Development and characterization of chitosan film containing hydroethanolic extract of Coffea arabica leaves for wound dressing application

The coffee leaves are considered by-products of the coffee industry, produced in significant quantities and containing numerous bioactive compounds. In the present work, chitosan films containing the hydroalcoholic extract of C. arabica L. leaves were developed with the aim of their application as wound dressing. The film's precursor solutions, containing chitosan (Chit; 2% w/v) and different concentrations of C. arabica L. extract (0, 125, 250 and 500 mg/cm3), were prepared and characterized by DLS, zeta potential, electrical conductivity, and stationary rheology. After the preparation of films, the physicochemical and mechanical properties, as well as the in vitro biological activity, were evaluated. The precursor solutions presented a pseudoplastic profile and aggregates of 5-20 mu m. Increasing values of electrical conductivity indicate a strong presence of ionic compounds in the extracts. On the other hand, viscosity, particle size, and zeta potential were reduced due to the addition of the extracts, which was attributed to the neutralization of chitosan chains by anionic ions from the extract. The chitosan/extract films showed uniformity in terms of weight and thickness. Additionally, the moisture, swelling, solubility, and thermal resistance values showed satisfactory results for the application of the films on skin wounds. However, the mechanical strength decreased with the extract concentration, due to the reduction of chitosan-chitosan interactions caused by the extract components inherited from the liquid phase to the solid phase. All films demonstrated antimicrobial activity against Staphylococcus aureus and Staphylococcus epidermidis and showed no reduction in L929 cell viability in the cytotoxicity assay. Furthermore, the films containing 125 and 250 mg/cm3 promoted cell migration in the scratch assay. The results obtained in this study open the possibility of using chitosan films containing C. arabica L. leaf extracts for the development of wound dressings, with the advantage of using materials of natural origin and with antimicrobial activity.