Olive Leaves Research Articles

Olive Leaf Extract Supplementation Improves Postmenopausal Symptoms: A Randomized, Double-Blind, Placebo-Controlled Parallel Study on Postmenopausal Women

Olive Leaf Extract Supplementation Improves Postmenopausal Symptoms: A Randomized, Double-Blind, Placebo-Controlled Parallel Study on Postmenopausal Women

Triple Enzymatic Cascade Reaction to Produce Hydroxytyrosol Acetate from Olive Leaves Using Integrated Membrane Bioreactors.

An integrated system of three membrane bioreactors (MBRs) has been developed that cascades three different enzymatic reactions. The integrated system was applied to produce hydroxytyrosol acetate from oleuropein extracted from olive leaves. Different reactor configurations for each reaction were tested and individually optimized to select the MBR to ensure high conversion and continuous production of oleuropein aglycone (OA), hydroxytyrosol (HY) and hydroxytyrosol acetate (HA). Based on this study, the most performing configuration of the integrated system was identified. In the first reaction, oleuropein was converted to OA using a biocatalytic membrane reactor (BMR) with immobilized β-glucosidase in polymeric membranes (conversion 95 %). The OA was then fed to another BMR, where it was converted to HY (conversion: 70 %) by an immobilized mutant of the promiscuous hydrolase/acyltransferase (PestE) (from the thermophilic archaeon Pyrobaculum calidifontis VA1). The HY produced was then acetylated using PestE immobilized on magnetic nanoparticles in a multiphase MBR (conversion: 98 %) and simultaneously extracted (extraction: 98 %) in ethyl acetate. The work demonstrates that continuous cascade enzymatic reactions can be engineered using artificial membranes to tailor enzyme compartmentalization, mass transport and phase contact according to reaction requirements. Besides, environmental factors proved the sustainability of the integrated membrane bioreactive system.

Health Benefits of Olive Leaf: The Focus on Efficacy of Antiglycation Mechanisms.

Olive leaves have been a therapeutic herbal agent for diseases for centuries. Olive leaves contain many health-beneficial nutrients and bioactive components. There is much evidence for the positive effects of the phenolic compounds they contain on health. The main active phenolic component in olive leaves is oleuropein, which can constitute 6%-9% of the leaf's dry matter and has been intensively studied for its promising results/effects on human health. In addition, olive leaf provides health benefits through bioactive components, such as secoiridoids, flavonoids, triterpenes, and lignans. The anti-inflammatory, antioxidant, anticancer, antidiabetic, and antihypertensive properties of bioactive components, especially oleuropein, are well known. In addition, various health benefits, such as neuroprotective effects and microbiota modulation, are also mentioned. In recent years, in vitro studies have shown that olive leaves and bioactive components from olive leaves may have antiglycation effects. Currently, it is thought that the components found in olive leaves have a direct or indirect antiglycation effect. It is thought that, their direct effects include reducing the interaction between sugars and amino acids, nucleic acids, and lipids and sequestering reactive dicarbonyl species, and their indirect effects include preventing the formation of advanced glycation end-products (AGEs) by reducing inflammation and oxidative stress. However, in vivo and clinical studies are needed to prove these mechanisms and understand how their metabolism works in the human body. This review examines the beneficial health effects of olive leaves and their potential antiglycation role.

Encapsulation of Olive Leaf Extract by Double Emulsion Method for Enriched Bakery Products: Enhancing Stability and Functionality

Encapsulation of Olive Leaf Extract by Double Emulsion Method for Enriched Bakery Products: Enhancing Stability and Functionality

Effect of Dietary Olive Leaf Integration on Qualitative Characteristics of Sheep Cheese During Ripening

