Relative Antioxidant Activity Research Articles

ICP-MS based metallomics and GC-MS based metabolomics reveals the physiological and metabolic responses of Dendrobium huoshanense plants exposed to Fe3O4 nanoparticles.

It is found that the growth of Dendrobium huoshanense was dependent on Fe3O4, while the bioavailability of plants to ordinary Fe3O4 was low on the earth. In order to improve the growth, quality and yield of D. huoshanense, we used Fe3O4 NPs (100 or 200 mg/L) that was easily absorbed by plants as nano-fertilizer to hydroponically treat seedlings of D. huoshanense for 3 weeks. Fe3O4 NPs induced not only earlier flowering and increased sugar content and photosynthesis, but also stressed to plants, increased MDA content and related antioxidant enzymes activities. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) revealed that Fe3O4 NPs caused a significant accumulation of Fe and some other nutrient elements (Mn, Co, B, Mo) in stems of D. huoshanense. Metabolomics revealed that the metabolites were reprogrammed in D. huoshanense when under Fe3O4 NPs exposure. Fe3O4 NPs inhibited antioxidant defense-related pathways, demonstrating that Fe3O4 NPs have antioxidant capacity to protect D. huoshanense from damage. As the first study associating Fe3O4 NPs with the quality of D. huoshanense, it provided vital insights into the molecular mechanisms of how D. huoshanense responds to Fe3O4 NPs, ensuring the reasonable use of Fe3O4 NPs as nano-fertilizer.

The sweet potato transcription factor IbbHLH33 enhances chilling tolerance in transgenic tobacco

Chilling is an important abiotic stress in plants. Sweet potato is sensitive to cold damage due to its tropical origin. In this study, we identified a basic helix-loop-helix (bHLH) gene, IbbHLH33, from our cold-tolerance-related transcriptomic data. Further analyses revealed that IbbHLH33 encoded a nuclear protein and was most closely related to AtbHLH33. RT-qPCR analysis showed that IbbHLH33 was expressed at the highest level in the roots, and its expression was strongly induced by low temperature (4 °C), H<sub>2</sub>O<sub>2</sub> and abscisic acid (ABA) treatments. Transgenic tobacco plants overexpressing IbbHLH33 were obtained by Agrobacterium-mediated transformation, which enhanced the chilling resistance of tobacco. At low temperatures, the proline content, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content increased significantly, while the relative conductivity decreased significantly. At the same time, the expression of proline synthesis related genes and antioxidant activity related genes increased, while the expression of ABA synthesis related genes decreased. The results showed that IbbHLH33 is a transcription factor encoding a gene of the bHLH family that regulates chilling tolerance. In conclusion, these data suggest that IbbHLH33 has the potential to improve chilling tolerance in tobacco and other plants.

Structure-antiradical activity relationships of 25 natural antioxidant phenolic compounds from different classes

In this study, 11 hydroxybenzoic acids, 6 hydroxycinnamic acids, 6 flavonoids, and 2 synthetic phenolic antioxidants were evaluated according to their scavenging capacity and structure relationships. The IC50 was calculated for all compounds and the effects of the concentration of antioxidant and the length of the reaction on antioxidant capacity were taken into consideration. Based on the data of tested phenolics some structure-activity relationships were suggested and discussed in detail. Poor correspondence of the results between ABTS+• and DPPH• assays was attained, indicating that the antioxidant properties of each compound differ with regards to the applied method. Nevertheless, it can be argued that the number of electron-donating substituents (-OH and -OCH3) and their configuration has a significant impact on the antioxidant capacity. Undoubtedly, concerns about the reliability of these assays demand further in-depth investigations to give detailed insight into the structure and antioxidant activity relationships.

