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Olive Antioxidants: Extraction, Biological Activity and Practical Applications—2nd Edition

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A special issue of Antioxidants (ISSN 2076-3921). This special issue belongs to the section "Extraction and Industrial Applications of Antioxidants".

Deadline for manuscript submissions: 25 October 2024 | Viewed by 13727

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Dr. Alejandra Bermudez-Oria

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Department of Food Phytochemistry, Instituto de la Grasa (Spanish National Research Council, CSIC), Pablo Olavide University, Building 46, Ctra de Utrera km 1, 41013 Seville, Spain
Interests: bioactive molecules; olive; alperujo; extraction processes; phenol–polysaccharide complex; antioxidant dietary fiber; phenolic compounds; modified pectin; flow cytometry; antiproliferative activity; anti-inflammatory activity; cancer
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Prof. Dr. Juan Fernández-Bolaños

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Department of Food Phytochemistry, Fat Institute, The Spanish National Research Council (CSIC), Pablo de Olavide University Campus - Building 46, 41013 Seville, Spain
Interests: food analysis; bioactive molecules; alperujo; phenolic compounds; extraction processes; phenol–polysaccharide complex; modified pectin; antioxidant activities; anti-inflammatory activity
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

We are delighted to be organizing Volume 2 of this Special Issue, entitled “Olive Antioxidants: Extraction, Biological Activity and Practical Applications”, especially given the success of Volume 1, which you can read here, along with other publications, free of charge: https://www.mdpi.com/journal/antioxidants/special_issues/Olive_Antioxidants

Olive extracts obtained from oil, fruit, leaves, wood, or waste are responsible for many health benefits, such as the reduction of hypertension and diabetes or the prevention of cardiovascular diseases and cancer. These effects are due, at least in part, to the high amount of antioxidants present in olive products, especially polyphenols (phenolic acid, flavonoids, lignans, secoiridoids derivatives), carotenoids (xanthophyll and β-carotene), chlorophylls, pheophytins, and tocopherol α (vitamin E), since they ameliorate the oxidative stress produced by free radicals and the consequent cellular damage. In recent years, studies have also focused on cell wall polysaccharide–polyphenol complexes that occur during the crushing and malaxation of olive paste before the extraction of the oil, containing nutritional, health, and antioxidant benefits. Thus, olive extracts have received considerable attention and have been increasingly investigated in relation to health effects, analytical approaches, extraction efficiency, and applications. We invite you to contribute your latest findings to this Special Issue that will include all aspects of the extracts from olive material; papers including the development and optimization of new extraction procedures from conventional extraction methods with solvent systems (hot water, organic solvents, maceration, Soxhlet extraction) to green non-conventional methods (deep eutectic solvent, ultrasound-, microwave-, and enzymatic-assisted extraction; supercritical fluid and subcritical water extraction; or pressurized liquid extraction). This information could be complemented with recent developments in the application of these extracts in the cosmetic, pharmaceutical, and food industries.

Dr. Alejandra Bermudez-Oria
Prof. Dr. Juan Fernández-Bolaños
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Antioxidants is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

antioxidant effect
olive oil
olive by-products
olive leaves
polyphenols
carotenoids
polysaccharide–polyphenol complexes
vitamin E
health
mediterranean diet

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Published Papers (8 papers)

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Research

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17 pages, 1853 KiB

Open AccessArticle

Lower Energy-Demanding Extraction of Bioactive Triterpene Acids by Microwave as the First Step towards Biorefining Residual Olive Skin

by Irene Gómez-Cruz, María del Mar Contreras, Inmaculada Romero and Eulogio Castro

Antioxidants 2024, 13(10), 1212; https://doi.org/10.3390/antiox13101212 - 9 Oct 2024

