Olive Leaf

Scientific Name(s): Olea europaea L. Family: Oleaceae

Common Name(s): Olive leaf

Uses

Interest in olive leaf use centers on antioxidant and antiviral activity, but clinical trials are lacking.

Dosing

There is no basis for dosage recommendations.

Contraindications

Contraindications have not been identified.

Pregnancy/Lactation

Information regarding safety and efficacy during pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

None well documented. Diabetic patients should be supervised carefully because of potential hypoglycemic effects.

Toxicology

The potential toxicity of olive leaf is not well documented.

Botany

The olive tree ( O. europaea ) is an evergreen that grows to approximately 10 m in height. Native to Mediterranean regions, olive trees also are cultivated in similar climate zones in the Americas. The small, leathery leaves are gray-green on top, and the underside contains fine white, scale-like hairs. The leaves are gathered throughout the year. 1

History

The olive tree was cultivated in Crete, where the leaves were used to clean wounds, as early as 3,500 BC. Symbolically, the olive branch symbolizes peace. The leaves were worn by athletes in ancient Olympic Games. In the 1800s, the plant was used to treat malaria. 2 , 3 , 4 , 5

Chemistry

Olive leaf contains the active iridoid constituent oleuropein (chief constituent 60 to 90 mg/g). Other secoiridoids include 11-demethyloleuropein, 7,11-dimethyl ester of oleoside, ligustroside, oleuroside, and unconjugated secoiridoid aldehydes. Triterpenes and flavonoids, including luteolin, apigenin, rutin, and diosmetin, also are present. Other compounds found in the leaves are oleasterol, leine, and glycoside oleoside. 2 , 3 , 6 , 7 , 8 , 9 , 10

Uses and Pharmacology

Clinical trials have not been performed to validate current use for antioxidant and antiviral activity.

Antioxidant activity

In vitro and animal experiments have been conducted to demonstrate the antioxidant activity of olive leaf extracts. In rat epithelial cells stimulated with cytokines, a concentrated polyphenol extract reduced nitrite concentration and free radical production. 11

Rabbits with induced diabetes showed a decrease in oxidative stress markers when treated with oleuropein. 12 Other experiments support the antioxidant activity of the phenols oleuropein and hydroxytyrosol. 9 , 10 , 13 , 14

Antimicrobial activity

Olive leaves are known to resist insect and microbial attack, and in vitro studies have been conducted to establish the range of activity of olive leaf extracts. 14 , 15

An aqueous extract of olive leaf was bactericidal against Pseudomonas aeruginosa , Klebsiella pneumoniae , Escherichia coli , and Staphylococcus aureus (0.6% w/v), as well as bacteriostatic against Bacillus subtilis (at 20% w/v). 16 Hydroxytyrosol demonstrated broader antimicrobial activity than oleuropein and is comparable to ampicillin and erythromycin in spectrum and potency. 15

Animal experiments and in vitro studies suggest olive leaf extracts possess antiviral activity. 5 , 17 Cell-to-cell transmission of HIV was inhibited in a dose-dependent manner, and HIV-1 replication was inhibited in an in vitro experiment. 5 Oleuropein has been patented in the United States for antiviral activity against viral diseases, including herpes, mononucleosis, and hepatitis. 18

Other uses
Antihypertensive

Animal experiments in rabbit and rat preparations found a hypotensive effect of oleuropein, possibly via direct action on smooth muscle. Oleuropeoside also may exert vasodilator activity. Additionally, olive leaf extracts may possess antispasmodic, vasodilator, and antiarrhythmic properties. 19 , 20

Diabetes

The hypoglycemic activity of olive leaf has been demonstrated in animals. In rabbits with induced diabetes, an ethanol extract of olive leaf decreased blood glucose. Suggested mechanisms include potentiation of glucose-induced insulin release and increased peripheral uptake of glucose. 12 , 21

Thyroid activity

An aqueous extract of olive leaf administered to rats for 14 days increased T 3 levels and reduced circulating thyroid-stimulating hormone levels, possibly via a feedback mechanism. 22

Dosage

Clinical trials to justify dosage recommendations are lacking. Many different commercial preparations of olive leaf and extracts are available and vary in strength. The 500 and 750 mg capsules contain approximately 20 mg of oleuropein/capsule.

Pregnancy/Lactation

Information regarding safety and efficacy during pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

None well documented. Diabetic patients should be supervised carefully because of potential hypoglycemic effects.