Development and characterization of active packaging films based on chitosan, plasticizer, and quercetin for repassed oil storage

Novel chitosan (Ch) films containing choline chloride and citric acid mixture as plasticizer (deep eutectic solvent, DES) and different amounts of quercetin (QUE) as antioxidant additive were prepared. Physicochemical and mechanical characteristics of the developed Ch/DES/QUE films were studied using FTIR, SEM, and AFM techniques. FTIR spectra revealed the possible interactions between all the components. The surface of the films was dense and rough. The addition of quercetin caused an increase in the tensile strength (TS) and Young's modulus, but significantly decreased the elongation at break. The films containing quercetin showed improved antioxidant activity in relation to Ch/DES film. Finally, the oxidation phenomena of rapeseed oils with and without chitosan films were evaluated as amounts of primary and secondary oxidation products and total oxidation index. The addition of Ch/DES films with quercetin to oil samples successfully retarded secondary lipid oxidation processes and improved its antioxidant activity under the accelerated storage condition.

Assessment of the Antioxidant Activity of Catechin in Nutraceuticals: Comparison between a Newly Developed Electrochemical Method and Spectrophotometric Methods.

The analysis of antioxidants in different foodstuffs has become an active area of research, which has led to many recently developed antioxidant assays. Many antioxidants exhibit inherent electroactivity, and, therefore, the use of electrochemical methods could be a viable approach for evaluating the overall antioxidant activity of a matrix of nutraceuticals without the need for adding reactive species. Green tea is believed to be a healthy beverage due to a number of therapeutic benefits. Catechin, one of its constituents, is an important antioxidant and possesses free radical scavenging abilities. The present paper describes the electrochemical properties of three screen-printed electrodes (SPEs), the first one based on carbon nanotubes (CNTs), the second one based on gold nanoparticles (GNPs) and the third one based on carbon nanotubes and gold nanoparticles (CNTs-GNPs). All three electrodes were modified with the laccase (Lac) enzyme, using glutaraldehyde as a cross-linking agent between the amino groups on the laccase and aldehyde groups of the reticulation agent. As this enzyme is a thermostable catalyst, the performance of the biosensors has been greatly improved. Electro-oxidative properties of catechin were investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV), and these demonstrated that the association of CNTs with GNPs significantly improved the sensitivity and selectivity of the biosensor. The corresponding limit of detection (LOD) was estimated to be 5.6 × 10−8 M catechin at the CNT-Lac/SPE, 1.3 × 10−7 M at the GNP-Lac/SPE and 4.9 × 10−8 M at the CNT-GNP-Lac/SPE. The biosensors were subjected to nutraceutical formulations containing green tea in order to study their catechin content, using CNT-GNP-Lac/SPE, through DPV. Using a paired t-test, the catechin content estimated was in agreement with the manufacturer’s specification. In addition, the relationship between the CNT-GNP-Lac/SPE response at a specific potential and the antioxidant activity of nutraceuticals, as determined by conventional spectrophotometric methods (DPPH, galvinoxyl and ABTS), is discussed in the context of developing a fast biosensor for the relative antioxidant activity quantification.

Reactive Oxygen Species and Oxidative Stress in Vascular-Related Diseases

Oxidative stress (OS) refers to the enhancement of oxidation and the decreased of related antioxidant enzymes activity under pathological conditions, resulting in relatively excess reactive oxygen species (ROS), causing cytotoxicity, which leads to tissue damage and is linked to neurodegenerative diseases, cardiovascular diseases, diabetes, cancers, and many other pathologies. As an important intracellular signaling molecule, ROS can regulate numerous physiological actions, such as vascular reactivity and neuronal function. According to several studies, the uncontrolled production of ROS is related to vascular injury. The growing evidence revealing how traditional risk factors translate into ROS and lead to vasculitis and other vascular diseases. In this review, we sought to mainly discuss the role of ROS and antioxidant mechanisms in vascular-related diseases, especially cardiovascular and common macrovascular diseases.

Biological Activity of Extracts of Red and Yellow Fruits of Cornus mas L.-An In Vitro Evaluation of Antioxidant Activity, Inhibitory Activity against α-Glucosidase, Acetylcholinesterase, and Binding Capacity to Human Serum Albumin.

