Quercetin content in olive oil and olive by-products as affected by cultivar, geographical origin, cultivation practices, and processing

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Abstract

Olive oil is rich in different classes of phenolic compounds, and their content is important for the quality assessment of virgin olive oil. Phenolic compounds contribute to the taste and aroma of olive oil and protect it from oxidation. The present review article aimed to collect and evaluate several research data concerning the effect of variety, geographical origin, cultivation practices, and processing on a less studied plant flavonol, namely quercetin, in olive oil and olive by-products. Collected data included measurements of quercetin content and total phenolic compounds in olive oil of Greek, Italian, Spanish, Turkish, Algerian, Tunisian, and Brazilian olive varieties. Olive varieties, geographical region, temperature, and malaxation processing affect the concentration of total phenolic content and, consequently, the quercetin content. In addition, differences in the reported quercetin content may partly stem from methodological variability. To enrich the article’s data and evaluate the concentration of phenolic compounds in olive oil, olives and olive leaves were also studied. However, a gap was identified in the literature, as research studies are lacking on the specific effect of the factors mentioned above on the quercetin content of olive oil. For this reason, the collection of several findings on the effect of such factors on quercetin content was considered to be necessary.

Keywords

quercetin / olive oil / olive leaves / olive varieties / glucosides / phenolic content

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References

[1] Chiappetta A, Muzzalupo I (2012) Botanical description, In: The olive cultivation, table olive and olive oil industry in Italy. http://doi.org/10.5772/51836

[2] Arenas-Castro S, Gonçalves JF, Moreno M, et al. (2020) Projected climate changes are expected to decrease the suitability and production of olive varieties in southern Spain. Sci Total Environ 709: 136161. https://doi.org/10.1016/j.scitotenv.2019.136161

[3] Sofo A, Manfreda S, Fiorentino M, et al. (2008) The olive tree: A paradigm for drought tolerance in Mediterranean climates. Hydrol Earth Syst Sci 12: 293-301 https://doi.org/10.5194/hess-12-293-2008

[4] Fleyfel LM, Leitner NKV, Deborde M, et al. (2022) Olive oil liquid wastes-Characteristics and treatments: A literature review. Process Saf Environ 168: 1031-1048. https://doi.org/10.1016/j.psep.2022.10.035

[5] Diamantakos P, Ioannidis K, Papanikolaou C, et al. (2021) A new definition of the term ‘high-phenolic olive oil’ based on large scale statistical data of Greek olive oils analyzed by qNMR. Molecules 26: 1115. https://doi.org/10.3390/molecules26041115

[6] Bajoub A, Pacchiarotta T, Hurtado-Fernández E, et al. (2016) Comparing two metabolic profiling approaches (liquid chromatography and gas chromatography coupled to mass spectrometry) for extra-virgin olive oil phenolic compounds analysis: A botanical classification perspective. J Chromatogr A 1428: 267-279. https://doi.org/10.1016/j.chroma.2015.10.059

[7] Yahia EM (2019) Postharvest physiology and biochemistry of fruits and vegetables, Duxford: Woodhead Publishing. https://doi.org/10.1016/B978-0-12-813278-4.00012-9

[8] Vollmannová A, Bojňanská T, Musilová J, et al. (2024) Quercetin as one of the most abundant represented biological valuable plant components with remarkable chemoprotective effects-A review. Heliyon 10: e33342. https://doi.org/10.1016/j.heliyon.2024.e33342

[9] Nile SH, Nile AS, Keum YS, et al. (2017) Utilization of quercetin and quercetin glycosides from onion (Allium cepa L.) solid waste as an antioxidant, urease and xanthine oxidase inhibitors. Food Chem 235: 119-126. https://doi.org/10.1016/j.foodchem.2017.05.043

[10] Zeng Y, Song J, Zhang M, et al. (2020) Comparison of in vitro and in vivo antioxidant activities of six flavonoids with similar structures. Antioxidants 9: 732. https://doi.org/10.3390/antiox9080732

[11] Joshi NS, Aggarwal P, Hirpara VK, et al. (2011) Novel quercetin derivatives as anti-cancer agents. Patent.

