Natural Anti-bacterial effects of Olive Leaf Extract

Olive leaf extract is obtained from the olive leaves of the tree called Olea europaea (olive tree) that is well known for its anti-microbial properties. Olive leaves in particular are popular for their ability to resist attack by insects and other microbes. The active constituents in olive leaves are the polyphenolic compounds, triterpenes, secoiridoids, flavonoids and the antioxidant oleuropein which exhibits potent antimicrobial properties (1,2,3). The bioactive compound secoiridoidoleuropein constitutes about 6-9 % of dry matter of the olive leaves.  

Olive leaf extract benefits

The benefits of olive leaf extract is attributed to the presence of the polyphenolic compounds in olive leaves. The monoterpenes, triterpenes and flavonoids in the olive leaves exhibit potent anti-microbial, antioxidant, natural anti inflammatory and immune-boosting properties which account for the olive leaf extract benefits.

Antioxidant effect: The specific molecules in olive leaves that show potent antioxidant effect are oleuropein, hydroxytyrosol,oleuropein aglycone, and tyrosol. The prime phenolic compounds in the olive leaf extract being the glycosylated form ofoleuropein and ligstroside. Research studies also reveal that the ethanol component of olive leaf extract exhibited protection against genotoxicity through powerful antioxidant action. Olive leaf extract benefits the body by inhibiting the oxidative stress and through free radical scavenging potential in cultured human cells.

Immune-booster: Studies have indicated that olive leaf extract inhibit acute infection and also prevent cell-to-cell transmission of HIV-1. The study conclusions show that treatment with olive leaf extract increased the apoptosis (cell death) of virulant cells, inhibited replication of virus and decreased HIV-1 associated changes. Olive leaf extracts were said to boost the immune system by effectively inactivating the virus cells. The compound oleuropein in olive leavespenetrated the viral cells and inhibited their replication.

Analgesic: All parts of olive tree are traditionally used as an analgesic owing to its anti-inflammatory effect. A study investigated the analgesic properties and concluded that olive leaf extract benefits as an analgesic and natural anti-inflammatory compound. The hydroxytyrosol and oleuropein compounds were found to contribute to the analgesic effect of the olive leaf extract. The same study confirmed the natural anti-inflammatory effect of olive leaf extract(4).

Anti-bacterial: The natural anti-bacterial effect of the olive leaf extract is exhibited by conversion of  the compoundoleuropein into elenoic acid in the body. Elenoic acid is known to be a potent virucidal agent which inhibits the replication of bacteria and virus(5). This compound is present in mature olive leaves is nature's defense mechanisms against micro-organisms and pests that infest the plant. 

Mechanism of anti-bacterial effect

Studies reveal that the beneficial effects of olive leaf extract are augmented by the bioavailability of their polyphenolic constituents. These compounds are easily absorbed through the gastrointestinal tract and reflects as higher levels in blood(6,7,10)

The antimicrobial and antibacterial activity of olive leaves were attributed to the presence of plant chemicals oleuropein and caffeic acid which inhibited the microbial action. A study showed that water extracts of olive leaves showed complete inhibition of bacterial activity and complete destruction of E.coli bacterial cells(8). The seven phenolic compounds identified in olive leaf extract namely caffeic acid, verbascosie, oleuropein, luteolin 7-O-glucosise, rutin, apigenin7-O-glucoside and luteolin 4'-O-glucoside  showed an unusual combined antibacterial and antifungal action against gram positive and gram negative bacteria(9).

The broad spectrum of olive leaf extract benefits with its rich array of phenolic compounds and plant chemical oleuropeinmakes it an effective nutraceutical and dietary supplement for maintaining everyday health. The natural anti-bacterial properties present in olive leaf extract implies the significance of olive leaves in human health and nutrition.


  1. Rodriguez MM, Perez J, Ramos-Cormenzana A, Martinez J. Effect of extracts obtained from olive oil mill waste waters on Bacillus megaterium ATCC 33085. Journal of Applied Bacteriology. 1988; 64:219-26.
  2. Tassou CC, Nychas GJE, Board RG. Effect of Phenolic Compounds and Oleuropein on the Germination of Bacillus cereus T Spores. Biotechnology and Applied Biochemistry. 1991; 13:231-37.
  3. El SN, Karakaya S; Olive tree (Olea europaea) leaves: potential beneficial effects on human health; Nutr Rev. 2009 Nov;67(11):632-8.
  4. Haloui, E.,; Hydroxytyrosol and oleuropein from olive leaves: Potent anti-inflammatory and analgesic activities; Journal of Food, Agriculture & Environment Vol.9 (3&4): 128-133. 2011
  5. Horn C. Olive leaf to fight infection. Natural Health 2000;30:40.
  6. Visioli, F., and Galli, C.,Biological properties of olive oil phytochemicals, Crit. Rev. Food Sci. Nutr., 42,  209-221(2002)
  7. Vissers M., Zock; Olive oil phenols are absorbed in humans., J Nutr.,132, 409-417(2002)
  8. Markin D, Duek L, Berdicevsky I; In vitro antimicrobial activity of olive leaves; Mycoses. 2003 Apr;46(3-4):132-6.
  9. Pereira AP,; Phenolic compounds and antimicrobial activity of olive (Olea europaea L. Cv. Cobrançosa) leaves; Molecules. 2007 May 26;12(5):1153-62.
  10. Abaza L,; Induction of growth inhibition and differentiation of human leukemia ( HL-60 cells) by Tunisian gerboui olive leaf extract, Biosci biotechnol biochem 71(5),1306-1312,2007.