Although extracts are broadly used in order to support the treatment of numerous diseases, only in a limited number of cases is the process of applying and establishing their mechanisms of action scientifically analyzed. Fruits of Cornelian cherry are an abundant source of iridoids, anthocyanins, flavonols and phenolic acids. The aim of the present study was to evaluate the in vitro bioactivity of red and yellow Cornelian cherry fruits’ extracts. The biological potential of extracts, in a broad sense, involved antioxidant activity in relation to phosphatidylcholine liposomes, inhibitory ability against α-glucosidase and acetylcholinesterase enzymes, as well as interactions with human serum albumin. Studies showed that both extracts were more effective in protecting liposome membranes against free radicals produced by AAPH in an aqueous environment due to the fact that they can be better eliminated by the hydrophilic components of the extracts than those produced by UVB radiation. Extracts exhibited inhibitory activity against acetylcholinesterase and α-glucosidase, wherein loganic acid extract showed noncompetitive inhibition of the enzyme. Moreover, extracts binded to albumin mainly through hydrogen bonds and van der Waals forces. Taken together, red and yellow cherry fruits’ extracts exhibit diverse biological properties and can be exploited as a source of natural therapeutic agents.

Effect of exogenous abscisic acid on growth, biochemical changes and antioxidant enzyme activities in black gram [Vigna mungo (L.) Hepper] under drought

Drought stress is a significant limitation to the production and yield of black gram [Vigna mungo (L.) Hepper] and abscisic acid plays a subtle role in the biosynthetic pathway during drought stress. The present study examined the morphology, biochemical, relative water content and antioxidant activities of black gram plants treated with various abscisic acid (ABA) levels under drought conditions. The ABA at 50 ppm concentration showed promising recovery of morphological characters compared to other concentrations. The photosynthetic pigments, biochemical constituents, malondialdehyde and antioxidant enzymes (CAT, POD, SOD and APX) were active at 50 ppm. Infrared Spectroscopic (IR) analysis of black gram leaves in a bandwidth ranging from 400 to 4000 cm-1 revealed a change in metabolites under drought stress and exogenous ABA application. The FTIR spectroscopy results warrant that the expression of functional organic compounds in the drought response of black gram can aid in the discovery of new drought-tolerant traits. As a result, ABA-responsive cultivars can cultivate and produce drought-resistant black gram varieties in arid and semi-arid climates.

Phytochemistry, Biological Activity and Toxicity of Botanical Dietary Supplement: KL21

The use of nutritional supplements has grown conspicuously over the last decades. The present study aimed to design, develop, and optimize the toxicological and biological procedures to perform the quantitative determination of botanical dietary supplement KL21. The concentrations of phenolics in KL21 were 11.90 and 258.58 mg for ethanol, 3.58 and 86.42 mg for methanol extract, respectively. Carvacrol is a major component of the extracts according to GC-MS analysis. DPPH activity of methanol extract was higher than that of the ethanol extract. Both extracts showed similar relative antioxidant activity according to ABTS+ assay. Only methanol extract exhibited antimicrobial activity. KL21 ethanol extract exhibited inhibitory activity with 50 % growth inhibitory concentration of 92.09, 95.47 and 44 μg/mL on MCF-7, HeLa and HEK-293 cells respectively. KL21 demonstrated no mutagenic activity with the Salmonella strains. The in vivo toxicity test results indicated that KL21 had no significant adverse effects. Dose-depended KL21 treatment seemed nontoxic due to biochemical, hematological values. No histological damage in the liver was observed in the tissues. These results suggested that KL21 polyherbal formulation is a naturel source of antioxidant with antimicrobial activities and has therapeutic potential in a safe range.

