Effect of olive leaf (Olea europaea L.) extract addition to broiler diets on the growth performance, breast meat quality, antioxidant capacity and caecal bacterial populations

This study aims to evaluate the effect of olive leaf extract (OLE) on growth performance, breast meat quality, antioxidant capacity and caecal microbiota regulation. OLE containing 51.5% oleuropein, 25.6% polyphenols and 6.2% flavonoids, was designed to different supplement levels ranging from 0.1% OLE (OLE0.1) to 0.5% OLE (OLE0.5) into a basal diet, separately. The whole feeding period lasts for 35 days after 7-day hatching from the egg. 720 1-day-age healthy Arbour Acres male broilers were thus divided into five experimental groups and one control group, consist of 20 broilers per group for six parallel experiments in triplicate. The results showed that the levels of average daily feed intake (ADFI) and average daily weight gain (ADG) of the broilers were decreased (p < 0.05) after the addition of 0.3% OLE. Moreover, the breast meat shear force was decreased by 34.4% (p < 0.05). The glutathione (GSH) levels in the meat were increased by 76.64% (p < 0.05); the levels of total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) were increased by 50.4% and 120%, respectively. And the malondialdehyde (MDA) levels in the meat were reduced by 34.2% (p < 0.05). Additionally, a decreased intensity of Escherichia coli (p < 0.05) and an increased intensity of Lactobacillus and Bifidobacterium (p < 0.05) were observed. Overall, supplementing 0.3% OLE into daily diet enables enhancing breast meat antioxidation, amplifying the abundance of Lactobacillus and Bifidobacterium as well as diminishing the abundance of E. coli in the caecum.HIGHLIGHTS OLE contains 51.5% oleuropein, 25.6% of TP and 6.2% TF levels. OLE addition at 0.3% lowers shear force and raises the GSH’s level of the meat. OLE causes a decrease in E. coli and an increase in Lactobacillus and Bifidobacterium

Screening and unveiling antibacterial mechanism of dandelion phenolic extracts against <i>Staphylococcus aureus</i> by inhibiting intracellular Na⁺–K⁺ ATPase based on molecular docking and molecular dynamics simulation

Staphylococcus aureus is one of the most frequently food-contaminated incidence of healthcare-associated Gram-positive bacteria. The antibacterial function and mechanism of phenolic compounds from dandelion are still unclear. Herein, this work aims to screen one of dandelion phenolic extracts with the strongest antibacterial function from its organ such as flower, stem, leaf and root, and to reveal its antibacterial mechanism. The results indicated dandelion flower phenolic extract (DFPE) containing the highest content of caffeic acid, followed by luteolin and luteolin-7-O-glucoside. They, especially caffeic acid and luteolin-7-O-glucoside, played a key role in making the bacterial cellular-membrane ruptured against the bacteria. The leakage of the intracellular substances (adenosine triphosphate and Na+–K+ ATPase) was further confirmed. Conventional hydrogen bond, pi-anion, pi-alkyl were involved in the interaction between caffeic acid or luteolin-7-O-glucoside and Na+–K+ ATPase. Additionally, the dynamic equilibrium of the liganded ATPase complex were achieved after 105 ns, and the lower values from the radius of gyration and solvent accessible surface area in the complex demonstrated the highly tight and compact structure of the liganded protein. The highest free binding energy (ΔGbind = −47.80 kJ/mol) between Na+–K+ ATPase and luteolin-7-O-glycloside was observed. Overall, DFPE can be used as an effective anti-bacterial agent due to the contribution of its bioactive ingredients such as caffeic acid and luteolin-7-O-glucoside for membrane-breaking. Communicated by Ramaswamy H. Sarma</p

Inhibitory effect of a Chinese quince seed peptide on protein glycation: A mechanism study

Non-enzymatic glycation can cause the formation and accumulation of advanced glycation end products (AGEs), and it poses great threats to human health. It is urgent to search for safe and efficient inhibitors to prevent reducing sugar induced protein glycation. In this study, we investigated the anti-glycation activity and mechanism of an identified peptide, Asparagine-Tyrosine-Arginine-Arginine-Glutamic acid (NYRRE) from Chinese quince seed protein hydrolysate, by multispectroscopy, confocal imaging, and computational molecular simulation. Firstly, it was found that NYRRE could scavenge hydroxyl radicals and chelate Fe2+. Besides, the NYRRE was effective in every stage of fructose induced bovine serum albumin (BSA) glycation. The NYRRE could reduce the formation of fructosamine, carbonyl compounds, glycoxidation products and β-amyloid structure. Meanwhile, NYRRE could protect thiol groups and stabilize the spatial conformation of BSA. The NYRRE presented strong inhibition in fluorescent AGEs, and 68.19% of total AGEs formation was prevented with NYRRE at 15 mmol/L. The results of molecular simulation indicated that NYRRE could insert into the hydrophobic pocket of BSA and interact with hot spots, including arginine and lysine residues. The mechanism of NYRRE inhibiting protein glycation could be due to its antioxidant activity, BSA structure stabilizing ability, and specific bond with glycation sites of BSA. These results provided a valuable reference for developing NYRRE as an efficient antiglycation agent in preventing glycation-mediated diseases

