•We discuss conceptual and technical limitations of ABTS+•, DPPH, and ORAC assays.•Steric accessibility to ABTS+• and DPPH radicals controls antioxidant reactions.•Kinetics is more relevant than ...stoichiometry for all antioxidant efficacy assays.•Kinetic patterns plus solvent/pH effects on rates distinguish HAT from SET mechanisms.•Redirection of assays to distinguish radical quenching mechanisms is recommended.
Assays developed to measure radical scavenging ability of natural compounds have been used as a basis for ranking and recommending best foods for consumption. However, assays often were adapted for screening assays with inadequate consideration of reaction chemistry, particularly kinetics. Recent research results raise serious questions about the chemistry, execution, and application of these assays. This paper critically evaluates conceptual and technical issues that limit use and compromise validity of three commonly-used assays – TEAC/ABTS•+, DPPH, and ORAC. Recommendations are made for discontinuing use of ABTS•+ and DPPH radicals for measuring radical quenching, redirecting them instead to distinguishing electron transfer reaction mechanisms. Conditions required for accurate results in ORAC are reviewed, and recommendations are made for redirecting this assay to distinguishing compounds that quench radicals by hydrogen atom transfer. The mechanistic information so gained can be then applied to understanding how natural antioxidants can be used most effectively in foods.
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•Ferulates-added oils exhibited a lesser increase in p-AnV, TPC, K232, and K268.•The contents of OxTGs, TGDs, and TGOs were reduced significantly by ferulates.•Alkyl ferulates were ...proven to inhibit the formation of glycerol core aldehydes.•Ferulates reduced the formation of n-alkanals, (E)-2-alkenals, and 4-oxo-alkanals.•The antioxidant effect of hexadecyl ferulate was the best among the four ferulates.
The hydrophilic nature of ferulic acid limits its applications under lipophilic conditions. This study set out to evaluate the antioxidant efficacy of alkyl ferulates with different chain lengths in soybean oil under frying conditions. Ferulic acid was esterified with four unbranched fatty alcohols (C4:0-C16:0), and tert-butylhydroquinone (TBHQ) served as a standard for comparison. The antioxidant effect of alkyl ferulates increased with the alkyl chain length. The addition of antioxidants could inhibit increases in the levels of p-anisidine, total polar compounds, conjugated dienes, conjugated trienes, oxidized triglyceride monomers, triglyceride dimers, triglyceride oligomers, and glycerol core aldehydes efficiently, and the inhibitory effects of hexadecyl ferulate was the strongest. Moreover, hexadecyl ferulate and TBHQ exhibited better inhibitory effects on the generation of n-alkanals, (E)-2-alkenals, and 4-oxo-alkanals determined by 1H nuclear magnetic resonance than others. Hence, the long-chain alkyl ferulates meet the industrial demands for ideal antioxidants with strong antioxidant capacity at high temperatures.
Free, esterified, and bound phenolic fractions of berries from five different cranberry genotypes and two market samples were evaluated for their total phenolic, flavonoid, and monomeric anthocyanin ...contents as well as their antioxidant efficacy using TEAC, ORAC, DPPH radical, reducing power, and ferrous ion chelation capacity assays. HPLC-MS/MS analysis was performed for two of the rich sources (Pilgrim and wild clone NL2) of phenolics and high antioxidant activity. Among the genotypes, Pilgrim showed the highest phenolic and flavonoid contents and wild clones NL3 and NL2 showed the highest monomeric anthocyanin and proanthocyanidin content, respectively. Protocatechuic and syringic acids were detected only in Pilgrim, whereas luteolin 7-O-glucoside, quercetin 3-O-rhamnoside, quercetin 3-O-galactoside, proanthocyanidin B-type, and myricetin 3-O-galactoside were found in wild clone NL3 genotype. Moreover, proanthocyanin trimer A-type and dimer B-type predominated in the wild clone NL2, whereas proanthocyanidin dimer B and trimer A were predominant in Pilgrim.
Nano-sized silver has drawn a great deal of attention in the field of health sciences owing to its remarkable therapeutic applications. Interestingly, the method applied to synthesize nanoparticles ...and the choice of reagents considerably influence their therapeutic potential and toxicities. Current research has explored the toxicity, anti-inflammatory, antinociceptive, and antioxidant responses of the malonic acid-capped silver nanoparticles (MA-AgNPs (C) by using sodium borohydride as a reducing agent at low temperatures by employing both
and
approaches. Furthermore, it has highlighted the synergistic effect of these novel compounds with conventional anti-inflammatory therapeutic agents. Acute and sub-acute toxicity analysis performed following OECD guidelines showed that the studied MA-AgNPs (C) are safer, and prominent toxic signs have not been detected at the highest studied dose of 2,000 mg/kg. Cytotoxicity evaluation through brine shrimp lethality revealed 20% lethality at the highest concentration of 169.8 μg/mL. Significantly, positive anti-inflammatory and analgesic responses alone as well as synergism with the standard were identified through
as well as
methods which were more potent at a lower dose (200 mg/kg). Notably synergistic outcomes were more pronounced than individual ones, indicating their prominent effect as a feasible drug delivery system. IL-6 and TNF-α assessment in excised paw tissue through RTPCR technique further supported their anti-inflammatory potential. DPPH assay revealed eminent
antioxidant activity which was further corroborated by
antioxidant assessment through evaluation of SOD in excised paw tissue.
