[In vitro comparison of the photodynamic activity of meso-tetra (m-hydroxyphenyl) chlorin and hematoporphyrin derivative].

Meso-tetra (hydroxyphenyl) chlorin (mTHPC) was evaluated in vitro in HT29 human colon adenocarcinoma cell line and compared with hematoporphyrin derivative (HpD). The incorporation kinetics, evaluated by flow cytometry showed that mTHPC and HpD cellular uptake was related to the incubation time until 12 hours, then a plateau appeared. Cytotoxicity assays were performed using MTT test after photoirradiation at 650 nm for mTHPC and 630 nm for HpD. The photodynamic activity of both photosensitizers was influenced by serum protein of the culture medium and time interval between irradiation and photocytotoxicity test with a maximal activity 24 and 48 hrs after the photoirradiation. In optimized experimental conditions i.e. 2% serum protein- containing culture medium, 24 hr-incubation period, cytotoxicity measured 48 hrs after exposure, 10 J/cm2 light fluence, mTHPC appeared approximately 20-fold more active than HpD with IC50 values of 0.2 micrograms/mL and 4.2 micrograms/mL, respectively.