Synthesis of 3,7-disubstituted-phenothiazin-5-ium iodides containing various amino groups.

Phenothiazinium salts have been important substances in dye and medicinal industry for decades. Due to the high singlet oxygen quantum efficiency and ease of synthesis, 3,7-bis(dialkylamino)phenothiazin-5-ium analogs have been recently reported to be potential photosensitizers for photodynamic therapy (PDT) and their in vitro PDT activities were found to be highly dependent on the lipophilicity (i.e., alkyl chain length). However, the ideal photosensitizers should be water-sol. or hydrophilic in order to be easily delivered to serum. Therefore, we have designed and synthesized a series of 3,7-bis(dialkylamino)phenothiazin-5-ium salts contg. both lipophilic and hydrophilic amino groups (3-12). The max. absorption wavelengths of 3-12 are 650-667 nm and the investigation on their in vitro PDT activities is under progress. [on SciFinder(R)]