Characterization of entrapment behavior of polyphenols in nanostructured lipid carriers and its effect on their antioxidative activity

Polyphenols are widely used as antioxidant agents to protect human health. Resveratrol, kaempferol, and quercetin have been reported to have potent antioxidant activity; however, these compounds have many problems related to their practical application, such as instability and insolubility. Thus, a nanostructured lipid carrier (NLC) was utilized as a drug delivery system (DDS) to overcome these limitations. This study investigated the particle stability, drug loading performance, and antioxidant activity of polyphenols-incorporated NLCs. The particle size and distribution were suitable for DDS applications, and all the samples demonstrated good stability after 2 months of storage. Based on Raman spectroscopy analysis, polyphenols were successfully encapsulated in NLCs. Quantitative high-performance liquid chromatography analysis indicated that NLCs could load resveratrol more than kaempferol and quercetin. In addition, NLCs have successfully improved all the antioxidant activity per unit concentration of polyphenol (specific antioxidant activity) compared to the free polyphenols. Quercetin-incorporated NLCs showed the highest specific antioxidant activity. This result is the opposite of entrapment efficiency and actual antioxidant activity, most likely influenced by the location of entrapped polyphenol molecules. As it was performed, NLCs are highly recommended to be applied as an antioxidant delivery system.