On the efficiency of water soluble antioxidants

Therapeutic effect of allicin in a mouse model of intracerebral hemorrhage

Natural compounds with sulfur moiety produce various biological actions that may be beneficial for the therapies of several devastative disorders of the central nervous system. Here we investigated potential therapeutic effect of allicin, an organosulfur compound derived from garlic, in a mouse model of intracerebral hemorrhage (ICH) based on intrastriatal collagenase injection. Daily intraperitoneal administration of allicin (50 mg/kg) from 3 h after induction of ICH afforded neuroprotective effects, as evidenced by the increase of surviving neurons in the hematoma, reduction of axonal transport impairment, and prevention of axon tract injury. In addition, allicin inhibited accumulation of activated microglia/macrophages around the hematoma and infiltration of neutrophils within the hematoma. Allicin also suppressed ICH-induced mRNA upregulation of pro-inflammatory factors such as interleukin 6 and C-X-C motif ligand 2 in the brain, suggesting its anti-inflammatory effect. Moreover, ICH-induced increase of malondialdehyde as well as decrease of total glutathione in the brain was attenuated by allicin. Finally, allicin-treated mice showed better recovery of sensorimotor functions after ICH than vehicle-treated mice. These results indicate that allicin produces a therapeutic effect on ICH pathology via alleviation of neuronal damage, inflammatory responses and oxidative stress in the brain.

A microfluidic-based approach to investigate the inflammatory response of macrophages to pristine and drug-loaded nanostructured hydroxyapatite

The in vitro biological characterization of biomaterials is largely based on static cell cultures. However, for highly reactive biomaterials such as calcium-deficient hydroxyapatite (CDHA), this static environment has limitations. Drastic alterations in the ionic composition of the cell culture medium can negatively affect cell behavior, which can lead to misleading results or data that is difficult to interpret. This challenge could be addressed by a microfluidics-based approach (i.e. on-chip), which offers the opportunity to provide a continuous flow of cell culture medium and a potentially more physiologically relevant microenvironment. The aim of this work was to explore microfluidic technology for its potential to characterize CDHA, particularly in the context of inflammation. Two different CDHA substrates (chemically identical, but varying in microstructure) were integrated on-chip and subsequently evaluated. We demonstrated that the on-chip environment can avoid drastic ionic alterations and increase protein sorption, which was reflected in cell studies with RAW 264.7 macrophages. The cells grown on-chip showed a high cell viability and enhanced proliferation compared to cells maintained under static conditions. Whereas no clear differences in the secretion of tumor necrosis factor alpha (TNF-α) were found, variations in cell morphology suggested a more anti-inflammatory environment on-chip. In the second part of this study, the CDHA substrates were loaded with the drug Trolox. We showed that it is possible to characterize drug release on-chip and moreover demonstrated that Trolox affects the TNF-α secretion and morphology of RAW 264.7 ​cells. Overall, these results highlight the potential of microfluidics to evaluate (bioactive) biomaterials, both in pristine form and when drug-loaded. This is of particular interest for the latter case, as it allows the biological characterization and assessment of drug release to take place under the same dynamic in vitro environment.

Identification of new biologically active synthetic molecules: comparative experimental and theoretical studies on the structure-antioxidant activity relationship of cyclic 1,3-ketoamides

Antioxidant agent is a chemical that prevents the oxidation of other chemical substances. Its use is the most effective means of protecting the organism by neutralizing the harmful effects of free radicals caused by oxidative stress. In the present work, a series of β-ketoamides containing a variety of monosubstituted amide groups were synthesized and tested as antioxidant agents. In order to establish a possible structure-antioxidant activity relationship, we are presenting a systematic theoretical study of these molecules with the aim of clarifying the active sites. In particular, we discuss the selectivity resulting from the choice of a free radical/antioxidant system. The theoretical study of these molecules was carried out using density functional theory (DFT) calculations at the B3LYP/6-311G (d,p) level of theory. In order to shed light on the antioxidant properties of β-ketoamides, O-H bond dissociation enthalpies (BDEs), ionization potentials (IPs), electron affinities (EAs), proton affinities (PAs), and electron transfer enthalpies (ETEs) are performed in the gas phase and in ethanol. The results obtained show that the HAT mechanism is thermodynamically more favored in the gas phase, while the SPLET is preferred in the polar solvent.

