POLYSACCHARIDE-BASED HYDROGELS, CONTAINING OLIVE MILL WASTEWATER (OMW), TO PRODUCE ANTIBACTERIAL FILMS FOR WOUND HEALING

The aim of this work was the development of polymeric films from polysaccharides, containing olive mill wastewater (OMW) as antibacterial agent [1], for skin injures and wound healing. An optimal wound dressing should be nontoxic, non-adherent, non-allergenic, it should also maintain a wet medium at the wound interfacing and be easily removed without any trauma. Polysaccharides represent an essential natural source of versatile materials and, in this work, they were chosen for their good technological properties and advantageous effects in terms of homogeneity, bioadhe- sion, and bioactivity. Among the different tested polymers, chitosan (at medium molecular weight), sodium alginate, sodium hyaluronate and xanthan gum were selected to prepare the studied films. All the polymers had already shown a good immunogenic capacity, making them excellent candidates for the treatment of wounds, and even an antimicrobial activity as in the case of chitosan. Films were prepared by solvent casting method, starting from pure or binary mixtures of biopolymer-based hydrogels, after characterization regarding rheological behavior, pH values and mucoadhesive properties. Hydrogels were prepared under gentle magnetic stirring by dispersing the selected biopolymer in water with subsequent casting of the mixture into circular Teflon moulds (diameter 1.7 cm) and placed in the incubator at 37.0°C ± 0.1 for 5 h. Then, the dried films were removed from the mould and stored at room temperature. The preliminary results suggested that hydrogels showed good casting properties, able to produce smooth films suitable for wound healing. The properties of the hydrogel films obtained, including morphology, thickness, water content and water holding were assessed [2]. Films showed a good deformability, suggesting an easy adaptability to any kind of surface. Moreover, each polymeric matrix showed a good ability in skin adhesion and in the absorption of adequate amounts of water, comparable to the extent of a wound exudate. Finally, OMW, made up of washing and process waters, as well as the aqueous fraction of drupe juices, was added in hydrogels before the film casting. Polyphenolic compounds inside waste products showed relevant pharmaceutical properties, such as antioxidant, anti-allergic, anti-inflammatory, anti-tumor and anti-hyper- tensive effects. Moreover, these compounds have an antimicrobial activity which can be exploited against human antibiotic- resistant pathogens (MDR), which represent one of the main problems in the nosocomial environment in which there is a greater diffusion of MDR bacterial species identified under the acronym ESKAPE, i.e. En- terococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomo- nas aeruginosa and Enterobacteriaceae. The antibacterial effects of OMW represent a promising area for therapeutic purposes in the human envi- ronment, in particular the phenolic compounds seem to offer a good activity both administered as an extract and used in film formulations.