How to standardize the multiplicity of methods to evaluate natural antioxidants

Synthesis, characterization and evaluation of anti-hyperalgesia, anticonvulsant and antioxidant activity of novel VV-hemorphin-5 analogs

Two series of new VV-hemorphin-5 analogs with structures Val-Val-Tyr-Xxx-Trp-Thr-Gln-NH2 and Adam-Val-Val-Tyr-Xxx-Trp-Thr-Gln-NH2 , where Xxx is Ac5c (1-aminocyclopentane-1-carboxylic acid), Ac6c (1-aminocyclohexane-1-carboxylic acid), Ac7c (1-aminocycloheptane-1-carboxylic acid), and Adam is the low-molecular-weight lipophilic adamantyl building block, were synthesized, characterized electrochemically and evaluated for antioxidant, anti-hyperalgesia, and anticonvulsant activity. The design of the compounds followed the strategy to improve the propensity for aqueous solubility and/or to increase their affinity for the target receptor or enzyme. The partition coefficient value shows that the peptide scaffold goes from hydrophilic to lipophilic with the increasing size of the cycloalkane ring and even more with the introduction of the adamantane. The peptides C5-V and C7-V were the only analogs that provoked an immediate antinociceptive effect changing the mechanical pain threshold. The six new peptide analogs produced a significant and long-lasting carrageenan model of inflammatory pain in rats. While the adamantane hemorphin analog Ad7-V was the only compound with the potency to suppress psychomotor seizures in the 6-Hz test, the C6-V and Ad6-V exhibited protective activity against the seizure spread in the maximal electroshock seizure test in mice. The active analogs did not show neurotoxicity or sedative effects. Our results revealed a structure-related specific activity of a newly designed hemorphin analog that could be used as a template for future modification and preparation of compounds with potential analgesic and anticonvulsant activity.

Phytochemical Screening on Phenolic, Flavonoid Contents, and Antioxidant Activities of Six Indigenous Plants Used in Traditional Thai Medicine

The antioxidant activity of a traditional Thai formula has been studied and compared to each plant. The formula comprised the roots of Caesalpinia digyna Rottler, Huberantha cerasoides (Roxb.) Benth), Oxyceros horridus Lour, Antidesma ghaesembilla Gaerth, Combretum quadrangulare Kurz, and Ziziphus cambodiana Pierre. The stem was also studied in comparison. The ethanolic extract from each plant part and the mixed plants mimicking the traditional formula were prepared and investigated for antioxidant capability in vitro via DPPH radical scavenging and ferric-reducing antioxidant power assays. The phytochemical constituents were determined by chemical screening, total phenolic (TPC) and flavonoid contents (TFC), and high-performance liquid chromatography. The relationship between antioxidant activity and the contributed phytochemicals was determined using correlation analysis and principal component analysis (PCA). Results showed that extracts from both parts of the plant formula showed the highest antioxidant activity compared to a single plant extract. Among the six plants, C. digyna exhibited the highest TPC and antioxidant activity. TPC had a strong positive correlation with antioxidant activity. PCA revealed that gallic acid contributed to the antioxidant activity. In conclusion, the ethanolic extracts of the traditional formula and C. digyna have the potential for further chemical characterization and study related to antioxidant activity.

Distributions of α- and δ-TOCopherol in Intact Olive and Soybean Oil-in-Water Emulsions at Various Acidities: A Test of the Sensitivity of the Pseudophase Kinetic Model

During the last years, the formalism of the pseudophase kinetic model (PKM) has been successfully applied to determine the distributions of antioxidants and their effective interfacial concentrations, and to assess the relative importance of emulsion and antioxidant properties (oil and surfactant nature, temperature, acidity, chemical structure, hydrophilic-liphophilic balance (HLB), etc.) on their efficiency in intact lipid-based emulsions. The PKM permits separating the contributions of the medium and of the concentration to the overall rate of the reaction. In this paper, we report the results of a specifically designed experiment to further test the suitability of the PKM to evaluate the distributions of antioxidants among the various regions of intact lipid-based emulsions and provide insights into their chemical reactivity in multiphasic systems. For this purpose, we employed the antioxidants α- and δ-TOCopherol (α- and δ-TOC, respectively) and determined, at different acidities well below their pKa, the interfacial rate constants k_I for the reaction between 16-ArN₂⁺ and α- and δ-TOC, and the antioxidant distributions in intact emulsions prepared with olive and soybean oils. Results show that the effective interfacial concentration of δ-TOC is higher than that of α-TOC in 1:9 (v/v) soybean and 1:9 olive oil emulsions. The effective interfacial concentrations of tocopherols are much higher (15-96-fold) than the stoichiometric concentrations, as the effective interfacial concentrations of both δ-TOC and α-TOC in soybean oil emulsions are higher (2-fold) than those in olive oil emulsions. Overall, the results demonstrate that the PKM grants an effective separation of the medium and concentration effects, demonstrating that the PKM constitutes a powerful non-destructive tool to determine antioxidant concentrations in intact emulsions and to assess the effects of various factors affecting them.

