Development and Evaluation of Elaeagnus rhamnoides (L.) A. Nelson Oil-Loaded Nanostructured Lipid Carrier for Improved Skin Hydration

Sea buckthorn (SB) (Elaeagnus rhamnoides (L.) A. Nelson) is rich in flavonoids, phenolic compounds, anthocyanins, carotenoids, and phytosterol. Its phytochemicals exhibit various biological activities, such as antioxidant, immunomodulatory and anti-carcinogenic activities. SB also helps prevent the development of wrinkles and protects the skin’s surface from UV rays. The purpose of the present study was to develop and characterize an SB oil (SBO)-loaded nanostructured lipid carrier (NLC) for improved skin hydration. The response surface methodology (RSM) and central composite design (CCD) were employed to optimize the influencing factors (wax percentage, surfactant percentage, and PEG400 percentage in the surfactant) to achieve the desirable qualities in SBO-NLCs. The optimum (minimum) size of SBO-NLCs (105.26 nm) was obtained with a combination of 2.5% wax, 7.5% surfactant, and 30% PEG400 in the surfactant. A narrow polydispersity index (PDI; 0.16), relatively low zeta potential (ZP; −15.63 mV), and high entrapment efficiency (EE; 90.88%) were observed in this study. Reduced quadratic and reduced 2FI models were adapted to predict conditions to attain the optimum size and PDI of SBO-NLCs, respectively. ZP and EE were predicted with the help of a reduced cubic model. All of the predicted models were statistically significant. Differential scanning calorimetry results suggested that the SBO-NLCs had less crystallinity and therefore reduced the rate of drug expulsion from the inner core of the NLCs. A noticeable level of occlusion effect was observed in the SBO-NLCs. The SBO-NLCs showed a faster vitamin E (biomarker for the drug) release rate into the skin within 24 h, and the released vitamin E level after 48 h was significantly higher than that for the free SBO. Additionally, SBO-NLCs delivered vitamin E into the inner skin significantly (22.73 ± 1.67 µg/cm2 of skin). In conclusion, the SBO-NLC is a potential delivery system that can be used to prevent skin water loss and improve skin hydration. Further investigations, such as drug stability and safety evaluations, are required prior to commercialization for human use.