Potentiation of the Pharmacological Effects of an Aristolochia clematitis L. Extract by Loading into Liposomes Facilitating Release to HaCaT Cells

Background: Aristolochia clematitis L. (AC), a plant with diverse traditional uses, has gained increasing scientific interest due to its rich content of bioactive compounds such as flavonoids and polyphenols. However, its systemic use is limited by the presence of aristolochic acids, which are known for their nephrotoxic and carcinogenic potential. Methods: In this context, the present study investigates the therapeutic potential of A. clematitis extract by encapsulating it in liposomes with the aim of enhancing its topical efficacy. Results: The extract was characterized in terms of its flavonoid content (67.23 ± 0.33 mg QE/g DW (quercetin/dry plant material)) and polyphenols expressed as gallic acid equivalents (64.38 ± 0.16 mg GAE/g DW), as well as its antioxidant capacity using the reagents 1,1-diphenyl-2-picrylhydrazyl (DPPH − IC50 = 0.1619 mg/mL extract) and diammonium 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS − IC50 = 205.57 μg/mL extract). Four types of liposomes were synthesized (two loaded with extract and two empty), and their characterization was performed using Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS), Zeta Potential, polydispersity index, and in vitro release studies. Conclusions: The results demonstrated a high entrapment efficiency (over 82%), good stability over 30 days, and controlled release of flavonoids. Microbiological studies revealed relevant antimicrobial activity against Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, and Pseudomonas aeruginosa strains. The evaluation on HaCaT skin-derived cells (at 10–100 µg/mL) proved that the samples displayed good overall tolerability, slightly decreasing cell viability (the most statistically significant being associated with AC treatment) and showing no structural, nuclear, or mitochondrial morphological changes.