The photoprotective skincare products are in high demand to meet the consumer market with concern on skin health. Seed oils are commonly used as ingredients in many cosmetic products due to their natural antioxidants and now being increasingly recognised for their effects on skin health and photoprotection. This article briefly reviews the application of seed oils in sunscreen development focusing on the antioxidants that contribute to photoprotection, thus preventing UV-induced erythema and photoaging. The addition of seed oils that contain specific natural bioactive compounds were discussed in the review. Besides that, seed oils acting in molecular pathways that benefit in photoprotection were also summarized. Seed oils (pomegranate seed oil, castor oil, cocoa butter, jojoba oil, rosehip oil, grapeseed oil, kenaf seed oil and pumpkin seed oil) utilization have high potential to act as natural UV filters and at the same time help in skin repairing. The seed oils contributed beneficial properties to the sunscreen formulation by their synergistic effect with antioxidants, antiaging properties, anti-inflammatory effect, and potential hormetic effect. The finding of specific bioactive compound from seed oils provide better understanding on the contribution of seed oils in sunscreen formulation.
The application of nanostructured lipid carrier (NLC) in UV filters encapsulation was found to enhance its safe use. In this work, kenaf seed oil-NLC (KSO-NLC) co-loaded with UV filters encapsulated was used as an active ingredient in α-tocopherol cream to develop a photoprotective prototype. It was then subjected to further analysis to determine the physical properties storage stability and cytotoxicity. The ratio of KSO-NLC to α-tocopherol cream was optimised based on the SPF value using UV transmittance analyser. The physical properties of the samples were analysed and the amount of α-tocopherol was quantified by ultra-high performance liquid chromatography (UHPLC). The optimised sample was then evaluated for in vitro antioxidant activities using DPPH and ABTS assays. Meanwhile, in vitro cytotoxicity was studied on normal human dermal fibroblast (NHDF) cell line using MTT and CCK-8 assays. The sample produced by KSO-NLC to α-tocopherol cream in ratio 1:2 (N3) showed SPF value > 50. Besides, the samples showed microbial stability and sustainable α-tocopherol content upon 12 weeks of storage. The cytotoxicity evaluation of N3 and α-tocopherol cream (N5) showed > 100 % cell proliferation indicated there is no side effect on the cell growth, yet it triggered the cell proliferation with the presence of bioactive compounds. Overall, the results herein gathered are very promising towards the development of new green cosmetic formulations with the utilisation of KSO-NLC and palm-based α-tocopherol cream.