Résumé
Plant oils are widely recognized for their beneficial effects in the cosmetic industry, possessing many biological activities. These natural oils provide multiple advantages such as superior antioxidant, nutraceutical, anti-aging, anti-inflammatory, antimicrobial and emollient properties. This study aims to consider the great importance of the various fractions of plant oils in the development of innovative sunscreen formulations based on nanostructured lipid carriers (NLCs) which act as delivery systems for three antioxidant and anti-UV bioactives. Amaranth oil (A0) - Amaranthus cruentus and pumpkin seed oil (PSO) - Cucurbita seed spp were fitted in the lipid NLCs core, forming new delivery systems able to simultaneously entrap two UVA and UVB filters (diethylamino hydroxybenzoyl hexyl benzoate - DHHB, 2-ethylhexyl salicylate - EHS), and an antioxidant (hesperidin - HES). The dimensional investigation showed that the type of vegetable oil had no significant influence on NLC size, the main diameters being ranged between 110 and 125 nm. The evaluation of physical stability during 3 months has revealed extremely electronegative zeta potential values, e.g. between - 44 and - 54 mV, reflecting an excellent physical stability. A unique feature of the developed nano-delivery systems is that they provide a differentiated release of the three active principles, e.g. a sustained release of the natural antioxidant versus maintaining significant amounts of UVA and UVB filters in the formulation. The antioxidant properties, evaluated by two in vitro techniques, showed that NLCs exhibit a high percent of short-time life radical inhibition, respectively 93-98%. The most effective scavenging system of oxygen free radicals has proved to be the NLC prepared with AO that contains 82% Squalene, while a better ability to inhibit ABTS cation radicals was detected for NLC prepared with an amaranth fraction of 34% Squalene. The entrapment process had a great influence on the UV-absorptive properties, the SPF and UVA-PF values being remarkable, even the amount of UV filters was extremely reduced in comparison with that one existent in commercial creams; the hydrogels based on NLC-EHS-DHHB-HES assure an absorption of 99% UVB radiations (SPF = 46/50.5) and have an ability tocombat 83% of UVA radiation (UVA-PF ranging between 13.9 and 15.5). In conclusion, this study provides an innovative and non-invasive design of herbal cosmetic formulations with superior photoprotection and enhanced antioxidant properties that could reduce the occurrence of skin cancer and delay the process of photoaging.