ABSTRACT
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.
Subject(s)
Epidermis/drug effects , Plant Oils/administration & dosage , Skin Absorption/drug effects , Administration, Cutaneous , Ascorbic Acid/administration & dosage , Diterpenes , Emulsions/administration & dosage , Epidermis/metabolism , Humans , Linear Models , Pyridoxine/administration & dosage , Retinyl Esters , Vitamin A/administration & dosage , Vitamin A/analogs & derivatives , alpha-Tocopherol/administration & dosageABSTRACT
The permeation of essential oils through SkinEthic reconstructed human epidermis, (RHE), was studied in vitro to establish a convenient tool to monitor the kinetics of release of active principles from cosmetic formulations. Twelve days old human epidermis held on polycarbonate disks was revitalized by addition of growth medium and incubated at 37 degrees C in 5% CO(2) atmosphere for five days prior to investigation. A system of six custom designed glass Franz-type diffusion cells were used for the permeation studies at 34 degrees C. The diffusion kinetic for 8 selected terpenes (camphor, carvone, 1,8-cineole, linalool, menthol, alpha-thujone, menthone, t-anethole), chosen as analytical markers of a mixture of plant essential oils contained in a cosmetic formulation, was probed by HS/SPME-GC-MS analysis and elaborated according to Fick's first law to obtain skin permeability coefficients (P(S) = 1.51, 1.47, 1.36, 0.80, 0.62, 0.40 and 0.14x10(-3) cm/h, respectively). The method proved to be sensitive, simple and reproducible, and RHE represents a convenient model for safety/quality assessment of cosmetic formulations.
