Antifungal activity of free and alginate-encapsulated Punica granatum fruit peel extract against dermatophytes using a human nail model.

BACKGROUND: Dermatophytosis and onychomycosis are among the most prevalent superficial fungal infections worldwide and remain difficult to treat because of prolonged therapy, recurrence, and emerging antifungal resistance. Punica granatum fruit, pomegranate, has a peel rich in phenolic compounds with documented antimicrobial properties; however, the therapeutic application of plant-derived extracts may be limited by physicochemical instability and low bioavailability. AIMS: To evaluate the antifungal activity of a hydroalcoholic extract of pomegranate peel and its alginate-encapsulated formulation against dermatophytes, using sterilized human nail fragments as a biologically relevant ex-vivo model. METHODS: The peel extract was obtained by hydroalcoholic maceration followed by lyophilization. Alginate microparticles were produced by spray drying. Encapsulation efficiency, release profile, antifungal and antibacterial activities, minimum fungicidal concentration, inhibition of hyphal elongation, ultrastructural alterations in fungal hyphae grown on human nail fragments, and cytotoxicity in Vero cells were evaluated. All experiments were performed in triplicate and repeated in at least three independent experiments. RESULTS: The extraction yield was 15.2%, and encapsulation efficiency reached 90.25%. The free extract exhibited rapid release, whereas alginate microparticles provided a controlled release profile. The extract showed antifungal activity against Trichophyton mentagrophytes and Trichophyton rubrum (MIC=125 μg/mL), and Nannizzia gypsea (MIC=250 μg/mL), as well as antibacterial activity against Staphylococcus aureus (MIC=125 μg/mL). No activity was observed against Pseudomonas aeruginosa. Both free and encapsulated formulations produced marked ultrastructural alterations in fungal hyphae grown on human nail fragments, including deformation, rupture, and cytoplasmic leakage. Microencapsulation reduced cytotoxicity (CC50=224 μg/mL) compared with the free extract (CC50=80 μg/mL) and improved the selectivity index. CONCLUSIONS: Alginate microencapsulation preserved the antifungal activity of pomegranate peel extract while reducing cytotoxicity and providing controlled release. The maintenance of antifungal activity in a human nail model supports the potential application of this formulation as a topical strategy for the management of dermatophyte-associated nail infections and warrants further preclinical investigation.