Coumarin's Anti-Quorum Sensing Activity Can Be Enhanced When Combined with Other Plant-Derived Small Molecules.

Dmitry Deryabin,Kseniya Inchagova,Elena Rusakova,Galimzhan Duskaev

doi:10.3390/molecules26010208

Abstract

Coumarins are class of natural aromatic compounds based on benzopyrones (2H-1-benzopyran-2-ones). They are identified as secondary metabolites in about 150 different plant species. The ability of coumarins to inhibit cell-to-cell communication in bacterial communities (quorum sensing; QS) has been previously described. Coumarin and its derivatives in plant extracts are often found together with other small molecules that show anti-QS properties too. The aim of this study was to find the most effective combinations of coumarins and small plant-derived molecules identified in various plants extracts that inhibit QS in Chromobacterium violaceum ATCC 31532 violacein production bioassay. The coumarin and its derivatives: 7-hydroxycoumarin, 7.8-dihydroxy-4-methylcoumarin, were included in the study. Combinations of coumarins with gamma-octalactone, 4-hexyl-1.3-benzenediol, 3.4.5-trimethoxyphenol and vanillin, previously identified in oak bark (Quercus cortex), and eucalyptus leaves (Eucalyptus viminalis) extracts, were analyzed in a bioassay. When testing two-component compositions, it was shown that 7.8-dihydroxy-4-methylcoumarin, 4-hexyl-1.3-benzendiol, and gamma-octalactone showed a supra-additive anti-QS effect. Combinations of all three molecules resulted in a three- to five-fold reduction in the concentration of each compound needed to achieve EC50 (half maximal effective concentration) against QS in C. violaceum ATCC 31532.

Highlights

Coumarins are a class of natural compounds based on benzopyrones (2H-1-benzopyran-2-ones) [1]
The aim of this study was to find the most effective combinations of coumarins with small plant-derived molecules previously identified in extracts of oak bark (Quercus cortex), and eucalyptus leaves (Eucalyptus viminalis) to inhibit LuxI/LuxR-type quorum sensing in C. violaceum ATCC (American Type Culture Collection) 31532
Cultivation of C. violaceum ATCC 31532 with coumarin, 7-hydroxycoumarin, and 7.8dihydroxy-4-methylcoumarin followed registration of the optical density values (OP450) of bacterial biomass and violacein production (OP600), allowed us to evaluate their effect on the growth and QS-dependent biosynthesis in the bioassay

Summary

Introduction

Coumarins are a class of natural compounds based on benzopyrones These compounds can be classified depending on the core’s structure and the presence of substituents. There are the “simplest” coumarins (e.g., coumarin and dihydrocoumarin), followed by oxy-, meth-oxy-, and methylenedioxycoumarins with various substitutions in benzene/pyron rings (e.g., umbelliferon, 3-hydroxycoumarin, and scopoletin). The furancoumarins (e.g., bergamotin) contain an additional condensed furan core. More structurally complex compounds are the result of coumarin condensation with pyran, benzene, and benzofuran rings. Most of the compounds of this class in plants are found in the free state, and only a small number are found in glycosides with D-glucose attached to the C6, C7, or C8 atoms of the coumarin nucleus [2]

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