Liposomal and Nanostructured Lipid Nanoformulations of a Pentacyclic Triterpenoid Birch Bark Extract: Structural Characterization and In Vitro Effects on Melanoma B16-F10 and Walker 256 Tumor Cells Apoptosis

<b>Background/Objectives</b>: Pentacyclic triterpenoids are increasingly studied as anticancer agents with many advantages compared to synthetic chemotherapeutics. The aim of this study was to prepare liposomal and nanostructured lipid formulations including a standardized extract of silver birch (<i>Betula pendula</i>) outer bark (TTs) and to evaluate their potential as anticancer agents in vitro, using Melanoma B16-F10 and Walker carcinoma cells. <b>Methods</b>: Appropriate solvents were selected for efficient TTs extraction, and original recipes were used to obtain Pegylated liposomes and nanolipid complexes with entrapped TTs, comparative to pure standards (betulinic acid and doxorubicin) in similar conditions. The composition, morphology, and sizes of all nanoformulations were checked by high-performance liquid chromatography/mass spectrometry, Transmission Electronic Microscopy, and Diffraction Light Scattering. The entrapment efficiency and its impact on cell viability, cell cycle arrest, and apoptosis by flow cytometry was also measured on both cancer cell lines. <b>Conclusions:</b> The standardized TTs, including betulin, lupeol, and betulinic acid, showed good stability and superior activity compared to pure betulinic acid. According to experimental data, TTs showed good entrapment in liposomal and NLC nanoformulations, both delivery systems including natural, biodegradable ingredients and enhanced bioavailability. The apoptosis and necrosis effects were more pronounced for TTs liposomal formulations in both types of cancer cells, with lower cytotoxicity compared to Doxorubicin, and can be correlated with their increased bioavailability.