Part 2. meso-tetraphenylporphyrin dimer derivatives as potential photosensitizers in photodynamic therapy

Studies on the synthesis, singlet oxygen and fluorescence yields and pharma cokinetic properties of three different dimeric porphyrins with an amide li nkage (D2-D4) are described and compared with the results recently reported for a dimeric porphyrin (D1), The pharmacokinetic behavior of all dimers w ere examined in Balb/c mice bearing MS-2 fibrosarcomas. The maximal efficie ncy and selectivity of photosensitizer accumulation in each tumor tissue ta kes place at 24 h after drug administration of 1.0 mg kg(-1) into DL-alpha- dipalmitoylphosphatidylcholine liposomes by intravenous injection. Since th e dimeric porphyrins exhibit high quantum yields of singlet oxygen generati on, Long triplet lifetimes and high photostability, the results obtained su ggest that the evaluated dimeric structures may be promising candidates for further use in PDT experiments. The results also allow the possibility to establish a correlation between the chemical structure of the dyes and the efficiency/selectivity of the tumor accumulation and can be used for buildi ng up optimal photosensitizing agents for tumors.