Advances in the control of lipid peroxidation in oil-in-water emulsions: kinetic approaches†

Large efforts have been, and still are, devoted to minimize the harmful effects of lipid peroxidation. Much of the early work focused in understanding both the lipid oxidation mechanisms and the action of antioxidants in bulk solution. However, food-grade oils are mostly present in the form of oil-in-water emulsions, bringing up an increasing complexity because of the three-dimensional interfacial region. This review presents an overview of the kinetic approaches employed in controlling the oxidative stability of edible oil-in-water emulsions and of the main outcomes, with particular emphasis on the role of antioxidants and on the kinetics of the inhibition reaction. Application of physical-organic chemistry methods, such as the pseudophase models to investigate antioxidant partitioning, constitute a remarkable example on how kinetic methodologies contribute to model chemical reactivity in multiphasic systems and to rationalize the role of interfaces, opening new opportunities for designing novel antioxidants with tailored properties and new prospects for modulating environmental conditions in attempting to optimize their efficiency. Here we will summarize the main kinetic features of the inhibition reaction and will discuss on the main factors affecting its rate, including the determination of antioxidant efficiencies from kinetic profiles, structure-reactivity relationships, partitioning of antioxidants and concentration effects.

A Systematic Study of the Antioxidant Capacity of Humic Substances against Peroxyl Radicals: Relation to Structure

Humic substances (HS) are natural supramolecular systems of high- and low-molecular-weight compounds with distinct immunomodulatory and protective properties. The key beneficial biological activity of HS is their antioxidant activity. However, systematic studies of the antioxidant activity of HS against biologically relevant peroxyl radicals are still scarce. The main objective of this work was to estimate the antioxidant capacity (AOC) of a broad set of HS widely differing in structure using an oxygen radical absorption capacity (ORAC) assay. For this purpose, 25 samples of soil, peat, coal, and aquatic HS and humic-like substances were characterized using elemental analysis and quantitative ¹³C solution-state NMR. The Folin–Ciocalteu method was used to quantify total phenol (TP) content in HS. The determined AOC values varied in the range of 0.31–2.56 μmol Trolox eqv. mg⁻¹, which is close to the values for ascorbic acid and vitamin E. Forward stepwise regression was used to reveal the four main factors contributing to the AOC value of HS: atomic C/N ratio, content of O-substituted methine and methoxyl groups, and TP. The results obtained clearly demonstrate the dependence of the AOC of HS on both phenolic and non-phenolic moieties in their structure, including carbohydrate fragments.

Traditional Uses, Nutritional and Pharmacological Potentials of Clerodendrum volubile

Clerodendrum volubile is an underutilized leafy vegetable consumed in some parts of Nigeria. The interest in C. volubile has continued to increase due to its multipurpose values, including traditional uses, nutritional properties, and some therapeutic potentials; however, the pharmacological prospects of the plant are yet to be fully explored. Therefore, in the present review, different databases such as PubMed, Scopus, Web of Science, Google Scholar, etc. were explored to retrieve publications used to write this review. The pharmacological potentials of C. volubile, such as anticancer, antioxidant, antiviral, antimicrobial, anti-inflammatory, hepatoprotective, antidiabetic, and anti-hypertensive properties, were highlighted. The toxicological potential of the plant is also discussed. Proposed mechanisms that underline its biological activities include modulation of redox homeostasis, leading to decreased oxidative stress; down-regulation of matrix metalloproteinase-9 (MMP-9) expression; inhibition of key enzymes implicated in diabetes mellitus, hypertension, and neurological diseases; and inhibition of oxidative burst and inflammatory cytokines. Furthermore, the prospect of endophytes from C. volubile as a bioresource to produce novel therapeutic agents, as well as the development of nanotherapeutics from the plant extracts and its phytoconstituents, are discussed. In conclusion, C. volubile possesses an enormous number of possible pharmacological properties and therapeutic potentials waiting to be explored.

