Abstract
Infected wounds pose a significant burden on healthcare systems due to complications such as tissue damage and delayed healing, which also impair patients’ quality of life. Researchers are therefore developing multifunctional dressings that support the multiphase wound repair process. In a context where the pharmaceutical sector embraces green economy principles, new materials must also ensure eco-sustainability and biocompatibility. This project aims to develop a new sustainable, biocompatible, and multifunctional wound dressing from Spanish Broom (Spartium junceum L.). Using a patented green extraction method, textile fibers are obtained from its stems and impregnated with natural extracts from Spanish Broom flowers and Glycyrrhiza glabra L. roots, encapsulated in phospholipid nanovesicles to ensure stability and controlled release. By-products from fiber extraction, such as waxes and pectins, are also recovered for potential use in pharmaceutical, cosmetic, and food applications.
Results achieved
The management of infected wounds has a significant economic impact on the health system due to severe consequences such as tissue damage and/or prolonged wound healing with negative effect on the quality of human life. Wounds are classified as acute or chronic wounds depending on the repair mechanism involved, and the healing process is influenced by different factors such as size, depth, and degree of injury of the wound. The knowledge of wound healing mechanisms has highlighted the need for multifunctional dressings that actively participate in the complex wound repair process. Cotton dressings are widely used in clinical applications to help with wound healing and prevent further complications. Recently, researchers showed more interest in designing new wound dressings as a valid alternative to cotton by utilizing sustainable, renewable, and inexpensive starting materials. In this context, biomaterials environmentally friendly and useful for health aligning with green economy goals are emerging. In this project new, sustainable, biocompatible and multifunctional Spanish Broom wound dressings able to improve the healing process have been developed. Spanish Broom (Spartium junceum L.), which is known in Italy as Ginestra, is a resistant, perennial shrub growing in poor, semiarid soils as a native species in Mediterranean scrub ecosystems. Spanish Broom fibers were extracted through an innovative and green process of extraction with the demonstrator plant realized in this project at Calabria University. Specifically, the new fiber extraction process consists of three steps: i) Partial dehydration of the plant by exposing it to sunlight for a period of 2 to 7 days or by controlled drying for a period of 5 hours to 3 days; ii) Rehydration of the plant with recycled water only, for a period of 2 to 5 days, depending on the duration of the drying phase; iii) separation of the cellulose fiber using rotating belts with retractable teeth. The fibers extracted are resistant, soft, and in general easily workable (carding, combing, and spinning). To support circular economy concept, vegetable wastes, i.e. waxy substances and pectins remaining after extraction of cellulose fibers, have been recovered and characterized for their efficient valorization in pharmaceutical, cosmetic and food fields. The chemical composition of waxes, performed by LC–MS/MS analysis, confirmed that all extracts shared a conserved chemical composition dominated by long-chain fatty alcohols and wax esters, suggesting that rehydration did not modify the intrinsic wax chemistry but affected its effective recovery and organization. Thermal and morphological analyses showed that increasing rehydration time promoted higher crystallinity and molecular packing, as evidenced by increased melting temperatures, fusion enthalpies, and the development of hierarchically organized crystalline structures. The antimicrobial assays revealed a clear structure–activity relationship. Waxes with higher crystallinity and more developed microstructures exhibited stronger and more selective activity against Gram-positive bacteria, with bactericidal effects observed for St. pyogenes. In contrast, waxes extracted after shorter rehydration showed limited biological activity. Regarding the recovery of pectins, this innovative method not only reduces environmental harm but also facilitates the extraction of pectin (6%). The results showed that the pectin content significantly changed as the rehydration time (2,3, and 4 D) of dried brooms. In particular, the recovery of pectin increased with an increasing hydration period of the plant stems. In fact, the extraction yield of 3D was doubled (3.1%), while 4D yield quadrupled (6.2%) compared to 2D yield (1.46%). Pectin obtained is characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM), providing valuable insights into its structural and morphological properties. Moreover, antimicrobial activity of pectins has been evaluated by agar well diffusion assay (WDA) against both Gram-positive and Gram-negative bacteria. Gram-positive strains were Streptococcus (St.) pyogenes ATCC 