Optimization of the production process of dried unripe olives (Olea europaea L.) as a nutraceutical ingredient naturally rich in phenolic compounds

Phenols from Olea europaea L. exert several beneficial effects on human health. Olive fruits, particularly the unripe ones, thanks to very high phenols contents (e.g. oleuropein, 80,000 mg/kg), can become a new source of income for olive oil producers, with only a negligible reduction of olive oil production. Aim of this research was to define the best process for obtaining dried unripe green olives very rich in phenols from Olea europaea L. analyzing three typical Tuscan cultivars. Four different freezing methods and different combinations of storage times and temperatures were applied to olives before lyophilization for selecting the best procedure to preserve the native phenols. Moraiolo harvested seven-ten days before complete stone lignification showed to be the most suitable cv for production of the ingredient, with oleuropein 100 g/kg and total phenols 178 g/kg. The application of liquid nitrogen immediately followed by lyophilization gave the best results, while other approaches led to losses of oleuropein of at least 68%. As far as storage before lyophilization, the best performance was for olives frozen in liquid nitrogen kept at 1280 \ub0C, with a loss of phenols less than 20% after five months, and oleuropein contents still higher than 80,000 mg/k

Phenolic Compounds and Triterpenes in Different Olive Tissues and Olive Oil By-Products, and Cytotoxicity on Human Colorectal Cancer Cells: The Case of Frantoio, Moraiolo and Leccino Cultivars (Olea europaea L.)

Phenolic and triterpenoid compounds of the olive tree are recognized as having a key role in health promotion, thanks to their multiple protective actions in humans. To expand the source of these bioactive compounds, the phenolic and triterpenoid profiles of leaf, branch, destoned fruit, destoned pomace, shell, seed, and extra virgin olive oil from the Frantoio, Leccino, and Moraiolo olive cultivars were simultaneously characterized by HPLC-DAD-MS. Overall, 43 molecules were quantitated and expressed on the obtained dry extracts. Oleuropein was mainly concentrated in branches (82.72 g/kg), fruits (55.79 g/kg), leaves (36.71 g/kg), and shells (1.26 g/kg), verbascoside (4.88 g/kg) in pomace, and nüzhenide 11-methyl oleoside (90.91 g/kg) in seeds. Among triterpenoids, which were absent in shells, the highest amount of oleanolic acid was found in olive leaves (11.88 g/kg). HCT-116 colorectal cells were chosen to assess the cytotoxicity of the dry extract, using the phytocomplex from Frantoio, which was the richest in phenols and triterpenoids. The IC50 was also determined for 13 pure molecules (phenols and terpenoids) detected in the extracts. The greatest inhibition on the cell’s proliferation was induced by the branch dry extract (IC50 88.25 μg/mL) and by ursolic acid (IC50 24 μM). A dose-dependent relationship was observed for the tested extracts

Biosurfactant–Protein Interaction: Influences of Mannosylerythritol Lipids‑A on β‑Glucosidase

In this work, the influences of a biosurfactant, mannosylerythritol lipids-A (MEL-A) toward β-glucosidase activity and their molecular interactions were studied by using differential scanning calorimetry (DSC), circular dichroism spectroscopy (CD), isothermal titration calorimetry (ITC), and docking simulation. The enzyme inhibition kinetics data showed that MEL-A at a low concentration (< critical micelle concentration (CMC), 20.0 ± 5.0 μM) enhanced β-glucosidase activity, whereas it inhibited the enzyme activity at higher concentrations more than 20.0 μM, followed by a decreased <i>V</i>_max and <i>K</i>_m of β-glucosidase. The thermodynamics and structural data demonstrated that the midpoint temperature (<i>T</i>_m) and unfolding enthalpy (Δ<i><i>H</i></i>) of β-glucosidase was shifted to high values (76.6 °C, 126.3 J/g) in the presence of MEL-A, and the secondary structure changes of β-glucosidase, including the increased α-helix, β-turn, or random coil contents, and a decreased β-sheet content were caused by MEL-A at a CMC concentration. The further ITC and docking simulations suggested the bindings of MEL-A toward β-glucosidase were driven by weak hydrophobic interactions happened between the amino acid residues of β-glucosidase and the fatty acid residues of MEL-A, in addition to hydrogen bonds between amino acids and hydroxyl in glycosyl residues of this biosurfactant