Rapid and Simple Analysis of <i>N</i>-Aspartylchlor in E6 (Talaporfin) Using Fluorescence Microtiterplate and Its Application for Determination in Cells, Tissues and Blood

Abstract

N -aspartylchlorin e6 (talaporfin) concentrations in cancer cells, mouse liver tissues, and human plasma specimens were determined with fluorescence microtiter plate analysis. Talaporfin standard curves were obtained in each of the sample specimens of cells, mouse tissues, or human plasma including serial concentration of talaporfin. The correlation co-efficiencies (r 2 ) of talaporfin standard curves were 0.99-1.00, and the CV less than 5%. Talaporfin incorporation into cells of human breast cancer cell line MCF-7 after incubating with 25 μg/mL talaporfin for up to 24 h revealed that the t-max of the drug incorporation was approximately 5 h, and the maximum drug concentration incorporated was 25 μg/10 7 cells. Talaporfin incorporation into MCF-7 cells was significantly decreased in the presence of 3 μg/mL cyc-losporine (p < 0.05). Balb/c nu/nu mice implanted human cholangiocarcinoma NOZ cells in liver were administered intravenously 5mg/mouse of talaporfin, and the tissues of normal liver and tumor, as well as plasma specimens, were analyzed for talaporfin concentrations. The mean (SD) of talaporfin concentration in plasma after 30 min of administration was 41.6 (2.3) μg/mL, while the level decreased to undetectable concentrations 2 h after administration. In contrast, the talaporfin concentrations in normal and tumor tissues after 30 min of administration were 1.1-7.8 μg/g tissue, and the level slightly increased or was almost maintained for up to 2-4 h after administration. The heparinized blood of the healthy subjects was incubated with 25 μg/mL talaporfin for up to 24 h. The plasma talaporfin concentration did not significantly change during the incubation, and thus talaporfin appears not to be incorporated into the blood cells. We established rapid and simple analysis procedures of talaporfin in biological specimens using a fluorescence microtiter plate assay. Using this assay procedure, the unique pattern of talaporfin disposition and pharmacokinetics were revealed in human cancer cells, liver tissues of tumor bearing mice, and human blood.