Spectroscopic studies of photobleaching and photoproduct formation of porphyrins used in tumour therapy

Rotomskis, Ričardas; Bagdonas, Saulius; Streckyte, Giedre

doi:10.1016/1011-1344(95)07228-4

Cited by 74 publications

(56 citation statements)

References 24 publications

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“…Considering the photobleaching of porphyrins during irradiation (Rotomski et al, 1996;Bezdetnaya et al, 1996;Moan et al, 1997), a threshold concentration of PpIX necessary for tissue destruction, and the high selectivity of h-ALA-induced PpIX, a small PpIX amount in healthy areas of the bladder, observed in this study will probably not induce any damage in these regions. However, the twofold increase of PpIX fluorescence after 6 h in neoplastic tissues by using h-ALA may further enhance the PDT effect as compared to the use of ALA.…”

Section: Discussionmentioning

confidence: 78%

Photodetection of early human bladder cancer based on the fluorescence of 5-aminolaevulinic acid hexylester-induced protoporphyrin IX: a pilot study

et al. 1999

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Fluorescence photodetection (PD) and photodynamic therapy (PDT) are techniques currently under clinical assessment for both visualization and local destruction of malignant tumours and premalignant lesions. One drawback of these methods found with some photosensitizers is a more or less long-term cutaneous photosensitivity (Wagnières et al, 1998;Dougherty et al, 1990). A more recent strategy for administering photosensitizers involves the application of 5-aminolaevulinic acid (ALA) in order to stimulate the formation of protoporphyrin IX (PpIX) in situ. The exogenous ALA bypasses the negative feedback control from haem to ALA synthase that catalyses the condensation of glycine and succinyl-coenzyme A (CoA). Given in excess, exogenous ALA thus can result in a temporary accumulation of PpIX, in particular, in cells with higher metabolic turnover. Since PPIX has fairly good photosensitizing properties (Cox et al, 1982;Kennedy et al, 1990) proposed ALA as a possible photodynamic agent. Following this pioneering work, this treatment modality has been widely studied for various cancers (Kennedy et al, 1992;Peng et al, 1992;Svanberg et al, 1994).As well as for the PDT of malignant or premalignant lesions, ALA-induced PpIX is now being used for the detection of such lesions. This technique has been shown to work, among other applications, in urology, where easy instillation in the bladder, combined with the fact that this organ is readily accessible endoscopically, makes it an ideal object. Alongside classical techniques such as cytology or white light examination, fluorescence PD by ALA-induced PpIX provides some advantages (Leveckis et al, 1994;Kriegmair et al, 1996;Jichlinski et al, 1997). This inspection modality allows an exact mapping which pinpoints, with a high level of sensitivity and specificity, the locations of carcinoma in situ (CIS) as well as early stages of cancer-like dysplasias, which are normally difficult to recognize under white light examination.However, when using topically instilled ALA for the PDT of CIS and precancerous lesions, this modality appears to be limited by the amount of ALA that enter the target cells or by the tissue penetration and the distribution of the resulting PpIX in the targeted tissue. Almost all of these possible disadvantages accompanying the use of ALA can be ascribed to the physical-chemical properties of the molecule itself. Applied under physiological conditions, ALA is a zwitterion (Novo et al, 1996). Because the lipid bilayer of biological membranes is relatively impermeable to charged molecules, the cellular uptake of ALA is shallow. Consequently, in order to increase the transport across cellular membranes, fairly high drug doses and increased administration times have to be used. This deficiency results in a low penetration depth (Warloe et al, 1992;Loh et al, 1993;Peng et al, 1995) and an ALA-induced PpIX distribution, which is not optimized for the PDT of the deep layers of nodular lesions in the urothelium (Iinuma et al, 1995;Chang et al, 1996) after topical A...

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Section: Discussionmentioning

confidence: 78%

Photodetection of early human bladder cancer based on the fluorescence of 5-aminolaevulinic acid hexylester-induced protoporphyrin IX: a pilot study

et al. 1999

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“…Spectroscopic studies have shown that photodegradation of many tetrapyrroles results in appearance of new fluorescent photoproducts with slightly different characteristics. This is the case for protoporphyrin (Juzenas et al, 2001), hematoporphyrin (Rotomskis, Bagdonas, & Streckyte, 1996), and cholorphyll a (Merzlyak et al, 1996). We did not observe this in the present study, however, one would expect that careful fluorescence analysis of light exposed cheese would enable studies of both degradation of the primary tetrapyrroles, as well as the formation of some of their photoproducts.…”

Section: Discussionmentioning

confidence: 93%

The role of naturally occurring chlorophyll and porphyrins in light-induced oxidation of dairy products. A study based on fluorescence spectroscopy and sensory analysis

Wold¹,

Veberg²,

Nilsen³

et al. 2005

International Dairy Journal

121

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“…The loss of absorption in the visible bands and the appearance of photoproducts absorbing in UV region at photosensitizer ring together with the formation of photoproduct at 650 nm (Rotomskis et al, 1996). However, in porphyrin, hematoporphyrin and chlorine derivatives, there is a reduction in visible spectra and an increase in absorption at UV and at 450, 500 and 640 nm upon similar irradiation (Rotomskis et al, 1996(Rotomskis et al, , 1997Streckyte et al, 1993).…”

Section: Resultsmentioning

confidence: 99%

Photobleaching of Sn(IV) chlorine e6 dichloride trisodium salt in different environments

Al-Khaza’leh¹,

Omar²,

Jaafar³

2011

Afr. J. Biotechnol.

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The photobleaching of Sn(IV) chlorine e6 dichloride trisodiuim salt in variety of solvents was investigated. The absorption of photosensitizer in polar solvent was much higher than in non-polar solvent. The results prove that this photosensitizer was high water soluble. The photosensitizer absorption decreased at all bands for all solvents. Increasing the irradiation time leads to gradual decrease in the absorption of photosensitizer in solvents. The photosensitizer binding to the protein will result in a reduction of the diffusional movement of the photosensitizer to equalize the protein. The presence of serum in the environment leads to increase in the photobleaching rate and response to light as well. A new peak position of absorption was observed in the ultra violet region with the presence of serum. Singlet oxygen was found to be responsible for photobleaching.

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Spectroscopic studies of photobleaching and photoproduct formation of porphyrins used in tumour therapy

Cited by 74 publications

References 24 publications

Photodetection of early human bladder cancer based on the fluorescence of 5-aminolaevulinic acid hexylester-induced protoporphyrin IX: a pilot study

Photodetection of early human bladder cancer based on the fluorescence of 5-aminolaevulinic acid hexylester-induced protoporphyrin IX: a pilot study

The role of naturally occurring chlorophyll and porphyrins in light-induced oxidation of dairy products. A study based on fluorescence spectroscopy and sensory analysis

Photobleaching of Sn(IV) chlorine e6 dichloride trisodium salt in different environments

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