Relative Antioxidant Capacity Index Research Articles

Chemical analysis and antioxidant properties of orange‐tree (Citrus sinensis L.) biomass extracts obtained via different extraction techniques

AbstractOrange orchards are typical Mediterranean crops and a major feature of the heritage of the Mediterranean basin, where they play an important environmental and economic role. Their high availability, low price, and potential industrial application make the development of new and valuable uses of the orange's biomass of high interest. This research was focused: (i) on recognition and mapping of orange cultivation in the Basilicata region; (ii) on the evaluation of the antioxidant capacity of extracts; (iii) on identification of extractives' traits. To achieve these objectives, the anti‐oxidative properties and chemical compounds of the extracts from orange orchard biomass were analyzed. Different extraction techniques were applied, including maceration, ultrasound‐assisted extraction, accelerated solvent extraction, and autoclaving. Results demonstrated the potential antioxidant activity of the bark and wood of orange‐tree biomass, which has not been investigated before. The relative antioxidant capacity index showed that bark extracts were more effective than wood ones, and accelerated solvent extraction was the most effective process for recovering antioxidants. Chemical characterization by liquid chromatography–mass spectrometry (LC–MS) showed the presence of different natural compounds, including caffeic acid, alkaloids, and flavonoids. The development of innovative applications that use biomass derivatives could lead to their possible use in the market as a commodity for the chemical or cosmetic industries, giving new added value to the current use of biomass from agricultural practices. Through multi‐criteria analysis it was possible to recognize the sustainability of these cropping models and their ecological function, using them for the preservation of environmental resources, environmental quality, and quality of life. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd

Phytochemicals of Minthostachys diffusa Epling and Their Health-Promoting Bioactivities.

The genus Minthostachys belonging to the Lamiaceae family, and is an important South American mint genus used commonly in folk medicine as an aroma in cooking. The phytochemical-rich samples of the aerial parts of Minthostachys diffusa Epling. were tested for pharmacological and health-promoting bioactivities using in vitro chemical and enzymatic assays. A range of radical scavenging activities of the samples against biological radicals such as nitric oxide and superoxide anion and against synthetic 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals, the ferric reducing antioxidant power and the lipid peroxidation inhibition were determined and ranked using the ‘relative antioxidant capacity index’ (RACI). The ethyl acetate fraction showed the highest RACI of +1.12. Analysis of the various fractions’ inhibitory ability against enzymes involved in diabetes (α-amylase and α-glucosidase), and against enzymes associated with Parkinson’s or Alzheimer’s diseases (acetylcholinesterase and butyrylcholinesterase) also suggested that the ethyl acetate fraction was the most active. Liquid chromatography–tandem mass spectrometry analysis of the ethyl acetate fraction showed more than 30 polyphenolic compounds, including triterpenes. The inhibitory cholinesterase effects of the triterpenes identified from M. diffusa were further analysed by in silico docking of these compounds into 3D-structures of acetylcholinesterase and butyrylcholinesterase. This is the first study on pharmacological activities and phytochemical profiling of the aerial parts of M. diffusa, showing that this plant, normally used as food in South America, is also rich in health-promoting phytochemicals.

Evaluation of the impact of chlorophyll removal techniques on polyphenols in rosemary and thyme by-products.