Olive leaf by-products may be an important feed source for ruminants in the Mediterranean area, due to their nutritional value and high levels of functional metabolites. Additionally, their use can enhance the environmental and economic sustainability of the productions. To evaluate the effect of olive leaf supplementation on the fatty acid profile of sheep cheese, two farms with Comisana breed sheep with free access to pasture and fedwith 300 g/head/day of concentrate were considered. One farm supplemented the feed with clover hay ad libitum (NOL) and the other farm replaced hay with olive leaves (OLI) in the autumn period. Cheese analyses were performed at 15, 30, and 60 days of ripening. Saturated fatty acids were lower in OLI cheese than NOL cheese, while MUFA and PUFA n-3 and n-6 were higher in OLI cheese. Myristic acid (C14:0) and palmitic acid (C16:0) were lower in OLI cheese compared to NOL (8.31% vs. 8.90% and 21.52% vs. 24.95%, respectively), while oleic acid (C18:1 cis-9) was higher in OLI cheese (20.66% vs. 18.78%). Also, CLA cis-9 trans-11 (0.98% vs. 0.84%), and other isomers were higher in OLI cheese. Health indexes, such as the thrombogenic and atherogenic index, were lower in OLI than in NOL cheese (1.96 vs. 2.38 and 1.69 vs. 2.05, respectively) showing the improvement in the health quality of cheese due to olive leaf integration in directly on farm sheep feeding.

Effect of olive leaf extract on the quality of Cantal cheese

This study aimed to evaluate the impact of olive leaf extract (OLE) on the quality of Cantal cheese. The cheeses were fortified with different concentrations (Control, 1, 2, and 3 %) of OLE and analysed for quality during storage. The cheeses were evaluated on days 1, 28, and 63 for physicochemical, compositional, textural, rheological parameters, colour, microbiological analysis, and antioxidant activity. The MIR and fluorescence spectroscopies were used to study the changes in the cheese structure. A positive impact of OLE was observed on the antioxidant capacity. A mild inhibitory effect was observed against some beneficial bacteria (such as Lactococcus and Lactobacillus), while a strong inhibitory effect was found against pathogen microorganisms. No negative impact was found on the texture and chemical composition. Significant colour and structural changes were observed. The results indicate the potential of OLE to be used as bioactive ingredient to improve the quality of cheese.

Demographic toxicology of insect growth regulators on the nontarget ectolarval parasitoid Habrobracon hebetor

Habrobracon hebetor Say (Hymenoptera: Braconidae) is one of the most important parasitoids of many pyralid moths, including the olive leaf moth, Palpita unionalis Hubner (Lepidoptera: Pyralidae). The widespread use of insecticides threatens natural enemies. Assessing the side effects of insecticides on nontarget organisms supports the rational use of insecticides during field application. The present study evaluates the lethal and sublethal effects of three insect growth regulators (IGRs), novaluron, methoxyfenozide, and pyriproxyfen, on P. unionalis and the demographic toxicology of these IGRs on its parasitoid H. hebetor. The LC50 values of these IGRs on P. unionalis were 0.97, 0.176, and 0.00009 ppm, respectively, indicating that pyriproxyfen was the most toxic. When H. hebetor adults were exposed to these LC50 levels under laboratory conditions to determine possible side effects. The IGRs did not affect the paralysis and parasitism rates of the parasitoid nor the sex ratio of its offspring. IGR treatments slightly reduced hatching rates and immature survival by 15–25%, indicating moderate effects on the early developmental stages of H. hebetor. The longevity and fecundity of treated females were each reduced to < 50% of their respective values in untreated females. Additionally, some demographic parameters of the parasitoid were significantly affected by the IGRs. Nevertheless, despite these observed effects, the positive net reproductive rate (R0 > 0) and intrinsic rate of increase (rm > 1) of H. hebetor indicated an exponential population increase that reflects the compatibility of the IGRs with the parasitoid. Our results demonstrated that the tested IGRs could be categorized as relatively harmless compounds to the parasitoid. Following these laboratory assessments, field studies will be required to confirm the effects of the tested IGRs on H. hebetor as well as other nontarget organisms.

Hypertension management: A comparative analysis of garlic, hibiscus, hawthorn, and olive leaf and a survey

Hypertension, a prevalent cardiovascular condition characterized by elevated blood pressure, poses a significant global health challenge. This paper reviews the potential of garlic, hibiscus, hawthorn, and olive leaf in reducing hypertension and improving one’s health. A survey was conducted among first year pharmacy students. The survey included 5 knowledge-based and 5 opinion-based questions, focusing on the four herbal remedies. The knowledge-based questions showed a correct answer rate of 61.1%, with the statement that garlic is generally safe to include in one’s diet, but excessive consumption can lead to adverse effects garnering a 91.1% correct response rate. 58.3% of the respondents failed to know the simple definition of hypertension. Opinion-based questions revealed a positive attitude towards herbal remedies with an average of 81% showing agreement on the potential benefits. Nearly 83% believed in consulting health professionals before integrating olive leaf extract, and about 89% agreed that garlic should be used as an approach to manage hypertension.