[12] Hussain SA, Ahmed ZA, Mahwi TO, et al. (2012) Quercetin dampens postprandial hyperglycemia in type 2 diabetic patients challenged with carbohydrates load. Int J Diabetes Res 1: 32-35. https://doi.org/10.5923/j.diabetes.20120103.01

[13] Edwards RL, Lyon T, Litwin SE, et al. (2007) Quercetin reduces blood pressure in hypertensive subjects. J Nutr 137: 2405-2411. https://doi.org/10.1093/jn/137.11.2405

[14] Javadi F, Ahmadzadeh A, Eghtesadi S, et al. (2017) The effect of quercetin on inflammatory factors and clinical symptoms in women with rheumatoid arthritis: A double-blind, randomized controlled trial. J Am Coll Nutr 36: 9-15. https://doi.org/10.1080/07315724.2016.1140093

[15] Osonga FJ, Akgul A, Miller RM, et al. (2019) Antimicrobial activity of a new class of phosphorylated and modified flavonoids. ACS Omega 4: 12865-12871. https://doi.org/10.1021/acsomega.9b00077

[16] Li K, Xing S, Wang M, et al. (2012) Anticomplement and antimicrobial activities of flavonoids from Entada phaseoloides. Nat Prod Commun 7: 1934578X1200700. https://doi.org/10.1177/1934578X1200700715

[17] Rocha MFG, Sales JA, da Rocha MG, et al. (2019) Antifungal effects of the flavonoids kaempferol and quercetin: A possible alternative for the control of fungal biofilms. Biofouling 35: 320-328. https://doi.org/10.1080/08927014.2019.1604948

[18] Shishodia SK, Tiwari S, Hoda S, et al. (2020) SEM and qRT-PCR revealed quercetin inhibits morphogenesis of Aspergillus flavus conidia via modulating calcineurin-Crz1 signalling pathway. Mycology 11: 118-125. https://doi.org/10.1080/21501203.2020.1711826

[19] Milanezi FG, Meireles LM, de Christo Scherer MM, et al. (2019) Antioxidant, antimicrobial and cytotoxic activities of gold nanoparticles capped with quercetin. Saudi Pharm J 27: 968-974. https://doi.org/10.1016/j.jsps.2019.07.005

[20] Colunga Biancatelli RML, Berrill M, Catravas JD, et al. (2020) Quercetin and vitamin C: An experimental, synergistic therapy for the prevention and treatment of SARS-CoV-2 related disease (COVID-19). Front Immunol 11: 1451. https://doi.org/10.3389/fimmu.2020.01450

[21] Cushnie TPT, Lamb AJ (2005) Antimicrobial activity of flavonoids. Int J Antimicrob Ag 26: 343-356. https://doi.org/10.1016/j.ijantimicag.2005.09.002

[22] dos Santos AE, Kuster RM, Yamamoto KA, et al. (2014) Quercetin and quercetin 3-O-glycosides from Bauhinia longifolia (Bong.) Steud. show anti-Mayaro virus activity. Parasites Vectors 7: 130. https://doi.org/10.1186/1756-3305-7-130

[23] Montone AMI, Papaianni M, Malvano F, et al. (2021) Lactoferrin, quercetin, and hydroxyapatite act synergistically against Pseudomonas fluorescens. Intl J Mol Sci 22: 9247- 9247. https://doi.org/10.3390/ijms22179247

[24] Yin J, Peng X, Lin J, et al. (2021) Quercetin ameliorates Aspergillus fumigatus keratitis by inhibiting fungal growth, toll-like receptors and inflammatory cytokines. Int Immunopharmacol 93: 107435. https://doi.org/10.1016/j.intimp.2021.107435

[25] Amin MU, Khurram M, Khattak B, et al. (2015) Antibiotic additive and synergistic action of rutin, morin and quercetin against methicillin resistant Staphylococcus aureus. BMC Complem Altern M 15: 59. https://doi.org/10.1186/s12906-015-0580-0

[26] da Costa Júnior, de Oliveira Santos JV, de Almeida Campos LA, et al. (2018) Antibacterial and antibiofilm activities of quercetin against clinical isolates of Staphyloccocus aureus and Staphylococcus saprophyticus with resistance profile. IJAEB 3: 1948-1958. https://doi.org/10.22161/ijeab/3.5.50

[27] Gao M, Wang H, Zhu L (2016) Quercetin assists fluconazole to inhibit biofilm formations of fluconazole-resistant Candida Albicans in in vitro and in vivo antifungal managements of vulvovaginal candidiasis. Cell Physiol Biochem 40: 727-742. https://doi.org/10.1159/000453134

