In Vitro Inhibition of Cholera Toxin Production in <i>Vibrio cholerae</i> by Methanol Extract of Sweet Fennel Seeds and Its Components

Abstract

SUMMARY: A newly emerged Vibrio cholerae O1 El Tor variant strain with multidrug resistance is considered a threat to public health. Recent strategies to suppress virulence factors production instead of bacterial growth may lead to less selective pressure for the emergence of resistant strains. The use of spices and their active constituents as the inhibitory agents against cholera toxin (CT) production in V. cholerae may be an alternative approach to treat cholera. In this study, we examined the potential of sweet fennel seed (Foeniculum vulgare Miller var. dulce) methanol extract to inhibit CT production in V. cholerae without affecting viability. The methanol extract of sweet fennel seeds significantly inhibited CT production in various V. cholerae strains, regardless of serogroup or biotype. Interestingly, transanethole and 4-allylanisole, essential oil components of sweet fennel seeds, also demonstrated similar effects. Here, we report that sub-bactericidal concentrations of sweet fennel seed methanol extract and its major components can drastically inhibit CT production in various V. cholerae strains.

Dual Inhibitory Activity of Petroselinic Acid Enriched in Fennel Against Porphyromonas gingivalis

“…It has been shown that essential oils obtained from the fennel leaves are characterized by a high anethole concentration and antimicrobial activity against Gram-positive bacteria ( Senatore et al, 2013 ). Furthermore, another study reported that the Gram-negative food-borne pathogen, Vibrio cholerae , was killed by methanol-extracted sweet fennel seeds by inhibition of cholera toxin production ( Chatterjee et al, 2016 ). However, the antimicrobial activity of fennel toward oral bacteria has not been systematically studied and mechanisms by which fennel contribute to antimicrobial activity remain unknown.…”