Abstract
-5 M in natural saline which are exposed to coherent or noncoherent light beams. The model simulates the tumor and the tests have shown that conjunctive and neovascularisations disappear after 1-2 treatments. 5-FU is a pyrimidine analog that belongs to the family of antimetabolites. It is weakly fluorescent, but it emits intense fluorescence after exposure to UV-VIS light. The UV-VIS absorption spectra of 5-FU did not show any structural modification after exposure to UV laser beams, but the FTIR spectra showed that the molecular geometry of 5-FU was changed after irradiation. The exposure to UV laser radiation transformed the 5-FU molecule into a tautomeric form. The increase of the fluorescence is attributed to a higher conversion to the keto-enol (lactim form) fluorescing tautomer due to monochromatic and high intensity laser radiation, which allows an effective and selective excitation. The radicals formed by the deprotonation of 5-FU could initiate the tumoricidal effect. The spectroscopic studies were coupled with preliminary tests on 5-FU photosensitizing properties measured on rabbit eyes conjunctive tissues [2]. Comparative data were obtained about the evolution of neovascularisations in the conjunctive tissue between untreated rabbit eyes and eyes impregnated with 5-FU 10 -4 M in natural saline and exposed to a UV-light beam emitted by a nitrogen pulsed laser. These experiments showed that the eye conjunctive inflammation and neovascularisation disappear faster after the treatment, as well. The development of bacteria resistance to antibiotic treatment is of interest. Out of the reports about cytostatics modified by exposure to laser radiation in order to be applied efficiently on tumor tissues in MDR cases we selected two widely utilized chemotherapeutic substances: Methotrexate (MTX) and 5 - Fluorouracil (5 - FU). Methotrexate (MTX) is an antifolate used in the chemotherapy of cancer, as well as in the treatment of psoriasis and rheumatoid arthritis. MTX stops DNA synthesis by inhibiting the action of the dihydrofolate reductase and thus reducing the tetrahydrofolate level in the cell. Studies on the photochemistry of folic acid showed the photodissociation effects of the light on the absorption and fluorescence characteristics of folic acid function of the exposure time [5,6]. MTX belongs to the pterine group, together with folic acid and aminopterine, which form under UV-VIS exposure 6-formylpterine derivates and p-aminobenzylglutamic acid [7].
Highlights
The Laser Use in Generating New Species of Medicines with Antitumor and Antibacterial Properties: New Processes in Drug Discovery
Reports made during the last decades, mention the development of drug resistance mechanisms acquired by tumor cells and bacteria
Out of the reports about cytostatics modified by exposure to laser radiation in order to be applied efficiently on tumor tissues in multiple drug resistance (MDR) cases we selected two widely utilized chemotherapeutic substances: Methotrexate (MTX) and 5 - Fluorouracil (5 - FU)
Summary
The Laser Use in Generating New Species of Medicines with Antitumor and Antibacterial Properties: New Processes in Drug Discovery. Out of the reports about cytostatics modified by exposure to laser radiation in order to be applied efficiently on tumor tissues in MDR cases we selected two widely utilized chemotherapeutic substances: Methotrexate (MTX) and 5 - Fluorouracil (5 - FU).
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