Photodynamic toxicity of porphyrins and chlorins for a human tumor cell line: combined light and concentration dose responses for the retained fraction.
In recent years porphyrins and related materials have been tested as antitumor agents. A technique was devised to obtain dose-response curves for the sensitizer fraction that resists one day of elution by tissue culture medium--the retained fraction. We found a steep "threshold" dose response relationship that helps to explain tumor destruction without damage to normal tissues. The family of dose-response curves produced by a wide range of light exposures suggests that chlorins and porphyrins do not act by identical mechanisms. Moreover, they suggest that chlorins will prove superior in practical use.
Nourse
W L
WL
Life Sciences Division, SRI International, Menlo Park, CA.
Parkhurst
R M
RM
Skinner
W A
WA
Jordan
R T
RT
D002277:Carcinoma; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002734:Chlorophyll / Q000031:analogs & derivatives*; D002735:Chlorophyllides / Q000633:toxicity*; D003110:Colonic Neoplasms; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D006415:Hematoporphyrins / Q000633:toxicity*; D006801:Humans; D008027:Light; D011166:Porphyrins / Q000633:toxicity*; D014407:Tumor Cells, Cultured / Q000187:drug effects* / Q000528:radiation effects
D002735:Chlorophyllides; D006415:Hematoporphyrins; D011166:Porphyrins; D002734:Chlorophyll; C006969:chlorin; C007020:chlorophyllin