Functionalization of selenium nanoparticles with olive polyphenols - impact on toxicity and antioxidative activity.

Selenium nanoparticles (SeNPs) represent novel selenium (Se) formulation characterized by improved biocompatibility and a wider therapeutic range in comparison to inorganic Se. The aim of this work was to investigate the possibilities of functionalization of SeNPs with olive pomace extract (OPE), rich in health-promoting polyphenols, and to obtain innovative forms of nutraceuticals. Cytotoxic and antioxidative activities of four types of SeNPs (polyvinylpyrrolidone stabilized (PVP SeNPs), polysorbate stabilized (PS SeNPs), polyvinylpyrrolidone stabilized and functionalized using OPE (f PVP SeNPs) and polysorbate stabilized and functionalized using OPE (f PS SeNPs) were investigated. SeNPs showed lower toxicity on human hepatocellular carcinoma (HepG2) and human colorectal adenocarcinoma (Caco2) cells compared to selenite. Functionalization with polyphenols significantly improved their direct antiradical (f PVP SeNPs: 24.4 ± 1.84 and f PS SeNPs: 30.9 ± 2.47 mg TE/mmol Se) and reducing properties (f PVP SeNPs: 50 ± 3.16 and f PS SeNPs: 53.6 ± 3.22 mg GAE/mmol) compared to non-functionalized SeNPs. The significant impact of tested SeNPs on intracellular antioxidative mechanisms has been observed and it was dependent on both cell type and physico-chemical properties of SeNPs, indicating the complexity of involved mechanisms.

Preparation of astaxanthin/zeaxanthin-loaded nanostructured lipid carriers for enhanced bioavailability: Characterization-, stability-and permeability study.

Astaxanthin (ASTA) and zeaxanthin (ZEA) are xanthophyll carotenoids showing a wide spectrum of health-promoting properties. However, their utilization is limited, mostly due to poor water solubility, limited bioavailability, and a tendency to oxidate, as well as photo- and thermal instability. The aim of this work was to develop ASTA- and ZEA-loaded nano-structured lipid carriers (NLCs) that would protect them against degradation and improve their intestinal stability/permeability. Obtained NLCs were characterized by an effective diameter of 294 nm for ASTA-NLC and 280 nm for ZEA-NLC; polydispersity index (PDI) lower than 0.2; and zeta potential of -29.4 mV and -29.0 mV, respectively. Interestingly, despite similar physicochemical characteristics, our investigation revealed differences in the encapsulation efficiency of ASTA-NLC and ZEA-NLC (58.0 % vs. 75.5 %, respectively). Obtained NLCs were stable during a 21 day-storage period in the dark at room temperature or at 4 °C. Investigation of gastrointestinal stability showed no change in effective diameter and PDI under gastric conditions while both parameters significantly changed under intestinal conditions. Our results showed for the first time that both ASTA- and ZEA-NLCs intestinal absorption investigated in the in vitro model is significantly increased (in relation to pure compounds) and is affected by the presence of mucus. This study provides useful data about the advantages of using NLC as a delivery system for ASTA and ZEA that might facilitate their applications in the food and pharmaceutical industry.

Effect of Alpha Lipoic Acid Supplementation on Oxidative Stress and Lipid Parameters in Women Diagnosed with Low-Grade Squamous Intraepithelial Lesions (LSILs): A Double-Blind, Randomized, Placebo-Controlled Trial.

Limited scientific evidence shows that alpha lipoic acid (ALA) can induce regression rates of low-grade squamous intraepithelial lesions (LSILs), but the mechanisms of these effects have not been elucidated. To gain a broader insight into its therapeutic potential and mechanisms of action, the effects of 3 months of supplementation with 600 mg of ALA on antioxidant and lipid status parameters in 100 patients with LSILs were investigated in a randomized, placebo-controlled study. The obtained results are discussed in terms of patients' initial metabolic status and diet quality (particularly nutritional intake of antioxidants). The obtained results showed that oxidative status biomarkers were not significantly affected by ALA supplementation. However, serum superoxide dismutase (SOD) activity was positively affected in the subgroup of patients with higher dietary antioxidant intake. Surprisingly, ALA supplementation resulted in a small but statistically significant increase in serum low density lipoprotein (LDL), and the observed effect was significantly affected by the initial lipid status of the participants. Larger studies are necessary to gain additional insights on the clinical significance of ALA as an antioxidant and hypolipemic agent and to optimize its potential application in LSIL treatment.

Phyto-Assisted Synthesis of Nanoselenium-Surface Modification and Stabilization by Polyphenols and Pectins Derived from Agricultural Wastes.

