d-limonene prevents ultraviolet irradiation: Induced cyclobutane pyrimidine dimers in Skh1 mouse skin

Figure 4 Immunostaining of proliferating cell nuclear antigen. Skin samples were obtained on 6 d after UVR exposure. A: Control; B: 100% d-limonene alone; C: UVR alone; D: UVR + 1.0% d-limonene; E: UVR + 10% d-limonene; F: UVR + 100% d-limonene. (A) In control skin few PCNA-positive cells are observed in epidermis. Both 100% d-limonene alone (B) and UVR alone (C) induced proliferative stimulation in epidermis and hair follicles. However, pre-treatment of mice with d-limonene significantly reduced the PCNA-positive cells in skin compared to UVR-only mice (D-F), which verifies the CPD finding that oral d-limonene was protective against UVR-induced tissue damage. UVR: Ultraviolet irradiation; PCNA: Proliferating cell nuclear antigen; CPD: Cyclobutane pyrimidine dimer.