[28] Singh BN, Upreti DK, Singh BR, et al. (2015) Quercetin sensitizes fluconazole-resistant candida albicans to induce apoptotic cell death by modulating quorum sensing. Antimicrob Agents Chemother 59: 2153-2168. https://doi.org/10.1128/aac.03599-14

[29] Oliveira VM, Carraro E, Auler ME, et al. (2015) Quercetin and rutin as potential agents antifungal against Cryptococcus spp. Braz J Biol 76: 1029-1034. https://doi.org/10.1590/1519-6984.07415

[30] Schmidt L, Prestes OD, Paula Rossini Augusti, et al. (2023) Phenolic compounds and contaminants in olive oil and pomace - A narrative review of their biological and toxic effects. 53: 102626. https://doi.org/10.1016/j.fbio.2023.102626

[31] Servili M, Sordini B, Esposto S, et al. (2013) Biological activities of phenolic compounds of extra virgin olive oil. Antioxidants 3: 1-23. https://doi.org/10.3390/antiox3010001

[32] Pang KL, Lumintang JN, Chin KY (2021) Thyroid-modulating activities of olive and its polyphenols: A systematic review. Nutrients 13: 529. https://doi.org/10.3390/nu13020529

[33] Tzekaki EE, Papaspyropoulos A, Tsolaki M, et al. (2021) Restoration of BMI1 levels after the administration of early harvest extra virgin olive oil as a therapeutic strategy against Alzheimer’s disease. Exp Gerontol 144: 111178. https://doi.org/10.1016/j.exger.2020.111178

[34] Rey-Giménez R, Sánchez-Gimeno AC (2023) Effect of cultivar and environment on chemical composition and geographical traceability of Spanish olive oils. J Am Oil Chem Soc 101: 371-382. https://doi.org/10.1002/aocs.12774

[35] Navas-López JF, Cano J, de la Rosa R, et al. (2020) Genotype by environment interaction for oil quality components in olive tree. Eur J Agron 119: 126115. https://doi.org/10.1016/j.eja.2020.126115

[36] Rocha P, Lamas S, Casal S, et al. (2026) Can the region of production affect the quality and composition of olive oil? Comparative study on two olive cultivars. Appl Food Res 6: 101689. https://doi.org/10.1016/j.afres.2026.101689

[37] Rodrigues N, Peres F, Casal S, et al. (2023) Geographical discrimination of olive oils from Cv. ‘Galega Vulgar’. Food Chem 398: 133945. https://doi.org/10.1016/j.foodchem.2022.133945

[38] Khdair AI, Ayoub S, Abu-Rumman G (2015) Effect of pressing techniques on olive oil quality. Am J Food Technol 10: 176-183. https://doi.org/10.3923/ajft.2015.176.183

[39] Boselli E, Di Lecce G, Strabbioli R, et al. (2009) Are virgin olive oils obtained below 27 ℃ better than those produced at higher temperatures? LWT-Food Sci Technol 42: 748-757. https://doi.org/10.1016/j.lwt.2008.09.018

[40] Angeloni G, Spadi A, Corti F, et al. (2024) Balancing efficiency and quality: Effects of gradual temperature increase on extra virgin olive oil extraction. AgriEngineering 6: 3553-3562. https://doi.org/10.3390/agriengineering6040202

[41] Sun X, Wang Y, Li H, et al. (2021) Changes in the volatile profile, fatty acid composition and oxidative stability of flaxseed oil during heating at different temperatures. LWT 151: 112137. https://doi.org/10.1016/j.lwt.2021.112137

[42] Flores M, Avendaño V, Bravo J, et al. (2021) Edible oil parameters during deterioration processes. Int J Food Sci 2021: 7105170. https://doi.org/10.1155/2021/7105170

[43] De Santis D, Ferri S, Milana G, et al. (2024) Stability of monovarietal Sicilian olive oils under different storage condition: Chemical composition, sensory characteristics, and consumer preference. Heliyon 10: e29833. https://doi.org/10.1016/j.heliyon.2024.e29833

[44] Gómez-Alonso S, Salvador MD, G. Fregapane (2004) Evolution of the oxidation process in olive oil triacylglycerol under accelerated storage conditions (40-60℃). J Am Oil Chem Soc 81: 177-184. https://doi.org/10.1007/s11746-004-0878-7

