Avaliação da toxicidade induzida pelo extrato glicólico comercial de Aloe vera (L.) Burm. f. associado à radiação ultravioleta A em células da linhagem A 549

Abstract

Aloe vera is a plant that belongs to the Aloaceae family, being the common name for over 400 plant species. Among the large variety of known species of Aloe, Aloe vera (L.) Burm. F. (Aloe vera) is the most used by the population because of its folk medicinal properties and by the cosmetic industry in order to compose shampoos, creams and other cosmetics. Aloe vera is a succulent and xeromorphic plant, whose leaves store a gelatinous substance, rich in substances wich medicinal properties are attributed. However, recent studies have shown that some components of the gel may exhibit photochemical properties that in the presence of ultraviolet A radiation, would be responsible for adverse effects. Among these components, two anthraquinones, aloe-emodin and aloin were identified as capable of absorbing UV radiation and produce reactive oxygen species. This study aims to evaluate the toxicity induced by a commercial glycolic extract of Aloe vera in combination with UVA radiation, in A549 eukaryotic cells line (alveolar basal epithelial cells of human adenocarcinoma). The aloe vera extract glycolic was donated by Mapric (São Paulo). Cytotoxicity of the extract and its association with UVA are being evaluated by cell proliferation assay WST-1 and exclusion of trypan blue test.To evaluate a possible statement of the mechanism of action and its association with UVA, it will be performed by flow cytometry oxidative stress marking flow with DCFDA in the samples tested. Initially, cells were exposed to the glycolic extract of aloe vera at proportions of 1.56; 3.13; 12.5; 25 to 50% for 2, 6, 12, 24 and 48 hours. This data demonstrate that lower proportions of aloe vera (1.56, 3.13 and 6.25%) were not cytotoxic, while the proportions of 12.5, 25 and 50% induced a significant reduction in cell survival. After that,cultures of A549 cells were incubated with the extract (50, 12.5, 6.25, 3.13 and 1.56%) in association with exposure to UVA (10w / s) for 30, 60, 90 and 120 minutes. Again the concentrations of 1.56, 3.13 and 6.25% did not show a toxic profile for the cells. The extract of Aloe vera, at concentrations 50 and 12.5% in combination with UVA radiation, induced greater cell death rate when compared to the results seen in the trials with the non-irradiated sample.Experiments were also conducted to analyze the presence of Emodin, anthraquinone, by cromatografia.The results point to the absence of such antroquinona in the extract. This result was also confirmed by spectrophotometry. Furthermore, to find out if the UVA radiation caused a change in the absorption peaks of these ratios and the medium HAM-F12, samples containing the medium and the proportions were irradiated for 2 hours and there was no difference in the middle absorption peaks and proportions tested, suggesting that the radiation does not cause physical and chemical changes in the extract.In addition, an assessment of oxidative stress produced by exposure to producing agents was performed by flow cytometry. Labeling with DCFDA a fluorogenic dye was performed 1 and 24 hours after exposure and the results showed an increase of reactive species of oxygen proportional to the time without statisticaldifference. This set of results suggest that the glycolic extract of aloe vera can be harmful to the cells when associated with UVA and people should be careful when using skin products with aloe vera under sunlight.