Semi-synthesis and PDT activities of a new amphiphilic chlorin derivative

An amphiphilic chlorin derivative (CHL-T) was prepared from methylpheophorbide a (CHL) and 2-Amino-2-(hydroxymethyl)-1,3-propanediol (TRISMA^®). The new chlorin was compared to other dyes (CHL and Hypericin) in relation to photophysical and photobiological activities in tumor and non-tumor cell lines. Cytotoxicity and cell death target were determined to evaluate the CHL-T efficiency, comparing to the precursor CHL and to the well-known dye hypericin (HY). All of the studied compounds exhibited absorption bands in the therapeutic window and presented a small fluorescence quantum yield compared to the reference dye (rhodamine B). CHL-T was about three times more efficient on singlet oxygen generation than the others photosensitizers. The lipophilicity order of the photosensitizers was CHL>HY>CHL-T. The tumoral HeLa cells presented improved accumulation for CHL and CHL-T compared to HY. The phototoxicity presented by the CHL-T was about ten times higher than by CHL, as demonstrated by the MTT assay. CHL-T showed more cytotoxicity to tumoral cell, comparing to non-tumoral cell in short incubation time. The cell death rises proportionally with increasing PSs concentrations, mainly by necrosis. These findings suggest that CHL-T is a potential new photosensitizer for PDT.