Formulation of tocopherol nanocarriers and in vitro delivery into human skin

Synopsis Objective Tocopherol is stronger antioxidant than tocopherol acetate but due to its viscous form, poor water solubility, instability to light and skin irritation issues it is not used in the current marketed formulations. To overcome the drawbacks, tocopherol was formulated as nanostructured lipid carriers and nanoemulsion. The objective of the study was to formulate tocopherol as nanocarriers. Method Nanostructured lipid carriers (NLCs) and nanoemulsion (NE) were prepared by homogenization technique. They were characterized for particle size and zeta potential. In vitro release study was performed using dialysis method, and skin permeation was carried out using human cadaver skin. Further, antioxidant activity was tested by ferric reducing antioxidant potential (FRAP) assay and skin irritation testing was performed on Epiderm skin model. Effect of UV degradation was studied using solar simulator. Results The size and zeta potential of NLC was 67.0 nm ± 1.2 and −32.0 mV ± 1.2, whereas for NE, it was 586.5 nm ± 209.6 and −10 mV ± 0.6. In vitro release study showed that 30% of tocopherol was released from NLC in the first 2 h of the study as compared to only 4% from NE. Permeation study from human skin showed that 762.3 ng mL−1 ± 184.6 of tocopherol was delivered into the epidermis when formulated as NLCs as compared to 182.3 ng mL−1 ± 52.7 from NE. FRAP assay was performed to test the antioxidant activity of formulated tocopherol, and it was seen that both formulations were able to retain the antioxidant activity. Skin irritation testing showed that NLC was non-irritant to the skin. NLC and NE were also able to protect tocopherol from UV degradation. Conclusion Based on the studies conducted, it can be concluded that formulating tocopherol as NLCs is beneficial to produce a stable, non-irritant and aqueous formulation. Resume Objectif Le Tocopherol est un antioxydant plus fort que le tocopherol acetate, mais en raison de sa forme visqueuse, sa faible solubilite dans l' eau, son instabilite envers la lumiere et des questions d'irritation de la peau, il n'est pas utilise dans les formulations actuellement commercialisees. Pour surmonter les inconvenients, le tocopherol a ete formule en tant dans des lipides nanostructures et sous forme de nanoemulsion. L'objectif de l'etude etait de formuler le tocopherol comme des nanovecteurs . Methode Les transporteurs lipidiques nanostructures (TLN) et nanoemulsion (NE) ont ete prepares par la technique d'homogeneisation. Ils ont ete caracterises pour la taille des particules et le potentiel zeta. L'etude in vitro de la liberation a ete effectuee en utilisant la methode de dialyse et la permeation de la peau a ete realisee en utilisant la peau de cadavre humain. En outre, l'activite antioxydante a ete testee par le potentiel de reduction ferrique antioxidante (FRAP) et l'irritation de la peau a ete realisee sur le modele de la peau Epiderm. L'effet de la degradation par les UV a ete etudie en utilisant un simulateur solaire. Resultats La taille et le potentiel zeta du TLN etait de 67,0 ± 1,2 nm et -32,0 mV ± 1.2 alors que pour NE c'etait 586.5 nm ± 209.6 et -10 mV ± 0,6. L'etude de liberation in vitro a montre que 30% de tocopherol a ete libere du TLN dans les deux premieres heures de l'etude, comparativement a seulement 4% de NE. L'etude de permeation de la peau humaine a montre que 762,3 ng / mL ± 184,6 de tocopherol ont ete livre dans l'epiderme lorsqu'ils sont formules comme TLN comparativement a 182,3 ng / mL ± 52,7 de NE. Le dosage de la FRAP a ete effectuee pour tester l' activite anti-oxydante des tocopherols formules et on a vu que les deux formulations ont ete capables de maintenir l'activite antioxydante. Le test d'irritation cutanee a montre que le TLN etait non irritant pour la peau. TLN et NE ont egalement ete en mesure de proteger le tocopherol de la degradation par des UV . Conclusion Sur la base des etudes realisees, on peut conclure que la formulation de tocopherol comme sous forme de TLN est benefique pour produire une formulation stable, non irritant et aqueuse.