Viewed by 361

Abstract

In the olive oil industry, a pit fraction is collected from olive pomace and split into a clean pit fraction and a residual olive skin-rich fraction, which does not an industrial application. Therefore, in this work, microwave-assisted extraction (MAE) was applied to obtain high-value triterpene acids (maslinic acid and oleanolic acid) from this biomass using the renewable solvent ethanol. The response surface methodology was used to gain a deeper understanding of how the solvent (ethanol–water, 50–100% v/v), time (4–30 min), and temperature (50–120 °C) affect the extraction performance, as well as the energy required for the process. The effect of milling was also studied and the solid-to-liquid ratio was also evaluated, and overall, a good compromise was found at 10% (w/v) using the raw sample (unmilled biomass). The optimised conditions were applied to residual olive skin sourced from various industries, yielding up to 5.1 g/100 g and 2.2 g/100 g dry biomass for maslinic acid and oleanolic acid, respectively. In conclusion, the residual olive skin is a promising natural source of these triterpene acids, which can be extracted using MAE, releasing extracted solids rich in polymeric carbohydrates and lignin that can be valorised under a holistic biorefinery process. Full article

(This article belongs to the Special Issue Olive Antioxidants: Extraction, Biological Activity and Practical Applications—2nd Edition)

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16 pages, 1016 KiB

Open AccessArticle

Effects of Some Olive Fruits-Derived Products on Oxidative Stress and Cardiovascular Biomarkers on Experimental Diabetes Mellitus

by José Pedro De La Cruz, Laura Iserte-Terrer, María Dolores Rodríguez-Pérez, Laura Ortega-Hombrados, Ana María Sánchez-Tévar, María Monsalud Arrebola-Ramírez, María África Fernández-Prior, Cristina Verdugo-Cabello, Juan Antonio Espejo-Calvo and José Antonio González-Correa

Antioxidants 2024, 13(9), 1127; https://doi.org/10.3390/antiox13091127 - 18 Sep 2024

Viewed by 513

Abstract

The aim of this study is to assess the possible effect of olive seed oil (OSO) and destoned and dehydrated olive oil (DDOO), in comparison with extra-virgin olive oil (EVOO), on some cardiovascular biomarkers in an experimental model of diabetes mellitus. Diabetic animals showed evident alterations in biomarkers involved in the evolution of diabetic vasculopathy, marked by increases in biomarkers that favor vascular damage, which was between 1.5 and five times as many as those in non-diabetic animals, and a smaller number of biomarkers that protect against such damage (25–75% less than in healthy controls) was observed. The three oils administered decreased the concentration of biomarkers of vascular damage (35–45% in the serum lipid profile, 15–40% in early biomarkers of vascular inflammation and 20–60% in platelet aggregation and in thromboxane/prostacyclin imbalance). The greatest effect was by the antioxidant, both in the inhibition of lipid peroxidation and in the increase of glutathione. DDOO showed a significantly greater effect on oxidative stress and on thromboxane/prostacyclin imbalance than those shown by OSO and EVOO. This greater effect may possibly be explained by its higher triterpenoid content (913 mg/kg, compared to 113 mg/kg in OSO and 75 mg/kg in EVOO). We conclude, in the light of the results of this study, that these oils meet two basic conditions: they could improve the yield of the olive industry, and they equal, and may even increase, the beneficial effects of EVOO on cardiovascular disease. Full article

(This article belongs to the Special Issue Olive Antioxidants: Extraction, Biological Activity and Practical Applications—2nd Edition)

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13 pages, 1643 KiB

Open AccessArticle

Health-Promoting Properties of Pectin–Polyphenol Complex Extracted from Olive Oil By-Product Alperujo: Antioxidant, Antiproliferative, and Anti-Inflammatory Activities

by Alejandra Bermúdez-Oria, María Luisa Castejón, Fátima Rubio-Senent, Guillermo Rodríguez-Gutiérrez and Juan Fernández-Bolaños

Antioxidants 2024, 13(9), 1066; https://doi.org/10.3390/antiox13091066 - 30 Aug 2024