[45] De Leonardis A, Angelico R, Macciola V, et al. (2013) Effects of polyphenol enzymatic-oxidation on the oxidative stability of virgin olive oil. Food Res Int 54: 2001-2007. https://doi.org/10.1016/j.foodres.2013.04.034

[46] Nissim Y, Shloberg M, Biton I, et al. (2020) High temperature environment reduces olive oil yield and quality. PLOS ONE 15: e0231956. https://doi.org/10.1371/journal.pone.0231956

[47] Kumar R, Vijayalakshmi S, Nadanasabapathi S (2017) Health benefits of quercetin. Def Life Sci J 2: 142-151. https://doi.org/10.14429/dlsj.2.11359

[48] Miho H, Moral J, López-González MA, et al. (2020) The phenolic profile of virgin olive oil is influenced by malaxation conditions and determines the oxidative stability. Food Chem 314: 126183. https://doi.org/10.1016/j.foodchem.2020.126183

[49] Angerosa F, Basti C (2001) Olive oil volatile compounds from the lipoxygenase pathway in relation to fruit ripeness. Ital J Food Sci 13: 421-428.

[50] Jiménez B, Sánchez-Ortiz A, Rivas A (2014) Influence of the malaxation time and olive ripening stage on oil quality and phenolic compounds of virgin olive oils. Int J Food Sci Technol 49: 2521-2527. https://doi.org/10.1111/ijfs.12592

[51] Inarejos-García AM, Gómez-Rico A, Salvador MD, et al. (2008) Influence of malaxation conditions on virgin olive oil yield, overall quality and composition. Eur Food Res Technol 228: 671-677. https://doi.org/10.1007/s00217-008-0977-9

[52] Marx ÍMG, Priego-Capote F (2025) Importance of malaxation conditions to virgin olive oil polar phenolic compounds content. Food Chem 480: 143884. https://doi.org/10.1016/j.foodchem.2025.143884

[53] Attard K, Oztop MH, Lia F (2022) The effect of hydrolysis on the antioxidant activity of olive mill waste. Appl Sci 12: 12187. https://doi.org/10.3390/app122312187

[54] De Ceglie C, Abbattista R, Losito I, et al. (2020) Influence of horizontal centrifugation processes on the content of phenolic secoiridoids and their oxidized derivatives in commercial olive oils: An insight by liquid chromatography-High-resolution mass spectrometry and chemometrics. J Agric Food Chem 68: 3171-3183. https://doi.org/10.1021/acs.jafc.0c00455

[55] Clodoveo ML (2012) Malaxation: Influence on virgin olive oil quality. Past, present and future-An overview. Trends Food Sci Technol 25: 13-23. https://doi.org/10.1016/j.tifs.2011.11.004

[56] Pardo JE, Rabadán A, Suárez M, et al. (2021) Influence of olive maturity and season on the quality of virgin olive oils from the area assigned to the protected designation of origin of ‘Aceite de la Alcarria’ (Spain). Agronomy 11: 1439. https://doi.org/10.3390/agronomy11071439

[57] Özcan MM, Fındık S, AlJuhaimi F, et al. (2019) The effect of harvest time and varieties on total phenolics, antioxidant activity and phenolic compounds of olive fruit and leaves. J. Food Sci Technol 56: 2373-2385. https://doi.org/10.1007/s13197-019-03650-8

[58] Breschi C, Guerrini L, Zanoni B, et al. (2022) Simulation of transport under different temperature conditions: Effects on extra virgin olive oil quality. Eur J Lipid Sci Tech 124: 2100242. https://doi.org/10.1002/ejlt.202100242

[59] Hamed M, Abdallah IA, Alaa Bedair, et al. (2023) Sample preparation methods for determination of quercetin and quercetin glycosides in diverse matrices. Microchem J 194: 109233. https://doi.org/10.1016/j.microc.2023.109233

[60] Rad SAG, Jalili M, Ansari F, et al. (2023) Maturity impact on physicochemical composition and polyphenol properties of extra virgin olive oils obtained from Manzanilla, Arbequina, and Koroneiki varieties in Iran. Food Sci Nutr 11: 5396-5408. https://doi.org/10.1002/fsn3.3497