Structure–antioxidant activity (oxygen radical absorbance capacity) relationships of phenolic compounds

Antioxidant capacity is the extent to which a compound can eliminate reactive oxygen species, and in vitro methods for its chemical evaluation have been proposed. Among these methods, the oxygen radical absorbance capacity (ORAC) assay comes close to the oxidation reaction in the living body because it generates radical species that mimic the lipid peroxyl radical involved in the peroxidation reaction of biological components and react in a phosphate buffer. In this study, PM7, a semi-empirical molecular orbital method, was used to calculate the thermodynamic properties (bond dissociation enthalpy, ionisation potential and proton affinity) associated with ORAC. We also applied the clusterwise linear regression analysis as a statistical method for grouping the antioxidants by structure. By analysing the data for antioxidants, the trend in the hydrophilic ORAC values was determined using the calculated structures and bond dissociation enthalpies of the groups classified according to the presence or absence of oxygen functional groups in the ortho position of phenol. Further studies of indicators other than bond dissociation enthalpy are needed to predict the ORAC of other antioxidants such as flavonoids and indoles.

Structure-antioxidant activity relationships of dendrocandin analogues determined using density functional theory.

Quantum-chemical calculations based on the density functional theory (DFT) at the B3LYP/6–311 + + G(2d,2p)//B3LYP/6–31G(d,p) level were employed to study the relationship between the antioxidant properties and chemical structures of six dendrocandin (DDCD) analogues in the gas phase and two solvents (methanol and water). The hydrogen atom transfer (HAT), electron-transfer-proton-transfer (ET-PT), and sequential proton-loss-electron-transfer (SPLET) mechanisms are explored. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), reactivity indices (η, μ, ω, ω+, and ω–), and molecular electrostatic potentials (MEPs) were also evaluated. The results suggest that the D ring plays an important role in mediating the antioxidant activity of DDCDs. For all the studied compounds, indicating that HAT was identified as the most favorable mechanism, whereas the SPLET mechanism was the most thermodynamically favorable pathway in polar solvents. The results of our study should aid in the development of new or modified antioxidant compounds.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11224-022-01895-2.

High polarity extracts obtained from Ilex guayusa Loes. leaves, exhibit antioxidant capacity

Background: Ilex guayusa Loes. belongs to the family Aquifoliaceae. It is an evergreen tree native to the Amazon region. According to traditional uses, it is used as a diaphoretic, narcotic, purgative, among other uses. Objective: To evaluate the antioxidant capacity, quantify phenols and total flavonoids of extracts obtained from Ilex guayusa leaves. Methods: Total ethanolic extract was obtained using Soxhlet-type equipment, with subsequent liquid/liquid fractionation with solvents of different polarities (petroleum ether, dichloromethane, and ethyl acetate); were reacted with 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS•+), determining the inhibitory concentration 50 (IC50) and relative antioxidant activity (%AAR), with subsequent statistical analysis (ANOVA and Tukey's post-hoc). Total phenols and flavonoids were quantified using the Folin-Ciocalteu method and complex formation with AlCl3, respectively. Results: The ethanolic extract of leaves showed the highest antioxidant activity in both the DPPH• and ABTS•+ methods with IC50 values of 4.58 and 3.82 ppm, respectively. Conclusions: According to the results obtained in this study, it was possible to corroborate that the ethanolic extract (EE) obtained from the leaves of I. guayusa showed the highest antioxidant capacity, by the DPPH• and ABTS•+ methods. Additionally, it was possible to relate this capacity to the high flavonoids content present in this extract. Based on the above and accompanied by future studies, the Ilex guayusa species could be proposed as an important source of antioxidant compounds with possible application in medicine and the food industry.

The Efficacies of 1-Methylcyclopropene and Chitosan Nanoparticles in Preserving the Postharvest Quality of Damask Rose and Their Underlying Biochemical and Physiological Mechanisms.

