Phototoxic process after rapid photosensitive membrane damage of 5,5"-bis(aminomethyl)-2,2':5',2"-terthiophene dihydrochloride.
We report a new aspect of rapid (<30 s) light-induced cell membrane damage photosensitized by 5,5"-bis(aminomethyl)-2,2':5',2"-terthiophene dihydrochloride (BAT), which is a water-soluble alpha-terthienyl analogue, using a high-power laser (light intensity 1.6 W cm(-2)). In this paper, we will discuss the relationship between the exposure time of the cells to the photosensitizer and the phototoxic process. Three toxic processes can be identified: first, a non-light-mediated toxicity dependent on BAT-cell incubation; second, a phototoxicity independent of BAT exposure time when the BAT concentration is in the 2-10-microM range; third, a phototoxicity dependent on BAT exposure time when BAT concentration becomes 20 microM. The cytotoxicity decreases when alpha-tocopherol, an antioxidant, is added to a cell membrane. This pattern of phototoxicity is the typical of a phospholipid peroxidation chain reaction and oxidative damage of membrane proteins triggered by a reactive oxygen species generated by a triplet state of BAT. The BAT exposure time is clearly correlated with the partition of the photosensitizer in the cell membrane and inside the cell.
Saito
T K
TK
Center for Collaborative Research, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8904, Japan.
Takahashi
M
M
Muguruma
H
H
Niki
E
E
Mabuchi
K
K
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D002839:Chromans / Q000378:metabolism / Q000494:pharmacology; D017484:Dermatitis, Phototoxic; D057927:Hydrophobic and Hydrophilic Interactions; D007834:Lasers / Q000009:adverse effects; D015394:Molecular Structure; D016716:PC12 Cells; D017319:Photosensitizing Agents / Q000494:pharmacology*; D051381:Rats; D013876:Thiophenes / Q000737:chemistry / Q000494:pharmacology; D013997:Time Factors
C115905:5',5''-bis(aminomethyl)-2,2'-5',2''-terthiophene; D002839:Chromans; D017319:Photosensitizing Agents; D013876:Thiophenes; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid