Olive Leaf: From Tradition to Clinic

Document Type : Review Article

Authors

Abstract

The olive (Olea europaea from the Oleaceae family) leaves have had a lot of medicinal usages in traditional and modern medicine. In traditional Iranian medicine (TIM), it has special indications for wound healing and skin applications such as antiperspirant applications, and also its ash is used in ophthalmic traditional remedies. Literature survey was performed via electronic search on Pubmed, Scopus and Siencedirect. We found 270 articles related to the topic. Conventional pharmacy texts including Martindale, British pharmacopoeia and Lexi natural products as well as TIM texts were reviewed. Our results showed that Olive leaf has responsible effects such as antioxidant, antitoxic and anticancer properties. Also it has antimicrobial and antiviral effects as well as effects on nervous system, endocrine system, gastrointestinal system and cardiovascular system. It has therapeutic effects on some metabolic disorders and cutaneous complications and some miscellaneous effects such as anti-arthritis and anti-bone loss effects. Despite the large amount of studies on the possible effects of olive leaf has been done, the number of available products and their therapeutic targets are limited. It is expected that more extensive studies done on the olive leaf in clinical trials and according to its dose adjustment and special cautions, it becomes more popular herbal medicine in markets and clinics.

Keywords


  1. References:
  2. [No authors listed]. Monograph: olive leaf. Altern Med Rev. 2009;14(1):62-66.
  3. El SN, Karakaya S. Olive tree (Olea europaea) leaves: Potential beneficial effects on human health. Nutr Rev. 2009;67(11):632-8.
  4. Mohagheghi F, Bigdeli MR, Rasoulian B, Hashemi P, Pour MR. The neuroprotective effect of olive leaf extract is related to improved blood–brain barrier permeability and brain edema in rat with experimental focal cerebral ischemia. Phytomedicine. 2011;18(2-3):170-5.
  5. Škerget M, Kotnik P, Hadolin M, Rižner Hraš A, Simonič M, Knez Ž. Proanthocyanidins, flavones and flavonols in some plant materials and their antioxidant activities. Food Chem. 2005;89(2):191-8.
  6. Campeol E, Luigi Cioni P, Morelli I, D'Andrea F, Cremonini R. 1,5-Anhydroxylitol from leaves of Olea europaea. Carbohydr Res. 2004;339(16):2731–2.
  7. Meirinhos J, Silva BM, Valentão P, Seabra RM, Pereira JA, Dias A, Andrade PB, Ferreres F. Analysis and quantification of flavonoidic compounds from Portuguese olive (Olea europaea L.) leaf cultivars. Nat Prod Res. 2005;19(2):189-95.
  8. Brahmi F, Dhibi M, Hammami M. Variations in phenolic compounds and antiradical scavenging activity of Olea europaea leaves and fruits extracts collected in two differentseasons. Ind Crops Prod. 2013;49: 256– 64.
  9. Ahmad-Qasem MH, Barrajon-Catalan E, Micol V, Mulet A, Garcia-Perez JV. Influence of freezing and dehydration of olive leaves (var. serrana) on extract composition and antioxidant potential. Food Res Int. 2013;50(1):189-96.
  10. Garcia MA, Alcaide ME. Effect of different drying procedures on the nutritive value of olive (Olea europaea var. europaea) leaves for ruminants. Anim Feed Sci Technol. 2008; 142:317–329.
  11. British Pharmacopoeia Commission: British Pharmacopoeia 2015. Volume 4, TSO; 2014: 292-293.
  12. Sharafkandi A. [Translator], The Persian translation of Qanoun fi al-Tibb (or the Canon of Medicine). Tehran: Soroush Press; 1987.
  13. Rhazes (9th century) , Kitab-al-asrar or secret book of alchemy. Compiled by: Sheybany H.A. Tehran: Tehran University Publication; 1992. p.511.
  14. Grahn BH, Paterson PG, Gottschall-Pass KT, Zhang Z. Zinc and the eye. J Am Coll Nutr. 2001;20(2):106-118.
  15. De Marino S, Festa C, Zollo F, Nini A, Antenucci L, Raimo G, Iorizzi M. Antioxidant activity and chemical components as potential anticancer agents in the olive leaf (Olea europaea L. cv. leccino) decoction. Anticancer Agents Med Chem. 2014;14(10):1376-85.
  16. Hayes J.E, Allen P, Brunton N, O’Grady M.N, Kerry J.P. Phenolic composition and in vitro antioxidant capacity of four commercial phytochemical products: Olive leaf extract (Olea europaea L.), lutein, sesamol and ellagic acid. Food Chem. 2011;126:948-55.
  17. Kontogianni VG, Gerothanassis IP. Phenolic compounds and antioxidant activity of olive leaf extracts. Nat Prod Res. 2012;26(2):186-9.
  18. Ahmadvand H, Bagheri S, Khosrobeigi A, Boshtam M, Abdolahpour F. Effects of olive leaves extract on LDL oxidation induced-CuSO4 in vitro. Pak J Pharm Sci. 2012;25(3):571-5.
  19. Sarbishegi M, Mehraein F, Soleimani M. Antioxidant role of oleuropein on midbrain and dopaminergic neurons of substantia nigra in aged rats. Iran Biomed J. 2014;18(1):16-22.
  20. Çoban J, Öztezcan S, Doğru-Abbasoğlu S, Bingül I, Yeşil-Mizrak K, Uysal M. Olive leaf extract decreases age-induced oxidative stress in major organs of aged rats. Geriatr Gerontol Int. 2014;14(4):996-1002.
  21. Goulas V, Papoti VT, Exarchou V, Tsimidou MZ, Gerothanassis IP. Contribution of flavonoids to the overall radical scavenging activity of olive (Olea europaea L.) leaf polar extracts. J Agric Food Chem. 2010;58(6):3303-8.
  22. Lee OH, Lee BY. Antioxidant and antimicrobial activities of individual and combined phenolics in Olea europaea leaf extract. Bioresour Technol. 2010;101(10):3751–4.
  23. Paiva-Martins F, Barbosa S, Silva M, Monteiro D, Pinheiro V, Mourão J, Fernandes J, Rocha S, Belo L, Santos-Silva A. The effect of olive leaf supplementation on the constituents of blood and oxidative stability of red blood cells. J Funct Foods. 2014;9:271-9.
  24. Cumaoğlu A, Rackova L, Stefek M, Kartal M, Maechler P, Karasu C. Effects of olive leaf polyphenols against H₂O₂ toxicity in insulin secreting β-cells. Acta Biochim Pol. 2011;58(1):45-50.
  25. Vassiliki T, Papoti KP, Perifantsi E, Nenadis N, Demopoulos V.J, Tsimidou MZ. Antioxidant and aldose reductase inhibition activity of Ligustrum japonicum and Olea europaea L. leaf extracts. Eur J Lipid Sci Tech. 2011;113(7):876-85.
  26. Seddik L, Bah TM, Aoues A, Slimani M, Benderdour M. Elucidation of mechanisms underlying the protective effects of olive leaf extract against lead-induced neurotoxicity in Wistar rats. J Toxicol Sci. 2011;36(6):797-809.
  27. Tavafi M, Ahmadvand H, Toolabi P. Inhibitory effect of olive leaf extract on gentamicin-induced nephrotoxicity in rats. Iran J Kidney Dis. 2012;6(1):25-32.
  28. Dekanski D1, Selaković V, Piperski V, Radulović Z, Korenić A, Radenović L. Protective effect of olive leaf extract on hippocampal injury induced by transient global cerebral ischemia and reperfusion in Mongolian gerbils. Phytomedicine. 2011;18(13):1137-43.
  29. Andreadou I, Sigala F, Iliodromitis EK, Papaefthimiou M, Sigalas C, Aligiannis N, et al. Acute doxorubicin cardiotoxicity is successfully treated with the phytochemical oleuropein through suppression of oxidative and nitrosative stress. J Mol Cell Cardiol. 2007;42(3):549-58.
  30. Garcia-Villalba R, Larrosa M, Possemiers S, Tomas-Barberan FA, Espin JC. Bioavailability of phenolics from an oleuropein-rich olive (Olea europaea) leaf extract and its acute effect on plasma antioxidant status: comparison between pre- and postmenopausal women. Eur J Nutr. 2014;53(4):1015-27.
  31. Turkez H, Togar B, Polat E. Olive leaf extract modulates permethrin induced genetic and oxidative damage in rats. Cytotechnology. 2012;64(4):459-64.
  32. Cumaoğlu A, Ari N, Kartal M, Karasu Ç. Polyphenolic extracts from Olea europea L. protect against cytokine-induced β-cell damage through maintenance of redox homeostasis. Rejuvenation Res. 2011;14(3):325-34.
  33. Cabarkapa A, Zivković L, Zukovec D, Djelić N, Bajić V, Dekanski D, Spremo-Potparević B. Protective effect of dry olive leaf extract in adrenaline induced DNA damage evaluated using in vitro comet assay with human peripheral leukocytes. Toxicol In Vitro, 2014;28(3):451-6.
  34. Parzonko A, Czerwińska ME, Kiss AK, Naruszewicz M. Oleuropein and oleacein may restore biological functions of endothelialprogenitor cells impaired by angiotensin II via activation of Nrf2/hemeoxygenase-1 pathway. Phytomedicine. 2013;20(12):1088-94.
  35. Chondrogianni N, Chinou I, Gonos E.S. Chapter 149 – Anti-aging properties of the olive constituent oleuropein in human cells. Olives and Olive Oil in Health and Disease Prevention. Tokyo; academic press; 2010. P.1335–43.
  36. Samet I, Han J, Jlaiel L, Sayadi S, Isoda H. Olive (Olea europaea) leaf extract induces apoptosis and monocyte/macrophage differentiation in human chronic myelogenous leukemia K562 cells: insight into the underlying mechanism. Oxid Med Cell Longev. 2014:1-16.
  37. Bouallagui Z, Han J, Isoda H, Sayadi S. Hydroxytyrosol rich extract from olive leaves modulates cell cycle progression in MCF-7 human breast cancer cells. Food Chem Toxicol. 2011;49(1): 179–84.
  38. Cabarkapa A, Zivković L, Zukovec D, Djelić N, Bajić V, Dekanski D, Spremo-Potparević B. Protective effect of dry olive leaf extract in adrenaline induced DNA damage evaluated using in vitro comet assay with human peripheral leukocytes. Toxicol In Vitro. 2014;28(3):451-6.
  39. Tezcan G, Tunca B, Bekar A, Budak F, Sahin S, Cecener G, Egeli U, Taskapılıoglu MO, Kocaeli H, Tolunay S, Malyer H, Demir C, Tumen G. Olea europaea leaf extract improves the treatment response of GBM stem cells by modulating miRNA expression. Am J Cancer Res. 2014;4(5):572-90.
  40. Anter J, Fernandez-Bedmar Z, Villatoro-Pulido M, Demyda-Peyras S, Moreno-Millan M, Alonso-Moraga A, Muñoz-Serrano A, Luque de Castro MD. A pilot study on the DNA-protective, cytotoxic, and apoptosis-inducing properties of olive-leaf extracts. Mutat Res. 2011;723(2):165-70.
  41. Abdel-Hamid NM, El-Moselhy MA, El-Baz A. Hepatocyte lysosomal membrane stabilization by olive leaves against chemically induced hepatocellular neoplasia in rats. Int J Hepatol. 2011:1-6.
  42. Ahmed KM. The effect of olive leaf extract in decreasing the expression of two pro-inflammatory cytokines in patients receiving chemotherapy for cancer. A randomized clinical trial. Saudi Dent J. 2013;25(4):141-7.
  43. Elamin MH, Daghestani MH, Omer SA, Elobeid MA, Virk P, Al-Olayan EM, et al. Olive oil oleuropein has anti-breast cancer properties with higher efficiency on ER-negative cells. Food Chem Toxicol. 2013;53:310-6.
  44. Mijatovic SA, Timotijevic GS, Miljkovic DM, Radovic JM, Maksimovic-Ivanic DD, Dekanski DP, Stosic-Grujicic SD. Multiple antimelanoma potential of dry olive leaf extract. Int J Cancer. 2011;128(5):1955-65.
  45. Sifaoui I, Lopez-Arencibia A, Ticona JC, Martin-Navarro CM, Reyes-Batlle M, Mejri M, et al. Bioassay guided isolation and identification of anti-acanthamoeba compounds from Tunisian olive leaf extracts. Exp Parasitol. 2014;145:S111–4.
  46. Flemmig J, Rusch D, Czerwińska M.E, Rauwald H, Arnhold J. Components of a standardised olive leaf dry extract (Ph. Eur.) promote hypothiocyanite production by lactoperoxidase. Arch Biochem Biophys. 2014;549:17-25.
  47. Bao J, Zhang DW, Zhang JZ, Huang PL, Huang PL, Lee-Huang S. Computational study of bindings of olive leaf extract (OLE) to HIV-1 fusion protein gp41. FEBS Lett. 2007;581(14):2737-42.
  48. Furneri PM, Marino A, Saija A, uccella N, Bisignano G. In vitro antimycoplasmal activity of oleuropein. Int J Antimicrob Agents. 2002;20(4):293-6.
  49. 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-1infection and OLE treatment. Biochem Biophys Res Commun. 2003;307(4):1029-37.
  50. 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 Research. 2005;66(2-3):129-36.
  51. Al-Othman MR, Mahmoud MA, Abd El-aziz A.R.M. Management of aflatoxin B1 production by aspergillus flavus isolated from rice using methanolic extract of Olea europaea L. leaves. J Pure Appl Microbiol. 2013;7(3).
  52. Roxas M, Jurenka J. Colds and influenza: a review of diagnosis and conventional, botanical, and nutritional considerations. Altern Med Rev. 2007;12(1):25-48.
  53. Omar SH. Cardioprotective and neuroprotective roles of oleuropein in olive. Saudi Pharm J. 2010;18(3):111-21.
  54. Rabiei Z, Bigdeli MR, Rasoulian B, Ghassempour A, Mirzajani F. The neuroprotection effect of pretreatment with olive leaf extract on brain lipidomics in rat stroke model. Phytomedicine. 2012;19(10):940-6.
  55. Esmaeili-Mahani S, Rezaeezadeh-Roukerd M, Esmaeilpour K, Abbasnejad M, Rasoulian B, Sheibani V, Kaeidi A, Hajializadeh Z. Olive (Olea europaea L.) leaf extract elicits antinociceptive activity, potentiates morphine analgesia and suppresses morphine hyperalgesia in rats. J Ethnopharmacol. 2010;132(1):200-5.
  56. Miljković D, Dekanski D, Miljković Z, Momcilović M, Mostarica-Stojkovic M. Dry olive leaf extract ameliorates experimental autoimmune encephalomyelitis. Clin Nutr. 2009;28(3):346-50.
  57. Lexi Comp, Lexi-Natural Products: Pocket PC Internet Edition. Lexi Comp; Internet edition 2002 (accesed 2014).
  58. Pasban-Aliabadi H, Esmaeili-Mahani S, Sheibani V, Abbasnejad M, Mehdizadeh A, Yaghoobi MM. Inhibition of 6-hydroxydopamine-induced PC12 cell apoptosis by olive (Olea europaea L.) leaf extract is performed by its main component oleuropein. Rejuvenation Res. 2013;16(2):134-42.
  59. Zare L, Esmaeili-Mahani S, Abbasnejad M, Rasoulian B, Sheibani V, Sahraei H, Kaeidi A. Oleuropein, chief constituent of olive leaf extract, prevents the development of morphine antinociceptive tolerance through inhibition of morphine-induced L-type calcium channel overexpression. Phytother Res. 2012;26(11):1731-7.
  60. Cvjetićanin T, Miljković D, Stojanović I, Dekanski D, Stosić-Grujicić S. Dried leaf extract of Olea europaea ameliorates islet-directed autoimmunity in mice. Br J Nutr. 2010;103(10):1413-24.
  61. Tavafi M, Ahmadvand H, Toolabi P. Inhibitory effect of olive leaf extract on gentamicin-induced nephrotoxicity in rats. Iran J Kidney Dis. 2012;6(1):25-32.
  62. Liu YN, Jung JH, Park H, Kim H. Olive leaf extract suppresses messenger RNA expression of proinflammatory cytokines and enhances insulin receptor substrate 1 expression in the rats with streptozotocin and high-fat diet–induced diabetes. Nutr Res. 2014;34(5):450-7.
  63. Park JH, Jung JH, Yang JY, Kim HS. Olive leaf down-regulates the oxidative stress and immune dysregulation in streptozotocin-induced diabetic mice. Nutr Res. 2013;33(11):942-51.
  64. Kaeidi A, Esmaeili-Mahani S, Sheibani V, Abbasnejad M, Rasoulian B, Hajializadeh Z, Afrazi S. Olive (Olea europaea L.) leaf extract attenuates early diabetic neuropathic pain through prevention of high glucose-induced apoptosis: In vitro and in vivo studies. J Ethnopharmacol. 2011;136(1):188-96.
  65. Ahmadvand H, Noori A, Ghasemi Dehnoo M, Bagheri SH, Cheraghi R. Hypoglycemic, hypolipidemic and antiatherogenic effects of oleuropein in alloxan-induced Type 1 diabetic rats. Asian Pac J Trop Dis. 2014;4(1):S421-S5.
  66. Gonzalez M, Zarzuelo A, Gamez MJ, Utrilla MP, Jimenez J, Osuna I. Hypoglycemic activity of olive leaf. Planta Med. 1992;58(6):513-5.
  67. De Bock M, Derraik J, Brennan C, Cutfield W. Olive leaf extract improves insulin sensitivity in overweight middle aged males: a randomized, double-blinded, placebo controlled, crossover trial. Obes Res Clin Pract. 2012;6(1):81.
  68. Wainstein J, Ganz T, Boaz M, Bar Dayan Y, Dolev E, Kerem Z, Madar Z. Olive leaf extract as a hypoglycemic agent in both human diabetic subjects and in rats. J Med Food. 2012;15(7):605-10.
  69. Kim Y, Choi Y, Park T. Hepatoprotective effect of oleuropein in mice: mechanisms uncovered by gene expression profiling. Biotechnol J. 2010;5(9):950-60.
  70. Fakhraei N, Abdolghaffari AH, Delfan B, Abbasi A, Rahimi N, Khansari A, Rahimian R, Dehpour AR. Protective effect of hydroalcoholic olive leaf extract on experimental model of colitis in rat: involvement of nitrergic and opioidergic systems. Phytother Res. 2014;28(9):1367-73.
  71. Dekanski D, Janićijević-Hudomal S, Ristić S, Radonjić NV, Petronijević ND, Piperski V, Mitrović DM. Attenuation of cold restraint stress-induced gastric lesions by an olive leaf extract. Gen Physiol Biophys. 2009;28:135-42.
  72. Al-Attar AM, Shawush NA. Influence of olive and rosemary leaves extracts on chemically induced liver cirrhosis in male rats. Saudi J Biol Sci. 2015;22(2):157-163.
  73. Somova LI, Shode FO, Ramnanan P, Nadar A. Antihypertensive, antiatherosclerotic and antioxidant activity of triterpenoids isolated from Olea europaea, subspecies africana leaves. J Ethnopharmacol. 2003;84(2-3):299-305.
  74. Scheffler A, Rauwald HW, Kampa B, Mann U, Mohr FW, Dhein S. Olea europaea leaf extract exerts L-type Ca2+ channel antagonistic effects. J Ethnopharmacol. 2008;120(2):233-40.
  75. Susalit E, Agus N, Effendi I, Tjandrawinata RR, Nofiarny D, Perrinjaquet-Moccetti T, Verbruggen M. Olive (Olea europaea) leaf extract effective in patients with stage-1 hypertension: comparison with Captopril. Phytomedicine. 2011;18(4):251-8.
  76. Fonolla J, Diaz-Ropero P, de la Fuente E, Quintela J.C. One-month consumption of an olive leaf extract enhances cardiovascular status in hypercholesterolemic subjects. Atheroscler Suppl. 2010;11(2):182.
  77. Zarzuelo A, Duarte J, Jimenez J, Gonzalez M, Utrilla MP. Vasodilator effect of olive leaf. Planta Med. 1991;57(5):417-9.
  78. Cherif S1, Rahal N, Haouala M, Hizaoui B, Dargouth F, Gueddiche M, Kallel Z, Balansard G, Boukef K. A clinical trial of a titrated Olea extract in the treatment of essential arterial hypertension. J Pharm Belg. 1996;51(2):69-71.
  79. Singh I, Mok M, Christensen AM, Turner AH, Hawley JA. The effects of polyphenols in olive leaves on platelet function. Nutr Metab Cardiovasc Dis. 2008;18(2):127-32.
  80. Salah MB, Abdelmelek H, Abderraba M. Effects of olive leave extract on metabolic disorders and oxidative stress induced by 2.45 GHz WIFI signals. Environ Toxicol Pharmacol. 2013;36(3):826-34.
  81. Wang L, Geng C, Jiang L, Gong D, Liu D, Yoshimura H, Zhong L. The anti-atherosclerotic effect of olive leaf extract is related to suppressed inflammatory response in rabbits with experimental atherosclerosis. Eur J Nutr. 2008;47(5):235-43.
  82. Flemmig J, Kuchta K, Arnhold J, Rauwald HW. Olea europaea leaf (Ph.Eur.) extract as well as several of its isolated phenolics inhibit the gout-related enzyme xanthine oxidase. Phytomedicine. 2011;18(7):561–6.
  83. Yildirim M, Amanvermez R, Polat C, Karadag A, Karayigit MO, Erzurumlu K. The olive leaf extract attenuates bacterial translocation and liver damage in obstructive jaundice. Bratisl Lek Listy. 2014;115(6):357-61.
  84. Shen Y, Song SJ, Keum N, Park T. Olive leaf extract attenuates obesity in high-fat diet-fed mice by modulating the expression of molecules involved in adipogenesis and thermogenesis. Evid Based Complement Alternat Med. 2014:1-12.
  85. Kimura Y, Sumiyoshi M. Olive leaf extract and Its main component oleuropein prevent chronic ultraviolet B radiation-induced skin damage and carcinogenesis in hairless Mice. J Nutr. 2009;139(11):2079-86.
  86. Gong D, Geng C, Jiang L, Wang L, Yoshimuram H, Zhong L. Olive leaf extract facilitates healing of experimental cartilaginous injuries in rabbits. J Med Food. 2011;14(3):268-75.
  87. Sumiyoshi M, Kimura Y. Effects of olive leaf extract and its main component oleuroepin on acute ultraviolet B irradiation-induced skin changes in C57BL/6J mice. Phytother Res. 2010;24(7):995-1003.
  88. Mehraein F, Sarbishegi M, Aslani A. Evaluation of effect of oleuropein on skin wound healing in aged male Balb/c mice. Cell J. 2014;16(1):25-30.
  89. Sifaoui I, Lopez-Arencibia A, Martin-Navarro CM, Chammem N, Reyes-Batlle M, Mejri M, et al. Activity of olive leaf extracts against the promastigote stage of Leishmania species and their correlation with the antioxidant activity. Exp Parasitol. 2014;141:106-11.
  90. Elamin MH, Al-Maliki SS. Leishmanicidal and apoptotic activities of oleuropein on Leishmania major. Int J Clin Pharmacol Ther. 2014;52(10):880-8.
  91. Gong D, Geng C, Jiang L, Wang L, Yoshimura H, Zhong L. Mechanisms of olive leaf extract-ameliorated rat arthritis caused by kaolin and carrageenan. Phytother Res. 2012;26(3):397-402.
  92. Puel C, Mathey J, Agalias A, Kati-Coulibaly S, Mardon J, Obled C, et al. Dose–response study of effect of oleuropein, an olive oil polyphenol, in an ovariectomy/inflammation experimental model of bone loss in the rat. Clin Nutr. 2006;25(5):859-68.
  93. Arantes-Rodrigues R, Henriques A, Pires MJ, Colaço B, Calado AM, Rema P, et al. High doses of olive leaf extract induce liver changes in mice. Food Chem Toxicol. 2011;49(9):1989–97.
  94. Brayfield A: Martindale: The Complete Drug Reference. 38th ed. Pharmaceutical Press, 2014. P.3568.
  95. Olive leaf extract 500 mg Veg Capsules. https://www.nowfoods.com/supplements/ olive-leaf-extract-500-mg-veg-capsules (accessed 2016).
  96. Fresh-Picked™ Olive leaf extract. http://olea.com.au/shop/fresh-picked%c2%89-olive-leaf-extract-60-%c2%89-high-strength-capsules/(accessed 2016).
  97. OVIO Olive leaf extract plus supplement. http://www.oviowellness.com/(accessed 2016).
  98. Seagate Products. Olive leaf extract 450 mg 90 V caps. http://seagateproducts.com/ product/223/Olive-Leaf-Extract-450mg-90-V-Caps.html (accessed 2016).
  99. Barlean's Olive leaf Complex Throat Spray: The World's Freshest & Most Beneficial Olive Leaf Complex. http://cheryltownsley.com/products/olivespray.html (accessed 2016).
  100. Certified Organic Olive Leaf Tea, Capsules, Extract, Skin Care. http:// www.olivus.com (accessed 2016).