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

Topical bioavailability of lipid- and water-soluble vitamins is a critical issue for protecting or anti-ageing formulations. Using 17-dayold SkinEthic reconstructed human epidermis, we investigated (at 34C) the role of lemon EO in enhancing the penetration of a-tocopherol (E) and retinyl acetate (A), pyridoxine (B6) and ascorbic acid (C), released from O/W or W/O emulsions. D-limonene, a-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.