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A method was developed for preparing highly purified pheophorbide a using the blue-green alga Anacystis nidulans as a source of chlorophyll a which was subsequently converted to the desired compound using a cation-exchange resin (Dowex 50Wx4, H+ -form) as a proton source. Pheophorbide a was found to be 20 times more photocytotoxic than was hematoporphyrin (under red light >560 nm) against EJ cells (a cell line established from a human transitional cell carcinoma of the bladder) in vitro. Pheophorbide a accumulated rapidly in EJ and IMR-90 (a non-neoplastic cell line established from human fibroblasts) cells, reaching the maximum by 30 minutes. However, the number of EJ cells fluorescing at 5, 15 and 30 minutes was 1.7, 1.5 and 1.2 times greater than IMR-90 cells respectively. Moreover, only 17 percent of IMR-90 versus 75 percent of EJ cells fluoresced at 48 hours following 4-hour pheophorbide a exposure. These results indicate that pheophorbide a is highly photocytotoxic for EJ cells in vitro and undergoes differential uptake and retention in neoplastic as compared with non-neoplastic cells.© (1988) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. |
