Syntheses and screening tests of new chlorin derivatives as photosensitizer

New chlorin derivatives were synthesized from protoporphyrin IX dimethyl ester (1) as a starting material. The tumor-localizing abilities were determined by bathochromic and hyperchromic shift test using albumin and the photosensitivities were evaluated by photooxidation test using dansyl-l-methionine. NOH-P-H (3) was the most excellent in the both tests. NOH-P-H (3) was conjugated with aspartic acid to evaluate the biodistribution with the time progress by nitrogen pulsed laser spectrofluorometry. The concentration of NOH-P-Asp (15) in cancer tissues showed the highest concentration at 6 h after the administration and corresponded to five to seven times in other organs. The concentration in cancer tissues showed a rapid decrease at 24 h after the administration. PDT effect of NOH-P-Asp (15) was evaluated using tumor-bearing mice. Remarkable anti-tumor effect was observed. NOH-P-Asp (15) was expected to be applicable to a new photosensitizer for PDT.