Nanostructured lipid carriers as a promising dermal delivery platform for st. john's wort extract: prelimi- nary studies

Purpose: Nanostructured lipid carriers (NLC) can improve the stability of various phytochemicals, so this re-search aimed to develop and employ such delivery systems for Hypericum perforatum extract containing the light-and oxygen-sensitive phloroglucinol hyperforin.Materials and methods: By varying the processing parameters and the solid and liquid lipids used, different NLC models were obtained via emulsification, followed by high-shear homogenization and ultrasonication. After char-acterization of the elaborated nanocarriers, those that ex-hibited optimal properties were loaded with St. John's wort extract by incorporating it in the lipid phase before emul-sification and also studied.Results: The NLC models developed by prolonged ultrasonication demonstrated favorable characteristics re-garding particle size, polydispersity index (PDI), and zeta potential (ZP). The physically stable during long-term stor-age nanosystems, which also showed a reduced degree of crystallinity of the solid lipid included, were loaded with St. John's wort extract. Of the carriers so-obtained, those developed by ultrasonication at ambient temperatures can be described as acceptably uniform systems (PDI from 0.23 +/- 0.01 to 0.27 +/- 0.01), comprising particles with dimen-sions below 200 nm, favorable ZP values (zeta > |30 mV|), and superior entrapment efficacy (EE) greater than 85%.Conclusion: In this research, different stable NLC dispersions were successfully developed. After the inclu-sion of the St. John's wort extract, the model possessing the highest EE (87.77 +/- 0.64%) was chosen as a carrier to conduct further studies evaluating its wound-healing po-tential.