Lemon (Citrus limon, Burm.f.) essential oil enhances the trans‐epidermal release of lipid‐ (A, E) and water‐ (B6, C) soluble vitamins from topical emulsions in reconstructed human epidermis

Synopsis Topical bioavailability of lipid‐ and water‐soluble vitamins is a critical issue for protecting or anti‐ageing formulations. Using 17‐day‐old SkinEthic ® reconstructed human epidermis, we investigated (at 34°C) the role of lemon EO in enhancing the penetration of α‐tocopherol (E) and retinyl acetate (A), pyridoxine (B 6 ) and ascorbic acid (C), released from O/W or W/O emulsions. D ‐limonene, α‐pinene and p ‐cymene (65.9, 2.2 and 0.5%w/w of the oil) had skin permeability coefficients Ps (10 −3 cm h −1 ) of 0.56 ± 0.03 (or 0.73 ± 0.02), 0.72 ± 0.05 (or 0.98 ± 0.05) and 0.84 ± 0.04 (or 1.14 ± 0.04), respectively, when incorporated in a W/O (or O/W) emulsion. Vitamins B6, C and A had Ps values of (3.0 ± 0.4) × 10 −3 , (7.9 ± 0.6) × 10 −3 and (0.37 ± 0.02) × 10 −5 cm h −1 , respectively, and their flux through the skin was enhanced by a factor of 4.1, 3.4 and 5.8, respectively, in the presence of lemon EO. The penetration of vitamin E was nine‐fold enhanced. Lemon EO produced only reversible modification of TEWL, and it is a safe and effective penetration enhancer for topical administration of lipid‐ and water‐soluble vitamins.