Verbascoside-rich Buddleja davidii extract in liposomal systems: modulation of release behavior for topical wound treatment

Vollständiger Abstract

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Introduction: Chronic wounds represent a major clinical challenge due to their complex pathophysiology, characterized by persistent inflammation, excessive production of reactive oxygen species (ROS), high risk of microbial contamination, and impaired tissue regeneration. Despite several plant extracts offering antioxidant, anti-inflammatory, and antibacterial properties, their therapeutic use is limited by poor stability and rapid clearance of the active compounds from the wound site, particularly in the case of hydrophilic molecules. In this study, a verbascoside-rich extract obtained from Buddleja davidii was encapsulated into liposomes for potential wound healing applications. Methods: The formulations were characterized in terms of vesicle size, polydispersity index, and zeta potential using dynamic and electrophoretic light scattering. Encapsulation efficiency and verbascoside release profiles were assessed by HPLC, while antioxidant activity was evaluated by the DPPH assay. Formulation stability was monitored for two months, and in vitro biocompatibility and antioxidant protective effects were investigated in human keratinocytes, while antimicrobial activity was tested against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli. Results: The liposomal formulations modulated the release kinetics of verbascoside, showing a prolonged release of the encapsulated fraction, limiting its rapid dispersion in aqueous environments and enabling sustained availability over time. Encapsulation preserved the antioxidant activity of the extract and ensured excellent in vitro biocompatibility across a wide concentration range. Finally, liposomes showed strong and concentration-dependent antimicrobial activity against MRSA, as well as bacteriostatic responses against E. coli. Discussion: Collectively, these findings highlight liposomal encapsulation as a solid strategy to prolong the release–and thus the residence time–of hydrophilic plant-derived actives while maintaining or potentiating their biological activities in the context of wound healing.