Formulation and Evaluation of Lipid Pickering Emulsions Encapsulating a Combretum glutinosum Extract: In Vivo Wound Healing Activity

ABSTRACT Background: Combretum glutinosum (Combretaceae) is a medicinal plant widely used in West African traditional medicine for its wound healing, antimicrobial, antioxidant and anti-inflammatory properties. However, the poor physicochemical stability and limited bioavailability of its active compounds restrict its therapeutic application. Objective: This study aimed to develop and characterize solid lipid nanoparticles (SLNs) and Pickering emulsions encapsulating a hydrophilic extract of C. glutinosum, and to evaluate their wound healing activity in a rat burn model. Methods: SLNs were prepared by hot spontaneous emulsification using Suppocire as the lipid matrix and Solutol® HS15 as a non-ionic surfactant. Pickering emulsions were formulated using the SLN suspension as the aqueous phase and medium-chain triglycerides as the oil phase. Three formulations were prepared incorporating C. glutinosum extract at 0%, 0.2% and 0.8% (w/w). In vivo wound healing was assessed over 28 days on Wistar rats with experimental second-degree burns using Kamoshida scoring. Results: SLNs exhibited a mean hydrodynamic diameter of approximately 40 nm with spherical morphology confirmed by TEM. Pickering emulsions showed satisfactory macroscopic and microscopic stability over 28 days. The formulation containing 0.8% extract achieved complete epithelialization at day 22, comparable to silver sulfadiazine, while 0% and 0.2% formulations required 26 and 25 days, respectively. Conclusion: SLN-based Pickering emulsions represent a promising colloidal delivery system to enhance the wound healing efficacy of C. glutinosum extracts. The encapsulation provides protection of bioactive compounds and enables controlled topical release in a dose-dependent manner.