Antimicrobial activity of commercial Olea europaea (olive) leaf extract

doi:10.1016/j.ijantimicag.2008.10.026

International Journal of Antimicrobial Agents

Volume 33, Issue 5, May 2009, Pages 461-463

https://doi.org/10.1016/j.ijantimicag.2008.10.026 Get rights and content

Abstract

The aim of this research was to investigate the activity of a commercial extract derived from the leaves of Olea europaea (olive) against a wide range of microorganisms (n = 122). Using agar dilution and broth microdilution techniques, olive leaf extract was found to be most active against Campylobacter jejuni, Helicobacter pylori and Staphylococcus aureus [including meticillin-resistant S. aureus (MRSA)], with minimum inhibitory concentrations (MICs) as low as 0.31–0.78% (v/v). In contrast, the extract showed little activity against all other test organisms (n = 79), with MICs for most ranging from 6.25% to 50% (v/v). In conclusion, olive leaf extract was not broad-spectrum in action, showing appreciable activity only against H. pylori, C. jejuni, S. aureus and MRSA. Given this specific activity, olive leaf extract may have a role in regulating the composition of the gastric flora by selectively reducing levels of H. pylori and C. jejuni.

Introduction

Olive leaf extract (OLE) is a dark brown, bitter-tasting liquid derived from the leaves of the olive tree (Olea europaea L., Oleaceae). OLE is marketed as a natural medicine with wide-ranging health benefits. Particular emphasis is placed on the antioxidant activity of the extract and the corresponding health benefits such as cardioprotective and chemopreventive effects [1]. OLE contains many different compounds collectively termed olive biophenols, which are thought to give the extract its varied therapeutic properties. The most abundant biophenol is oleuropein, with other biophenols such as verbascoside, apigenin-7-glucoside and luteolin-7-glucoside present in lower quantities [2]. Like many natural products, variation due to differences such as geographical location, plant nutrition and cultivar can influence the composition of the extract.

In addition to the health benefits described above, it is claimed that OLE may aid in the treatment of a broad range of infectious diseases if ingested. Although the antimicrobial activity of the component oleuropein has been examined previously [3], [4], very few reports describe the activity of the entire extract [5]. Therefore, the aim of this research was to examine the activity of OLE against a wide range of microorganisms to determine the spectrum of activity of the extract and to provide data either to support or dispute the claims made for the product.

Section snippets

Organisms

Reference strains (n = 34) and clinical isolates (n = 88) were obtained from the Division of Microbiology and Infectious Diseases, PathWest Laboratory Medicine WA, the Discipline of Microbiology and Immunology at The University of Western Australia, and Royal Perth Hospital, Perth, Western Australia.

Olea europaea (olive) leaf extract

‘High Strength Olive Leaf Extract’ (natural flavour), by Olive Leaf Australia (Coominya, Australia), was purchased from a local health food store. According to the label, the OLE was produced in

Results and discussion

The organisms least susceptible to OLE, with one or more isolates having MICs of ≥50% OLE, were Bacillus subtilis, Candida spp., Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Serratia marcescens (Table 1). Conversely, the most susceptible organism was Campylobacter jejuni, with MICs as low as 0.31%, followed by Helicobacter pylori with MICs of 0.62% and Staphylococcus aureus with MICs of 0.78%. The data indicate that OLE does not show broad-spectrum activity and has

Acknowledgments

The authors thank Dr. Helen Windsor for providing isolates of H. pylori, Mr. Steve Munyard for providing isolates of C. jejuni and Mr. Ray Mogyrosy for providing isolates of Listeria monocytogenes.

Funding: KAH was supported by a grant from the Raine Medical Research Foundation, Australia.

Competing interests: None declared.

Ethical approval: Not required.

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Dynamic ultrasound-assisted extraction of oleuropein and related biophenols from olive leaves
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Bactericidal activities of plant essential oils and some of their isolated constituents against Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, and Salmonella enterica
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Helicobacter pylori and antimicrobial resistance: molecular mechanisms and clinical implications
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Oleuropein, an antioxidant polyphenol from olive oil, is poorly absorbed from isolated perfused rat intestine
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Bioavailability and antioxidant effects of olive oil phenolic compounds in humans: a review
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On the in-vitro antimicrobial activity of oleuropein and hydroxytyrosol
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There are more references available in the full text version of this article.

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¹: Present address: Royal Perth Hospital, Perth, WA 6000, Australia.

²: Present address: Pharmacy Help, Hillarys, WA 6025, Australia.

³: Present address: Fremantle Hospital, Fremantle, WA 6160, Australia.

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International Journal of Antimicrobial Agents

Abstract

Introduction

Section snippets

Organisms

Olea europaea (olive) leaf extract

Results and discussion

Acknowledgments

References (12)

Dynamic ultrasound-assisted extraction of oleuropein and related biophenols from olive leaves

J Chromatogr A

Bactericidal activities of plant essential oils and some of their isolated constituents against Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, and Salmonella enterica

J Food Prot

Helicobacter pylori and antimicrobial resistance: molecular mechanisms and clinical implications

Lancet Infect Dis

Oleuropein, an antioxidant polyphenol from olive oil, is poorly absorbed from isolated perfused rat intestine

J Nutr

Bioavailability and antioxidant effects of olive oil phenolic compounds in humans: a review

Ann Ist Super Sanita

On the in-vitro antimicrobial activity of oleuropein and hydroxytyrosol

J Pharm Pharmacol

Cited by (254)

Evaluation of the effectiveness of natural extract as a substituent for synthetic preservatives and antioxidants in pharmaceutical preparations

Alternative approaches to therapeutics and subtherapeutics for sustainable poultry production

Valorization of Olea europaea and olive oil processing by-products/wastes

Mid-Infrared spectroscopic characterization: New insights on bioactive molecules of Olea europaea L. leaves from selected Italian cultivars

Obtaining green extracts rich in phenolic compounds from underexploited food by-products using natural deep eutectic solvents. Opportunities and challenges

The bioprofiling of antibacterials in olive leaf extracts via thin layer chromatography-effect directed analysis (TLC-EDA)

Short communicationAntimicrobial activity of commercial Olea europaea (olive) leaf extract

Abstract

Introduction

Section snippets

Organisms

Olea europaea (olive) leaf extract

Results and discussion

Acknowledgments

J Chromatogr A

J Food Prot

Lancet Infect Dis

J Nutr

Bioavailability and antioxidant effects of olive oil phenolic compounds in humans: a review

Ann Ist Super Sanita

On the in-vitro antimicrobial activity of oleuropein and hydroxytyrosol

J Pharm Pharmacol

Short communication
Antimicrobial activity of commercial Olea europaea (olive) leaf extract