Olive leaf extract effect on cardiometabolic risk factors: a systematic review and meta-analysis of randomized clinical trials.

CONTEXT: Olive leaf extract (OLE) is rich in phenolic compounds, which are known for their health benefits. Cardiovascular diseases, primarily coronary heart disease and stroke, are leading causes of mortality globally. OBJECTIVE: This systematic review aimed to assess the impact of OLE on cardiometabolic risk factors in adults. The selection of studies was based on intervention and outcomes, using relevant search descriptors. DATA SOURCES: The databases PubMed, EMBASE, and Web of Science were systematically searched for pertinent studies published up to August 2021. DATA EXTRACTION: Only randomized clinical trials, either cross-over or parallel, involving adult individuals aged ≥18 years, were considered. Additionally, trials that had a comparative or placebo group and used pure OLEs for oral treatment were included. DATA ANALYSIS: Twelve randomized clinical trials (RCTs) met the inclusion criteria. These trials had follow-up periods ranging from 2 days to 12 weeks and involved 703 patients aged 18 years-79 years. The outcomes demonstrated a positive correlation between the intervention group and glucose metabolism (4 RCTs), blood pressure (2 RCTs), lipid profile (2 RCTs), and inflammatory markers (2 RCTs). The RoB2 tool and the GRADE system were used to evaluate the risk of bias and the quality of evidence in the studies. CONCLUSIONS: In the meta-analysis, fasting glycemia, as evaluated in studies using a low dose of OLE, showed a significant result favoring the control group. To obtain more consistent results, further clinical studies in humans, using similar methodologies, are required. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42020200877.

Oleuropein-Enriched Extract From Olive Mill Leaves by Homogenizer-Assisted Extraction and Its Antioxidant and Antiglycating Activities.

Olive oil consumption has increased in the last two decades and consequently, its wastes have increased, which generates a tremendous environmental impact. Among the by-products are the olive mill leaves, which are easier and inexpensive to treat than other olive by-products. However, little research has been done on their chemical composition and potential bioactivity. Hence, in this study, olive mill leaves were used to obtain Oleuropein-Enriched Extracts (OLEU-EE) using Conventional Extraction, Ultrasound-Assisted Extraction, and Homogenization-Assisted Extraction. These three techniques were evaluated using a Factorial Design to determine the parameters to obtain an OLEU-EE with high contents of Total Phenolic Compounds (TPC), Antioxidant Activity (AA), and Oleuropein concentration (OLEU). From the results, the Homogenizer-Assisted Extraction (HAE) technique was selected at 18,000 rpm, solid:liquid ratio 1:10, and 30 s of homogenization with 70% ethanol, due to its high TPC (5,196 mg GA/100 g), AA (57,867 µmol of TE/100 g), and OLEU (4,345 mg of OLEU/100 g). In addition, the antiglycating effect of OLEU-EE on the levels of (1) fluorescent Advanced Glycation End Products (AGEs) were IC50 of 0.1899 and 0.1697 mg/mL for 1λEXC 325/λEM 440 and 2λEXC 389/λEM 443, respectively; (2) protein oxidative damage markers such as dityrosine (DiTyr), N-formylkynurenine (N-formyl Kyn), and kynurenine (Kyn) were IC50 of 0.1852, 0.2044, and 0.1720 mg/mL, respectively. In conclusion, OLEU-EE from olive mill leaves has different capacities to inhibit AGEs evidenced by the IC50 of fluorescent AGEs and protein oxidation products, together with the scavenging free radical evidenced by the concentration of Trolox Equivalent. Therefore, OLEU-EE could be potential functional ingredients that prevent oxidative damage caused by free radicals and AGEs accumulation.

Evolution of the phenolic compounds profile of olive leaf extract encapsulated by spray-drying during in vitro gastrointestinal digestion.

An olive leaf extract (OLE) was microencapsulated with sodium alginate (SA) by spray-drying to study the evolution of oleuropein (ORP) during in vitro gastrointestinal digestion, and its bioaccessibility and potential bioavailability from OLE and OLE-SA microparticles. Secoiridoids, flavonoids, simple phenols, oleosides and elenolic acid were identified in OLE. OLE/SA ratio 1:1.6 and inlet air temperature 135 °C were the optimal conditions for OLE-SA microparticles. ORP (70%) from OLE was degraded during gastric digestion, giving hydroxytyrosol and ORP-aglycone, whereas only the superficial ORP was released from microparticles. The remaining ORP from OLE was degraded under intestinal conditions, leading to oleosides; whereas alginate was swollen and disintegrated, releasing the ORP (90% of encapsulated ORP). ORP from both OLE and microparticles was degraded to hydroxytyrosol under colonic conditions. Encapsulation of OLE allowed the protection of ORP under gastric conditions and its controlled release at intestinal conditions, and higher bioaccessibility (58%) and potential bioavailability (20%).

Ação antiproliferativado flavonoide morina e do extrato da folha de oliveira (Oleaeuropaea L. ) contra a linhagem de célula H460 / The antiproliferative action of morin flavonoid and olive leaf extract (Olea europaea L. ) against the cell line H460

RESUMO O presente estudo investigou a indução de morte celular por apoptose pelo flavonóide morina e pelo extrato da folha de oliveira (Oleaeuropaea L.) em linhagens de células de câncer de pulmão do tipo não pequenas (H460). O tratamento com morina e o extrato de oliveira em células H460 resultou na redução do crescimento tumoral e indução de morte celular avaliados pelos ensaios de MTT e lactato desidrogenase (LDH) e a morte celular por apoptose confirmada por microscopia de fluorescência e análise por citometria de fluxo. Os dados indicaram que o flavonóide morina e o extrato de oliveira diminuíram a viabilidade celular para taxas percentuais de 7,22± 1,54% e 62,37± 2,85% nas concentrações de 800µM e µg/mL, respectivamente. As maiores taxas percentuais de morte celular por apoptose foram100% para morina na concentração de 800µM e 70,49 ± 5,91% para o extrato de oliveira na concentração de 800 µg/mL. Estes resultados foram associados com a alteração do potencial de membrana mitocondrial, cujos valores são de 54,91% para morina na concentração de 400µM e 42,2% para o extrato de oliveira na concentração de 800 µg/mL sugerindo envolvimento da via intrínseca da morte celular por apoptose. Portanto, morina e o extrato de oliveira afetaram a viabilidade celular da linhagem H460 induzindo morte celular por apoptose.

ABSTRACT This study investigates possible apoptosis induction mechanism by the flavonoid morin and the olive leaf extract (Olea europaea L.) in non-small lung cancer cells (H460). The treatment with morin and olive leaves extract resulted in growth inhibition and induction of apoptosis in H460 cells lines measured by the MTT assay methods and confirmed by fluorescence microscopy, flow cytometry analysis. The data indicated that themurin and the extract of olive decreased the cell viability percentage rates of 7.22 ± 1,54% and 62.37 ± 2,85% in the concentrations of 800 µM and µg/mL, respectively. The highest percentage rates of cell death by apoptosis were 100% for themorin in a concentration of 800 µM and 70.49 ± 5.91% for the olive extract in a concentration of 800 µg/mL. These findings were associated with altered mitochondrial membrane potential, whose value is 54.91% for the murin concentration of 400 µM and 42.2% for the olive extract in a concentration of 800 mg / mL, suggesting involvement of the intrinsic pathway of cell death by apoptosis. Therefore, the morin and the olive extract affect the cell viability of H460 cell lines inducing cell death by apoptosis.