Antibacterial and Synergistic Effects of <i>Terminalia citrina</i> Leaf Extracts Against Gastrointestinal Pathogens: Insights from Metabolomic Analysis

<b>Background/Objectives</b>: Bacterial contamination leads to foodborne illnesses, and new antibiotics are required to combat these pathogens. Interest has increased in medicinal plants as targets for new antibiotics. <b>Methods</b>: This study evaluated the antibacterial ac...

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Main Authors: Sze-Tieng Ang, Tak Hyun Kim, Matthew James Cheesman, Ian Edwin Cock
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Antibiotics
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Online Access:https://www.mdpi.com/2079-6382/14/6/593
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author Sze-Tieng Ang
Tak Hyun Kim
Matthew James Cheesman
Ian Edwin Cock
author_facet Sze-Tieng Ang
Tak Hyun Kim
Matthew James Cheesman
Ian Edwin Cock
author_sort Sze-Tieng Ang
collection DOAJ
description <b>Background/Objectives</b>: Bacterial contamination leads to foodborne illnesses, and new antibiotics are required to combat these pathogens. Interest has increased in medicinal plants as targets for new antibiotics. <b>Methods</b>: This study evaluated the antibacterial activity of leaf extracts from <i>Terminalia citrina</i> (Gaertn.) Roxb. ex Fleming against four bacterial pathogens (including a methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) strain) using disc diffusion and liquid microdilution assays. The phytochemical composition of the extracts were determined using ultra-high-performance liquid chromatography–mass spectrometry (UPLC-MS). <b>Results</b>: Both the aqueous and methanol extracts demonstrated noteworthy antibacterial activity against <i>Bacillus cereus</i> (MICs of 468.8 µg/mL and 562.5 µg/mL, respectively). Additionally, the extracts were effective against MRSA (MICs = 625 µg/mL). Strong antibacterial effects were also observed against <i>S. aureus</i>, with MICs of 625 µg/mL (aqueous extract) and 833.3 µg/mL (methanol extract). Twelve combinations of extracts and conventional antibiotics were synergistic against <i>B. cereus</i> and <i>S. flexneri</i>. UPLC-MS analysis revealed two flavonoids, orientin 2″-O-gallate and astragalin, exclusive to the aqueous extract, whilst pinocembrin and gallic acid were only detected in the methanol extract. Both extracts contained vitexin 2″-O-p-coumarate, ellagic acid, orientin, rutin, chebulic acid, terminalin, and quercetin-3β-D-glucoside. Both extracts were determined to be nontoxic. <b>Conclusions</b>: The abundance and diversity of polyphenols in the extracts may contribute to their strong antibacterial properties. Further research is required to investigate the antibacterial effects of the individual extract compounds, including their effects when combined with conventional antibiotics, and the potential mechanisms of action against foodborne pathogens.
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spelling doaj-art-ab349cc7253e47c6be9e24bd950981f22025-08-20T03:26:48ZengMDPI AGAntibiotics2079-63822025-06-0114659310.3390/antibiotics14060593Antibacterial and Synergistic Effects of <i>Terminalia citrina</i> Leaf Extracts Against Gastrointestinal Pathogens: Insights from Metabolomic AnalysisSze-Tieng Ang0Tak Hyun Kim1Matthew James Cheesman2Ian Edwin Cock3School of Environmental and Science, Griffith University, Nathan Campus, Brisbane 4111, AustraliaSchool of Environmental and Science, Griffith University, Nathan Campus, Brisbane 4111, AustraliaSchool of Pharmacy and Medical Sciences, Griffith University, Gold Coast Campus, Gold Coast 4222, AustraliaSchool of Environmental and Science, Griffith University, Nathan Campus, Brisbane 4111, Australia<b>Background/Objectives</b>: Bacterial contamination leads to foodborne illnesses, and new antibiotics are required to combat these pathogens. Interest has increased in medicinal plants as targets for new antibiotics. <b>Methods</b>: This study evaluated the antibacterial activity of leaf extracts from <i>Terminalia citrina</i> (Gaertn.) Roxb. ex Fleming against four bacterial pathogens (including a methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) strain) using disc diffusion and liquid microdilution assays. The phytochemical composition of the extracts were determined using ultra-high-performance liquid chromatography–mass spectrometry (UPLC-MS). <b>Results</b>: Both the aqueous and methanol extracts demonstrated noteworthy antibacterial activity against <i>Bacillus cereus</i> (MICs of 468.8 µg/mL and 562.5 µg/mL, respectively). Additionally, the extracts were effective against MRSA (MICs = 625 µg/mL). Strong antibacterial effects were also observed against <i>S. aureus</i>, with MICs of 625 µg/mL (aqueous extract) and 833.3 µg/mL (methanol extract). Twelve combinations of extracts and conventional antibiotics were synergistic against <i>B. cereus</i> and <i>S. flexneri</i>. UPLC-MS analysis revealed two flavonoids, orientin 2″-O-gallate and astragalin, exclusive to the aqueous extract, whilst pinocembrin and gallic acid were only detected in the methanol extract. Both extracts contained vitexin 2″-O-p-coumarate, ellagic acid, orientin, rutin, chebulic acid, terminalin, and quercetin-3β-D-glucoside. Both extracts were determined to be nontoxic. <b>Conclusions</b>: The abundance and diversity of polyphenols in the extracts may contribute to their strong antibacterial properties. Further research is required to investigate the antibacterial effects of the individual extract compounds, including their effects when combined with conventional antibiotics, and the potential mechanisms of action against foodborne pathogens.https://www.mdpi.com/2079-6382/14/6/593Combretaceaeplant extractsgastrointestinal pathogensMRSAantibacterial activitycombinational therapies
spellingShingle Sze-Tieng Ang
Tak Hyun Kim
Matthew James Cheesman
Ian Edwin Cock
Antibacterial and Synergistic Effects of <i>Terminalia citrina</i> Leaf Extracts Against Gastrointestinal Pathogens: Insights from Metabolomic Analysis
Antibiotics
Combretaceae
plant extracts
gastrointestinal pathogens
MRSA
antibacterial activity
combinational therapies
title Antibacterial and Synergistic Effects of <i>Terminalia citrina</i> Leaf Extracts Against Gastrointestinal Pathogens: Insights from Metabolomic Analysis
title_full Antibacterial and Synergistic Effects of <i>Terminalia citrina</i> Leaf Extracts Against Gastrointestinal Pathogens: Insights from Metabolomic Analysis
title_fullStr Antibacterial and Synergistic Effects of <i>Terminalia citrina</i> Leaf Extracts Against Gastrointestinal Pathogens: Insights from Metabolomic Analysis
title_full_unstemmed Antibacterial and Synergistic Effects of <i>Terminalia citrina</i> Leaf Extracts Against Gastrointestinal Pathogens: Insights from Metabolomic Analysis
title_short Antibacterial and Synergistic Effects of <i>Terminalia citrina</i> Leaf Extracts Against Gastrointestinal Pathogens: Insights from Metabolomic Analysis
title_sort antibacterial and synergistic effects of i terminalia citrina i leaf extracts against gastrointestinal pathogens insights from metabolomic analysis
topic Combretaceae
plant extracts
gastrointestinal pathogens
MRSA
antibacterial activity
combinational therapies
url https://www.mdpi.com/2079-6382/14/6/593
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