An in vitro Study on the Potential Quorum Sensing Inhibitory Effects of Bean Sprout (Vigna radiata L.), Carrot (Daucus carota L.), and Yellow Pepper (Capsicum annuum L. var. annuum) Extracts Against Chromobacterium violaceum 12472 and Methicillin-Resistan

Abstract

The objective was to determine the presence of a biofilm inhibitory effect of mung bean
sprout, carrot, and yellow pepper extracts against MRSA. This pilot study was done to
assess their potential quorum sensing (QS) inhibitory effects and also to determine the
presence of anti-quorum sensing activity against Chromobacterium violaceum (CV12472).
There were two phases in this study: Phase 1 involved testing the presence of
antibacterial properties of the extracts using the Kirby-Bauer (KB) assay followed by an
assessment of their biofilm inhibitory properties against MRSA. Phase 2 involved the
evaluation of the capacity of the extracts to inhibit QS-controlled violacein production of
CV12472. The KB assay showed that none of the extracts exhibited bactericidal effects
against MRSA. All extracts showed significant biofilm inhibitory effects (p<0.05) compared to
the negative control. Yellow pepper showed the greatest inhibitory effect in a dosedependent
manner. Violacein production was also reduced in a dose-dependent manner
with the yellow pepper extract. Yellow pepper extract strongly suggests a potential QS
inhibitory effect. It is recommended to conduct further studies to test other virulence factors
which the yellow pepper extract may also inhibit and to study the subcomponents of yellow
pepper to isolate its active QS inhibiting compound.

Key words: quorum sensing, biofilm inhibition, MRSA, yellow pepper extract