 

The porphyrin photodynamic precursor, (I), was prepared by Love et al. (1) and oligomerized and used in photodynamic therapy. 

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