Development of Spray- and Freeze-Dried High-Concentration Sesamol Emulsions and Antioxidant Evaluation in Fibroblasts and UV-Exposed Rat Skin Slices
Résumé
Dry sesamol emulsions were synthesized from several combinations of saccharose with
hydroxypropylmethylcellulose (HPMC) or sodium caseinate (SC) using spray-drying techniques at 120°C to
180 °C, or freeze-drying. On the basis of physical characteristics such as droplet size distribution, residual
moisture, and microscopic structure, the best material was obtained when spray-drying was applied at
either 150° or 180°C with SC or HPMC as excipients, respectively. The extent to which the antioxidant
properties of free sesamol towards a set of free radicals (galvinoxyl, diphenylpicrylhydrazyl, superoxide,
and hydroxyl) were altered in the starting and reconstituted liquid emulsions submitted to normal storage
or pre-exposed to a flux hydroxyl radicals was investigated. Emulsions were further evaluated for their
antioxidant properties in cultured 3T3 murine fibroblasts and in an ex vivo model of ultraviolet irradiated
rat skin. It was found that, in the material having the best physical properties, encapsulation was decisive
in: (1) improving the overall antioxidant behavior of reconstituted versus starting liquid emulsions: (2)
sparing sesamol consumption due to free radical attack; and (3) significantly protecting cells and skin
against free radical- or irradiation-induced enzymatic release and/or lipid peroxidation. Demonstrating a
high activity at high dilutions where interactions of excipient become negligible, the new emulsions could
be of great interest in sesamol-based pharmacology or topical applications.