Use of various vegetable oils in designing photoprotective nanostructured formulations for UV protection and antioxidant activity

• Photoprotective nanostructured lipid carriers were developed using vegetable oils.
• The NLCs showed a good physical stability over two months.
• Pomegranate seed oil presents significant UVB absorbing properties.
• The pomegranate seed oil and wheat germ oil – NLC had the best photoprotection.
• The NLCs presented an enhanced antioxidant activity when compared to the free oils.

Vegetable oils are well-known for their beneficial health effects, mainly due to their antioxidant activity, which is maintained or enhanced when they are encapsulated at nanoscale. This study aims to design new nanostructured lipid carriers (NLCs) containing various vegetable oils and their combinations in order to obtain efficient formulations with UV protection performance and antioxidant activity. Pomegranate seed oil, wheat germ oil, blackcurrant seed oil, sesame seed oil, carrot root oil, raspberry seed oil and rice bran oil were used for obtaining NLCs, as carriers for a photoprotective agent that absorbs the UVA radiation: diethylamino hydroxybenzoyl hexyl benzoate. The NLCs were characterized by mean particle size, physical stability over time, and entrapment efficiency of the UVA filter. The UV protection performance was assessed using both in vitro sun protection factor (SPF) and the UVA protection factor (UVAPF). The antioxidant activity was determined by chemiluminescence analysis. All vegetable oils used led to the development of appropriate NLCs, having mean particle sizes ranging between 100 nm and 145 nm and good physical stability with zeta potential values less negative than −35 mV. The UV protection factors were evaluated on the individual vegetable oils and on cream formulations based on NLCs. Out of the seven cream formulations, the best UV protection was assured by the pomegranate seed oil based cream resulting in a SPF of 4.1 and an UVAPF of 7.8. Knowing that a synergistic interaction can occur among the active compounds of different oils, new NLCs were developed by using a mixture of pomegranate seed oil and one of the other oils. The NLCs based on pomegranate seed oil combined with wheat germ oil have shown the best entrapment efficiency (70%) and photoprotection (SPF of 5.1 and a UVAPF of 9.5). All vegetable oils showed a good antioxidant activity, which was improved by their incorporation into NLCs. The results have shown that vegetable oils and especially their combinations can be used as renewable raw materials in designing effective and eco-friendly photoprotective nanostructured formulations.

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