[61] Sulastri E, Zubair MS, Anas NI, et al. (2018) Total phenolic, total flavonoid, quercetin content and antioxidant activity of standardized extract of Moringa oleifera leaf from regions with different elevation. Pharmacogn J 10: s104-s108. https://doi.org/10.5530/pj.2018.6s.20

[62] Andjelkovic M, Van Camp J, Pedra M, et al. (2008) Correlations of the phenolic compounds and the phenolic content in some Spanish and French olive oils. J Agri Food Chem 56: 5181-5187. https://doi.org/10.1021/jf0724419

[63] Ninfali P, Bacchiocca M, Biagiotti E, et al. (2002) Validation of the oxygen radical absorbance capacity (ORAC) parameter as a new index of quality and stability of virgin olive oil. J Am Oil Chem Soc 79: 977-982. https://doi.org/10.1007/s11746-002-0590-7

[64] Bakhouche A, Lozano-Sánchez J, Beltrán-Debón R, et al. (2013) Phenolic characterization and geographical classification of commercial Arbequina extra-virgin olive oils produced in southern Catalonia. Food Res Int 50: 401-408. https://doi.org/10.1016/j.foodres.2012.11.001

[65] Uluata S, Altuntaş Ü, Özçelik B (2016) Biochemical characterization of Arbequina extra virgin olive oil produced in Turkey. J Am Oil Chem Soc 93: 617-626. https://doi.org/10.1007/s11746-016-2811-z

[66] Kennedy FKA, Anjo FA, Matumoto‐Pintro PT, et al. (2025) Field and processing conditions of olive fruits of ‘Arbequina’ cultivar on the oil’s quality sold in Brazil. Eur J Lipid Sci Technol 127: E70054. https://doi.org/10.1002/ejlt.70054

[67] García A, Brenes M, García P, et al. (2003) Phenolic content of commercial olive oils. Eur Food Res Technol 216: 520-525. https://doi.org/10.1007/s00217-003-0706-3

[68] Allalout A, Krichène D, Methenni K, et al. (2009) Characterization of virgin olive oil from Super Intensive Spanish and Greek varieties grown in northern Tunisia. Sci Hortic 120: 77-83. https://doi.org/10.1016/j.scienta.2008.10.006

[69] Škevin D, Rade D, Štrucelj D, et al. (2003) The influence of variety and harvest time on the bitterness and phenolic compounds of olive oil. Eur J Lipid Sci Technol 105: 536-541, https://doi.org/10.1002/ejlt.200300782

[70] Seydou S, Koca G, Onar O, et al. (2022) Antioxidant activities of Turkish extra virgin olive oils. Commun Fac Sci Univ Ank Ser C 31: 26-38. https://doi.org/10.53447/communc.1069705

[71] Yıldırım F, Yıldırım AN, Özkan G, et al. (2020) Early harvest effects on hydrophilic phenolic components of extra virgin olive oils cvs. ‘Ayvalık’, ‘Memecik’ and ‘Topakaşı’. Biochem Genet 58: 981-992. https://doi.org/10.1007/s10528-020-10008-9

[72] O Soufi, Romero C, Hadid M, et al. (2018) Characterization of phenolic profile and antioxidant potential of some Algerian olive oils cultivars. J Food Qual Hazards Control 5: 49-53. https://doi.org/10.29252/jfqhc.5.2.4

[73] Franco MN, Galeano-Díaz T, Sánchez J, et al. (2014) Total phenolic compounds and tocopherols profiles of seven olive oil varieties grown in the south-west of Spain. J Oleo Sci 63: 115-125. https://doi.org/10.5650/jos.ess13098

[74] Ballus CA, Quirantes-Piné R, Bakhouche A, et al. (2015) Profile of phenolic compounds of Brazilian virgin olive oils by rapid resolution liquid chromatography coupled to electrospray ionisation time-of-flight mass spectrometry (RRLC-ESI-TOF-MS). Food Chem 170: 366-377. https://doi.org/10.1016/j.foodchem.2014.08.054

[75] Medina G, Sanz C, L. León, et al. (2021) Phenolic variability in fruit from the ‘Arbequina’ olive cultivar under Mediterranean and Subtropical climatic conditions. Grasas Aceites 72: e438- e438. https://doi.org/10.3989/gya.1002202