Viewed by 586

Abstract

This research explores the health-promoting properties of the pectin–polyphenol complex extracted from alperujo, a by-product of olive oil production. This study investigates the chemical composition and antioxidant activity of the extracts, revealing their high antioxidant activity in vitro. Cell viability assays conducted on colon carcinoma cells (Caco-2) demonstrate the inhibitory effect of the extracts on cell proliferation. However, the extracts do not affect the viability of differentiated Caco-2 cells, suggesting a selective antiproliferative action. Additionally, the extracts reduce intracellular reactive oxygen species (ROS) and nitrite (NO) production in LPS-stimulated murine peritoneal macrophages. Furthermore, the extracts exhibit anti-inflammatory effects by downregulating the secretion of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 in these macrophages. These findings highlight the potential of pectin–polyphenol complexes as functional ingredients with significant health benefits, demonstrating antioxidant, antiproliferative, and anti-inflammatory properties. Full article

(This article belongs to the Special Issue Olive Antioxidants: Extraction, Biological Activity and Practical Applications—2nd Edition)

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11 pages, 1175 KiB

Open AccessArticle

Beneficial Effects of Olive Oil Enriched with Lycopene on the Plasma Antioxidant and Anti-Inflammatory Profile of Hypercholesterolemic Patients

by Jesus Roman Martínez Álvarez, Ana Belen Lopez Jaen, Monica Cavia-Saiz, Pilar Muñiz and Victoria Valls-Belles

Antioxidants 2023, 12(7), 1458; https://doi.org/10.3390/antiox12071458 - 20 Jul 2023

Cited by 1 | Viewed by 1983

Abstract

Olive oil and lycopene are foods that have potent antioxidant activity. The objective was to determine the effects of consumption of olive oil enriched with lycopene on oxidative stress biomarkers in hypercholesterolemic subjects. We examined the effects of oil enriched with lycopene extract daily intake during 1 month on plasma antioxidant capacity, lipids profile (triacylgycerols, total cholesterol, cHDL; cLDL, ox-LDL), biomarkers of oxidative stress, and inflammatory markers related with atherosclerosis risk (C-reactive protein (CRP), IL-6; sDC4L) in subjects hypercholesteremics (cholesterol > 220 mg/dL). In the group consuming olive oil-lycopene, significant increases (p < 0.05) in the levels of plasma lycopene concentration (0.146 ± 0.03 versus 0.202 ± 0.04 (µmol/L)), α-carotene (0.166 ± 0.064 versus 0.238 ± 0.07) and in β-carotene (0.493 ± 0.187 versus 0.713 ± 0.221) were observed. These results are linked with the increases of plasma antioxidants and decreases biomarkers of oxidative stress (carbonyl groups, malondialdehyde and 8-hydroxy-deoxiguanosine) observed in hypercholesterolemic group. In relation to lipid profile, a significant decrease was observed in the levels of ox-LDL (781 ± 302 versus 494 ± 200), remaining unchanged the levels of TG, cholesterol, HDL and LDL-c. Regarding inflammatory biomarkers, the levels of CRP and IL-6 decreased significantly. The positive results obtained in this study support the use of olive oil enriched with lycopene to reduce the risk of coronary disease. Full article

(This article belongs to the Special Issue Olive Antioxidants: Extraction, Biological Activity and Practical Applications—2nd Edition)

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14 pages, 969 KiB

Open AccessArticle

Application of a Cold-Pressing Treatment to Improve Virgin Olive Oil Production and the Antioxidant Phenolic Profile of Its by-Products

by África Fernández-Prior, Juan Cubero Cardoso, Alejandra Bermúdez-Oria, Ángeles Trujillo Reyes, Juan Fernández-Bolaños and Guillermo Rodríguez-Gutiérrez

Antioxidants 2023, 12(6), 1162; https://doi.org/10.3390/antiox12061162 - 27 May 2023

