Photobilin e. Photooxidation von bacteriochlorophyll-e-derivaten

Risch, Nikolaus; Schormann, Anette; Brockmann, Hans

doi:10.1016/s0040-4039(01)81741-x

Cited by 20 publications

(6 citation statements)

References 6 publications

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“…Currently, the nonabsorbing second class requires further investigation, but the spectra of the first weakly absorbing class are reminiscent of linear open chain tetrapyrroles. Indeed, linear tetrapyrrolic bilins, derived from ring‐opening at C‐20, have been identified as photoproducts of BChls c and e , which are, however, chlorins (17,18‐dihydroporphyrins) rather than bacteriochlorins (7,8,17,18‐tetrahydroporphyrins) (23–25,50). BChls c and e also have a methyl substituent at C‐20, which seems to facilitate this photochemical ring opening at C‐20 because C‐20—substituted Chl a derivatives have also been shown to yield bilins (24), and in all such cases, the oxidative ring opening always occurred at C‐20.…”

Section: Discussionmentioning

confidence: 99%

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Photostability of Bacteriochlorophyll a and Derivatives: Potential Sensitizers for Photodynamic Tumor Therapy

Limantara

Koehler

Wilhelm

et al. 2006

Photochem & Photobiology

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The photostabilities of bacteriochlorophyll a and several of its derivatives, which are of interest as potential sensitizers in photodynamic tumor therapy, were investigated. The pigments were irradiated with light >630 nm in organic solvents (acetone, tetrahydrofuran, pyridine, methanol, ethanol, n-propanol, 2-propanol and toluene) and in aqueous detergent solutions (cetyl-trimethyl-ammonium bromide [CTAB], lauryldimethyl-aminoxide [LDAO] or sodium dodecyl-sulfate [SDS] and Triton X-100 [TX100]). Their stabilities in these different solvents were determined in the presence and absence of an external sensitizer (pyromethyl-pheophorbide a), oxygen, sodium ascorbate and inert gas (Ar) or vacuum. The photodegradation products of bacteriochlorophyll a in acetone solution were isolated, purified by HPLC and analyzed by their absorption spectra and mass spectroscopy. Besides the well-known dehydrogenation products, such as [3-acetyl]-chlorophyll a, which were obtained as by-products, the major products had low absorption in the visible-near infrared spectral range. The spectral signature of the major component of these products was characteristic of linear open-chain tetrapyrroles, but they lacked the characteristic protonation-deprotonation behavior and reactivity of bilins with Zn(++).

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Section: Discussionmentioning

confidence: 99%

“…1, Formula 2). Photochemical ring-opening at C-20 has (23)(24)(25); the latter, however, are not bacteriochlorins (see Fig. 1, Formula l), but chlorins (see Fig.…”

Section: Introductionmentioning

confidence: 99%

Photostability of Bacteriochlorophyll a and Derivatives: Potential Sensitizers for Photodynamic Tumor Therapy

Limantara

Koehler

Wilhelm

et al. 2006

Photochem & Photobiology

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“…Thus, trans-octaethyl-2,3-dihydrobiliverdin (37) has been obtained in 25% yield from both trans-octaethylchlorin (36) and its zinc complex." Under the same conditions, porphyrins yield the corresponding thallium(III) chelates.?"…”

Section: Oxidation Of Porphyrin Chelates or Chlorins With Thallium(llmentioning

confidence: 97%

Synthesis of Bilins

Gossauer

2003

The Porphyrin Handbook

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“…In the 20-chlorinated pigments, the Mg-complexes are the reactive species, and the metal-free pheophorbides are unreactive; the situation is just opposite in the 20-methylated-pigments. Here, the pheophorbides react smoothly, but not the chlorophylls (Mg-complexes) (Brockmann et al, 1979;Brown et a[., 1980;Risch et al, 1984). These different reactivities indicate subtle substituent effects, which may be related to the differences observed in Raman spectra of C-20 substituted chlorophylls (T. M. Cotton, private communication, 1989).…”

Section: Oh %Ycylmentioning

confidence: 98%