Formation, structural characteristics and physicochemical properties of beeswax oleogels prepared with tea polyphenol loaded gelators

In this study, a tea polyphenol (TP) loaded beeswax gelator (TP gelator) was constructed and incorporated into soybean oil to improve the oxidative stability of oleogels. The effects of TP on the structure and storage stability of oleogels were investigated. The TP gelator prepared by embedding TP into beeswax improved the dispersity of TP in lipids. The thermal characteristics and X-ray diffraction analysis showed that the components of the TP gelator coexisted homogeneously and TP was well dispersed in beeswax. The Fourier-transform infrared spectra indicated that the phenolic hydroxyl group of TP had intermolecular force with the quaternary ammonium nitrogen in the choline portion of soybean lecithin. The formation of needle-like crystals by beeswax restricted the flow of liquid oil, and TP did not participate in the construction of the internal network structure of the oleogel. In the accelerated storage experiment at 60 °C, the peroxide value of the TP loaded oleogel decreased by 60.6% at the end of the storage period compared with soybean oil. TP was successfully embedded in the oleogel without changing its structure, which not only solved the problem of poor dispersion of TP in oil, but also showed a significant inhibitory effect on lipid oxidation.

A novel mechanism of Gamma-aminobutyric acid (GABA) protecting human umbilical vein endothelial cells (HUVECs) against H2O2-induced oxidative injury

Vascular endothelial cell damage is related to many vascular diseases, including cardiovascular disease (CVD). Reactive oxygen species (ROS) play a vital role in the pathogenesis of many cardiovascular diseases. Herein, H₂O₂-induced human umbilical vein endothelial cell (HUVEC) injury model was used to explore the mechanisms involved in the pathogenesis of ROS-induced oxidative stress and cell dysfunction. Gamma-aminobutyric acid (GABA), a naturally occurring four-carbon non-protein amino acid, has antioxidant activity and anti-inflammatory action. In the present study, we demonstrated that GABA could scavenge free radicals including DPPH and ABTS, reverse H₂O₂-induced suppression on HUVEC proliferation, HUVEC apoptosis and ROS formation via p65 signaling. Interestingly, GABA treatment alone did not cause significant changes in p65 phosphorylation, suggesting that GABA will not cause imbalance in NF-κB signaling and ROS formation without oxidative stress. Moreover, GABA also modulated Keap1-Nrf2 and Notch signaling pathways upon H₂O₂ stimulation, suggesting that GABA may exert its effect via multi mechanisms. In conclusion, the present study demonstrated that GABA inhibits H₂O₂-induced oxidative stress in HUVECs via inhibiting ROS-induced NF-κB and Caspase 3 pathway activation. GABA may, therefore, have potential as a pharmacological agent in the prevention or treatment of oxidative injury-related cardiovascular disease.

Rice Bioactive Peptide Binding with TLR4 To Overcome H2O2-Induced Injury in Human Umbilical Vein Endothelial Cells through NF-κB Signaling

