Cytotoxic and Photosensitizing Properties of Lichen Extracts in Relation to the Human Tumor Cell Line (MCF-7)

The ability of the thirty-five extracts from five common lichen species in Belarus to correct the viability of the MCF-7 human carcinoma line has been studied. For this, we analyzed the cell survival curves under culture conditions with the concentration gradient of extracts. Next, the survival of cells was assessed under irradiation in a dose gradient of ultraviolet radiation and pretreatment with extracts. An expressed cytotoxic effect (IC 50 < 30 μg/mL) was detected in eleven extracts: acetone, hexane, chloroform, and ethyl acetate from the species Cladonia arbusucla ; acetone and hexane from Evernia prunastri ; acetone and ethanol extract from Hypogimnia physodes ; chloroform from the species Ramalina pollinaria ; and chloroform and ethyl acetate from Xanthoria parietina . Up to complete suppression of cell viability, the ability of extracts from lichens to increase the damaging effect of subtoxic doses of ultraviolet light was shown. A group of extracts that have a sufficiently strong and concentration-dependent photosensitizing effect was identified: acetone, benzene, hexane, and ethyl acetate extracts from Hypogymnia physodes , Evernia prunastri, and Ramalina pollinaria, the maximum effect of which was shown in a concentration of 10 μg/mL. Similar extracts from Cladonia arbuscula and Xanthoria parietina were able to demonstrate the maximum amplification of the damaging effect of ultraviolet radiation at concentrations of 2.5 µg/mL and above. Throughout the radiation dose gradient, most of the extracts demonstrate the characteristic dynamics of changes in the photosensitivity of cells, increasing it already at the lowest experimental doses of radiation.