Phytochemical Screening of Quaking Aspen (Populus tremuloides) Extracts by UPLC-QTOF-MS and Evaluation of their Antimicrobial Activity.

Annabelle St-Pierre,André Lajeunesse,Dorian Blondeau,Isabel Desgagné-Penix,Julien Bley,Nathalie Bourdeau

doi:10.3390/molecules23071739

Abstract

The continual emergence of pathogen resistance is a recurring challenge and pushes for the development of antimicrobial compounds. Here, we investigated compounds from quaking aspen trees (Populus tremuloides) as potential antimicrobial agents. Several extractions using different solvents were realized, and corresponding antimicrobial activity was tested against eight microorganisms. Results revealed that polar extraction solvents including water, ethanol and methanol gave the best extraction yields (>15.07%). Minimal inhibition concentration (MIC) and minimal bactericidal/fungicidal concentration (MBC/MFC) demonstrated that water extracts had the best antimicrobial activity by a weak to moderate inhibition of growth of all eight tested microorganisms in addition to having a bactericidal effect on three of them. The quaking aspen methanol extract also displayed antimicrobial activity but to a lower level than the water extract. Ultra-performance liquid chromatography quadrupole time-of flight mass spectrometry (UPLC-QTOF-MS) analysis led to the identification of 92 compounds, mainly polyphenols in both extracts, with 22 molecules previously known for their antimicrobial properties. According to the relative abundance, 4-hydroxybenzaldehyde (5.44% in methanol extract) and kaempferol (5.03% in water extract) were the most abundant antimicrobial compounds. Among antimicrobial molecules identified, nine were from the flavonoid family. The results of our study demonstrate the interest of using quaking aspen as source of antimicrobial compounds.

Highlights

Continual emergence of pathogens resistant to antibiotics, antiseptics and disinfectants is a real challenge and it motivates innovation in the field of antimicrobial agent development [1,2].This research field is in perpetual expansion in order to discover new molecules with antimicrobial activity
The aim of this study was to determine the antimicrobial potential of quaking aspen bark residues through the extraction of bioactive metabolites
We found that specialized metabolite extractions are relevant to isolate antimicrobial molecules from bark residues

Summary

Introduction

Continual emergence of pathogens resistant to antibiotics, antiseptics and disinfectants is a real challenge and it motivates innovation in the field of antimicrobial agent development [1,2]. This research field is in perpetual expansion in order to discover new molecules with antimicrobial activity. Synthetic antimicrobial agent development has largely contributed to the field, the current environmental concerns coupled with the need to deal with our natural resource residues has prompted a renewed interest in natural antimicrobial molecules. It is relevant to look at plant specialized (aka secondary) metabolites known for their biological and therapeutic activities. Molecules 2018, 23, 1739 by plants with the purpose of developing antimicrobial agents. It was estimated that there are around 25% of prescribed drugs on the market that come from plant metabolites [3,4]

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