Reactive oxygen species-induced vessel endothelium injury is crucial in cardiovascular diseases progression. Rice-derived bran bioactive peptides (RBAP) might exert antioxidant effect through unknown mechanisms. Herein, we validated the antioxidant effect and mechanism of RBAP on H₂O₂-induced oxidative injury in human umbilical vein endothelial cells (HUVECs). Here, HUVECs were treated with RBAP under H₂O₂ stimulation; the effects of RBAP on HUVECs oxidative injury were evaluated. H₂O₂ injury-induced cell morphology changes were ameliorated by RBAP. The effect of H₂O₂- on HUVEC apoptosis (percentage of apoptotic cell: 38.00 ± 2.00 in H₂O₂ group vs 21.07 ± 2.06 in RBAP + H₂O₂ group, P = 0.0013 compared to H₂O₂ group), the protein levels of cleaved caspase-3 (relative protein expression: 2.90 ± 0.10 in H₂O₂ group vs 1.82 ± 0.09 in RBAP + H₂O₂ group, P < 0.0001 compared to H₂O₂ group) and p-p65 (relative protein expression: 1.86 ± 0.09 in H₂O₂ group vs 1.35 ± 0.08 in RBAP + H₂O₂ group, P < 0.0001 compared to H₂O₂ group) could be attenuated by RBAP. RBAP exerts its protective function through binding with Toll-like receptor 4 (TLR4). Taken together, RBAP protects HUVECs against H₂O₂-induced oxidant injury, which provided the theoretical basis for the molecular mechanism of rice deep processing and exploitation of functional peptides.

Formation of N-Nitrosodimethylamine during Chloramination of Secondary and Tertiary Amines: Role of Molecular Oxygen and Radical Intermediates

N-Nitrosodimethylamine (NDMA) is a carcinogenic disinfection byproduct from water chloramination. Despite the identification of numerous NDMA precursors, essential parts of the reaction mechanism such as the incorporation of molecular O₂ are poorly understood. In laboratory model systems for the chloramination of secondary and tertiary amines, we investigated the kinetics of precursor disappearance and NDMA formation, quantified the stoichiometries of monochloramine (NH₂Cl) and aqueous O₂ consumption, derived ¹⁸O-kinetic isotope effects (¹⁸O-KIE) for the reactions of aqueous O₂, and studied the impact of radical scavengers on NDMA formation. Although the molar NDMA yields from five N,N-dimethylamine-containing precursors varied between 1.4% and 90%, we observed the stoichiometric removal of one O₂ per N,N-dimethylamine group of the precursor indicating that the oxygenation of N atoms did not determine the molar NDMA yield. Small ¹⁸O-KIEs between 1.0026 ± 0.0003 and 1.0092 ± 0.0009 found for all precursors as well as completely inhibited NDMA formation in the presence of radical scavengers (ABTS and trolox) imply that O₂ reacted with radical species. Our study suggests that aminyl radicals from the oxidation of organic amines by NH₂Cl and N-peroxyl radicals from the reaction of aminyl radicals with aqueous O₂ are part of the NDMA formation mechanism.

On the Dimers Stability of Allicin and Its Derivatives Interacting with AT, GC, and DNA Bridge: DFT Study

Allicin and its derivatives are physiologically active molecules with many potential health benefits. It is not clear if they have a direct effect on DNA or protein. In order to elucidate the allicin and its derivatives’ effect on DNA base pairs, we investigated various complexes of base pair and its bridge with an allicin and its derivatives. The investigated allicin derivatives were (E)-Ajoene, (Z)-Ajoene, Amz121, and Bmz73 radicals. The DFT calculation results revealed that the investigated molecules would favor binding to bridge of the base pairs instead of directly affecting the base pairs. The Bmz73 radical could break DNA by change bonding in it because the Bmz73 radical significantly affected the P-O bond of the bridge of base pair.

The Impact of Sonication on the Surface Quality of Single-Walled Carbon Nanotubes

Sonication process is regularly adopted for dispersing single-walled carbon nanotubes (SWCNTs) in an aqueous medium. This can be achieved by either covalent functionalization of SWCNTs with strong acid or by noncovalent functionalization using dispersants that adsorb onto the surface of SWCNTs during dispersion. Because the dispersion process is usually performed using sonication, unintentional free radical formation during sonication process may induce covalent modification of SWCNT surface. Herein, we have systematically investigated the status of SWCNT surface modification under various sonication conditions using Raman spectroscopy. Comparing ID /IG (Raman intensities between D and G bands) ratio of SWCNTs under various sonication conditions suggests that typical sonication conditions (1-6 h bath sonication with sonication power between 3 and 80 W) in aqueous media do not induce covalent modification of SWCNT surface. In addition, we confirm that SWCNT dispersion with single-stranded DNA (ssDNA) involves noncovalent adsorption of ssDNA onto the surface of SWCNTs, but not covalent linkage between ssDNA and SWCNT surface.

