Avaliação do potencial fotoprotetor de Camellia sinensis em camundongos expostos à radiação UVB

Abstract

Skin exposure to ultraviolet (UV) radiation is directly related to premature ageing and skin cancer. Although sunscreens are the basis of UV protection, their effectiveness is limited by low consumer adherence. Therefore, oral formulations capable of providing systemic photoprotection must be tested scientifically. Phytotherapeutics such as green tea (Camellia sinensis), which has anti-inflammatory properties, can promote photoprotective action when exposed to UVB radiation. Twelve adult male mice were randomly assigned to the following groups: CONT (n=4), control mice not exposed to radiation or treatment; UVB (n=4), mice exposed to UVB radiation; and UVB-CV (n=4), mice treated with a single dose of green tea (46 mg/kg) administered via gavage and exposed to UVB radiation. This study was approved by the Araguaia Animal Use Ethics Committee (23108.031795/2022-19). The green tea extract was characterized and prepared in partnership with Magthec. One hour after gavage, the animals were anesthetized with 85 mg/kg Ketamine and 8.5 mg/Kg xylazine (intraperitoneal). The dorsal shaved skin was exposed to UVB radiation for 20 minutes using a specific lamp positioned at a distance of 10 cm. Forty-eight hours after exposure, the animals were killed by anesthetic overdose. Photographs were taken of the dorsal region to determine the degree of erythema in the animals, following the score: (0) = absent, (+) = mild, (++) = moderate, and (+++) = intense. The dorsal skin of the mice was collected from all the experimental groups for histological analysis of the epidermis and dermis and determination of Interleukin IL-6 and Interleukin IL-10. Micrographs of skin sections were analyzed using ImageJ software, while cytokines were analyzed by flow cytometry using a specific kit (BD Cytometric Bead ArrayCBA), according to the manufacturer’s protocol. Data were analyzed using ANOVA (Tukey's test, p < 0.05) and expressed as mean ± standard deviation (SD). The groups subjected to UVB radiation showed a greater degree of erythema (mild) than the control group (absent) (P<0.05). Slight erythema was observed in the UVB and UVB-CV groups, and there were no differences in relation to the photoprotection of green tea (P>0.05). In terms of histology, the experimental groups had no significant difference (P>0.05) in the increase in epidermal thickness in the UVB-CV (1.58 ± 0.42μm) and UVB (1.58 ± 0.74 μm) groups compared to the Control (1.5 ± 0.1 μm).There was no difference (P>0.05) in the thickness of the dermis in the UVB-CV (83.3 ± 26.4 μm) and UVB (64.9 ± 26.4) groups compared to the Control (42.4 ± 20 μm).In the quantification of cytokines, the UVB-CV (1777.5 ± 899.9 pg/mL) and UVB (2,302.7 ± 1,224.7 pg/mL) groups showed a significant increase (P>0.05) in the production of interleukin IL-6 compared to the Control group (57.6 ± 65.6 pg/mL).For interleukin IL-10, the UVB-CV group (22.3 ± 3.5 pg/mL) showed similar levels compared to the Control (22.8 ± 6.2 pg/mL) while the UVB group (13.3 ± 6.8 pg/mL) showed a significant decrease (P>0.05) compared to the Control group (22.8 ± 6.2 pg/mL).Our preliminary results showed that oral administration of green tea has photoprotective effects against UVB radiation under the conditions of dose, administration time, and exposure used in mice.