[76] Talhaoui N, Gómez-Caravaca AM, León L, et al. (2014) Determination of phenolic compounds of ‘Sikitita’ olive leaves by HPLC-DAD-TOF-MS. Comparison with its parents ‘Arbequina’ and ‘Picual’ olive leaves. LWT-Food Sci Technol 58: 28-34. https://doi.org/10.1016/j.lwt.2014.03.014

[77] Oğraş ŞŞ (2022) Comparative study of phenolic compounds in olive oils from different geographic regions. Turk J Agric For 46: 318-326. https://doi.org/10.55730/1300-011X.3005

[78] Xiang C, Xu Z, Liu J, et al. (2017) Quality, composition, and antioxidant activity of virgin olive oil from introduced varieties at Liangshan. LWT 78: 226-234. https://doi.org/10.1016/j.lwt.2016.12.029

[79] Malheiro R, Rodrigues N, José Alberto Pereira (2015) Olive oil phenolic composition as affected by geographic origin, olive cultivar, and cultivation systems. In: Olive and olive oil bioactive constituents 93-121. https://doi.org/10.1016/B978-1-63067-041-2.50010-

[80] Esti M, Cinquanta L, Notte EL (1998) Phenolic compounds in different olive varieties. J Agric Food Chem 46: 32-35. https://doi.org/10.1021/jf970391+

[81] Ghasemi S, Koohi DE, Emmamzadehhashemi MSB, et al. (2018) Investigation of phenolic compounds and antioxidant activity of leaves extracts from seventeen cultivars of Iranian olive (Olea europaea L.) . J Food Sci Technol 55: 4600-4607. https://doi.org/10.1007/s13197-018-3398-1

[82] Vinha AF, Ferreres F, Silva BM, et al. (2005) Phenolic profiles of Portuguese olive fruits (Olea europaea L.): Influences of cultivar and geographical origin. Food Chem 89: 561-568. https://doi.org/10.1016/j.foodchem.2004.03.012

[83] Banco AP, Puertas CM, Trentacoste ER, et al. (2022) Promising olive varieties for extra virgin oil production in Mendoza, Argentina. J Saudi Soc Agric Sci 22: 62-70. https://doi.org/10.1016/j.jssas.2022.06.003

[84] Soufi O, Romero C, Motilva MJ, et al. (2016) Effect of dry salting on flavonoid profile and antioxidant capacity of Algerian olive cultivars. Grasas Aceites 67: e132. http://doi.org/10.3989/gya.0641152

[85] Djemaa-Landri K, Hamri-Zeghichi S, Belkhiri-Beder W, et al. (2021) Phenolic content, antioxidant and anti-inflammatory activities of some Algerian olive stone extracts obtained by conventional solvent and microwave-assisted extractions under optimized conditions. J Food Meas Charact 15: 4166-4180. https://doi.org/10.1007/s11694-021-00992-w

[86] Mansouri F, Ben Moumen A, Houmy N, et al. (2014) Evaluation of the oxidative stability of blends of ‘Arbequina’ olive oils with other monovarietal olive oils. Olivae 23-30.

[87] Mansouri F, Ben Moumen A, S. Aazza, et al. (2019) Quality and chemical profiles of virgin olive oils of three European cultivars suitable for super-high-density planting conditions in eastern Morocco. Mater Today Proc 13: 998-1007. https://doi.org/10.1016/j.matpr.2019.04.065

[88] Khaliq A, Sabir SM, Ahmed SD, et al. (2015) Antioxidant activities and phenolic composition of Olive (Olea europaea) leaves. J. Appl. Bot. Food Qual. 88: 16-21. https://doi.org/10.5073/JABFQ.2015.088.004

[89] Ribas JCR, Lazzari A, Gonzalez LBF, et al. (2023) Bioactive compounds and antioxidant activity of leaves from olive trees grown in Paraná, Brazil. Pesq Agropec Bras 58: e03025. https://doi.org/10.1590/S1678-3921.pab2023.v58.03025

[90] da Fonseca Antunes B, Otero DM, Bonemann DH, et al. (2021) Evaluation of physicochemical, bioactive composition and profile of fatty acids in leaves of different olive cultivars. Rev Ceres 68: 511-520. https://doi.org/10.1590/0034-737X202168060002

