Fig. 9: Observation of captopril in vascular endothelial cells.

Living cells were cultured with 50 µM of 3o (a, b), left untreated (c), cultured with 50 μM of 7o and 50 µM of 2a containing 0.1% DMSO as controls (d, e), or cultured with the mixture of 50 μM of 3o and 100 μM of 7o as a competition experiment (f). The fluorescence of 3o inside the cells was clearly visualized (a, b), whereas no fluorescence was observed inside of the untreated cells (c). Inside of cells treated by captopril (d) and TAP-VK1 (e) showed very weak fluorescence, and their fluorescence intensities were much lower than that of 3o. The presence of 2.0 equiv. of captopril competed with 3o and substantially reduced the fluorescence of 3o (f). The Cell nuclei were stained by PI (propidium iodide; red fluorescence) for detailed fluorescence observation (b–f). The fluorescence of 3o was observed in the cytoplasm. The uptake of 3o was monitored by confocal microscopy (ZEISS LSM700; Carl Zeiss) in a fluorescence image with excitation and emission wavelengths of 405 and 490 nm, respectively (a–f). Scale bar = 20 µm.