Olive leaf tea may have hematological health benefit over green tea

Hematopoietic Stem Cells as an Integrative Hub Linking Lifestyle to Cardiovascular Health

Despite breakthroughs in modern medical care, the incidence of cardiovascular disease (CVD) is even more prevalent globally. Increasing epidemiologic evidence indicates that emerging cardiovascular risk factors arising from the modern lifestyle, including psychosocial stress, sleep problems, unhealthy diet patterns, physical inactivity/sedentary behavior, alcohol consumption, and tobacco smoking, contribute significantly to this worldwide epidemic, while its underpinning mechanisms are enigmatic. Hematological and immune systems were recently demonstrated to play integrative roles in linking lifestyle to cardiovascular health. In particular, alterations in hematopoietic stem cell (HSC) homeostasis, which is usually characterized by proliferation, expansion, mobilization, megakaryocyte/myeloid-biased differentiation, and/or the pro-inflammatory priming of HSCs, have been shown to be involved in the persistent overproduction of pro-inflammatory myeloid leukocytes and platelets, the cellular protagonists of cardiovascular inflammation and thrombosis, respectively. Furthermore, certain lifestyle factors, such as a healthy diet pattern and physical exercise, have been documented to exert cardiovascular protective effects through promoting quiescence, bone marrow retention, balanced differentiation, and/or the anti-inflammatory priming of HSCs. Here, we review the current understanding of and progression in research on the mechanistic interrelationships among lifestyle, HSC homeostasis, and cardiovascular health. Given that adhering to a healthy lifestyle has become a mainstream primary preventative approach to lowering the cardiovascular burden, unmasking the causal links between lifestyle and cardiovascular health from the perspective of hematopoiesis would open new opportunities to prevent and treat CVD in the present age.

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.

Hematinic Potential of Olive Leaf Extract: Evidence from an In Vivo Study in Mice and a Pilot Study in Healthy Human Volunteers

Natural resources have recently received considerable attention as complementary or alternative hematinic agents. In this regard, olive leaf extract, which is rich in bioactive phenolic compounds, has been reported to induce erythroid differentiation in human hematopoietic stem cells. Therefore, in the present study, we aimed to explore the potential hematinic properties of aqueous olive leaf extract (WOL) in vivo. After 24 days of administering WOL to healthy mice orally, red blood cell (RBC), hematocrit, reticulocyte, and reticulocyte hemoglobin content (CHr) showed a significant increase. Additionally, WOL promoted plasma iron levels and the expression of splenic ferroportin (Fpn), an iron transporter. Additionally, a single-arm pilot study involving a limited number of healthy volunteers was conducted to assess WOL's feasibility, compliance, and potential benefits. Following an 8-week intervention with WOL, RBC count and hemoglobin level were significantly increased. Notably, there were no significant changes in the safety measures related to liver and kidney functions. Furthermore, we identified oleuropein and oleuroside as the active components in WOL to induce erythroid differentiation in the K562 cell line. Altogether, our study presents evidence of the hematinic potential of WOL in the in vivo studies, opening up exciting possibilities for future applications in preventing or treating anemia.

A research paper on the immunomodulatory and anti-inflammatory activities of olive tree (Olea europaea L.) leaf

Olive tree (Olea europaea L.) leaf is known to have a number of bioactive properties being antioxidant, antihypertensive, antiatherogenic, anti-inflammatory, antifungal, antiviral and antimicrobial. In this study, the immunomodulatory roles of Olive tree (Olea europaea L.) leaf against oxidative damage caused by carbon tetrachloride (CCl4) in Saccharomyces cerevisiae were investigated. In the study, four groups were formed; namely, (i) Control Group: Yeast only planted group; (ii) CCl4 Group: Group given CCl4 (15 mM); (iii) Olive Tree Leaf Group: The group given olive tree leaf (10%); and (iv) Olive Tree Leaf + CCl4 Group: Olive tree leaf (10%) + CCl4 (15 mM) given group. Cultures of Saccharomyces cerevisiae were grown at 30 °C for 1, 3, 5, and 24 hours. Malondialdehyde (MDA), glutathione levels (GSH), cell growth and catalase (CAT) activity measurements were determined by spectrophotometer. Total protein concentrations were determined by SDS-PAGE electrophoresis and the Bradford protein method. According to the results obtained; compared to the CCl4 group, cell growth (1, 3, 5 and 24 hours), total protein synthesis, and GSH and CAT activities (24 hours) increased in olive tree leaf groups, while MDA level (24 hours) decreased. Thanks to its strong bioactive properties, olive tree leaf has been found to increase cell growth and total protein synthesis by decreasing CCl4 induced oxidative stress in Saccharomyces cerevisiae culture. It has been concluded that if the olive tree leaf is used regularly, it will be beneficial in eliminating many health problems.

