Anti-Inflammatory Effects of Olive Leaf Extract and Its Bioactive Compounds Oleacin and Oleuropein-Aglycone on Senescent Endothelial and Small Airway Epithelial Cells

Anti-Inflammatory and Neuroprotective Polyphenols Derived from the European Olive Tree, Olea europaea L., in Long COVID and Other Conditions Involving Cognitive Impairment

The European olive tree, Olea europaea L., and its polyphenols hold great therapeutic potential to treat neuroinflammation and cognitive impairment. This review examines the evidence for the anti-inflammatory and neuroprotective actions of olive polyphenols and their potential in the treatment of long COVID and neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Key findings suggest that olive polyphenols exhibit antioxidant, anti-inflammatory, neuroprotective, and antiviral properties, making them promising candidates for therapeutic intervention, especially when formulated in unique combinations. Recommendations for future research directions include elucidating molecular pathways through mechanistic studies, exploring the therapeutic implications of olive polyphenol supplementation, and conducting clinical trials to assess efficacy and safety. Investigating potential synergistic effects with other agents addressing different targets is suggested for further exploration. The evidence reviewed strengthens the translational value of olive polyphenols in conditions involving cognitive dysfunction and emphasizes the novelty of new formulations.

Multiple-heated cooking oil promotes early hepatic and renal senescence in adult male rats: the potential regenerative capacity of oleuropein

For economic purposes, cooking oil is repeatedly heated in food preparation, which imposes serious health threats. This study investigated the detrimental effects of multiple-heated cooking oil (MHO) on hepatic and renal tissues with particular focusing on cellular senescence (CS), and the potential regenerative capacity of oleuropein (OLE). Adult male rats were fed MHO-enriched diet for 8 weeks and OLE (50 mg/kg, PO) was administered daily for the last four weeks. Liver and kidney functions and oxidative stress markers were measured. Cell cycle markers p53, p21, cyclin D, and proliferating cell nuclear antigen (PCNA) were evaluated in hepatic and renal tissues. Tumor necrosis factor-α (TNF-α) and Bax were assessed by immunohistochemistry. General histology and collagen deposition were also examined. MHO disturbed hepatic and renal structures and functions. MHO-fed rats showed increased oxidative stress, TNF-α, Bax, and fibrosis in liver and kidney tissues. MHO also enhanced the renal and hepatic expression of p53, p21, cyclin D and PCNA. On the contrary, OLE mitigated MHO-induced oxidative stress, inflammatory burden, apoptotic and fibrotic changes. OLE also suppressed CS and preserved kidney and liver functions. Collectively, OLE displays marked regenerative capacity against MHO-induced hepatic and renal CS, via its potent antioxidant and anti-inflammatory effects.

Two Olea europaea L. Extracts Reduce Harmful Effects in a Model of Neurotoxicity: Involvement of the Endoplasmic Reticulum

Prolonged exposure to lead has been recognized as harmful to human health as it may cause neurotoxic effects including mitochondrial damage, apoptosis, excitotoxicity, and myelin formation alterations, among others. Numerous data have shown that consuming olive oil and its valuable components could reduce neurotoxicity and degenerative conditions. Olive oil is traditionally obtained from olive trees; this plant (Olea europaea L.) is an evergreen fruit tree.In this manuscript, two extracts have been used and compared: the extract from the leaves of Olea europaea L. (OE) and the extract derived from OE but with a further sonication process (s-OE). Therefore, the objectives of this experimental work were as follows: 1) to generate an innovative extract; 2) to test both extracts on a model of neurotoxicity of human neurons induced following lead exposure; and 3) to study the mechanisms behind lead-induced neurotoxicity.The results showed that the mechanism involved in the neurotoxicity of lead included dysfunction of the cellular endoplasmic reticulum, which suffered oxidative damage. In addition, in all experiments, s-OE was more effective than OE, having greater and better effects against lead-induced damage and being dissolved in a smaller amount of EtOH, which promotes its sustainability.

Systemic Health Effects of Oleuropein and Hydroxytyrosol Supplementation: A Systematic Review of Randomized Controlled Trials

Non-communicable diseases (NCDs) cause 41 million deaths annually, accounting for 74% of global fatalities. The so-called Mediterranean diet, with its especially significant consumption of olive oil, has shown promising results in reducing the risk of developing NCDs, such as cardiovascular, liver, or bone diseases. In the context of the nutritional health benefits of foods, phenolic compounds such as olive oil's main components, oleuropein (OLE) and hydroxytyrosol (HT), have been shown to possess different beneficial effects. However, no systematic review has evaluated the health-promoting effects of OLE and HT until now. Consequently, this systematic review analyzed 12 human randomized controlled trials (RCTs), involving 683 participants, to assess the effects of supplements, pure compounds, or enriched foods containing OLE and HT regarding systemic health outcomes, including CVD risk factors, liver parameters, and bone, joint, and cognitive health. The review found contrasting but encouraging results, with some studies reporting significant modulation of body weight, lipid profile, and glucose metabolism, and improvements in bone, joint, and cognitive functions. The studies described different dosages and forms of supplementation, ranging from 5 mg/d HT to 990 mL/d olive leaf infusion (320.8 mg OLE and 11.9 mg HT), highlighting the need for further research to determine the optimal dosing and duration. Despite the mixed outcomes, OLE and HT supplementation show potential for improving some of the cardiometabolic health outcomes and bone, joint, and cognitive health. However, further studies are necessary to understand their benefits better and address existing limitations.

Expression of Na+/Ca2+ exchangers was enhanced following pre-treatment of olive leaf extract and olive oil in animal model of ischemic stroke

BACKGROUND

Neuroprotective role of olive and its natural products can introduce them as alternative candidates for the management of neurodegenerative diseases including stroke. The present study was designed to evaluate whether pretreatment of olive oil and leaf extract can attenuate the most important destructive processes in cerebral ischemia called excitotoxicity.

MATERIAL AND METHODS

The male rats were categorized into control, virgin olive oil (OVV), MCAO, MCAO + OVV (with doses of 0.25, 0.50 and 0.75 ml/kg as treatment groups), olive leaf extract, MCAO + olive leaf extract (with doses 50, 75 and 100 mg/kg as treatment groups) groups. Rats of treatment groups received gastric gavage with olive oil or leaf extract for 30 consecutive days. After pretreatment, the intraluminal filament technique was used to block middle cerebral artery (MCA) transiently. Neurological deficits, infarct volume and expression of Na+/Ca2+ exchangers (NCX1, NCX2 and NCX3) proteins were measured.

RESULTS

The results revealed that olive oil at doses of 0.50 and 0.75 ml/kg reduced the infarction and neurological score and upregulated NCXs expression in rat brain. In addition, olive leaf extract at doses of 75 and 100 mg/kg attenuated the infarction and neurological score and enhanced NCXs expression in rat brain.

CONCLUSION

These findings support the view that olive oil and leaf extract play the neuroprotective role in cerebral ischemia due to the upregulation of NCXs protein expression.