| Abstract [eng] |
It is reported in literature that ascorbic acid is an oxidant and antioxidant. There is information that ascorbic acid can enhance the effect of photodynamic therapy [2]. The aim of this work was to evaluate the effect of oxidative and reducing properties of L-ascorbic acid (L-asc) on the stability of photosensitizer, aluminum phthalocyanine tetrasulphonate (AlPcS4), and anthocyanins at different pH in aqueous media during photosensitization. L-asc and AlPcS4 solutions were studied with near-ultraviolet and visible (UV-VIS) spectrometry to investigate how L-asc affects the stability of AlPcS4 during photosensitization. Solutions of L-asc, AlPcS4, and blue bean extract were also examined to determine whether L-asc protects anthocyanins from oxidative processes caused by AlPcS4 and light. Irradiated L-asc and AlPcS4 solutions were studied by electron paramagnetic resonance (EPR) spectrometry to determine how the pH of the medium affects AlPcS4 and L-asc radicals. Examination of the UV-VIS spectra showed that under intense light, L-asc at acidic and neutral pH causes damage to the AlPcS4 chromophore (causes true bleaching), while at alkaline pH L-asc reduces oxidized AlPcS4. At alkaline and neutral pH, L-asc reduces oxidized anthocyanins, and anthocyanins do not significantly affect AlPcS4 bleaching. Examining the EPR spectra, it was observed that the stability of AlPcS4 is related to the ratio of L-asc radicals to AlPcS4 radicals. The higher this ratio, the more stable AlPcS4. |
