Olive Leaf Extracts for a Green Synthesis of Silver-Functionalized Multi-Walled Carbon Nanotubes.

Green biosynthesis, one of the most dependable and cost-effective methods for producing carbon nanotubes, was used to synthesize nonhazardous silver-functionalized multi-walled carbon nanotubes (SFMWCNTs) successfully. It has been shown that the water-soluble organic materials present in the olive oil plant play a vital role in converting silver ions into silver nanoparticles (Ag-NPs). Olive-leaf extracts contain medicinal properties and combining these extracts with Ag-NPs is often a viable option for enhancing drug delivery; thus, this possibility was employed for in vitro treating cancer cells as a proof of concept. In this study, the green technique for preparing SFMWCNTs composites using plant extracts was followed. This process yielded various compounds, the most important of which were Hydroxytyrosol, Tyrosol, and Oleuropein. Subsequently, a thin film was fabricated from the extract, resulting in a natural polymer. The obtained nanomaterials have an absorption peak of 419 nm in their UV-Vis. spectra. SEM and EDS were also used to investigate the SFMWCNT nanocomposites' morphology simultaneously. Moreover, the MTT assay was used to evaluate the ability of SFMWCNTs to suppress cancer cell viability on different cancer cell lines, MCF7 (human breast adenocarcinoma), HepG2 (human hepatocellular carcinoma), and SW620 (human colorectal cancer). Using varying doses of SFMWCNT resulted in the most significant cell viability inhibition, indicating the good sensitivity of SFMWCNTs for treating cancer cells. It was found that performing olive-leaf extraction at a low temperature in an ice bath leads to superior results, and the developed SFMWCNT nanocomposites could be potential treatment options for in vitro cancer cells.

Olive Fruit Extracts Supplement Improve Antioxidant Capacity via Altering Colonic Microbiota Composition in Mice.

Oxidative stress, one of the most common biological dysfunctions, is usually associated with pathological conditions and multiple diseases in humans and animals. Chinese olive fruit (Canarium album L.) extracts (OE) are natural plant extracts rich in polyphenols (such as hydroxytyrosol, HT) and with antioxidant, anti-hyperlipidemia, and anti-inflammatory potentials. This study was conducted to investigate the antioxidant capacity of OE supplementation and its related molecular mechanism in mice. Mice (25.46 ± 1.65 g) were treated with 100 mg/kg body weight (BW) OE or saline solution for 4 weeks, and then the antioxidant and anti-inflammatory capacities of mice were examined. The results showed that OE supplement significantly increased the serum antioxidative enzyme activities of total antioxidant activity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase and decreased the serum malondialdehyde (MDA) level, indicating that OE treatment enhanced the antioxidant capacity in mice. qPCR results showed that the transcriptional expression of antioxidant SOD1, CAT, Gpx1, and Gpx2 were significantly down-regulated in the small intestine (jejunum and ileum) after OE administration. Meanwhile, OE treatment significantly decreased the T-AOC and increased the MDA level in the small intestine. Furthermore, OE administration dramatically reduced the mRNA expression of pro-inflammatory cytokines (TNF-α and IL-1ß), which confirmed its antioxidant and anti-inflammatory capacities with OE administration. Using amplicon sequencing technology, 16S rRNA sequencing results showed that OE supplement significantly increased the colonic Firmicutes/Bacteroidetes ratio, which also had a negative correlation with the serum MDA level and positively correlated with serum GSH-Px activity through Pearson correlation analysis. Besides that, Alloprevotella was negatively correlated with serum T-AOC. Colidextribacter was positively correlated with serum MDA and negatively correlated with serum T-AOC, SOD, and GSH-Px levels. In summary, this study showed that treatment with 100 mg/kg BW polyphenol-rich OE could alter colonic microbiota community, which was strongly associated with improved antioxidant capacity in mice.

Supplementation Effect of a Combination of Olive (Olea europea L.) Leaf and Fruit Extracts in the Clinical Management of Hypertension and Metabolic Syndrome.

