Tidbits: eugenolo

In un ancora più recente articolo su Applied and Environmental Microbiology, si esamina l’effetto antibatterico dell’eugenolo. E’ da molto tempo noto che questo composto (presente nell’olio essenziale di chiodi di garofano, di foglia di cannella, di alcune varietà di basilico, e in molte altre piante) mostra attività antibatterica diretta, come molti dei derivati volatili del percorso dell’acido shichimico, attraverso l’interazione con la membrana e la sua destabilizzazione o lisi. In questo articolo si osserva che anche concentrazioni al di sotto del livello inibitorio agiscono sui processi patologici associati alle infezioni batteriche. In particolare l’eugenolo sembra in grado di ridurre l’espressione di varie esoproteine (due enterotossine, SEA e SEB, e la toxic shock syndrome toxin 1) mediante azione a livello dell’espressiione genica.

Eugenol, an essential oil component in plants, has been demonstrated to possess activity against both Gram-positive and Gram-negative bacteria. This study examined the influence that subinhibitory concentrations of eugenol may have on the expression of the major exotoxins produced by Staphylococcus aureus. The results from a tumor necrosis factor (TNF) release assay and a hemolysin assay indicated that S. aureus cultured with graded subinhibitory concentrations of eugenol (16 to 128 µg/ml) dose dependently decreased the TNF-inducing and hemolytic activities of culture supernatants. Western blot analysis showed that eugenol significantly reduced the production of staphylococcal enterotoxin A (SEA), SEB, and toxic shock syndrome toxin 1 (the key exotoxins to induce TNF release), as well as the expression of {alpha}-hemolysin (the major hemolysin to cause hemolysis). In addition, this suppression was also evaluated at the transcriptional level via real-time reverse transcription (RT)-PCR analysis. The transcriptional analysis indicated that 128 µg/ml of eugenol remarkably repressed the transcription of the S. aureus sea, seb, tst, and hla genes. According to these results, eugenol has the potential to be rationally applied on food products as a novel food antimicrobial agent both to inhibit the growth of bacteria and to suppress the production of exotoxins by S. aureus.