12344, Staphylococcus (Staph.) aureus DSM 799, Enterococcus (Ent.) hirae ATCC 10541, while Gram-negative strains were Escherichia (E.) coli NCTC 10538, E.coli ATCC 10536, and Pseudomonas (P.) aeruginosa ATCC 15442. The results showed that the three different Spanish Broom pectin extracts, namely PEC I, PEC II and PEC III obtained after rehydration of broom stems for 2, 3, and 4 days, did not shown significative bactericidal activity against bacteria studied. Our data are in accordance with literature, which showed that native pectin is characterized of a low antimicrobial activity compared to modified pectin (sulphated, pectin-oleate, pectin-linoleate, and pectin palmitate). In the context of a circular economy, our research on Spanish Broom has focused on maximizing the value of the entire plant, transforming its by-products, flowers and pods, into valuable materials, thus creating a "zero-waste" or near-zero-waste process. In particular, flowers were recovered, and SB flower extracts were obtained successfully using water, ethanol, or a water/ethanol mixture as a solvent. Extracts obtained are a natural source of polyphenolic compounds and flavonoids with antioxidant and antibacterial properties, whose biological stability can be preserved through nanoencapsulation. To prevent physical and chemical degradation and based on the antimicrobial analysis, only alcoholic extract has been easily encapsulated into ethosomes, chitosomes and hyalurosomes facilitating its use in wound care products. On the contrary, pods were ground and extracted with a hydroalcoholic mixture (50:50 v/v H₂O/EtOH). The extract was rich of polyphenols and flavonoids rendering it useful in pharmaceutical and cosmetic products. The extract was encapsulated in ethosomes in order to increase the stability and antioxidant activity. Moreover, in this project has been used also licorice (Glycyrrhiza glabra L.), which is among the most widely used medicinal plants, thanks to its known anti-inflammatory and antimicrobial properties. Roots were extracted through maceration in the dark for 72 hours using as solvent the mixture H2O:EtOH 50:50 v/v. To preserve biological activity, extract was successfully encapsulated into new nanovesicles based on unsaturated fatty acids, namely ufasomes (UFAs) made up of oleic and linoleic acid and ufasomes based only on oleic acid, which we indicated as aosomes (AOs). The biological studies demonstrated their biosafety and antioxidant properties, two important requirements for rapid wound closure, avoiding medical consequences. Moreover, Glycyrrhiza glabra L. was extracted using also different ratio of H20:EtOH (30:70 v/v) mixture and encapsulated in ethosomes using the ethanol injection method. Ethosomes showed good entrapment efficiency, nanometric size, good stability over time, and a slow release of polyphenols compared to the free extract and were not cytotoxic. In addition, during the project, it has been evaluated also the hydroalcholic Prunus spinosa L. extract, rich in polyphenols and exhibits strong antioxidant activity, supporting its suitability for wound-healing applications. Similarly to the aforementioned crude extracts, it was encapsulated into glycerosomes and transferosomes, based on lecithin, glycerol or tween 80 using the sonication technique. The loaded vesicles have a nanometric size (<200 nm), good size distribution (PDI lower than 0.2), and appropriate encapsulation efficiency (~60%). Moreover, the nanovesicles showed good stability over time, and allowed for a sustained release of polyphenols. Biological assays revealed that loaded nanovesicles are not cytotoxic and exhibit antibacterial activity towards Staphylococcus aureus. Finally, to obtain multifunctional properties (antioxidant, anti-inflammatory, antimicrobial, and healing), Spanish Broom dressings have been impregnated with crude extracts obtained from Glycyrrhiza glabra L. roots, Spanish Broom flowers, and Prunus spinosa L. blackthorns, respectively, and with the corresponding loaded nanovesicles. The healing ability of all developed Spanish broom dressings was evaluated by scratch test on WS1 cell fibroblasts. The results showed that all developed dressings were able to accelerate wound closure by reducing wound healing time. To conclude, our investigation into Spanish Broom has concentrated on optimizing the value of the entire plant by extracting the fibers with natural, eco-friendly process and converting its by-products, pectins, waxes, flowers, and pods into valuable materials, so establishing a "zero-waste" or near-zero-waste process. In addition, our findings have demonstrated the potential use of Spanish Broom in the pharmaceutical field as multifunctional gauze, opening new perspectives of use for this plant.Dettagli del progetto
Responsabile scientifico: Teresa Cerchiara
Strutture Unibo coinvolte:
Dipartimento di Farmacia e Biotecnologie
Coordinatore:
ALMA MATER STUDIORUM - Università di Bologna(Italy)
Contributo totale di progetto: Euro (EUR) 202.453,00
Contributo totale Unibo: Euro (EUR) 97.953,00
Durata del progetto in mesi: 24
Data di inizio
28/09/2023
Data di fine:
28/02/2026
