Antimicrobial activities of waxes extracted from Spartium junceum L.

Spartium junceum L., which is known in Italy as Ginestra, gained interest as a natural, sustainable and renewable fiber for textile and technical applications. The fibers were extracted through an innovative green process called Deshydrex, which involved a rehydration step of the dried stems, and the wastes generated through the processing were subjected to extraction for recovering waxes to be used in the pharmacological field. In this study, once the fiber was obtained, it was dried in an oven and subjected to the extraction process to obtain the waxes. The highest wax content was obtained from the broom fiber rehydrated for 3 days with a value of 22.9 ± 1.3 mg/g, followed by 2 and 4 days with a value of 14.1 ± 0.1 and 4.7 ± 0.2 mg/g, respectively. The waxes were subsequently qualified by LC/MS, which allowed the identification of 17 different waxes. The antimicrobial activities of three extracts (WI, WII, WIII) was evaluated against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Enterococcus hirae, Streptococcus pyogenes, Staphylococcus aureus) bacteria. Antimicrobial activity was assessed through agar well diffusion (AWD) and time-kill (TK) tests. The extracts showed different antimicrobial effects against S. aureus, S. pyogenes, and E. hirae. In AWD tests, the WII extract displayed antimicrobial activity up to 0.7 mg/mL. In TK tests, WIII, at 0.5 mg/mL, reduced the S. pyogenes loads below the detection limit, and at 1 mg/mL, reduced S. aureus by 6 logs. These findings suggest Spartium junceum waxes extracts as a natural antimicrobial agent, which could be employed in the development of dressings to prevent infections. This study was funded by the European Union Next Generation EU, in the framework of the “SBresswound”, PRIN 2022, project n. 2022JL9S9S, CUP J53D23001100006.