The Role of Greek Olive Leaf Extract in Patients with Mild Alzheimer’s Disease (the GOLDEN Study): A Randomized Controlled Clinical Trial

Background: Olive leaves are a significant source of biophenols, which have a beneficial impact on cognitive performance. Objective: To examine, for the first time, in humans the effect of the daily consumption of a beverage containing olive leaf extract (OLE) versus a Mediterranean diet (MeDi) on patients diagnosed with mild Alzheimer’s Disease (AD), in addition to their regular treatment. Methods: A randomized clinical trial compared OLE’s effects on cognitive and functional performance in 55 mild AD patients. Each participant was randomly assigned to two groups: (1) Group 1 was given olive leaves for making a daily beverage and MeDi instructions through monthly diet programs; (2) Group 2 received only the MeDi instructions. After six months, all participants underwent a second neuropsychological evaluation. Results: Group 1 participants had statistically significantly higher MMSE scores compared to Group 2 with a p-value of 0.0135. Specifically, the mean MMSE difference in patients receiving OLE was close to 0, indicating no memory deterioration, whereas in controls it was −4.1, indicative of cognitive decline. The remaining neuropsychological assessments (FRSSD, FUCAS, ADAS-Cog, CDR, GDS, and NPI) revealed better results in the OLE group, except for GDS, which showed no change, but without statistically significant differences between the two groups.

Antimutagenic and anticoagulant therapeutic effects of Ag/Ag2O nanoparticles from Olea europaea leaf extract: mitigating metribuzin-induced hepato-and nephrotoxicity.

Silver nanoparticles (Ag/Ag₂O NPs) have garnered attention for their potent antioxidant, antimicrobial, and anti-inflammatory properties, showing promise for therapeutic applications, particularly in mitigating chemical-induced toxicity. This study aimed to synthesize Ag/Ag₂O NPs using Olea europaea (olive) leaf extract as a green, eco-friendly reducing agent and evaluate their protective effects against metribuzin-induced toxicity in Wistar rats, focusing on oxidative stress, hematological parameters, and lipid profiles, with specific dose optimization. Ag/Ag₂O NPs were synthesized using Olea europaea leaf extract, and their properties were confirmed via XRD, FTIR, SEM, EDS, and UV-visible spectroscopy. Wistar rats exposed to metribuzin (110mg/kg/day) were treated with two doses of Ag/Ag₂O NPs (0.062mg/kg and 0.125mg/kg). Hematological and biochemical markers were assessed to evaluate the NPs' protective effects. Physicochemical characterization confirmed the successful formation of Ag/Ag₂O NPs loaded with phytochemicals, exhibiting crystallite sizes of 23nm and 19nm, a particle size of 25nm, and significant peaks in XRD, FTIR, and UV-Vis spectra indicating the formation of Ag/Ag₂O. Metribuzin exposure led to significant hematological disruptions (elevated WBC, reduced RBC and hemoglobin) and worsened lipid profiles (increased cholesterol, LDL, and triglycerides). The lower NP dose (0.062mg/kg) improved WBC, RBC, hemoglobin, and platelet counts, normalized lipid levels, and positively influenced biochemical markers such as serum creatinine and uric acid. In contrast, the higher NP dose (0.125mg/kg) showed mixed results, with some improvements but an increase in triglycerides and continued elevation of ASAT and ALAT enzyme levels. Ag/Ag₂O NPs synthesized via green methods using olive leaf extract effectively mitigated metribuzin-induced toxicity, especially at lower doses, by improving oxidative stress markers and hematological and biochemical profiles. Dose optimization is crucial to maximize therapeutic benefits and minimize adverse effects, underscoring their potential in treating chemical-induced toxicity.