Cited by 3 | Viewed by 1741

Abstract

The olive oil sector is continuously evolving in order to improve the quality of olive oil and its by-products. In fact, the trend is to use increasingly greener olives to improve quality by decreasing the extraction yield, thus obtaining a higher content of antioxidant phenolics. The application of a cold-pressing system to the olive before the extraction of oil was tested with three varieties: picual at three different stages of maturity and arbequina and hojiblanca at early stages of maturity. The Abencor system was used for the extraction of virgin olive oil and its by-products. For the quantification of phenols and total sugars for all phases, organic solvent extractions and colorimetric measurements and high-performance liquid chromatography (HPLC) with a UV detector were used. The results show that the new treatment significantly improved the amount of oil extracted by between 1 and 2% and even increased its concentration of total phenols by up to 33%. Regarding the by-products, the concentrations of the main phenols, such as hydroxytyrosol, increased by almost 50%, as did the glycoside. The treatment also facilitated the separation of phases in by-products and improved the phenolic profile, although not in terms of total phenols, but individual phenols with higher antioxidant activity were obtained. Full article

(This article belongs to the Special Issue Olive Antioxidants: Extraction, Biological Activity and Practical Applications—2nd Edition)

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15 pages, 1544 KiB

Open AccessArticle

Green Extraction of Antioxidant Compounds from Olive Tree Leaves Based on Natural Deep Eutectic Solvents

by Aina Mir-Cerdà, Mercè Granados, Javier Saurina and Sonia Sentellas

Antioxidants 2023, 12(5), 995; https://doi.org/10.3390/antiox12050995 - 25 Apr 2023

Cited by 7 | Viewed by 2145

Abstract

Agri-food industries generate a large amount of waste that offers great revalorization opportunities within the circular economy framework. In recent years, new methodologies for the extraction of compounds with more eco-friendly solvents have been developed, such as the case of natural deep eutectic solvents (NADES). In this study, a methodology for extracting phenolic compounds from olive tree leaves using NADES has been optimized. The conditions established as the optimal rely on a solvent composed of choline chloride and glycerol at a molar ratio of 1:5 with 30% water. The extraction was carried out at 80 °C for 2 h with constant agitation. The extracts obtained have been analyzed by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) in MRM mode. The comparison with conventional ethanol/water extraction has shown that NADES, a more environmentally friendly alternative, has improved extraction efficiency. The main polyphenols identified in the NADES extract were Luteolin-7-O-glucoside, Oleuropein, 3-Hydroxytyrosol, Rutin, and Luteolin at the concentrations of 262, 173, 129, 34, and 29 mg kg⁻¹ fresh weight, respectively. Full article

(This article belongs to the Special Issue Olive Antioxidants: Extraction, Biological Activity and Practical Applications—2nd Edition)

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25 pages, 3818 KiB

Open AccessArticle

Exploitation of Olive (Olea europaea L.) Seed Proteins as Upgraded Source of Bioactive Peptides with Multifunctional Properties: Focus on Antioxidant and Dipeptidyl-Dipeptidase—IV Inhibitory Activities, and Glucagon-like Peptide 1 Improved Modulation

by Martina Bartolomei, Anna Laura Capriotti, Yuchen Li, Carlotta Bollati, Jianqiang Li, Andrea Cerrato, Lorenzo Cecchi, Raffaele Pugliese, Maria Bellumori, Nadia Mulinacci, Aldo Laganà, Anna Arnoldi and Carmen Lammi

Antioxidants 2022, 11(9), 1730; https://doi.org/10.3390/antiox11091730 - 31 Aug 2022

