The modification of spectral characteristics of cytostatics by optical beams

摘要

Besides the biochemical action of methotrexate (MTX) and 5-fluorouracil (FU) their effect in destroying cancer tumours could be enhanced by exposure to light at different doses. Absorption, excitation and emission spectra of 10~(-4)M-10~(-5)M MTX solutions in natural saline and sodium hydroxide at pH = 8.4 were measured, while their exposure to coherent and uncoherent light in the visible and near ultraviolet (UV) spectral ranges was made (Hg lamps and Nitrogen pulsed laser radiation were used). Absorption spectra exhibit spectral bands in the range 200 nm - 450 nm. The 200 - 450 nm excitation spectra were measured with emission centred on 470 nm; MTX fluorescence excitation was measured at 390 nm and the emission was detected between 400 nm and 600 nm showing a maximum at 470 nm. Spectra modifications, nonlinearly depending on exposure time (varying from 1 min to 20 min), evidenced MTX photo-dissociation to the fluorescent compound 2,4 diamino-formylpteridine. In the 5-FU case the absorption spectra exhibit bands between 200 nm and 450 nm. The emission fluorescence spectra were measured between 400 nm and 600 nm, with λ_(ex) = 350 nm for UV Hg lamp and with λ_(ex) = 360 nm for laser irradiated samples; at irradiation with N_2 laser emitted radiation the excitation spectra were measured in the range of 200 nm- 400 nm, with λ_(em) = 440 nm. New vascularity rapid destruction was observed for conjunctive impregnated with 5-FU solution whilst exposed to incoherent UV and visible light.