Avaliação do potencial fotoprotetor do extrato de Myrciaria dubia em cultura de células expostas a radiação UVB

Abstract

Camu-Camu (Myrciaria Dubia) is a fruit of Amazonian origin that has high levels of ascorbic acid and phenolic compounds in its composition, which have the ability to reduce oxidative stress and help the immune system against damage caused by exposure to radiation ultraviolet. Thus, the objective of the present study was to produce and characterize a hydroalcoholic extract of Camu-Camu and to evaluate its photoprotective potential, in simultaneous treatments, pre-treatment and post-treatment, for exposed renal cells of Macaca mulatta (LLC-MK2) type B ultraviolet radiation (UVB). The experimental design for the production of the extract, a DCCR (rotational central composite design) 2² with two independent variables (extraction time and solvent concentration), showed that the time of 20 minutes and 50% ethanol and 50% water were the best solid-liquid extraction conditions, in terms of phenolic compounds. The determination of the antioxidant capacity of the final extract resulted in an EC50 of 100±3.2 μg mL-1 and the physical-chemical analysis showed that the extract has an acidic character, with a pH value of 2.94, 10.68% of total acidity and 3504.788±63.5 mg ascorbic acid 100 mL-1 of extract. The MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) cytotoxicity test with LLC-MK2 cells showed that the fruit extract was not cytotoxic for this cell lineage, but the radiation levels (30, 60, 90, 120 and 150 mJ cm-2) promoted mortality of these cells. The design and build of a radiation chamber were necessary to conduce the cytoprotection tests. The tests results showed that concentrations of 10, 25, 50 and 75 μL mL-1 of Camu-Camu extract were able to promote photoprotection for the LLC-MK2 cell line exposed to 30 mJ cm-2 of UVB radiation. Furthermore, the post-treatment (Camu-Camu treated 2 hours after exposing the cells to radiation) showed the best results in terms of cytoprotection. Thus, the data from the present study demonstrated that this fruit deserves attention in the search for research of treatments to prevent damage caused by exposure to ultraviolet radiation.