Dietary Antioxidants in the Treatment of Male Infertility: Counteracting Oxidative Stress

Infertility affects about 15% of the population and male factors only are responsible for ~25-30% of cases of infertility. Currently, the etiology of suboptimal semen quality is poorly understood, and many environmental and genetic factors, including oxidative stress, have been implicated. Oxidative stress is an imbalance between the production of free radicals, or reactive oxygen species (ROS), and the capacity of the body to counteract their harmful effects through neutralization by antioxidants. The purpose of this review, by employing the joint expertise of international researchers specialized in nutrition and male fertility areas, is to update the knowledge about the reproductive consequences of excessive ROS concentrations and oxidative stress on the semen quality and Assisted Reproduction Techniques (ART) clinical outcomes, to discuss the role of antioxidants in fertility outcomes, and finally to discuss why foods and dietary patterns are more innocuous long term solution for ameliorating oxidative stress and therefore semen quality results and ART fertility outcomes. Since this is a narrative review and not a systematic/meta-analysis, the summarized information in the present study should be considered cautiously.

Influence of Olive Pomace Blending on Antioxidant Activity: Additive, Synergistic, and Antagonistic Effects

Food innovation is moving rapidly and comprises new categories of food products and/or ingredients with a natural and ecological origin. Monocultivar olive pomaces, individually or combined, can be a source of natural bioactive compounds suitable for food or cosmetic applications. This work aimed to assess the phenolics content and antioxidant activity of four monocultivar olive pomaces (Arbosana, Koroneiki, Oliana, and Arbequina) and forty-nine blends prepared with different proportions of each. Additive, synergistic, and antagonistic effects were studied. Among the monocultivar pomaces, Koroneiki and Arbosana were the richest in total phenolics (~15 mg gallic acid eq./g). Most of the interactions found in the blends were additive or synergistic, while very few antagonistic effects were observed. The best results were obtained for those blends where the Koroneiki variety predominated: (i) 90% Koroneiki, 4.75% Oliana, 3.75% Arbequina, 1.5% Arbosana; (ii) 65% Koroneiki, 29% Oliana, 3.25% Arbequina, 2.75% Arbosana; and (iii) 85% Koroneiki, 8.75% Arbequina, 3.5% Arbosana, 2.75% Oliana. In sum, these combinations can be advantageous in comparison to the individual use of monocultivar pomaces, presenting a higher potential to be used as functional ingredients or for bioactive compounds extraction, having in view the obtention of natural preservatives or food/cosmetic formula enhancers.

The influence of nanodelivery systems on the antioxidant activity of natural bioactive compounds

Bioactive compounds may lose their antioxidant activity (e.g., phenolic compounds) at elevated temperatures, enhanced oxidative conditions and severe light exposures so they should be protected by various strategies such as nano/microencapsulation methods. Encapsulation technology has been employed as a proper method for using antioxidant ingredients and to provide easy dispersibility of antioxidants in all matrices including food and pharmaceutical products. It can improve the food fortification processes, release of antioxidant ingredients, and extending the shelf-life and bioavailability of them when ingested in the intestine. In this study, our main goal is to have an overview of the influence of nanoencapsulation on the bioactivity and bioavailability, and cellular activities of antioxidant ingredients in different delivery systems. Also, the effect of encapsulation process conditions, storage conditions, carrier wall materials, and release profile on the antioxidant activity of different natural bioactives are explained. Finally, analytical techniques for measuring antioxidant activity of nanoencapsulated ingredients will be covered.

Modulation and Protection Effects of Antioxidant Compounds against Oxidant Induced Developmental Toxicity in Zebrafish

The antioxidant effect of compounds is regularly evaluated by in vitro assays that do not have the capability to predict in vivo protective activity or to determine their underlying mechanisms of action. The aim of this study was to develop an experimental system to evaluate the in vivo protective effects of different antioxidant compounds, based on the zebrafish embryo test. Zebrafish embryos were exposed to tert-butyl hydroperoxide (tBOOH), tetrachlorohydroquinone (TCHQ) and lipopolysaccharides from Escherichia coli (LPS), chemicals that are known inducers of oxidative stress in zebrafish. The developmental toxic effects (lethality or dysmorphogenesis) induced by these chemicals were modulated with n-acetyl l-cysteine and Nω-nitro l-arginine methyl ester hydrochloride, dimethyl maleate and dl-buthionine sulfoximine in order to validate the oxidant mechanism of oxidative stress inducers. The oxidant effects of tBOOH, TCHQ, and LPS were confirmed by the determination of significant differences in the comparison between the concentration–response curves of the oxidative stress inducers and of the modulators of antioxidant status. This concept was also applied to the study of the effects of well-known antioxidants, such as vitamin E, quercetin, and lipoic acid. Our results confirm the zebrafish model as an in vivo useful tool to test the protective effects of antioxidant compounds.