Antioxidant potential of olive leaf (&lt;i&gt;Olea europaea&lt;/i&gt; L.) sustainable extracts evaluated &lt;i&gt;in vitro&lt;/i&gt; and minced beef meat

In this work, by using water steam only, two antioxidant extracts were obtained from olive leaves (Olea europaea L.), a by-product of olive oil chain. Olive leaf extracts (OLEs) were tested as such (water extract: WE) and partially purified with ethyl acetate (ethyl acetate [EA] extract). Total phenols were 7.4 mg/mL and 3.8 mg/mL in WE and EA final solutions, respectively, evidencing a different composition by high-performance liquid chromatography analysis. Both extracts were evaluated in vitro in comparison to pure hydroxytyrosol (Hy). A 2,2-diphenyl-1-picrylhydrazyl (DPPH) EC50 of 57.6, 76.5, and 39.7 µg/mL and a ferric reducing antioxidant power EC50 of 84.8, 69.9, 41.2 µg/mL were determined for WE, EA, and Hy solution, respectively. The Rancimat induction time determined at 120°C in a lard sample with 200-ppm total phenol equivalent addition of WE, EA, and Hy was 8.92 h, 12.74 h, and 7.27 h, respectively (vs. 2.24 h for lard only). Extracts were added at the same dose (200 ppm) to minced beef patties that were put in closed containers under controlled air headspace composition (NA, natural air; HOA, modified air with 80% O2; and 20% N2) and stored at 4°C up to 10 days. Extracts showed significant effectiveness in contrasting decrease of O2 level in containers as well as pH and color changes of patties. A significant increase (expressed as mg of malondialdehyde MDA/kg; thiobarbituric acid-reactive substance (TBARS) assay was conducted in control samples at an interval of 0–10 days (from 0.52 to 0.78 mg of MDA/kg in NA samples; and from 0.55 to 1.31 mg of MDA/kg in HOA samples), while minimal changes were observed in treated samples. These findings suggest a potential use of OLEs for maintaining quality and oxidative stability of beef patties during storage.

Investigating the effects of wild olive Olea europaea leaf extract on growth, body composition, digestive enzyme activity, hematological parameters, and immune function in Nile Tilapia

AbstractObjectiveThis study investigated the effects of supplementing Nile Tilapia Oreochromis niloticus diets with wild olive Olea europaea leaf extract (WLE) on growth performance, digestive enzymes, and antioxidant and immunological parameters.MethodsWild olive leaf extract was added at different concentrations (WLE 0.0 [control], 1.0, 1.5, and 2.0%) and fed to triplicate fish groups for 12 weeks. At the end of the trial period, growth performance, body composition, digestive enzyme activities, and hematological, biochemical, antioxidant, and immunological parameters were evaluated.ResultAccording to the results, fish that were fed with WLE 1.5% and WLE 2.0% exhibited significantly improved weight gain, specific growth rate, and feed intake. The feed conversion ratio (FCR) was significantly reduced in fish supplied with WLE 1.5% and WLE 2.0%. Additionally, weight gain and FCR showed significance at both the linear and quadratic levels, as indicated by polynomial contrasts. However, the experimental diets did not impact fish body composition, digestive enzyme activity, or survival rate. Fish that received WLE 1.5% and WLE 2.0% showed significantly higher levels of white blood cells, red blood cells, hemoglobin, and hematocrit compared with the WLE 1.0% and control groups. Moreover, significant enhancements were observed in serum parameters, including total protein, albumin, globulin, lysozyme, catalase, superoxide dismutase, and total immunoglobulins, for the WLE 1.5% and WLE 2.0% groups compared with the control. Fish that were fed WLE 1.5% exhibited the lowest serum cortisol level.ConclusionIn conclusion, experimental diets with WLE levels of 1.5% and 2.0% effectively enhanced both the growth and immunological parameters of Nile Tilapia.

Targeted breast cancer therapy using novel nanovesicle formulations of Olea europaea extract