Simple SummaryDamask rose is one of the most important aromatic plants that is being used in the perfume, cosmetic and pharmaceutical industries. However, the short blooming period leads to a reduced oil quantity and quality; therefore, preserving the flower shelf life is a crucial step in maintaining the economic viability of this crop. This research aimed to study the effect of 400 mg m−3 of 1-methylcyclopropene (1-MCP) and either the pre- or postharvest application of 1% chitosan nanoparticles (CSNPs) on maintaining the quality of damask rose flowers during storage at 4 or 20 °C. The results showed that both treatments were shown to help preserve the quality and extend the shelf life of damask rose. CSNPs were more effective than 1-MCP. Collectively, 1-MCP or CSNPs as eco-friendly applications are recommended as novel and promising approaches for the commercial industry for retaining the quality of damask rose during storage.Preserving the flower shelf life of damask rose is a crucial matter in promoting its economic viability. Chitosan nanoparticles (CSNPs) and 1-methylcyclopropene (1-MCP) may potentially decrease the postharvest loss of several horticultural commodities, but no findings on damask rose have been published. Therefore, the aim of this research was to study the effect of 1-MCP (400 mg m−3) and either the pre- or postharvest application of CSNPs (1%) on maintaining the quality of damask rose flowers during storage at 4 or 20 °C. The shelf life of damask rose has been significantly extended, along with a reduction in weight loss due to 1-MCP, CSNPs and pre-CSNP treatments. 1-MCP or CSNP applications have resulted in a higher relative water content, volatile oil, total anthocyanins, total carotenoids, total phenolics and antioxidant activity. Ethylene evolution, H2O2 generation and malondialdehyde content were significantly decreased due to 1-MCP or CSNPs treatment, and hence, the cell membrane functions have been maintained. The 1-MCP or CSNP-treated flowers have shown higher activities of catalase and ascorbate peroxidase and lower activities of polyphenol oxidase and lipoxygenase in comparison to untreated flowers. Our results showed that the postharvest application of 1-MCP or CSNPs is a very promising method to maintain the postharvest quality of damask rose during storage.

Evaluation of a diverse collection of red clover for forage quality and antioxidant activity

Description of the subject. Red clover is an important forage legume and a rich source of high quality forage for livestock feed. This study assesses a diverse red clover collection for agronomic value, forage quality and antioxidant activity in relation to status (cultivar vs natural population) and ploidy level (diploid or tetraploid) for the purpose of diversity study and for identification of potential heterotic groups and classification of accessions according to the results of analyses. Objectives. The aims of this research were to: i) explore agronomic traits, forage quality, and antioxidant activity in relation to status and ploidy level; ii) assess trait associations and the possibility of indirect selection; iii) cluster red clover accessions with regard to forage quality and antioxidant activity. Method. Red clover was represented by 46 accessions, the cultivars and natural populations of diploid (2n) and tetraploid (4n) ploidy levels from 17 countries, which were collected and preserved in the Institute of Field and Vegetable Crops in Novi Sad, Serbia. The following traits were determined from the two-year field trial at Rimski Šančevi, Serbia: plant height (PH), internodes number (IN), green mass yield (GMY), dry matter yield (DMY), crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), digestible dry matter (DDM), dry matter intake (DMI), relative feed value (RFV) and antioxidant activity. All accessions were characterized in the second cut of the second year of life when 20-25% of flowers appeared. Results. The cultivars had higher values for PH, IN, GMY, DMY, DDM, DMI, and RFV. The tetraploid accessions had higher values for IN, GMY, DMY, CP, NDF and DDM. The natural populations and diploid accessions had 39.9% and 21.9% smaller antioxidant capacity, respectively. The antioxidant capacity was positively associated with RFV, DDM, DMI, PH, IN, GMY and DMY, but negatively with ADF and NDF. Conclusions. The grouping of red clover accessions based on forage quality parameters and antioxidant activity was represented by five clusters. High-quality cultivars had a shorter length of internodes and a good leaf to stem ratio with a high leaf proportion.

Quality grade evaluation and related antioxidant activity research of different medicinal parts of Catalpa fruit.