Phytochemical Profiles and Bioactivities of Cake Tea Leaves Obtained From the Same Cultivar: A Comparative Analysis

Cake tea, a traditional beverage of China, has excellent health benefits. Our study investigated the phytochemical profiles, antioxidant, and antiproliferative activities of cake tea leaves, which were obtained from the same cultivar and processed at different intervals. The effects of bioactive compounds and antioxidant activities of 4 cake tea varieties on a human lung cancer cell line (A549 cells) were systematically examined. The content of total polyphenol, an active ingredient of tea, was significantly higher in green cake teas (14.0% ± 0.4a) than their black (4.8 ± 0.3c), yellow (10.0 ± 0.6b), and white (8.8 ± 0.5b) counterparts. Likewise, the content of total free amino acids in green cake tea (3.6% ± 0.5a) was significantly higher than the other tea varieties. Our results indicated that the extent of fermentation of tea leaves could decrease the antioxidant activities of cake tea leaves. Furthermore, the white tea cake variety demonstrated the maximum antiproliferative activity on A549 cells as opposed to other types of cake tea leaves. Such an observation allows future researchers to narrow down their focus on using specific cake tea types (sourced from the same cultivar) that provide the maximum health benefits.

Improving the efficiency of natural antioxidant compounds via different nanocarriers

Encapsulation technology, as a promising approach, has been employed for the protection and controlled release of different bioactive compounds including natural antioxidants; there are restrictions for applying these valuable ingredients in real food products, pharmaceuticals, and cosmetics such as low solubility, low shelf life, difficultly in their packaging and handling, losses due to environmental stresses and food processes, undesirable flavors and odors, untargeted release and instability in various conditions during digestion in gastrointestinal tract. Nanocarriers can be employed to overcome these challenges. There are five groups of nanocarriers based on the principal mechanism/ingredient used to make them for the encapsulation of natural antioxidants titled biopolymeric nanoparticles, lipid-based and surfactant-based nanocarriers, nanocarriers made with specially designed equipment, nature-inspired nanocarriers, and miscellaneous ones. The main goal of this study is to have an overview of role of different nanocarriers in improving the efficiency of natural antioxidant compounds for different purposes. It has been verified that antioxidant-loaded nanocarriers can be applied in many formulations with a higher and controlled release antioxidant activity, which would meet the current needs of consumers' expectations towards clean label products.

Evaluating the In Vitro Potential of Natural Extracts to Protect Lipids from Oxidative Damage

Lipid peroxidation is a chemical reaction known to have negative impacts on living organisms' health and on consumer products' quality and safety. Therefore, it has been the subject of extensive scientific research concerning the possibilities to reduce it, both in vivo and in nonliving organic matrices. It can be started by a variety of oxidants, by both ROS-dependent and -independent pathways, all of them reviewed in this document. Another feature of this reaction is the capacity of lipid peroxyl radicals to react with the non-oxidized lipids, propagating the reaction even in the absence of an external trigger. Due to these specificities of lipid peroxidation, regular antioxidant strategies-although being helpful in controlling oxidative triggers-are not tailored to tackle this challenge. Thus, more suited antioxidant compounds or technologies are required and sought after by researchers, either in the fields of medicine and physiology, or in product development and biotechnology. Despite the existence of several laboratory procedures associated with the study of lipid peroxidation, a methodology to perform bioprospecting of natural products to prevent lipid peroxidation (a Lipid Peroxidation Inhibitory Potential assay, LPIP) is not yet well established. In this review, a critical look into the possibility of testing the capacity of natural products to inhibit lipid peroxidation is presented. In vitro systems used to peroxidize a lipid sample are also reviewed on the basis of lipid substrate origin, and, for each of them, procedural insights, oxidation initiation strategies, and lipid peroxidation extent monitoring are discussed.