Acylated derivatives of the dietary phenolic, resveratrol, were prepared via enzymatic and chemical transesterification modification with selected vinyl fatty acids to expand the potential ...application of resveratrol and its acylated derivatives in functional supplement, cosmetic/skincare, and pharmaceutical fields. The acylation was implemented using eight vinyl fatty acids with varying chain lengths (C2:0-C18:0). Eight monoesters enzymatically prepared, eight diesters and four triesters, chemically prepared, were isolated and purified and identified via MS (mass spectra) or/and NMR (nuclear magnetic resonance). The lipophilicity of resveratrol and its acylated derivatives was calculated using ALOGPS 2.1. Compared with related acylated products, resveratrol itself rendered higher antioxidant efficacy in all the antioxidant assays, namely DPPH, ABTS, FRAP, and ferrous chelation tests. Within various ester derivatives of resveratrol, short-chain fatty acid mono- and di-substituted resveratrols, especially the resveratrol monoacetate/diacetate, exhibited higher antioxidant efficacy in DPPH and ABTS assays than the rest of resveratrol derivatives, but the medium-chain monoesters of resveratrol, including caproate, caprylate, caprate, and laurate, showed a higher metal ion chelation ability compared to other acylated resveratrols. These results imply that resveratrol derivatives may be used in lipidic media as health-beneficial antioxidants.
Pharmacologically active stem of the oriental herbal adaptogen, Siberian ginseng, was employed for the ecofriendly synthesis of Siberian ginseng silver nanoparticles (Sg-AgNPs) and Siberian ginseng ...gold nanoparticles (Sg-AuNPs). First, for metabolic characterization of the sample, liquid chromatography-tandem mass spectrometry analysis (indicated the presence of eleutherosides A and E), total phenol content, and total reducing sugar were analyzed. Second, the water extract of the sample mediated the biological synthesis of both Sg-AgNPs and Sg-AuNPs that were crystalline face-centered cubical structures with a Z-average hydrodynamic diameter of 126 and 189 nm, respectively. Moreover, Fourier transform infrared analysis indicated that proteins and aromatic hydrocarbons play a key role in the formation and stabilization of Sg-AgNPs, whereas phenolic compounds accounted for the synthesis and stability of Sg-AuNPs. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide (MTT) assay determined that Sg-AgNPs conferred strong cytotoxicity against MCF7 (human breast cancer cell line) and was only slightly toxic to HaCaT (human keratinocyte cell line) at 10 µg⋅mL(-1). However, Sg-AuNPs did not display cytotoxic effects against both of the cell lines. The disc diffusion assay indicated a dose-dependent increase in the zone of inhibition of Staphylococcus aureus (ATCC 6538), Bacillus anthracis (NCTC 10340), Vibrio parahaemolyticus (ATCC 33844), and Escherichia coli (BL21) treated with Sg-AgNPs, whereas Sg-AuNPs did not show inhibitory activity. In addition, the 2,2-diphenyl-1-picrylhydrazyl assay demonstrated that both Sg-AgNPs and Sg-AuNPs possess strong antioxidant activity. To the best of our knowledge, this is the first report unraveling the potential of Eleutherococcus senticosus for silver and gold nanoparticle synthesis along with its biological applications, which in turn would promote widespread usage of the endemic Siberian ginseng.
This investigation reports an eco-friendly fabrication of cerium vanadate nanoparticles (CeVO
4
NPs) for the first time by an utterly green approach using
Azadirachta indica
leaves extract as a ...natural fuel. Textural properties of the as-prepared CeVO
4
NPs, such as structural, topological, and optical, were explored through X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), UV-visible diffuse reflectance spectra (DRS), field-emission scanning electron microscope (FESEM), energy dispersive X-ray analysis (EDX), high-resolution transmission electron microscopy (HRTEM), and zeta potential techniques. These results indicated that the as-synthesized NPs revealed a pseudo-spherical shape with a size of 43 nm. Moreover, as-prepared NPs were subjected to anticancer performance against HeLa cancer cell lines using MTT assays. In addition, the antioxidant efficacy of biosynthesized CeVO
4
NPs was scrutinized using DPPH and ABTS assays. Therefore, our study presents a facile, safe, cheap, rapid, and greener approach for producing CeVO
4
NPs and opening a new door for clinical applications.