Antioxidants: Characterization, natural sources, extraction and analysis

Recently many review papers regarding antioxidants from different sources and different extraction and quantification procedures have been published. However none of them has all the information regarding antioxidants (chemistry, sources, extraction and quantification). This article tries to take a different perspective on antioxidants for the new researcher involved in this field. Antioxidants from fruit, vegetables and beverages play an important role in human health, for example preventing cancer and cardiovascular diseases, and lowering the incidence of different diseases. In this paper the main classes of antioxidants are presented: vitamins, carotenoids and polyphenols. Recently, many analytical methodologies involving diverse instrumental techniques have been developed for the extraction, separation, identification and quantification of these compounds. Antioxidants have been quantified by different researchers using one or more of these methods: in vivo, in vitro, electrochemical, chemiluminescent, electron spin resonance, chromatography, capillary electrophoresis, nuclear magnetic resonance, near infrared spectroscopy and mass spectrometry methods.

Scavenging effect of Trolox released from brushite cements

In this study a brushite cement was doped with the chain-breaking antioxidant Trolox. The effect of the antioxidant on the physical properties of the cement was evaluated and the release of Trolox was monitored by UV spectroscopy. The ability of the Trolox set free to scavenge reactive oxygen species (ROS) released by macrophages was determined in vitro using a luminol-amplified chemiluminescence assay. Trolox did not modify the crystalline phases of the set cement, which mainly formed crystalline brushite after 7 days in humid conditions. The setting time, compressive strength and morphology of the cement also remained unaltered after the addition of the antioxidant. Trolox was slowly released from the cement following a non-Fickian transport mechanism and nearly 64% of the total amount was released after 3 days. Moreover, the capacity of Trolox to scavenge the ROS released by macrophages increased in a dose-dependent manner. Trolox-loaded cements are expected to reduce some of the first harmful effects of acute inflammation and can thus potentially protect the surrounding tissue during implantation of these as well as other materials used in conjunction.

High levels of melatonin generated during the brewing process

Beer is a beverage consumed worldwide. It is produced from cereals (barley or wheat) and contains a wide array of bioactive phytochemicals and nutraceutical compounds. Specifically, high melatonin concentrations have been found in beer. Beers with high alcohol content are those that present the greatest concentrations of melatonin and vice versa. In this study, gel filtration chromatography and ELISA were combined for melatonin determination. We brewed beer to determine, for the first time, the beer production steps in which melatonin appears. We conclude that the barley, which is malted and ground in the early process, and the yeast, during the second fermentation, are the largest contributors to the enrichment of the beer with melatonin.

THEORETICAL STUDY OF THE SUBSTITUENT EFFECTS ON THE REACTION ENTHALPIES OF THE ANTIOXIDANT MECHANISMS OF STOBADINE DERIVATIVES IN THE GAS-PHASE AND WATER

In this paper the reaction enthalpies of three antioxidant action mechanisms, HAT, SET–PT, and SPLET, for mono-substituted Stobadines were calculated in gas-phase and water. Results show that electron-withdrawing substituents increase the bond dissociation enthalpy (BDE), ionization potential (IP), and electron transfer enthalpy (ETE), while electron-donating ones cause a rise in the proton dissociation enthalpy (PDE) and proton affinity (PA). In comparison to gas-phase, water attenuates the substituent effect on all reaction enthalpies. Results show that IP and BDE values can be successfully correlated with the indolic N–H bond length after electron abstraction, R(N–H+•), and the partial charge on the indolyl radical nitrogen atom, q( N ). Furthermore, calculated IP and PA values for mono-substituted Stobadines show linear dependence on the energy of the highest occupied molecular orbital (E HOMO ) of studied molecules in the two environments. SPLET represents the thermodynamically preferred mechanism in water.