Polyphenols, food and pharma. Current knowledge and directions for future research

Polyphenols are a large family of phytochemicals with great chemical diversity, known to be bioactive compounds of foods, species, medicinal plants and nutraceuticals. These compounds are ingested through the diet in significant amounts, around 1 g per day, an amount that be may be increased through supplements. The in vitro action of many representative polyphenols has been reported. However, their beneficial effects and their role in modulating the risk of high-prevalence diseases are difficult to demonstrate due to the wide variability of polyphenol structures and bioactive actions; the complexity of estimating the polyphenol content of food as a result of their variability in foods and cooked dishes; the potential modulation of the effects of polyphenols by food matrices; the addition of polyphenols and their synergistic interactions with each other and with other dietary bioactive components; the modulation of polyphenol bioavailability as a consequence of food composition and culinary techniques; their metabolism by the human body and the polyphenol gut microbiota metabolism in each metabotypes. Computational strategies, including virtual screening, shape-similarity-screening and molecular docking, were recently used to identify potential targets of polyphenols and thus gain a better understanding of the therapeutic effects exerted of polyphenols and modify natural polyphenol structures to potentiate specific activities. Here, we present the most relevant current knowledge and propose directions for future research in these fields, from the culinary world to the clinical setting. We hope this commentary will prompt scientists and clinicians to consider the therapeutic value of bioactive polyphenols and help shed some light on how much scientific truth lies in Hippocrates' famous quote: "Let your food be your medicine".

Simultaneous optimization of ultrasonic-assisted extraction of antioxidant and anticoagulation activities of compounds from Leonurus japonicus Houtt. by response surface methodology

Leonurus japonicus Houtt. is a herbaceous annual of the Lamiaceae family with pantropical distribution; it is called motherwort in China. It plays important roles in anticoagulation and antioxidation. This study aimed to explore the optimization of ultrasound-assisted extraction of multiple compounds from motherwort as well as their antioxidant and anticoagulation activities using response surface methodology. Box–Behnken design was employed to optimize three significant influences, namely extraction time, extraction temperature and ethanol concentration. The optimum extraction parameters acquired based on a combination of the yield of the target compounds and their antioxidant and anticoagulation activities were an extraction time of 38.2 min, an extraction temperature of 30.0 °C, an ethanol concentration of 48.9% (v/v), a solid–liquid ratio of 30.0 mL g⁻¹ and an ultrasonic power of 500.0 W. Under the optimal conditions, the maximal yield of the anticoagulation and antioxidant compounds of motherwort was 0.994%; the thrombin time was 19.872 s; prothrombin time was 8.270 s; the activated partial thromboplastin time was 15.535 s; the fibrinogen was 1.420 g L⁻¹; and the 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity was 1.503 mg mL⁻¹. The optimized conditions model showed a good correlation between the predicted and experimental values. According to the results of our study, the optimization extraction significantly enabled study of the anticoagulation and antioxidant activities of compounds in motherwort; this may contribute to future research on the pharmacological activities of motherwort.

Leonurus japonicus Houtt. is a herbaceous annual of the Lamiaceae family with pantropical distribution; it is called motherwort in China.

Low-density lipoprotein oxidation biomarkers in human health and disease and effects of bioactive compounds

Based on the significance of oxidized low-density lipoprotein (LDL) in health and disease, this review focuses on human studies addressing oxidation of LDL, including three lines of biomarkers, (i) ex vivo LDL resistance to oxidation, a "challenge test" model, (ii) circulating oxidized LDL, indicating the "current in vivo status", and (iii) autoantibodies against oxidized LDL as fingerprints of an immune response to oxidized LDL, along with circulating oxysterols and 4-hydroxynonenal as biomarkers of lipid peroxidation. Lipid peroxidation and oxidized LDL are hallmarks in the development of various metabolic, cardiovascular and other diseases. Changes further occur across life stages from infancy to older age as well as in athletes and smokers. Given their responsiveness to targeted nutritional interventions, markers of LDL oxidation have been employed in a rapidly growing number of human studies for more than 2 decades. There is growing interest in foods, which, besides providing energy and nutrients, exert beneficial effects on human health, such as protection of DNA, proteins and lipids from oxidative damage. Any health claim, however, needs to be substantiated by supportive evidence derived from human studies, using reliable biomarkers to demonstrate such beneficial effects. A large body of evidence has accumulated, demonstrating protection of LDL from oxidation by bioactive food compounds, including vitamins, other micronutrients and secondary plant ingredients, which will facilitate the selection of oxidation biomarkers for future human intervention studies and health claim support.

