Synthesis and cellular studies of a carboranylchlorin for the PDT and BNCT of tumors

Abstract The syntheses of closo - and nido -carboranylchlorins 4 and 5 from a known carboranylporphyrin are described. Water-soluble nido -carboranylporphyrin 5 was found to have very low dark cytotoxicity (IC 50  > 500 μM using a MTT-based assay) but to be toxic in the presence of red light (IC 50  = 80 μM at 0.55 J/cm 2 light dose). Under the same experimental conditions, carboranylchlorin 5 was taken up by human glioma T98G cells to a significantly higher extent than chlorin e 6 , a chlorophyll degradation product. The preferred sites of subcellular localization of carboranylchlorin 5 were found to be the cell lysosomes. Our results suggest that carboranylchlorin 5 is a promising new dual sensitizer for the PDT and BNCT treatment of tumors.