Registration of fluorescence of endogenous porphyrins and flavins in living cells and their extracts

Abstract

In the present work, for the first time, using steady-state and kinetic spectrofluorimetry, free-base porphyrins and their zinc complexes were discovered and identified in living human cervical epithelial carcinoma (HeLa) cells, in the sperm of farm animals (boar, goat) and sturgeon fish as well as in their extracts.
Registration of the fluorescence of endogenous porphyrin sensitizers in living cancer cells in vitro is associated with significant difficulties due to the intense fluorescence of flavins, the concentration of which is 2-3 orders of magnitude higher than the concentration of porphyrins, and the quantum yield of fluorescence of riboflavin and flavin mononucleotide is 5-7 times higher than the corresponding indicator for endogenous porphyrins in the aquatic environment.
By optimizing the excitation wavelength (ex = 405–415 nm), it was possible to register, against the background of flavin fluorescence in living HeLa cells under in vitro conditions, the fluorescence of endogenous porphyrins with maxima in the region em = 586 nm, 635-640 nm, 700 nm). The porphyrin component is absent when it is excited in the region ex = 440–450 nm, when the fluorescence spectrum is formed only due to the flavin component.
The important role of endogenous porphyrin sensitizers in the implementation of photobiomodulation effects in HeLa cells is evidenced by data on a higher rate of decrease in their viability when exposed to radiation with a wavelength of 405 nm compared to a wavelength of 445 nm.

Speaker

Vitaly Yu. Plavskii
B.I. Stepanov Institute of Physics of the National Academy of Sciences of Belarus, Minsk, Belarus
Belarus

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