Measurement of antioxidant activity with the thiobarbituric acid reactive substances assay

The thiobarbituric acid reactive substances (TBARS) assay is widely used to measure lipid oxidation and antioxidant activity in food and physiological systems. However, there has been no review (to our knowledge) that focuses exclusively on this test. This review presents an overview of the current use of the TBARS test in food and physiological systems, before looking at the various ways in which the assay is used in studies on antioxidant activity. As an antioxidant assay, the TBARS test may lack acceptable reproducibility, and long reaction times may preclude its adoption as a rapid screening method. Despite these potential limitations, there are features of the TBARS test that make it useful as a complement to popular screening tests such as Trolox equivalent antioxidant capacity. This review concludes with proposals for development of the TBARS test so that it can be used as a rapid and robust antioxidant assay.

Ultrasound-assisted extraction of natural antioxidants from the flower of Limonium sinuatum: Optimization and comparison with conventional methods

Natural antioxidants are widely used as dietary supplements or food additives. An optimized method of ultrasound-assisted extraction (UAE) was proposed for the effective extraction of antioxidants from the flowers of Limonium sinuatum and evaluated by response surface methodology. In this study, ethanol concentration, ratio of solvent to solid, ultrasonication time and temperature were investigated and optimized using a central composite rotatable design. The optimum extraction conditions were as follows: ethanol concentration, 60%; ratio of solvent to solid, 56.9:1mL/g; ultrasonication time, 9.8min; and temperature, 40°C. Under the optimal UAE conditions, the experimental values (483.01±15.39μmolTrolox/gDW) matched with those predicted (494.13μmolTrolox/gDW) within a 95% confidence level. In addition, the antioxidant activities of UAE were compared with those of conventional maceration and Soxhlet extraction methods, and the ultrasound-assisted extraction could give higher yield of antioxidants and markedly reduce the extraction time.

Antioxidant Activities and Reduced Amyloid-β Toxicity of 7-Hydroxycalamenene Isolated from the Essential Oil of Zelkova serrata Heartwood

The in vitro and in vivo antioxidant activities and its potential to protect against amyloid-β toxicity of essential oils from Zelkova serrata (Thunb.) Makino were investigated in the model organism Caenorhabditis elegans. The results revealed that the essential oil of Z. serrata heartwood exhibited great radical scavenging activities and high total phenolic content. In vivo assays showed significant inhibition of oxidative damage in wild-type C. elegans under juglone-induced oxidative stress and heat shock. Based on results from both in vitro and in vivo assays, the major compound in essential oil of heartwood, (-)-(1 S, 4 S)-7-hydroxycalamenene (1 S, 4 S-7HC), may contribute significantly to the observed antioxidant activity. Further evidence showed that 1 S, 4 S-7HC significantly delayed the paralysis phenotype in amyloid beta-expressing transgenic C. elegans. These findings suggest that 1 S, 4 S-7HC from the essential oil of Z. serrata heartwood has potential as a source for antioxidant or Alzheimer's disease treatment.

Hydrophilic antioxidants from Andean tomato landraces assessed by their bioactivities in vitro and in vivo

Potential nutraceutical properties of hydrophilic antioxidants in fruits of tomato landraces collected in Andean valleys were characterised. Antioxidant metabolites were measured by HPLC-DAD-MS/MS in mature fruits and their biological activities were assessed by in vitro and in vivo methods. In vitro antioxidant capacities were established by TEAC and FRAP methods. For in vivo biological activities we used a procedure based on Caenorhabditis elegans subjected to thermal stress. In addition, Saccharomyces cerevisiae was also used as a rapid screening system to evaluate tomato antioxidant capacity. All tomato accessions displayed significant differences regarding metabolic composition, biological activity and antioxidant capacity. Metabolite composition was associated with geographical origin and fruit size. Antioxidant activities showed significant association with phenolic compounds, such as caffeoylquinic acids, ferulic acid-O-hexosides and rutin. Combination of in vitro and in vivo methods applied here allowed evaluation of the variability in nutraceutical properties of tomato landraces, which could be applied to other fruits or food products.

