Methyl pyropheophorbide

It is interesting to note that the magnesium or zinc complexes of methyl pheophorbide a (11, M = Mg, Zn R = C02Me) or methyl pyropheophorbide a (11, M = Mg, Zn R = H) are cleaved between positions 20 and 1 by singlet oxygen, whereas in contrast nature cleaves the chlorin at the 4,5-C —C double bond.44-45a h46 The ring fission at the 4.5-C —C double bond can be achieved with the cadmium(II) complex of methyl pheophorbide (11, M = Cd R = C02Me) to produce 12.43i... 

Figure 20. Absorption (upper curve) and corrected fluorescence excitation (lower curve) spectra for carotenopyropheophorbide 27 in toluene. The spectra have been normalized over the 6(X)-630 nm region. The excitation spectrum is virtually identical in shape to the absorption spectrum of methyl pyropheophorbide-a, and singlet-singlet energy transfer from the carotenoid to the tetrapyrrole is therefore minimal (<7%).

PENNINGTON F c, STRAIN H H, SVEC w A and KATZ J J (1964), Preparation and properties of pyrochlorophyll a, methyl pyrochlorophyllide a, pyropheophytin a, and methyl pyropheophorbide a derived from chlorophyll by decarbomethoxylation , J Am Chem Soc, 86, 1418-1426. 

Figure 9. AB spectra of methyl pyropheophorbide a ring V CHt group. Splittings observed at 300 and 600 MHz are —19.92 and —19.25 Hz, respectively.

Chlorins 10 (Figure 10.2) were prepared using a similar route, from methyl pyropheophorbide-a (a chlorophyll-a derivative) by functionalization of the vinyl group using various alcohols ROH (R = methyl, propyl, pentyl, heptyl, nonyl), followed by cleavage of the ester group, activation with oxalyl chloride, and reaction with the tetramethylammonium salt of Chlorins 10... 

Pennington, F.C., Strain, H.H., Svec, W.A., and Katz, J.J., Preparation and properties of pyrochlo-rophyll a, methyl-pyrochlorophyUide a, pyropheophytin a and methyl-pyropheophorbide a derived from dhlorophyll by decarbomethoxylation,/. Amer. Chem. Soc., 86,1418, 1964. 

Methyl ester of meso-pyropheophorbide 6 Methyl ester of meso-pyropheophorbide 6-3-methanol (15 minutes) i-CjH7(CJ 22. ... 

Methyl ester of 9-hy-droxydesoxo-meso-pyropheophorbide b- -methanol (2 to 4 hours) i-CsH7(C) 22... 

In order to compare the photophysical and biological properties of all the pyropheophorbide sugar derivatives the methyl ester derivatives 264 and 265 were also prepared by treatment with the corresponding acids with 3% sulfuric acid in methanol. The initial results obtained with these amphiphihc conjugates 262-265 showed a tendency to aggregate in aqueous and aque-ous/ethanolic solutions [169]. 

The formation of 17-alkylamide analogues of purpurin imide from the corresponding methyl ester affords a simple approach for the preparation of photosensitizers with additional lipophilic characteristic for optimizing the PDT efficacy of the parent molecule. Such modification of the pyropheophorbide analogues has induced significant... 

So far, chlorin-type photosensitizers derived from various porphyrins and from pyropheophorbide a or purpurin-18 methyl ester have been discussed. These sensitizers have a strong absorption near 700 nm, which almost doubles the tissue-penetration distance of the incident light compared with Photofrin (630 nm). However, an ideal sensitizer should absorb light at or near 800 nm, not only because of its deeper tissue penetration, but also due to the availability of cheaper diode lasers for sensitizer excitation. 

Thirty-nine chlorophyll transformation products were separated on a C g colunw (. = 400nm) using a 40-min gradient from 90/10 methanol/water to 90/5/5 acetone/methanol/wato- [457]. Positive identification of methylated compounds within fiactions was made by thermospray MS. Pheophoibide a methyl ester, zeaxanthin, pyropheophorbide a methyl ester, isorenieratene, pheophytin a and b and pyiopheoph5 in a and b were confirmed. 

Matroule, J.Y., Bonizzi, G., Morhere, R, PaiUous, N., Santus, R., Bours, V., and Piette, J., Pyropheophorbide-a methyl ester-mediated photosensitization activates transcription factor NFkB through the interleukin-1 receptor-dependent signaling pathway,/. Biol Chem., 270,2899,1999. Legrand-Poels, S., Schoonbroodts, S., Matroule, J.Y., and Piette, J., NF-kB an important transcription factor in photobiology, /. Photochem. Photohiol B, 45,1,1998. 

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