Photoproducts formed from photofrin II in cells

✍ Scribed by Johan Moan; David Kessel

• Book ID: 103992896
• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 488 KB
• Volume: 1
• Category: Article
• ISSN: 1011-1344
• DOI: 10.1016/1011-1344(88)85003-6

✦ Synopsis

Fluorescence and absorption spectra of light-exposed cells containing the tumour-localizing porphyrin preparation Photofrin II (PII) have been studied. Light exposure results in spectral changes that may be due to a photoinduced modification of the porphyrins without breakage of the porphyrin macrocycle and/or to a photoinduced displacement of the porphyrins in the cells. Photochemical reactions involving breakage of the porphyrin macrocycle also occur as can be seen from the loss of absorbance within the Soret band region during light exposure.

Singlet oxygen may be involved in the photodegradation of PI1 in cells since the process is slowed down on bubbling Nz through the samples and is slightly faster in suspensions in Dulbecco's phosphate buffered saline (PBS) made of D,O compared with suspensions in PBS made of H20.

During light exposure a fluorescent product is formed in the cells with fluorescence excitation and emission characteristics similar to those of the "age pigment" lipofuscin (A,,, = 350 nm, A,, = 440 nm).