Structure-Functional Study of Tyrosine and Methionine Dipeptides: An Approach to Antioxidant Activity Prediction

Quantum chemical methods allow screening and prediction of peptide antioxidant activity on the basis of known experimental data. It can be used to design the selective proteolysis of protein sources in order to obtain products with antioxidant activity. Molecular geometry and electronic descriptors of redox-active amino acids, as well as tyrosine and methionine-containing dipeptides, were studied by Density Functional Theory method. The calculated data was used to reveal several descriptors responsible for the antioxidant capacities of the model compounds based on their experimentally obtained antioxidant capacities against ABTS (2,2'-Azino-bis-(3-ethyl-benzothiazoline-6-sulfonate)) and peroxyl radical. A formula to predict antioxidant activity of peptides was proposed.

Measuring antioxidant and prooxidant capacity using the Crocin Bleaching Assay (CBA)

The Crocin Bleaching Assay (CBA) appears in literature as an in vitro method for measuring antioxidant and prooxidant capacity of model dietary antioxidants, food formulations, pharmaceuticals, and biological samples. The assay is based on simple competitive reactions between a colored probe, crocin, and the test compounds/constituents for scavenging peroxyl radicals generated after thermolysis of a water-soluble azo-initiator. So far, several researchers in the fields of food chemistry, nutrition and clinical biochemistry have sporadically addressed critical views about advantages, limitations and potential field of CBA application. This chapter presents step-by-step critical aspects of CBA in order to assist standardization of its performance. Detailed procedures for calculation of two attributes of peroxyl radical scavenging reactions, the relative rate constant and "total antioxidant capacity", are also presented.

Development of Iron-Chelating Poly(ethylene terephthalate) Packaging for Inhibiting Lipid Oxidation in Oil-in-Water Emulsions

Foods such as bulk oils, salad dressings, and nutritionally fortified beverages that are susceptible to oxidative degradation are often packaged in poly(ethylene terephthalate) (PET) bottles with metal chelators added to the food to maintain product quality. In the present work, a metal-chelating active packaging material is designed and characterized, in which poly(hydroxamic acid) (PHA) metal-chelating moieties were grafted from the surface of PET. Biomimetic PHA groups were grafted in a two-step UV-initiated process without the use of a photoinitiator. Surface characterization of the films by attenuated total reflective Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) suggested successful grafting and conversion of poly(hydroxyethyl acrylate) (PHEA) to PHA chelating moieties from the surface of PET. Colorimetric (ferrozine) and inductively coupled plasma mass spectroscopy (ICP-MS) assays demonstrated the ability of PET-g-PHA to chelate iron in a low-pH (3.0) environment containing a competitive metal chelator (citric acid). Lipid oxidation studies demonstrated the antioxidant activity of PET-g-PHA films in inhibiting iron-promoted oxidation in an acidified oil-in-water (O/W) emulsion model system (pH 3.0). Particle size and ζ-potential analysis indicated that the addition of PET-g-PHA films did not affect the physical stability of the emulsion system. This work suggests that biomimetic chelating moieties can be grafted from PET and effectively inhibit iron-promoted degradation reactions, enabling removal of metal-chelating additives from product formulations.

Houttuynia cordata Extract Improves Physical Endurance Performance by Regulating Endothelial Production of Nitric Oxide

Vascular function is mediated by various regulatory molecules, including endothelial nitric oxide (NO), which regulates the vasodilation of smooth muscle cells. We investigated whether standardized Houttuynia cordata extract (SHCE) could improve physical endurance performance by regulating the endothelial production of NO. For the standardization of Houttuynia cordata (HC) extract, its bioactive components were identified and quantified using ultraperformance liquid chromatography-mass spectrometry. Bioaccessibility and biological activity were measured by the in vitro digestion model system and free radical scavenging capacity, respectively. The vascular function in the endothelium was assessed by the phosphorylation of endothelial nitric oxide synthase (eNOS). A preliminary clinical trial was carried out to assess the physical endurance performance. HC extract was standardized to bioactive components, including chlorogenic acid, rutin, and quercitrin, with the concentration of 5.53, 6.09, and 16.15 mg from 1 g of dry weight, respectively. Bioaccessibility was 33.17%, 31.67%, and 11.18% for chlorogenic acid, rutin, and quercitrin, respectively. Antioxidant activities of SHCE were expressed as vitamin C equivalent antioxidant capacity in 55.81 and 17.23 mg/g of HC extract using ABTS and DPPH scavenging assay, respectively. In human aortic endothelial cells, insulin-mediated phosphorylation of eNOS was increased by SHCE in the presence of palmitate. However, the expression of blood pressure-regulating genes was not altered. The level of blood lactate concentration and the heart rate of subjects who drank SHCE were lower than those of subjects who drank plain water. Oxygen uptake from subjects drinking SHCE was slightly higher than that from those who drank plain water. This study demonstrated that SHCE decreased heart rate and blood lactate, increased oxygen uptake, and improved physical performance, presumably due to the increased NO production.