Comprehensive transcriptome analysis of erythroid differentiation potential of olive leaf in haematopoietic stem cells

Anaemia is one of the leading causes of disability in young adults and is associated with increased morbidity and mortality in elderly. With a global target to reduce the disease burden of anaemia, recent researches focus on novel compounds with the ability to induce erythropoiesis and regulate iron homeostasis. We aimed to explore the biological events and potential polypharmacological effects of water-extracted olive leaf (WOL) on human bone marrow-derived haematopoietic stem cells (hHSCs) using a comprehensive gene expression analysis. HPLC analysis identifies six bioactive polyphenols in the WOL. Treatment with WOL for 12 days regulated gene expressions related to erythroid differentiation, oxygen homeostasis, iron homeostasis, haem metabolism and Hb biosynthesis in hHSCs. Functional clustering analysis reveals several major functions of WOL such as ribosomal biogenesis and mitochondrial translation machinery, glycolytic process, ATP biosynthesis and immune response. Additionally, the colonies of both primitive and mature erythroid progenitors, CFU-E and BFU-E, were significantly increased in WOL-treated hHSCs. The expressions of erythroid markers, CD47, glycophorin A (GYPA), and transferrin receptor (TFRC) and adult Hb subunits-HBA and HBB were also confirmed in immunofluorescent staining and flow cytometer analysis in WOL-treated hHSCs. It is well known that induction of lineage-specific differentiation, as well as the maturation of early haematopoietic precursors into fully mature erythrocytes, involves multiple simultaneous biological events and complex signalling networks. In this regard, our genome-wide transcriptome profiling with microarray study on WOL-treated hHSCs provides general insights into the multitarget prophylactic and/or therapeutic potential of WOL in anaemia and other haematological disorders.

The challenge of exploiting polyphenols from olive leaves: addition to foods to improve their shelf-life and nutritional value

Olive leaves represent a waste from the olive oil industry which can be reused as source of polyphenols. The most representative phenolic compound of olive leaves is the secoiridoid oleuropein, followed by verbascoside, apigenin-7-O-glucoside, luteolin-7-O-glucoside, and simple phenols. The attention towards these compounds derives above all from the large number of studies demonstrating their beneficial effect on health, in fact olive leaves have been widely used in folk medicine in the Mediterranean regions. Moreover, the growing demand from consumers to replace the synthetic antioxidants, led researchers to conduct studies on the addition of plant bioactives in foods to improve their shelf-life and/or to obtain functional products. The current study overviews the findings on the addition of polyphenol-rich olive leaf extract (OLE) to foods. In particular, the effect of OLE addition on the antioxidant, microbiological and nutritional properties of different foods is examined. Most studies have highlighted the antioxidant effect of OLE in different food matrices, such as oils, meat, baked goods, vegetables, and dairy products. Furthermore, the antimicrobial activity of OLE has been observed in meat and vegetable foods, highlighting the potential of OLE as a replacer of synthetic preservatives. Finally, several authors studied the effect of OLE addition with the aim of improving the nutritional properties of vegetable products, tea, milk, meat and biscuits. Advantages and drawbacks of the different use of OLE were reported and discussed. © 2020 Society of Chemical Industry.

Analysis of chemical compounds and toxicological evaluation of Forsythia suspensa leaves tea

To determine the compositions of Forsythia suspensa leaves tea (FSLT) and its safety, the chemical compounds were analysed with some methods, and the toxicity was evaluated in Kunming mice and Wistar rats. The results showed that FSLT contained rich flavonoid, lignans, triperpene acids, amino acids, and mineral elements. In the acute toxicity study, none of the mice died, and no obvious poisoning symptoms were observed after 14 days in mice at the dose of 15 mg/g·body weight (bw) FSLT; in the sub-chronic toxicity, no abnormal or dead rat was found at the dose of 1, 3, and 10 mg/g·bw during 90 days feeding administration; there was no significant difference in bw and food consumption; no significant differences were found in each hematology and serum biochemistry parameter and organ/body weight ratio comparing with the control experimental group. The results revealed that the FSLT has low or no toxicity via oral administration. Therefore, FSLT is very suitable and safe to be used as a new resource food.

HPLC-DAD Analysis, Antioxidant and Protective Effects of Tunisian Rhanterium suaveolens against Acetamiprid Induced Oxidative Stress on Mice Erythrocytes

The present study was performed to assess the HPLC-DAD analysis as well as antioxidant and protective effects of Tunisian Rhanterium suaveolens (Rs) against acetamiprid (ACT) induced oxidative stress on mice erythrocytes. The in vitro assays showed that the methanolic extract of Rs has an impressive antioxidant effect proved by testing the total antioxidant and scavenging activities using BCB, DPPH and ABTS assays, respectively. Moreover, qualitative and quantitative analysis using HPLC-DAD revealed the richness of Rs in polyphenols where p-Coumaric, Apigenin-7-glucoside and Ferulic acid were detected as the most abundant polyphenols. In the in vivo experiment, ACT, used as a toxicity model, was given to mice at a dose of 20 mg/kg. The latter was the origin of hemolytic anemia characterized by a significant decrease in red blood cells, hemoglobin and hematocrit levels and an increase in bilirubin, LDH, osmotic fragility, reticulocytes and white blood cells number. Characteristic erythrocyte morphological alterations were also determined as spherocytosis, schistocytosis and dacryocystitis. The oxidative status of ACT-treated mice was also altered manifested by a significant increase in MDA and GSH levels and a decrease in SOD, CAT and GPx activities. When receiving the Rs methanolic extract at a dose of 300 mg/kg, all the parameters cited above were restored in mice. These remarkable corrections could only confirm the important antioxidant effect and the noticeable protective properties that possess Rs owing to its broad range of secondary bioactive metabolites.