Catalpa fruit is a traditional Chinese medicine used in the treatment of diuresis and detumescence; however one-sided quantitative or qualitative investigation limits its overall quality evaluation. Hence, this study proposed to qualitatively and quantitatively evaluate the quality consistency of Catalpa fruit from the perspectives of chromatography and spectroscopy. First, the fusion fingerprints of 15 batches of Catalpa fruit pericarp and 15 batches of Catalpa fruit seed were established by high performance liquid chromatography (HPLC) and ultraviolet (UV) spectroscopy in equal weights, respectively, to avoid the unilaterality of a single analytical technique. The different medicinal parts of Catalpa fruit were graded and evaluated based on a systematically quantified fingerprint method, and the quality of the pericarp and seed was further investigated. The results revealed that the quality of most pericarp and seed samples was within the acceptable level range (grade ≤ 5), and that seed quality was clearly superior to pericarp quality. Furthermore, according to the research findings, the content of p-hydroxybenzoic acid in Catalpa fruit pericarp was generally higher than that in Catalpa fruit seed, while the content of catalposide was generally lower than that in Catalpa fruit seed. Additionally, the fingerprint-efficacy relationship with HPLC was discussed by binary correlation analysis, which indicated that catalposide had the strongest antioxidant activity. This study demonstrated that the analytical techniques based on chromatographic fingerprinting, spectral fingerprinting and antioxidant activity provided new theoretical foundation as well as technical guidance for Catalpa fruit quality control and rational utilization.

Agroeconomic Production and Antioxidant Activity of the Hibiscus Cultivated Under Organic Practices and Plant Arrangements

In order to obtain better productivity and a good level of secondary metabolites for cultivating plants with organic residues, it is necessary to define the method of application and the best combination considering plant density. Our objective was to study the influence of the plant arrangement and methods of application of poultry manure in the soil over agroeconomic performance and the antioxidant activity of the hibiscus. Treatments in the field consisted of two plant arrangements (single or double rows, both with 0.50 meters between plants) and four methods of application of poultry manure to the soil [incorporating (10 t ha-1), mulching (10 t ha-1), mulching (5 t ha-1) + incorporating (5 t ha-1) and a control—no poultry manure] and, in the laboratory, antioxidant activity in relation to the treatments in the field and preparation methods (maceration or infusion). Treatments were arranged in randomized blocks of 2 × 4 with four replicates. The greatest production of dried calyx (0.68 t ha-1) and of capsules (1.32 t ha-1), the greatest number of fruits (2.10 million ha-1) and the greatest net income (R$ 36,115.42) resulted of plants cultivated in single rows with the poultry manure covering the crops. The antioxidant activity of the hibiscus calyces showed no variation in relation with field treatments or with the method of preparation. Cultivation in single rows covered with poultry manure is adequate for the hibiscus plant.

Chemical Profile of Ruta graveolens, Evaluation of the Antioxidant and Antibacterial Potential of Its Essential Oil, and Molecular Docking Simulations

The research aimed to investigate the chemical composition and antioxidant and antibacterial potential of the essential oil (EO) isolated from the aerial parts (flowers, leaves, and stems) of Ruta graveolens L., growing in western Romania. Ruta graveolens L. essential oil (RGEO) was isolated by steam distillation (0.29% v/w), and the content was assessed by gas chromatography-mass spectrometry (GC-MS). Findings revealed that 2-Undecanone (76.19%) and 2-Nonanone (7.83%) followed by 2-Undecanol (1.85%) and 2-Tridecanone (1.42%) are the main detected compounds of the oil. The RGEO exerted broad-spectrum antibacterial and antifungal effects, S. pyogenes, S. aureus, and S. mutans being the most susceptible tested strains. The antioxidant activity of RGEO was assessed by peroxide and thiobarbituric acid value, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), and β-carotene/linoleic acid bleaching testing. The results indicated moderate radical scavenging and relative antioxidative activity in DPPH and β-carotene bleaching tests. However, between the 8th and 16th days of the incubation period, the inhibition of primary oxidation compounds induced by the RGEO was significantly stronger (p < 0.001) than butylated hydroxyanisole (BHA). Molecular docking analysis highlighted that a potential antimicrobial mechanism of the RGEO could be exerted through the inhibition of D-Alanine-d-alanine ligase (DDl) by several RGEO components. Docking analysis also revealed that a high number RGEO components could exert a potential in vitro protein-targeted antioxidant effect through xanthine oxidase and lipoxygenase inhibition. Consequently, RGEO could be a new natural source of antiseptics and antioxidants, representing an option for the use of synthetic additives in the food and pharmaceutical industry.

