Studies on porphyrin photoproducts in solution, cells, and tumor tissue

Koenig, Karsten; Schneckenburger, Herbert; Rueck, Angelika C.; Koenig, Roland

doi:10.1117/12.179988

Cited by 4 publications

(4 citation statements)

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“…The mechanism of the formation of photoproducts is unclear. While it was proposed that the photoproducts from PpIX are formed via photooxidation (19), some evidence shows that photoproduct formation is different in different media (16,29). Furthermore, photoproduct formation has been observed under conditions with a depleted oxygen concentration (28).…”

Section: Discussionmentioning

confidence: 99%

Phototransformations of 5-Aminolevulinic Acid-induced Protoporphyrin IX in vitro: A Spectroscopic Study¶

Bagdonas

Iani

et al. 2007

Photochemistry and Photobiology

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Human adenocarcinoma cells of the line WiDr were incubated with 5-aminolevulinic acid to induce protoporphyrin IX (PpIX) and then exposed to laser light of wavelength 635 nm. The PpIX fluorescence decreased with increasing exposure. The decay rate was slightly dependent on the initial PpIX concentration. The PpIX fluorescence was halved by a fluence of about 40 J/cm 2 . Several fluorescing photoproducts were formed. The main one, supposedly the chlorin-type photoprotoporphyrin (Ppp), had a fluorescence excitation spectrum stretching out to about 680 nm with a maximum at around 668 nm. The formation kinetics of this product was dependent on the initial PpIX concentration. Moreover, it was selectively bleached by exposure to light at 670 nm. A photoproduct with an emission maximum at 652 nm, different from Ppp, remained after this exposure. Traces of a photoproduct(s) with fluorescence emission slightly blueshifted compared with that of PpIX, supposedly watersoluble porphyrins, were also detected after light exposure. MATERIALS AND METHODSCell line. WiDr cells, derived from a primary human adenocarcinoma of the rectosigmoid colon, were used (a doubling period about

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Section: Discussionmentioning

confidence: 99%

Phototransformations of 5-Aminolevulinic Acid-induced Protoporphyrin IX in vitro: A Spectroscopic Study¶

Bagdonas

Iani

et al. 2007

Photochemistry and Photobiology

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“…16,30,31 Increased bleaching of PpIX and initial rate of Ppp formation are seen when PDT is performed in the presence of D 2 O, demonstrating enhanced singlet oxygen mediated Ppp formation. 16,26 This is clearly not the only mechanism of Ppp production, since large amounts of Ppp are produced under hypoxic conditions (Fig. 5a), for which the cell survival data (Fig.…”

Section: Photoprotoporphyrin (Ppp) Productionmentioning

confidence: 97%

“…Cellular localization appears to be an important factor for oxygen independent bleaching, as evidenced by the lack of bleaching observed for PpIX in solution in the absence of oxygen or in the presence of sodium azide, a known singlet oxygen quencher. 25,26 PpIX has been reported to photobleach during nitrogen flushing in vitro. 22 At high PpIX concentrations we found the rate of bleaching was greater under hypoxic than under well oxygenated conditions.…”

Section: Ppix Photobleachingmentioning

confidence: 99%

Photobleaching kinetics, photoproduct formation, and dose estimation during ALA induced PpIX PDT of MLL cells under well oxygenated and hypoxic conditions

Dysart

Patterson

2006

Photochem Photobiol Sci

101

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Fluorescence photobleaching and photoproduct formation were investigated during delta-aminolevulinic acid (ALA) induced protoporphyrin IX (PpIX) PDT of MLL cells in vitro. Cells were incubated in either 0.1 or 1.0 mM ALA for 4 h and were treated with 532 nm or 635 nm light under well oxygenated or hypoxic conditions. Fluorescence spectra were acquired during treatment. Photobleaching and photoproduct formation were quantified using singular value decomposition fitting of fluorescence spectra to experimentally determined basis spectra for PpIX, photoprotoporphyrin (Ppp), product II (peak at 655 nm), and product III (peak at 618 nm). PpIX photobleaching occurred under both normal and hypoxic conditions. The photobleaching kinetics could not be explained by purely first- or second-order photobleaching kinetics, and were attributed to differences in PpIX binding at the two ALA incubation concentrations. Ppp was the main photoproduct and accumulated in higher levels in the absence of oxygen, likely a result of reduced Ppp photobleaching under hypoxia. Increases in product II fluorescence occurred mainly in the presence of oxygen. To assess potential fluorescence based PDT dose metrics, cell viability was measured at select times during treatment using a colony formation assay. Cell survival correlated well to changes in product II fluorescence, independent of oxygenation, sensitizer concentration, and treatment wavelength, suggesting that this product is primarily a result of singlet oxygen mediated reactions and may potentially be useful to quantify singlet oxygen dose during PDT.

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“…Finally, we will remark that there is a controversy in the literature regarding the necessity of oxygen for the formation of PPp from PpIX: initially, it was proposed that PPp was formed from PpIX via photooxidation (32). Some years later, some evidence showed that photoproduct formation was different in different media (41,42). Later, photoproduct formation was observed under conditions with a depleted oxygen concentration (43).…”

Section: Resultsmentioning

confidence: 99%

Assessment of the Quality Attributes of Cod Caviar Paste by Means of Front-Face Fluorescence Spectroscopy

Airado‐Rodríguez

Skaret

Wold

2010

J. Agric. Food Chem.

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This paper describes the fluorescent behavior of cod caviar paste, stored under different conditions, in terms of light exposure and concentration of oxygen in the headspace. Multivariate curve resolution was employed to decompose the overall fluorescence spectra into pure fluorescent components and calculate the relative concentrations of these components in the different samples. Profiles corresponding to protoporphyrin IX, photoprotoporphyrin, and fluorescent oxidation products were identified. Sensory evaluation, TBARS, and analysis of volatiles are typical methods employed in the routine analysis and quality control of such food. Successful calibration models were established between fluorescence and those routine methods. Correlation coefficients higher than 0.80 were found for 79% and higher than 0.90 for 50% of the assessed odors and flavors. For instance, R values of 0.94, and 0.96 were obtained for fresh and rancid flavors respectively, and 0.89 for TBARS. On the basis of these data, it can be argued that front-face fluorescence spectroscopy can substitute all of these expensive and tedious methodologies.

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Studies on porphyrin photoproducts in solution, cells, and tumor tissue

Cited by 4 publications

References 0 publications

Phototransformations of 5-Aminolevulinic Acid-induced Protoporphyrin IX in vitro: A Spectroscopic Study¶

Phototransformations of 5-Aminolevulinic Acid-induced Protoporphyrin IX in vitro: A Spectroscopic Study¶

Photobleaching kinetics, photoproduct formation, and dose estimation during ALA induced PpIX PDT of MLL cells under well oxygenated and hypoxic conditions

Assessment of the Quality Attributes of Cod Caviar Paste by Means of Front-Face Fluorescence Spectroscopy

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