Table 2.
Overview of recent studies reporting probable modes of action of phenolic compounds on AHL-mediated QS in bacteria.
| Phenolic compound (potential QSI) | MIC | Anti-QS effect (phenotypes) | Mechanism and Method | References |
|---|---|---|---|---|
| Resveratrol | >1000 μg/mL against P. aeruginosa PAO1 and clinical isolates. | Inhibition of biofilm formation and enhancement of the effects of aminoglycoside antibiotics. | Lowering expression of lasI and rhlI, analyzed by qRT-PCR. | [121] |
| Curcumin and resveratrol | >100 μΜ for C. violaceum ATCC 12472 and 026. | Inhibition of violacein, biofilm formation and swarming motility. | In silico study (docking) with CviR QS regulator of C. violaceum. | [122] |
| Gingerol | >50 μg/mL for P. aeruginosa AM26. | Reduced biofilm formation, exopolysaccarides (EPS), pyocyanin and rhamnolipids. | In silico studies - docking and molecular dynamics - with LasR, RhlR, PhzR. | [123] |
| Phloretin, chrysin, quercetin, baicalein. | >100 μΜ for P. aeruginosa PA14. | Suppression of virulence factors production in P. aeruginosa. | Allosteric inhibition of LasR/RhlR. | [95] |
| Methyl gallate | 512 μg/mL for P. aeruginosa PAO1. | Reduction on biofilm formation, EPS, swarming motility, and virulence factors in P. aeruginosa. | Reduced expression of lasI, lasR, rhlI, and rhlR. | [70] |
| Vanillic acid | >250 μg/mL for S. marcescens MG1 and clinical isolate; >500 μg/mL for S. marcescens ATCC 14756. | Reduction of biofilm formation and expression of virulence factors in S. marcescens. | Affecting S-layer, flagellin and fatty acid biosynthesis proteins. | [107] |
| Rosmarinic acid | >100 μΜ for P. aeruginosa PAO1. | Induced the expression of 128 genes, many implicated in QS; and seven sRNAs encoded in regions close to QS-induced genes. | In silico study, RNA-Seq and qRT-PCR analysis. | [124] |
| Naringenin | >1 μM for E. coli LasR-based biosensor strain. | Inhibited QS-regulated virulence factors in P. aeruginosa PAO1. | Reduced expression of QS-regulated genes by directly binding to LasR, competing with its cognate activator (3OC12-HSL). | [125] |
| Chlorogenic acid | 5.12 mg/mL for P. aeruginosa PAO1 and C. violaceum. | Inhibited biofilm formation, swarming and violacein production in C. violaceum; inhibited virulence factors in P. aeruginosa PAO1 and attenuated C. elegans killing by P. aeruginosa. | In silico study (LasR, RhlR, PqsR); reduced expression of QS-related genes (lasI, lasR, rhlI, rhlR, pqsA, pqsR, cviI). | [126] |