Korean red ginseng (KRG) extract is proposed for cosmetic use, but no data on biological effects of KRG-loaded vehicles exist. The study aimed to optimize new multi- and monophase vehicles for KRG extract delivery, assess their biocompatibility and evaluate their radical scavenging effect in vitro. Storage stability of oil-in-water nanoemulsions (NEs) and hydroalcoholic gels (2 % w/w KRG) was assessed over twelve weeks using dynamic light scattering, rheology and pH measurements. Release profiles of ginsenosides Rb1 (more hydrophilic) and Rg1 (moderately lipophilic) through a cellulose membrane were also investigated employing Franz diffusion cells. Antioxidant potential and biocompatibility were assessed via 2,2-diphenyl-1-picrylhydrazyl (DPPH) and cell viability assays. Vehicles remained stable over twelve weeks at 8 °C (NEs D_h stable, gel viscosity + 3.5 %). Diffusion studies showed higher release of Rg1 vs. Rb1 (7.10 vs. 1.39 µg/cm^-2 after 28 h). KRG-formulations demonstrated good biocompatibility with primary human dermal fibroblasts and HaCaT keratinocytes (72-94 % viability). Radical scavenging capacity of KRG extract did not differ between pure and incorporated form and was lower than that of a Hypericum extract or ascorbic acid. Results render KRG-formulations a potentially promising alternative to conventional antioxidants used in daily products.

Diffusion studies are crucial for cosmetic and pharmaceutical formulation development to assess skin permeation of small molecules, often accessible via ultraviolet-visible (UV/Vis) absorption. For complex plant extracts, ultra high performance liquid chromatography/mass spectrometry (UHPLC/MS) has emerged as a predominant analytical tool. However, the commonly used phosphate-buffered saline (PBS) as physiological receptor fluid can affect LC-MS analysis by altering chromatographic performance and ionization efficiency. Alternative protocols for testing release and skin permeation of phytochemicals remain to be established. We therefore evaluated different buffer media at pH 7.4 (PBS according to European Pharmacopoeia, ammonium acetate 0.1 M, ammonium formate 0.15 M) for their suitability as acceptor fluids in release and permeation studies with cellulose acetate and porcine membranes. Korean red ginseng (KRG) extract was incorporated as model extract in three different formulation types (nanoemulsion, hydroalcoholic gel, amphiphilic cream). Storage stability was assessed via rheology and pH where required. Representative ginsenoside saponins Rb1 and Rg1 (logP 0.23 and 1.12) were quantified via UHPLC/MS. Interestingly, the results and differences between buffer media differed depending on membrane type. Drug release and permeation through the synthetic membrane varied among buffers for all vehicles (23.2-70.8 µg/cm²), whereas permeation through pig skin was comparable for all tested buffers (0.2-10.4 µg/cm²). Using alternative buffers, a comparison of vehicle types showed hydroalcoholic gels superior to the two multiphase systems regarding drug release and permeation. These results suggest that all tested alternative buffer media are suitable for comparative diffusion studies of plant-based actives studies especially when using biological membranes.