Evaluating <I>in vitro</I> and <I>in vivo</I> the photoprotective effectiveness of combinations of lichen extracts

In a series of experiments, the photoprotective properties of ethanol and ethanol-castor compositions based on perspective combinations of lichen extracts (1:1) were studied in terms of a set of parameters: 1) SPF, λcrit and UV-A/UV-B — in vitro; 2) morphological and functional characteristics of the skin, pro- and antioxidant processes in mice’ blood (line Af) after topical application of the compositions and exposure to UV-A/B — in vivo. In general, photometric studies showed a very high level of photoprotection in all created lichen compositions, which are close to each other quantitatively and approach the category of “sunscreens”. Compositions based on the combination of extracts “ethylacetate Cladonia arbuscula + methanol Ramalina pollinaria” favorably stand out in terms of the combination “SPF — λcrit — UV-A/UV-B”. According to biochemical and morphometric parameters, ethanol and a 30% solution of castor oil in ethanol do not have a noticeable modifying effect on the action of UV on the skin and blood serum and can be used for topical applications of lichen extracts. Among the tested ethanol compositions of extracts in the entire series of experiments at concentrations of 0.2 g/l and 15-20 g/l, according to the sum of the burn severity values at 20 min of UV irradiation, the combinations of extracts “ethylacetate C. arbuscula + methanol R. pollinaria” and “benzene Evernia prunastri + ethanol C. arbuscula” have shown the best photoprotective effect (5-6 points on a 10-point scale). These combinations of extracts worked in a similar way in ethanol-castor compositions, where they showed a less stable photoprotective effect. The introduction of castor oil into ethanol increased the severity of the burn by 6.5-10.5% for all combinations of extracts. The summary of UV effects based on biochemical parameters with a clear direction (GPx, TBARS, TAOC, GSH) shows the photosensitizing nature of all lichen compositions at a concentration of 0.2 g/l. This was observed to the greatest extent for the combination of methanol extracts of Hypogymnia physodes and C. arbuscula. The lowest photosensitivity was noted for the combination of extracts “ethylacetate C. arbuscula + methanol R. pollinaria”, which in various compositions and by the totality of photometric, biochemical and morphometric parameters demonstrated the most expressed photoprotective properties.