Abstract
Chinese herbs are a useful resource bank for natural drug development, and have attracted considerable attention to exploit quorum sensing inhibitors (QSIs). This study was designed to screen QSIs from raw Chinese herb materials. Of the 38 common herbs examined, the ethanol extract of Campsis grandiflora flower had the strongest QSI activity. The C. grandiflora flower ethanol extract (CFEE) was purified by HPD600, and the QSI activities were examined in further detail. CFEE inhibited violacein production of Chromobacterium violaceum 026 in a dose-dependent manner, and inhibit the swarming abilities of Escherichia coli K-12 and Pseudomonas aeruginosa PAO1. Furthermore, CFEE could inhibited biofilm formation and destroyed mature biofilms of E. coli K-12 and P. aeruginosa PAO1. The composition of CFEE was determined by UPLC-MS/MS to distinguish active QSI compounds, and 21 compounds were identified. In addition to gallic acid and caffeic acid, two organic acids, malic acid and succinic acid, were confirmed for the first time to have autoinducer type 1 QSI activities. Therefore, CFEE is a potential QSI that could be used as a novel antimicrobial agent and should be considered for medicinal development.
Highlights
Since their discovery, antibiotics, have played a vital role in the treatment of bacterial infections and diseases in humans and animals [1]
Thirty-eight flowers from plants used for Chinese herbs were screened using Chromobacterium violaceum 026
Our results demonstrate for the first time that malic acid and succinic acid have inhibitory effects on the autoinducer type 1 (AI-1) Quorum sensing (QS) system of C. violaceum 026
Summary
Antibiotics, have played a vital role in the treatment of bacterial infections and diseases in humans and animals [1]. A limited number of new antibiotics have been developed in the past 50 years [2], and infections caused by drug-resistant bacteria are currently one of the leading causes of death worldwide. Bacteria can perform coordinated activities, including biofilm formation, swarming motility, and virulence, and this coordination was previously thought to be restricted to multicellular organisms [3,4,5]. QS is defined as environmental signal sensing system to monitor population density of bacterial, and regulate a set of bacterial behaviors including bioluminescence, biofilm formation, virulence, swarming motility, competence, antibiotic production, Molecules 2020, 25, 4727; doi:10.3390/molecules25204727 www.mdpi.com/journal/molecules
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