Olive leaf is a byproduct of the olive tree that is rich in phenolic compounds with potential anticarcinogenic effects against various cancers, including breast cancer. Nevertheless, the ingestion or topical application of such plant extracts faces certain limitations. These limitations can be addressed by encapsulating the extracts in nanovesicles to enhance their release and bioavailability. This study aims to develop nanovesicles using Olea europaea leaf extract to exploit its potential anti-cancer properties. Soy lecithin was used to form liposomes for encapsulation of the olive leaf extract. In addition, ethanol and glycerol were added to form ethosomes and glycerosomes, respectively. The antiproliferative effect of both the free extract and the three formed nanovesicles was tested in MCF7 and MCF10A cell lines. To comprehend the mechanisms leading to reduced cell viability after exposure to olive leaf extract and its nanovesicles, levels of reactive oxygen species (ROS), mitochondrial membrane potential, and apoptotic stage were evaluated. The results suggest that both, the nanovesicles and the free extract, are antiproliferative agents against MCF7 tumour cells. However, when examining the impact of olive leaf extract and the formulated nanovesicles on MCF10A cells, no reduction in cell viability was observed. Our findings indicate that the anti-tumour effect of the extract and its nanovesicles may be due to increased oxidative stress, mediated by mitochondrial damage. The mechanism through which olive leaf extract exerts its antiproliferative effect on the breast cancer tumour line implies that apoptosis may be induced by the extract via the involvement of a mitochondria-dependent ROS-mediated pathway.

A New Validated Method for Rapid Determination of OLEU Concentration in Dietary Supplements: Comparison with Total Phenol Content and Antioxidant Activity

The market for olive leaf dietary supplements is expanding rapidly and is valued at $437.15 million today. However, information on the control of these products is sketchy and the origin and variety of olives are rarely stated. The aim of this research was to validate a simple and rapid screening method for oleuropein determination in olive leaf dietary supplements. A matrix blank was prepared by removal of oleuropein from a mixture of dietary supplements and the matrix was then spiked with known concentrations to create a spiked matrix calibration curve in the range 5 - 40% oleuropein. Five replicate extractions and analyses of the matrix standards were carried out over 10 days. Precision was less than 6% RSD and linearity was demonstrated by the Fischer test. Extraction recovery was > 90% and there was a strong linear relationship between authentic and matrix standards. All tested products conformed to the label claim which was strongly correlated with total polyphenols measured by the Folin-Ciocalteau method. Antioxidant activity was measured by the DPPH assay and was found to be strongly correlated with total phenol content and oleuropein concentration.

Use of Olives-derived Phytochemicals for Prevention and Treatment of Atherosclerosis: An Update.

Mediterranean diet is frequently associated with longevity and a lower incidence of adverse cardiovascular events because of the biological activities and health effects of olives - its key component. Olive oil, olive leaf extract, fruits and different by-products contain many bioactive components that exert anti-oxidant, anti-inflammatory and anti-apoptotic activities. In this review, we focus on the recent studies exploring molecular mechanisms underlying the cardioprotective properties of different olive oils, olive leave extracts, and specific micro-constituents (such as oleuropein, tyrosol, hydroxytyrosol and others) in vitro on rodent models and in clinical trials on human subjects. Particularly, hydroxytyrosol and oleuropein were identified as the major bioactive compounds responsible for the antioxidant, anti-inflammatory, anti-platelet aggregation and anti-atherogenic activities of olive oil. In total, the discussed results demonstrated a positive association between the consumption of olive oil and improvement in outcomes in atherosclerosis, diabetes, myocardial infarction, heart failure, hypertension and obesity.

Investigating Variables of Time, Extraction Solvent Composition and Ratio of Solvent-to-plant on Antioxidant and Antibacterial Characteristics of Striata Plants and Olive Leaves Using Microwave and Ultrasonic Extraction Methods

Investigating Variables of Time, Extraction Solvent Composition and Ratio of Solvent-to-plant on Antioxidant and Antibacterial Characteristics of Striata Plants and Olive Leaves Using Microwave and Ultrasonic Extraction Methods

Effect of edible film prepared with plasma‐activated water and olive leaf extract (Olea europaea L.) as a potential packaging in cooked meat product