Identification of phenolic compounds in red wine extract samples and zebrafish embryos by HPLC-ESI-LTQ-Orbitrap-MS

The zebrafish embryo is a highly interesting biological model with applications in different scientific fields, such as biomedicine, pharmacology and toxicology. In this study, we used liquid chromatography/electrospray ionisation-linear ion trap quadrupole-Orbitrap-mass spectrometry (HPLC/ESI-LTQ-Orbitrap-MS) to identify the polyphenol compounds in a red wine extract and zebrafish embryos. Phenolic compounds and anthocyanin metabolites were determined in zebrafish embryos previously exposed to the red wine extract. Compounds were identified by injection in a high-resolution system (LTQ-Orbitrap) using accurate mass measurements in MS, MS(2) and MS(3) modes. To our knowledge, this research constitutes the first comprehensive identification of phenolic compounds in zebrafish by HPLC coupled to high-resolution mass spectrometry.

Free radical scavenging ability of Aspalathus linearis in two in vitro models of diabetes and cancer

The free radical scavenging activity of Aspalathus linearis (Rooibos tea) and its effect on reactive oxygen species (ROS), catalase (CAT), and superoxide dismutase (SOD) were investigated in two in vitro disease models of cancer and diabetes. Although the antioxidant activity of this tea has been reported in several studies, its effects in disease models of ROS-induced oxidative stress have not been systematically evaluated to date. The oxygen radical absorbance capacity (ORAC) assay was used in this study to quantify the antioxidant capacity of the extract, whereas the ROS scavenging ability in hyperglycemia-induced human umbilical vein endothelial cells (HUVECs) and HeLa cells were investigated. The CAT and SOD assays were also carried out in the two disease models in order to evaluate the effect of the extract in the stimulation of these two enzyme activities. The extract was observed to have reduced ROS in a dose-dependent manner in both HUVECs and HeLa cells. The stimulation of the CAT and SOD enzyme activities were observed to be dose-dependent as well. The high ORAC value of the extract indicated the presence of antioxidant compounds which could directly quench ROS, whereby this mechanism of action could be hypothesized to have been further complemented through the stimulation of CAT and SOD. Overall, the Aspalathus linearis extract was observed to have increased the CAT and SOD activities in two in vitro disease models of cancer and hyperglycemia. Given the correlation between the ORAC values, the increases in CAT and SOD activities and the reduction in ROS in a dose-dependent manner, it could be hypothesized that the extract had a significant therapeutic potential for either the prevention of the onset of the two diseases or their progression because ROS has been identified as their root causes.

Coccoloba uvifera(L.) (Polygonaceae) Fruit: Phytochemical Screening and Potential Antioxidant Activity

The flora of Latin America attracts gaining interest as it provides a plethora of still unexplored or underutilized fruits that can contribute to human well-being due to their nutritional value and their content of bioactive compounds. Antioxidant compounds are now of considerable interest due to their effect of preventing or delaying aging and their apparent involvement in prevention of numerous human diseases, including cancer, atherosclerosis, Alzheimer’s disease, inflammation, and rheumatoid arthritis. In this work, the fruit ofCoccoloba uvifera(L.) was investigated for theirin vitroantioxidant capacity using two assays based on reactions with a relatively stable single reagent radical (Trolox equivalent antioxidant capacity, TEAC; and DPPH free radical scavenging assay, DPPH), two assays based on chelating of metallic cations, and one based on the reduction of oxidized species. The TEAC value on ABTS radical, DPPH scavenging activity, ion chelation, and reducing power were found to be 897.6 μM of Trolox/100 g of sample, 22.8% of DPPH free radical scavenging, 11.3% of Cu2+-chelating activity, 23.9% of Fe2+-chelating activity, and a Fe2+-reducing power of 0.76 mg/mL, respectively. The free radical scavenging and antioxidant characteristics ofC. uviferamay be due to the presence of diverse phytochemicals in the fruit as anthocyanins, ascorbic acid, phenolic compounds, and flavonoids.