| Abstract [eng] |
Tomas Biekša Study on photosensitiser induced photochemical reaction mechanism, using hematoporphyrin and L-ascorbic acid In this final Master‘s work the history of ascorbic acid in cancer therapy is overviewed and its reactions which may take place in human body are discussed. Also, the problems encountered during the treatment of tumors possessing hypoxic areas were discussed. The solution for enhancement of the efficiency of photodynamic therapy under such conditions by using ascorbic acid is proposed. In this work a steady state absorption and electron paramagnetic resonance (EPR) spectrometric methods were used. The effect mechanism of L-ascorbic acid to phototransformations of hematoporphyrin was investigated. By irradiating the samples by means of diode pumped λ = 532 nm solid-state laser radiation at different intensities, spectral changes arising in neutral pH (pH ꞊ 7) and acidic (pH ꞊ 5) were observed. Also, the hematoporphyrin phototransformations in model conditions favorable for Fenton reactions were examined by observing spectral changes after addition of CuCl2 and H2O2. Finally, using electron paramagnetic resonance spectrometry, free radical formation in the samples was observed by changing laser radiation intensity. In this work spectral changes resulting during sample irradiation at different pH are discussed, and photoproducts formed are identified. Also, an expanded scheme of hematoporphyrin phototransformations in different model media is presented and by using electron paramagnetic spectrometry the effect mechanism of L-ascorbic acid to phototransformations of hematoporphyrin is explained. |
