Evidence for the involvement of singlet oxygen in the photodestruction by chloroaluminum phthalocyanine tetrasulfonate.
In recent years, choloroaluminum phthalocyanine tetrasulfonate (A1PCTS) has been shown to be a promising photosensitizer for the photodynamic therapy (PDT) of cancer. Although its mechanism of photodynamic action is not well defined, A1PCTS is going to be under clinical trials of PDT. In this study, in vitro addition of A1PCTS to a suspension of rat epidermal microsomes followed by irradiation with red light (approximately 675 nm) resulted in significant destruction of cytochrome P-450 and associated monooxygenase activities. The photodestructive effect was dependent on both the dose of A1PCTS and the duration of light exposure. Studies using various quenchers of reactive oxygen species showed that only scavengers of singlet oxygen such as histidine, 2,5-dimethylfuran, beta-carotene and sodium azide afforded substantial protection against photodestruction. Our data indicate the direct involvement of singlet oxygen in the A1PCTS-mediated photodestructive process.
Agarwal
R
R
Department of Dermatology, University Hospitals of Cleveland, OH.
Athar
M
M
Bickers
D R
DR
Mukhtar
H
H
D000535:Aluminum / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism / Q000528:radiation effects*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism / Q000528:radiation effects; D004817:Epidermis / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D007211:Indoles / Q000494:pharmacology*; D008027:Light; D008861:Microsomes / Q000201:enzymology*; D008970:Molecular Weight; D009942:Organometallic Compounds / Q000494:pharmacology*; D010100:Oxygen; D010777:Photochemistry; D010782:Photolysis; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D026082:Singlet Oxygen; D012867:Skin / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects
D007211:Indoles; D009942:Organometallic Compounds; D011838:Radiation-Sensitizing Agents; C052736:chloroaluminum tetrasulfophthalocyanine; D026082:Singlet Oxygen; D003577:Cytochrome P-450 Enzyme System; D000535:Aluminum; D001189:Aryl Hydrocarbon Hydroxylases; D010100:Oxygen