Citral prevents UVB-induced skin carcinogenesis in hairless mice

The incidence of skin cancers has increased worldwide, requiring more prevention of this type of cancer. The use of sunscreen and the control of the time of exposure to sunlight are the recognized forms of prevention. However, new substances have been researched in order to develop formulations with more efficient protective activity. Citral is a natural compound with lemon scent that is used in food and cosmetic industries. The present work evaluated the chemoprotective effect of citral during UVB-induced skin carcinogenesis. Male hairless mice HRS/J, 8-12 weeks old, were exposed to UVB irradiation for 24 weeks, with a cumulative radiation dose of 13.875 J/cm(2). Citral (0.1, 0.5 and 1%) was applied to the skin at a dosage of 0.1 g/animal, 5 min after UVB exposure. At the end of the experiment, the number of lesion/animal, and size of lesions were measured. The histological sections of the skin were evaluated for the presence and intensity of actinic keratosis and squamous cell carcinoma. TUNEL assay was performed for apoptosis evaluation. Skin samples were used for the measurement of oxidative stress parameters (total radical-trapping antioxidant parameter of skin, glutathione, catalase activity and malondialdehyde), and cytokines levels (IL-1 beta, IL-4, IL-10, IL-23, TNF-alpha, and IFN gamma). Citral 1% completely inhibited UVB-induced skin carcinogenesis by reducing levels of oxidative stress and pro-inflammatory cytokines, increasing apoptotic rate in the skin.