Graphical Abstract
This investigation reports an eco-benevolent fabrication of cerium vanadate nanoparticles (CeVO
4
NPs) for the first time by an entirely green chemistry approach using
Azadirachta indica
leaves extract as a natural fuel. The physicochemical characteristics of the as-prepared CeVO
4
NPs, such as structural, topological, and optical, were explored through XRD, FTIR, UV-DRS, FESEM-EDX, HRTEM, and zeta potential techniques. Moreover, as-synthesized NPs were subjected to anticancer performance against HeLa cancer cell lines and antioxidant efficacy using DPPH and ABTS assays. Therefore, our study presents a facile, safe, affordable, swift and greener approach for producing CeVO
4
NPs and opening a new door for clinical applications.
Highlights
First-time synthesis of CeVO
4
nanoparticles using Azadirachta indica leaves extract through a green chemistry approach.
Textural properties of CeVO
4
nanoparticles were revealed through XRD, FTIR, UVDRS, FESEM, EDX-mapping, HRTEM-SAED, and zeta potential techniques.
The as-synthesized CeVO
4
nanoparticles evinced a pseudo-spherical shape with a size of 43 nm.
Greenly produced CeVO
4
nanoparticles exhibited excellent anticancer (HeLa cell line) and antioxidant (DPPH & ABTS assays) potentials.
Assays developed to measure radical scavenging ability of natural compounds have been used as a basis for ranking and recommending best foods for consumption. However, assays often were adapted for ...screening assays with inadequate consideration of reaction chemistry, particularly kinetics. Recent research results raise serious questions about the chemistry, execution, and application of these assays. This paper critically evaluates conceptual and technical issues that limit use and compromise validity of three commonly-used assays – TEAC/ABTS•+, DPPH, and ORAC. Recommendations are made for discontinuing use of ABTS•+ and DPPH radicals for measuring radical quenching, redirecting them instead to distinguishing electron transfer reaction mechanisms. Conditions required for accurate results in ORAC are reviewed, and recommendations are made for redirecting this assay to distinguishing compounds that quench radicals by hydrogen atom transfer. The mechanistic information so gained can be then applied to understand how natural antioxidants can be used most effectively in foods.
The oxidation of oils has an adverse effect on the organoleptic properties and shelf-life of stored oils. Flacourtia inermis is one of the underutilized fruits grown in Sri Lanka with promising ...antioxidant properties. F. inermis peel extract (FIPE) was used to retard rancidity in edible oils. The efficacy of added FIPE (500, 1000, 2000 ppm) on sunflower oil (SO) and virgin coconut oil (VCO) was monitored at 3-day intervals at 65 ± 5 °C against a positive control (α-tocopherol at 500 ppm level) using Free Fatty Acid (FFA) and Peroxide Value (PV). Oils without FIPE were used as the control. Antioxidant efficacy (IC50) and Total Phenol Content (TPC) of FIPE were determined by DPPH assay and the Folin-Ciocalteu method. Fourier transform infrared spectroscopy was used to monitor the oxidative stability. The IC50 value and TPC of FIPE were 227.14 ± 4.12 µg·mL-1 and 4.87 ± 0.01 mg GAE/g extract, respectively. After 21 days, VCO (control) sample exhibited significantly (p < 0.05) higher FFA and PV than the treatments. FIPE exhibited comparable results with α-tocopherol. Conclusively, FIPE had strong antioxidant properties and thus, could be used as an alternative to α-tocopherol to improve the oxidative stability of virgin coconut oil and sunflower oil. However, only minor differences in the FTIR spectra were detected in treated and untreated virgin coconut and sunflower oil samples after 21 days storage at 65 ± 5 °C.
Polygoni cuspidati root is a resveratrol-rich source with anti-inflammatory, angiogenic and neuroprotective effects. The raw material was standardized for the content of resveratrol, for which there ...is a special justification for administration within the oral mucosa. To improve the solubility of resveratrol and to assure its high content in plant material, an ultrasound-assisted extraction method was applied. The addition of cyclodextrin was found to increase the extraction efficiency of resveratrol (from 13 to 297 µg per 1 g of plant material in case of 50% ethanol extracts) and enhanced its antioxidant activity as compared to pure Polygoni cuspidati extract/resveratrol. Cyclodextrin plays the role of a functional extract regarding technological properties (increasing the extraction of resveratrol from the extract, improving mucoadhesive properties). Therefore, the aim of this study was to develop mucoadhesive tablets containing combinations of the Polygoni cuspidati extract with a cyclodextrin carrier for buccal delivery. The tests sequentially included extract preparation and characterization of its physical and biological properties and then formulation studies with a broad description of the prototype properties. The test results indicate that cyclodextrin increases the efficiency of resveratrol extraction from Polygoni cuspidati rhizome, which is a rich source of resveratrol, and its extract enclosed in a mucoadhesive tablet guarantees prolonged action at the site of administration.
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