Raw and purified mandarin peel-derived pectins were characterized and combined with olive pomace extract (OPE) in the green synthesis of selenium nanoparticles (SeNPs). SeNPs were characterized in terms of size distribution and zeta potential, and their stability was monitored during 30 days of storage. HepG2 and Caco-2 cell models were used for the assessment of biocompatibility, while antioxidant activity was investigated by the combination of chemical and cellular-based assays. SeNP average diameters ranged from 171.3 nm up to 216.9 nm; smaller SeNPs were obtained by the utilization of purified pectins, and functionalization with OPE slightly increased the average. At concentrations of 15 mg/L SeNPs were found to be biocompatible, and their toxicity was significantly lower in comparison to inorganic selenium forms. Functionalization of SeNPs with OPE increased their antioxidant activity in chemical models. The effect was not clear in cell-based models, even though all investigated SeNPs improved cell viability and protected intracellular reduced GSH under induced oxidative stress conditions in both investigated cell lines. Exposure of cell lines to SeNPs did not prevent ROS formation after exposure to prooxidant, probably due to low transepithelial permeability. Future studies should focus on further improving the bioavailability/permeability of SeNPs and enhancing the utilization of easily available secondary raw materials in the process of phyto-mediated SeNP synthesis.

Effect of Alpha-Lipoic Acid Supplementation on Low-Grade Squamous Intraepithelial Lesions-Double-Blind, Randomized, Placebo-Controlled Trial.

Low-grade squamous intraepithelial lesion (SIL) is a cytologic diagnosis etiologically related to human papilloma virus (HPV) infection that leads to the release of inflammation mediators, the formation of reactive oxygen species (ROS) and decreased levels of antioxidants in tissues, which is why antioxidants might be considered effective against SIL progression. This randomized double-blind placebo-controlled study aimed to investigate the effectiveness of alpha-lipoic acid (ALA) supplementation (600 mg/day) on the regression of low-grade SIL in 100 patients. Low-grade SIL was determined after the cytological screening, colposcopic examination and targeted biopsy and histological confirmation of cytological−colposcopic diagnosis. Inflammation parameters and the presence of HPV were determined by standard laboratory methods. Dietary and lifestyle habits were investigated using a standardized and validated semi-quantitative food questionnaire (FFQ). ALA supplementation significantly reduced the proportion of patients with low-grade cytological abnormalities, in comparison to placebo. Given the obtained level of significance (p < 0.001), the presented results indicate that short-term ALA supplementation shows a clinically significant effect on cervical cytology. Future studies should focus on the use of innovative formulations of ALA that might induce bioavailability and therapeutic efficiency against HPV infection and the investigation of synergistic effects of concurrent dietary/lifestyle modification and ALA supplementation in both low-grade and high-grade SIL.

Utilization of Olive Pomace in Green Synthesis of Selenium Nanoparticles: Physico-Chemical Characterization, Bioaccessibility and Biocompatibility.

Olive pomace extract (OPE) was investigated as a potential surface modifier for the development of the green synthesis process of selenium nanoparticles (SeNPs). In order to evaluate them as potential nutraceuticals, the obtained nanosystems were characterized in terms of size distribution, shape, zeta potential, stability in different media, gastrointestinal bioaccessibility and biocompatibility. Systems with a unimodal size distribution of spherical particles were obtained, with average diameters ranging from 53.3 nm to 181.7 nm, depending on the type of coating agent used and the presence of OPE in the reaction mixture. The nanosystems were significantly affected by the gastrointestinal conditions. Bioaccessibility ranged from 33.57% to 56.93% and it was significantly increased by functionalization of with OPE. Biocompatibility was investigated in the HepG2 and Caco2 cell models, proving that they had significantly lower toxicity in comparison to sodium selenite. Significant differences were observed in cellular responses depending on the type of cells used, indicating differences in the mechanisms of toxicity induced by SeNPs. The obtained results provide new insight into the possibilities for the utilization of valuable food-waste extracts in the sustainable development of nanonutraceuticals.

Food (Matrix) Effects on Bioaccessibility and Intestinal Permeability of Major Olive Antioxidants.

BACKGROUND: olive pomace extract (OPE) is a rich source of health promoting polyphenols (hydroxytyrosol (HTS) and tyrosol (TS)) and can be used as a nutraceutical ingredient of dietary supplements and functional foods. Its adequate bioavailability is a prerequisite for excreting biological activity and can be significantly and specifically affected by different food matrices. METHODS: in order to investigate food effects on polyphenol bioaccessibility, OPE was co-digested with different foods according to internationally harmonized in vitro digestibility method. Impact of particular nutrients on HTS and TS permeability was assessed on Caco-2 cell monolayer. RESULTS: HTS and TS bioaccessibility and transepithelial permeability can be significantly affected by foods (nutrients), especially by casein and certain types of dietary fiber. Those effects are polyphenol-and nutrient-specific and are achieved either through complexation in gastrointestinal lumen and/or through direct effects of nutrients on intestinal monolayer. CONCLUSIONS: obtained results emphasize the significance and complexity of polyphenol interactions within the food matrix and the necessity of individual investigational approaches with respect to particular food/nutrient and interacting phenolic compounds.