Toxicology

The potential toxicity of olive leaf is not well documented. Oleuropein in doses up to 1 g/kg body weight in albino mice was not lethal. 6 At 1 mg/mL, an extract of olive leaf was not toxic to human cells. 5

Bibliography

1. USDA, NRCS. 2006. The PLANTS Database ( http://plants.usda.gov 6 September 2006). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
2. Chevallier A . The Encyclopedia of Medicinal Plants . New York, NY: DK Publishing; 1996:239.
3. Weiss RF . Herbal Medicine . Meass AR, trans. Beaconsfield, England: Beaconsfield Pub. Ltd.; 1988: 160-161.
4. Bruneton J . Pharmacognosy, Phytochemistry, Medicinal Plants . Paris, France: Lavoisier Publishing; 1995:487-489.
5. Lee-Huang S , Zhang L , Huang PL , Chang YT , Huang PL . Anti-HIV activity of olive leaf extract (OLE) and modulation of host cell gene expression by HIV-1 infection and OLE treatment . Biochem Biophys Res Commun . 2003;307:1029-1037.
6. Petkov V , Manolov P . Pharmacological analysis of the iridoid oleuropein . Arzneimitteiforschung . 1972;22:1476-1486.
7. Vioque B , Fernandez-Maculet JC , Albi MA , Castellano JM , Vioque A . Perioxidases and ethylene formation in olive tree leaves [in Spanish]. Rev Esp Fisiol . 1989;45:47-52.
8. Meirinhos J , Silva BM , Valentao P , et al. Analysis and quantification of flavonoidic compounds from Portuguese olive ( Olea europaea L.) leaf cultivars . Nat Prod Res . 2005;19:189-195.
9. Benavente-Garcia O , Castillo J , Lorente J , Ortuno A , Del Rio JA . Antioxidant activity of phenolics extracted from Olea europaea L. leaves . Food Chem . 2000;68:457-462.
10. Briante R , Patumi M , Terenziani S , Bismuto E , Febbraio F , Nucci R . Olea europaea L. leaf extract and derivatives: antioxidant properties . J Agric Food Chem . 2002;50:4934-4940.
11. Zaslaver M , Offer S , Kerem Z , et al. Natural compounds derived from foods modulate nitric oxide production and oxidative status in epithelial lung cells . J Agric Food Chem . 2005;53:9934-9939.
12. Al-Azzawie HF , Alhamdani MS . Hypoglycemic and antioxidant effect of oleuropein in alloxan-diabetic rabbits . Life Sci . 2006;78:1371-1377.
13. Visioli F , Poli A , Gall C . Antioxidant and other biological activities of phenols from olives and olive oil . Med Res Rev . 2002;22:65-75.
14. Caturla N , Perez-Fons L , Estepa A , Micol V . Differential effects of oleuropein, a biophenol from Olea europaea , on anionic and zwiterionic phospholipid model membranes . Chem Phys Lipids . 2005;137:2-17.
15. Bisignano G , Tomaino A , Lo Cascio R , Crisafi G , Uccella N , Saija A . On the in-vitro antimicrobial activity of oleuropein and hydroxytyrosol . J Pharm Pharmacol . 1999;51:971-974.
16. Markin D , Duek L , Berdicevsky I . In vitro antimicrobial activity of olive leaves . Mycoses . 2003;46:132-136.
17. Micol V , Caturla N , Perez-Fons L , Mas V , Perez L , Estepa A . The olive leaf extract exhibits antiviral activity against viral haemorrhagic septicaemia rhabdovirus (VHSV) . Antiviral Res . 2005;66:129-136.
18. Fredrickson WR , Inventor; F & S Group, Inc., assignee. Method and composition for antiviral therapy with olive leaves . US patent 6 117 884. September 12, 2000.
19. Zarzuelo A , Duarte J , Jimenez J , Gonzalez M , Utrilla MP . Vasodilator effect of olive leaf . Planta Med . 1991;57:417-419.
20. Khayyal MT , el-Ghazaly MA , Abdallah DM , Nassar NN , Okpanyi SN , Kreuter MH . Blood pressure lowering effect of an olive leaf extract ( Olea europaea ) in L-NAME induced hypertension in rats . Arzneimittelforschung . 2002;52:797-802.
21. Gonzalez M , Zarzuelo A , Gamez MJ , Utrilla MP , Jimenez J , Osuna I . Hypoglycemic activity of olive leaf . Planta Med . 1992;58:513-515.
22. Al-Qarawi AA , Al-Damegh MA , ElMougy SA . Effect of freeze dried extract of Olea europaea on the pituitary-thyroid axis in rats . Phytotherapy Res . 2002;16:286-287.

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