Cited by 9 | Viewed by 2969

Abstract

Agri-food industry wastes and by-products include highly valuable components that can upgraded, providing low-cost bioactives or used as an alternative protein source. In this context, by-products from olive production and olive oil extraction process, i.e., seeds, can be fostered. In particular, this work was aimed at extracting and characterizing proteins for Olea europaea L. seeds and at producing two protein hydrolysates using alcalase and papain, respectively. Peptidomic analysis were performed, allowing to determine both medium- and short-sized peptides and to identify their potential biological activities. Moreover, an extensive characterization of the antioxidant properties of Olea europaea L. seed hydrolysates was carried out both in vitro by 2,2-diphenyl-1-picrylhydrazyl (DPPH), by ferric reducing antioxidant power (FRAP), and by 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assays, respectively, and at cellular level by measuring the ability of these hydrolysates to significant reduce the H₂O₂-induced reactive oxygen species (ROS) and lipid peroxidation levels in human intestinal Caco-2 cells. The results of the both hydrolysates showed significant antioxidant properties by reducing the free radical scavenging activities up to 65.0 ± 0.1% for the sample hydrolyzed with alcalase and up to 75.7 ± 0.4% for the papain hydrolysates tested at 5 mg/mL, respectively. Moreover, similar values were obtained by the ABTS assays, whereas the FRAP increased up to 13,025.0 ± 241.5% for the alcalase hydrolysates and up to 12,462.5 ± 311.9% for the papain hydrolysates, both tested at 1 mg/mL. According to the in vitro results, both papain and alcalase hydrolysates restore the cellular ROS levels up 130.4 ± 4.24% and 128.5 ± 3.60%, respectively, at 0.1 mg/mL and reduce the lipid peroxidation levels up to 109.2 ± 7.95% and 73.0 ± 7.64%, respectively, at 1.0 mg/mL. In addition, results underlined that the same hydrolysates reduced the activity of dipeptidyl peptidase-IV (DPP-IV) in vitro and at cellular levels up to 42.9 ± 6.5% and 38.7 ± 7.2% at 5.0 mg/mL for alcalase and papain hydrolysates, respectively. Interestingly, they stimulate the release and stability of glucagon-like peptide 1 (GLP-1) hormone through an increase of its levels up to 660.7 ± 21.9 pM and 613.4 ± 39.1 pM for alcalase and papain hydrolysates, respectively. Based on these results, olive seed hydrolysates may represent new ingredients with antioxidant and anti-diabetic properties for the development of nutraceuticals and functional foods for the prevention of metabolic syndrome onset. Full article

(This article belongs to the Special Issue Olive Antioxidants: Extraction, Biological Activity and Practical Applications—2nd Edition)

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Review

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25 pages, 367 KiB

Open AccessReview

Olive Oil Phenolic Compounds’ Activity against Age-Associated Cognitive Decline: Clinical and Experimental Evidence

by Anna Boronat, Gabriele Serreli, Jose Rodríguez-Morató, Monica Deiana and Rafael de la Torre

Antioxidants 2023, 12(7), 1472; https://doi.org/10.3390/antiox12071472 - 22 Jul 2023

Cited by 2 | Viewed by 2608

Abstract

Epidemiological studies have shown that consuming olive oil rich in phenolic bioactive compounds is associated with a lower risk of neurodegenerative diseases and better cognitive performance in aged populations. Since oxidative stress is a common hallmark of age-related cognitive decline, incorporating exogenous antioxidants could have beneficial effects on brain aging. In this review, we firstly summarize and critically discuss the current preclinical evidence and the potential neuroprotective mechanisms. Existing studies indicate that olive oil phenolic compounds can modulate and counteract oxidative stress and neuroinflammation, two relevant pathways linked to the onset and progression of neurodegenerative processes. Secondly, we summarize the current clinical evidence. In contrast to preclinical studies, there is no direct evidence in humans of the bioactivity of olive oil phenolic compounds. Instead, we have summarized current findings regarding nutritional interventions supplemented with olive oil on cognition. A growing body of research indicates that high consumption of olive oil phenolic compounds is associated with better preservation of cognitive performance, conferring an additional benefit, independent of the dietary pattern. In conclusion, the consumption of olive oil rich in phenolic bioactive compounds has potential neuroprotective effects. Further research is needed to understand the underlying mechanisms and potential clinical applications. Full article

(This article belongs to the Special Issue Olive Antioxidants: Extraction, Biological Activity and Practical Applications—2nd Edition)

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