SUSTAINABLE POLYMERIC LIQUID DRESSING ENRICHED WITH POMEGRANATE PEEL EXTRACTS: RHEOLOGICAL DESIGN

The global rise of complex chronic wounds and antimicrobial resistance demands novel healing technologies based on biocompatible polymers and natural compounds. Polymeric liquid dressings (in situ film-forming systems) emerge as sophisticated alternatives because they conform perfectly to the topographical irregularities of the lesion before drying, acting as a protective physical barrier and a local reservoir for bioactives. This study aimed to develop and comprehensively characterize an innovative polymeric liquid dressing containing pomegranate peel extract (PPE) derived from the valorization of agro-industrial waste. Ellagic acid-rich PPE was obtained via ultrasound-assisted extraction (80% acetone). Its superior antimicrobial activity was validated in a previous study by our group, demonstrating a minimum inhibitory concentration (MIC) of 2 mg/mL against skin pathogens Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, and Malassezia furfur (BRITO-OLIVEIRA et al., 2025). The polymeric matrix was optimized using poly(vinylpyrrolidone) (PVP: 20% w/v), carboxymethylcellulose (CMC: 3% w/v), xanthan gum (XG: 1% w/v), and glycerol (7% w/v) as a plasticizer. The final system was incorporated with PPE (2 mg/mL) and evaluated via rheology (25 °C), fluorescence microscopy, and FTIR. A 20% PVP concentration ensured the polymer chain entanglement essential for forming continuous films. Glycerol promoted molecular plasticization through hydrogen bonding with the pyrrolidone ring of PVP, providing flexibility and reducing the brittleness of the dried film. CMC and XG acted synergistically in structuring the fluid system. Rheological analysis revealed a predominantly elastic gel-like behavior (G' > G'') and a high yield stress, which are fundamental properties that prevent undesired running of the product after application and ensure its fixation on the wound bed until complete drying. FTIR and microscopy confirmed the homogeneous insertion of PPE into the biopolymeric matrix through intermolecular hydrogen interactions, evidenced by shifts in the hydroxyl band (~3200 cm⁻¹) and aromatic backbone vibrations (~1500 cm⁻¹). Although the phenolic extract caused minor reductions in the viscoelastic moduli and the consistency index (K), the structural integrity and in situ film-forming capacity were fully maintained. The incorporation of PPE (validated by BRITO-OLIVEIRA et al., 2025) into the synergistic PVP-CMC-XG matrix generated a stable and highly feasible liquid dressing. This approach valorizes industrial co-products and offers a promising therapeutic alternative aligned with circular economy principles.

FAPESP (grants 2023/03439-5, 2018/14582-5, 2019/13496-0, 2025/20131-0)