Photoprotective activity of extracts obtained from Arrabidaea chica
Sun exposure is the major cause of photocarcinogenesis, photosensitivity, and photoaging. Sunscreen lotion is an important mode of photoprotection. This area has increased in importance economically and with respect to health, stimulating the search for natural compounds for UV protection and development of non-toxic sunscreens . Arrabidaea chica (Bignoniaceae) is common in the Amazon region, and has been used by indigenous peoples to make tattoos [2,3]. We assessed the photoprotective activity of the crude extract and fractions obtained from leaves of Arrabidaea chica. Photoacoustic spectroscopy identified a UV absorption band for all samples, exhibiting protective properties of organic and inorganic components. The toxicity of the sunscreen formulation was evaluated on the skin of ears of rabbits for 7 days (G1), 14 days (G2) and 60 days (G3). A histological, toxicological, pathological, and permeation evaluation was carried out at the end of the trial period. Histological analyses demonstrated that the comedogenic potential was absent in G1 and G2, and only a slight comedogenic effect in G3 was detected. No changes in biochemical and hematological parameters were found. In the pathology studies of the kidney, liver, and spleen, preservation of the structures was noted when compared with the control group. Photoacoustic spectroscopy showed the presence of sunscreen on ear skin of rabbits. The sunscreen containing fractions of A. chica showed the presence of chemical and physical agents in the same formulation.
Acknowledgements: This study was supported through grants from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Ensino Superior (CAPES), and Financiadora de Estudos e Projetos (FINEP).
References: 1. Lautenschlager, S. et al. (2007) Lancet 370:528–537.
2. Takemura, O S. et al. (1995) Phytochemistry 38:1299–1300.
3. Zorn, B. et al. (2001) Phytochemistry, 56:831–835.