[91] Touss J, Romero A, Plana J, et al. (1997) Chemical and sensory characteristics of «Arbequina» olive oil obtained in different growing areas of Spain. Grasas Aceites 48: 415-424. https://doi.org/10.3989/gya.1997.v48.i6.814

[92] Cavalheiro CV, Picoloto RS, Cichoski AJ, et al. (2015) Olive leaves offer more than phenolic compounds - Fatty acids and mineral composition of varieties from Southern Brazil. Ind Crop Prod 71: 122-127. https://doi.org/10.1016/j.indcrop.2015.03.054

[93] Otero DM, Oliveira FM, Lorini A, et al. (2020) Oleuropein: Methods for extraction, purifying and applying. Rev Ceres 67: 315-329. https://doi.org/10.1590/0034-737X202067040009

[94] Zagmutt S, Guzmán L, Orrego R, et al. (2015) Phenolic compound identification and antioxidant capacity of Alperujo extracts from region del Maule, Chile. Int J Food Prop 19: 2016-2025. https://doi.org/10.1080/10942912.2015.1092162

[95] Palmeri R, Siracusa L, Carrubba M, et al. (2022) Olive leaves, a promising byproduct of olive oil industry: Assessment of metabolic profiles and antioxidant capacity as a function of cultivar and seasonal change. Agronomy 12: 2007. https://doi.org/10.3390/agronomy12092007

[96] Dabbou S, Issaoui M, Esposto S, et al. (2009) Cultivar and growing area effects on minor compounds of olive oil from autochthonous and European introduced cultivars in Tunisia. J Sci Food Agric 89: 1314-1325. https://doi.org/10.1002/jsfa.3588

[97] de los Angeles de Fernandez M, SotoVargas VC, Silva MF (2014) Phenolic compounds and antioxidant capacity of monovarietal olive oils produced in Argentina. J Am Oil Chem Soc 91: 2021-2033. https://doi.org/10.1007/s11746-014-2558-3

[98] Manai-Djebali H, Krichène D, Ouni Y, et al. (2012) Chemical profiles of five minor olive oil varieties grown in central Tunisia. J Food Compos Anal 27: 109-119. https://doi.org/10.1016/j.jfca.2012.04.010

[99] Bouaziz M, Chamkha M, Sayadi S (2004) Comparative study on phenolic content and antioxidant activity during maturation of the olive cultivar Chemlali from Tunisia. J Agric Food Chem 52: 5476-5481. https://doi.org/10.1021/jf0497004

[100] Deraz MS, El-Kholany AS, et al. (2022) Chemical evaluation and biological activity of olive leaves extract. Al-Azhar J Agric Res 47: 35-45. https://doi.org/10.21608/ajar.2022.266482

[101] Deng Y, Zhou J, Qu J, et al. (2025) Deep eutectic solvents and wall-breaking technique: A new frontier in the extraction of oleuropein and flavonoids from olive leaves with superior antioxidant and antitumor potential. Molecules 30: 1150. https://doi.org/10.3390/molecules30051150

[102] Wang B, Shen S, Qu J, et al. (2021) Optimizing total phenolic and oleuropein of Chinese olive (Olea europaea) leaves for enhancement of the phenols content and antioxidant activity. Agronomy 11: 686. https://doi.org/10.3390/agronomy11040686

[103] Uslu N, Özcan MM (2022) Effect of collection period and irrigation process on antioxidant activity and phenolic compounds of olive leaves. Akademik Gıda 20: 122-131. https://doi.org/10.24323/akademik-gida.1149746

[104] Ben Salah M, Abdelmelek H, Abderraba M (2012) Study of phenolic composition and biological activities assessment of olive leaves from different varieties grown in Tunisia. Med Chem 2: 5. https://doi.org/10.4172/2161-0444.1000124

[105] Khelouf I, Karoui IJ, Lakoud A, et al. (2023) Comparative chemical composition and antioxidant activity of olive leaves Olea europaea L. of Tunisian and Algerian varieties. Heliyon 9: e22217. https://doi.org/10.1016/j.heliyon.2023.e22217

[106] Kiritsakis K, Kontominas MG, Kontogiorgis C, et al. (2009) Composition and antioxidant activity of olive leaf extracts from Greek olive cultivars. J Am Oil Chem Soc 87: 369-376. https://doi.org/10.1007/s11746-009-1517-x