Cellular Antioxidant Activity of Olive Pomace Extracts: Impact of Gastrointestinal Digestion and Cyclodextrin Encapsulation.

Olive pomace is a valuable secondary raw material rich in polyphenols, left behind after the production of olive oil. The present study investigated the protective effect of a polyphenolic extract from olive pomace (OPE) on cell viability and antioxidant defense of cultured human HepG2 cells submitted to oxidative stress induced by tert-butylhydroperoxide (tBOOH). The investigation considered possible matrix effects, impact of gastrointestinal digestion and cyclodextrin (CD) encapsulation. Pre-treatment of cells with OPE prevented cell damage and increased intracellular glutathione but did not affect the activity of glutathione peroxidase and superoxide dismutase. OPE matrix significantly enhanced cell protective effects of major antioxidants, such as hydroxytyrosol (HTS), while cyclodextrin encapsulation enhanced activity of OPE against intracellular reactive oxygen species (ROS) accumulation. The obtained results show that OPE is more potent antioxidant in comparison to equivalent dose of main polyphenols (HTS and TS) and that increasing solubility of OPE polyphenols by CD encapsulation or digestion enhances their potential to act as intracellular antioxidants. Antioxidative protection of cells by OPE was primarily achieved through direct radical-scavenging/reducing actions rather than activation of endogenous defense systems in the cell.

Influence of Pomace Matrix and Cyclodextrin Encapsulation on Olive Pomace Polyphenols' Bioaccessibility and Intestinal Permeability.

Olive pomace is a rich source of biologically active compounds, mainly polyphenols. Recently, an efficient and sustainable cyclodextrin (CD)-enhanced extraction was developed. It enabled a relatively simple formulation of high-quality olive pomace extracts (OPEs) that can be used as alternative sources of olive-derived polyphenols in the nutrition and pharma industries. However, biological effects and nutraceutical potential of OPEs are primarily limited by generally low oral bioavailability of major polyphenols (hydroxytyrosol and its derivatives) that can be significantly influenced by OPE matrix and the presence of CDs in formulation. The major goal of this research was to investigate the impact of complex matrix and different types of CDs on gastrointestinal stability and intestinal permeability of major OPE polyphenols, and provide additional data about mechanisms of absorption and antioxidant activity in gut lumen. Obtained results showed high bioaccessibility but relatively low permeability of OPE polyphenols, which was negatively affected by OPE matrix. CDs improved antioxidant efficiency of tested OPEs and tyrosol gastrointestinal stability. Effects of CDs on permeability and the metabolism of particular OPE polyphenols were CD- and polyphenol-specific.

Valorization of Olive Pomace-Based Nutraceuticals as Antioxidants in Chemical, Food, and Biological Models.

Waste remaining after the production of olive oil (olive pomace) is known to contain significant amounts of phenolic compounds that exert different types of biological activities, primarily acting as antioxidants. In this work, a sustainable approach that combines ultrasound-assisted extraction with food-grade solvents and encapsulation with different types of cyclodextrins was used to prepare olive pomace-based polyphenol rich extracts that were tested as antioxidants in various chemical, food, and biological model systems. Encapsulation with cyclodextrins had a significant positive impact on the chemical composition of obtained extracts and it positively affected their antioxidant activity. Observed effects can be explained by an increased content of polyphenols in the formulations, specific physical properties of encapsulated compounds improving their antioxidant activity in complex food/physiological environment, and enhanced interaction with natural substrates. Depending on the applied model, the tested samples showed significant antioxidant protection in the concentration range 0.1⁻3%. Among the investigated cyclodextrins, hydroxypropyl-ß-cyclodextrin and randomly methylated-ß-cyclodextrin encapsulated extracts showed particularly good antioxidant activity and were especially potent in oil-in-water emulsion systems (1242 mg/g and 1422 mg/g of Trolox equivalents, respectively), showing significantly higher antioxidant activity than Trolox (reference antioxidant). In other models, they provided antioxidant protection comparable to commonly used synthetic antioxidants at concentration levels of 2⁻3%.

Evidence for Detrimental Cross Interactions between Reactive Oxygen and Nitrogen Species in Leber's Hereditary Optic Neuropathy Cells.

Here we have collected evidence suggesting that chronic changes in the NO homeostasis and the rise of reactive oxygen species bioavailability can contribute to cell dysfunction in Leber's hereditary optic neuropathy (LHON) patients. We report that peripheral blood mononuclear cells (PBMCs), derived from a female LHON patient with bilateral reduced vision and carrying the pathogenic mutation 11778/ND4, display increased levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS), as revealed by flow cytometry, fluorometric measurements of nitrite/nitrate, and 3-nitrotyrosine immunodetection. Moreover, viability assays with the tetrazolium dye MTT showed that lymphoblasts from the same patient are more sensitive to prolonged NO exposure, leading to cell death. Taken together these findings suggest that oxidative and nitrosative stress cooperatively play an important role in driving LHON pathology when excess NO remains available over time in the cell environment.