AbstractThis research determined the use of edible film (EF) prepared with olive leaf extract (OLE) and plasma‐activated water (PAW) on the shelf life and quality of cooked meat (M. longissimus thoracis et lumborum) product. The characterization of PAW composition and the antioxidant activity and the total phenolic content (TPC) of OLE were determined. Also, physicochemical and microbiological properties and lipid oxidation of cooked meat product coated with EF stored at +4°C for 14 d were evaluated. Cold plasma treatment increased the nitrite/nitrate concentrations and ORP value and decreased the pH value of distilled water (DW). The amount of TPC, IC50 value, and the antioxidant activity of OLE were 71.52 mg GAE/g, 0.46 mg/mL, and 77.39%, respectively. The combined use of OLE and PAW in EF during storage reduced the pH of cooked meat product. Furthermore, the addition of OLE in EF increased the b* values and reduced the a* values of cooked meat product, whereas the addition of PAW did not influence the CIE L*, a*, b* color values. The use of EF prevented lipid oxidation in cooked meat product during storage, especially the addition of OLE to the EF reduced the TBARS values. In this research, the addition of OLE to EF prepared with PAW has a promising application potential in the preservation of RTE‐cooked meat products. Also, these findings suggested that OLE, a by‐product from production of olive oil, might be applied as active packaging in biodegradable films.

Integrating genetic analysis of germplasm wealth for enhanced selection and improvement in olive (Olea europaea L.): insights from leaves.

High-throughput next-generation sequencing of 161 olive germplas. 33 samples were selected as core olive germplasm and Fingerprints were constructed. After GWAS analysis of olive leaf shape, 14 candidate genes were localized. Olive (Olea europaea L.) has been introduced to China since the 1960s. After a prolonged period of variation and domestication, there is a lack of comprehensive research on its genetics. The olive oil directly extracted from Olea europaea L. is recognized as 'liquid gold', nevertheless, people constantly overlook the valuable wealth of olive leaves. High-throughput next-generation sequencing was performed on 161 olive germplasm to analyze the kinship, genetic structure and diversity of olives, and the core germplasm of olives were selected and fingerprints were constructed. Meanwhile, Genome-wide association analysis (GWAS) was performed to locate the gene for regulating olive leaf shape. Herein, the results parsed that most of the Chinese olive germplasm was more closely related to the Italian germplasm. A wealth of hybridized germplasm possessed high genetic diversity and had the potential to be used as superior parental material for olive germplasm. A total of 33 samples were selected and characterized as core germplasm of olive and Fingerprints were also constructed. A total of 14 candidate genes were localized after GWAS analysis of four olive leaf shape phenotypes, including leaf shape, leaf curvature shape, leaf tip and leaf base shape. Collectively, this study revealed the genetic basis of olives in China and also succeeded in constructing the core germplasm that stands for the genetic diversity of olives, which can contributeto the scientific and effective collection and preservation of olive germplasm resources, and provide a scientific basis for the in-depth excavation and utilization of genes regulating olive leaf shape.

Sustainable Extraction of Hydroxytyrosol from Olive Leaves Based on a Nature‐Inspired Deep Eutectic Solvent (NADES)

Sustainable Extraction of Hydroxytyrosol from Olive Leaves Based on a Nature‐Inspired Deep Eutectic Solvent (NADES)

Investigation of Olive Leaf Polyphenol Extract Loaded Silver Nanoparticle Optimization by Box-Behnken Design.

Silver nanoparticles (AgNPs) are synthesized and optimized by reducing and stabilizing them with olive leaf extract. The successful synthesis of AgNPs was verified by UV-vis spectroscopy, SEM imaging, and DLS measurements, demonstrating characteristic features such as a surface plasmon resonance peak, spherical morphology, crystalline structure, and narrow size distribution with good stability. Utilizing Box-Behnken Design (BBD), the optimal synthesis conditions were determined, with a silver nitrate concentration of 1 mM, olive leaf extract volume of 10 mL, and reaction time of 60 minutes, yielding AgNPs with desirable properties. Statistical analysis revealed the significant influence of individual variables and their interactions on AgNP characteristics. Lower concentrations of silver nitrate and olive leaf extract led to smaller particle sizes and higher zeta potentials, while longer reaction times resulted in larger particles and lower zeta potentials. Among the experimental runs, Run 11 exhibited the most favorable properties, with 54 nm particle size, -36 mV zeta potential, and an encapsulation efficiency of 92.28%. ANOVA analysis further elucidated the significant effects of synthesis parameters on zeta potential, particle size, and encapsulation efficiency. In conclusion, the optimized formulation obtained through BBD offers a tailored approach for the synthesis of AgNPs with desired properties, suitable for various applications such as biomedical, catalytic, and sensing applications. The comprehensive understanding of synthesis parameters and their effects provided by this study facilitates the rational design of AgNPs for specific applications, enhancing their potential in diverse fields.