BACKGROUND: The role of herbal products in the prevention of cardiovascular disease requires supporting evidence. This open pilot study assessed the effect of 2-month supplementation of a combination of olive leaf and fruit extracts (Tensiofytol®, Tilman SA, Baillonville, Belgium) in the clinical management of hypertension and metabolic syndrome (MetS). METHODS: A total of 663 (pre)-hypertensive patients were enrolled by general practitioners and supplemented for two months with Tensiofytol®, two capsules per day (100 mg/d of oleuropein and 20 mg/d of hydroxytyrosol). Systolic and diastolic blood pressures (SBP/DBP) were measured before and after treatment. Markers of MetS, high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), fasting blood glucose (FG) and waist circumference (WC), were also examined. RESULTS: Significant reductions (p < 0.0001) in SBP/DBP (13 ± 10/7.1 ± 6.6 mmHg) were observed and similarly in pre-diabetic and diabetic patients. Improvements in SBP/DPB were independent of age and gender but greater for elevated baseline SBP/DBP. Tensiofytol® supplementation also significantly improved markers of MetS, with a decrease of TG (11%), WC (1.4%) and FG (4.8%) and an increase of HDL-C (5.3%). Minor side effects were reported in 3.2% patients. CONCLUSIONS: This real-life, observational, non-controlled, non-randomized pilot study shows that supplementation of a combination of olive leaf and fruit extracts may be used efficiently and safely in reducing hypertension and MetS markers.

Determination of hydroxytyrosol and tyrosol by liquid chromatography for the quality control of cosmetic products based on olive extracts.

An analytical method for the simultaneous determination of hydroxytyrosol and tyrosol in different types of olive extract raw materials and cosmetic cream samples has been developed. The determination was performed by liquid chromatography with UV spectrophotometric detection. Different chromatographic parameters, such as mobile phase pH and composition, oven temperature and different sample preparation variables were studied. The best chromatographic separation was obtained under the following conditions: C18 column set at 35°C and isocratic elution of a mixture ethanol: 1% acetic acid solution at pH 5 (5:95, v/v) as mobile phase pumped at 1 mL min(-1). The detection wavelength was set at 280 nm and the total run time required for the chromatographic analysis was 10 min, except for cosmetic cream samples where 20 min runtime was required (including a cleaning step). The method was satisfactorily applied to 23 samples including solid, water-soluble and fat-soluble olive extracts and cosmetic cream samples containing hydroxytyrosol and tyrosol. Good recoveries (95-107%) and repeatability (1.1-3.6%) were obtained, besides of limits of detection values below the µg mL(-1) level. These good analytical features, as well as its environmentally-friendly characteristics, make the presented method suitable to carry out both the control of the whole manufacture process of raw materials containing the target analytes and the quality control of the finished cosmetic products.

Investigations into the genotoxic potential of olive extracts.

The phenolic anti-oxidant 3-hydroxytyrosol (HT) is a major constituent of olives and olive oil. Published data showed it was negative in the Ames test at concentrations up to 5 µL per plate, but did induce chromosomal aberrations in human lymphocytes. HIDROX, an olive extract containing approximately 2.4% HT, was reported as both positive and equivocal in an Ames test in different papers from the same laboratory. Negative results for micronucleus induction in vivo in both an acute study and as part of a 90-day rat toxicity study were also reported for HIDROX. Given the widespread use and consumption of olives, olive oil and olive extracts, it was important to obtain more data. Here we confirm that pure HT, and an olive extract containing 15% HT, both induced micronuclei in cultured cells in vitro, but show that these responses were either due to high levels of cytotoxicity or to reaction of HT with culture medium components to produce hydrogen peroxide. Another extract (H40) containing 40% HT also induced micronuclei in vitro, probably via the same mechanism. However, both extracts were negative in robust Ames tests. The 15% HT formulated extract did not induce micronuclei in rat bone marrow after 4 weeks of dosing up to 561 mg HT/kg/day. H40 produced increased rat bone marrow micronucleus frequencies at 250 and 500 mg HT/kg/day in a 90-day toxicity study, but the results were questionable for various reasons. However, when two different batches of this extract were tested in acute micronucleus studies at doses up to 2000 mg HT/kg, giving plasma exposures that exceeded those in the 90-day study, negative results were obtained. Based on weight of evidence it is concluded that the olive extracts tested are not genotoxic at high doses in vivo, and any genotoxic risks for human consumers are negligible.