Peptides derived from the gastrointestinal digestion of amaranth 11S globulin: Structure and antioxidant functionality

The relationship between structural and physicochemical properties and antioxidant activity of peptides from amaranth 11S-globulin was studied. Peptides AWEEREQGSR, TEVWDSNEQ, IYIEQGNGITGM and YLAGKPQQEH had the greatest in vitro activity (ORAC, HORAC). GDRFQDQHQ, HVIKPPSRA and KFNRPETT were the most active ones against Cu+2/H2O2-induced-LDL oxidation. In a cellular system (H2O2-induced-Caco2-TC7), TEVWDSNEQ, IYIEQGNGITGM, GDRFQDQHQ, LAGKPQQEHSGEHQ and KFNRPETT were the most effective in decreasing ROS, while the effects on SOD, GPx, and GSH were variable. To understand the structure–antioxidant activity relationships, the content of aromatic and acidic amino acids, the degree of hydrophobicity and the charge distribution on the accessible surface of peptides structures obtained by molecular dynamics were analysed. The low correlation between in vitro, ex vivo and cellular activities could be explained by the influence of physicochemical and structural properties on the interaction with complex systems (LDL/cells), peptide modifications and/or mechanisms other than direct ROS inhibition in the cells.

Synthesis and Evaluation of Antioxidant Properties of 2-Substituted Quinazolin-4(3H)-ones.

Quinazolinones represent an important scaffold in medicinal chemistry with diverse biological activities. Here, two series of 2-substituted quinazolin-4(3H)-ones were synthesized and evaluated for their antioxidant properties using three different methods, namely DPPH, ABTS and TEACCUPRAC, to obtain key information about the structure–antioxidant activity relationships of a diverse set of substituents at position 2 of the main quinazolinone scaffold. Regarding the antioxidant activity, ABTS and TEACCUPRAC assays were more sensitive and gave more reliable results than the DPPH assay. To obtain antioxidant activity of 2-phenylquinazolin-4(3H)-one, the presence of at least one hydroxyl group in addition to the methoxy substituent or the second hydroxyl on the phenyl ring in the ortho or para positions is required. An additional ethylene linker between quinazolinone ring and phenolic substituent, present in the second series (compounds 25a and 25b), leads to increased antioxidant activity. Furthermore, in addition to antioxidant activity, the derivatives with two hydroxyl groups in the ortho position on the phenyl ring exhibited metal-chelating properties. Our study represents a successful use of three different antioxidant activity evaluation methods to define 2-(2,3-dihydroxyphenyl)quinazolin-4(3H)-one 21e as a potent antioxidant with promising metal-chelating properties.

Synergistic effect on antioxidant activity of vitamin C provided with acidic vesiculation of hybrid fatty acids

• Conjugated linoleic acid and saturated fatty acids (SFA) vesiculated in acidic pH. • The SFA induced larger and thicker vesicles, in positive relation with their chain length. • SFA improved the encapsulation efficiency and sustain release of VC. • The encapsulated VC exhibited dramatically higher antioxidant activity and stability. Vitamin C has often been applied in capsule due to its sensitivity to oxygen, and it is only stable at acidic conditions; although most encapsulation of vitamin C has been carried out in neutral environment. Herein, hybrid fatty acid vesicles were constructed from conjugated linoleic acid (CLA) and saturated fatty acids (SFA) to encapsulate vitamin C in aid of sodium dodecyl sulfate under acidic conditions, with significantly improved encapsulation efficiency and sustain release of VC. The CLA-SFA and the encapsulated VC synergistically presented dramatic higher antioxidant activity in positive relation with chain length of the SFA. The possible mechanism that the SFA improved encapsulation was proposed. The SFA made larger and thicker vesicles, and the enhancement was in positive relation with chain length of the SFA, although SFA slightly broadened the vesiculation pH windows towards alkaline direction. Meanwhile, the prepared hybrid fatty acid vesicles presented good stability at room temperature.