The impact of dechlorophyllization (n-hexane: water partitioning, activated charcoal bleaching, and ChloroFiltr® decolorization) on major polyphenols of two herbal by-products (rosemary and thyme) was assessed. The aim was to produce decolorized extracts for food preservation and improve the quantification of their main phenolics. Activated charcoal bleaching and ChloroFiltr® decolorization effectively removed the chlorophyll a and b, whereas traces were detected after n-hexane: water partitioning. Dechlorophyllized thyme extracts prepared using activated charcoal and ChloroFiltr® had the lowest relative antioxidant capacity index (RACI) values based on 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant assays. Conversely, rosemary extracts had positive RACI values following treatment with activated charcoal, whereas n-hexane led to a significant antioxidant loss. Chromatography-mass spectrometry analyses indicated that phenolic diterpenes (carnosol and carnosic acid), as well as rosmarinic acid were in general not significantly decreased (p˃.05) after activated charcoal treatment, while n-hexane maintained the flavonoids and phenolic acids with nonsignificant losses. PRACTICAL APPLICATIONS: Commercial exploitation of polyphenol-rich plant based extracts as natural antioxidant agents is impeded by their high chlorophyll content, which when incorporated in food products can result in products that do not meet the consumer expectations for appearance. This study has shown that the activated charcoal bleaching has potentials to remove chlorophyll and retain antioxidant polyphenols in particular diterpenes in fresh herb by-products. Moreover, the commonly used n-hexane was less effective in removing chlorophyll but retained the major flavonoids and phenolic acids. Thus, the choice of chlorophyll removal methods depend on retaining the class of antioxidant polyphenols abundant in the plant matrix.

Serbian aromatized wine “Bermet”: Electrochemical, chemiluminescent and spectrophotometric determination of antioxidant activity

Serbian aromatized wine ?Bermet? from grapes grown on Fruska Gora Mountain has been in production since the 15th century. Ten commercial Bermets produced according to the traditional procedure by different manufacturers, and six prepared within the scope of this study were assessed for antioxidant (AO) activity using electrochemical, chemiluminescent and spectrophotometric AO assays. Direct current polarographic assay based on the decrease of anodic current of [hydrogen(peroxido)(1-)]hydroxidomercury(II) complex formation in alkaline H2O2 solution at potential of mercury oxidation, chemiluminescent H2O2 scavenging assay, as well as commonly used spectrophotometric assays (2,2?-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) based Trolox equivalent antioxidant capacity (TEAC), 2,2-diphenyl-1- picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP)) were used. Total phenolic content (TPC) was determined by Folin?Ciocalteu assay. The results obtained were correlated using regression analysis, ANOVA and F-test. An integrated approach to AO capacity determination allowed a more comprehensive comparison between samples. The approach is based on the introduction of the relative antioxidant capacity index, calculated by assigning each AO assay equal weight, and by PCA analysis. In addition, the introduction of phenolic antioxidant coefficients, calculated as the ratio between individual AO capacity and TPC, enabled a better understanding of their relation.

Antioxidant, Antidiabetic, and Anticholinesterase Activities and Phytochemical Profile of Azorella glabra Wedd.

Oxidative stress is involved in different diseases, such as diabetes and neurodegenerative diseases. The genus Azorella includes about 70 species of flowering plant species; most of them are commonly used as food and in particular as a tea infusion in the Andean region of South America in folk medicine to treat various chronic diseases. Azorella glabra Wedd. aerial parts were firstly analyzed for their in vitro antioxidant activity using different complementary assays. In particular, radical scavenging activity was tested against biological neutral radical DPPH; ferric reducing power and lipid peroxidation inhibitory capacity (FRAP and Beta-Carotene Bleaching tests) were also determined. The Relative Antioxidant Capacity Index (RACI) was used to compare data obtained by different assays. Then, the inhibitory ability of samples was investigated against α-amylase and α-glucosidase enzymes involved in diabetes and against acetylcholinesterase and butyrylcholinesterase enzymes considered as strategy for the treatment of Parkinson’s or Alzheimer’s diseases. Moreover, the phytochemical profile of the sample showing the highest RACI (1.35) and interesting enzymatic activities (IC50 of 163.54 ± 9.72 and 215.29 ± 17.10 μg/mL in α-glucosidase and acetylcholinesterase inhibition, respectively) was subjected to characterization and quantification of its phenolic composition using LC-MS/MS analysis. In fact, the ethyl acetate fraction derived from ethanol extract by liquid/liquid extraction showed 29 compounds, most of them are cinnamic acid derivatives, flavonoid derivatives, and a terpene. To the best of our knowledge, this is the first report about the evaluation of significant biological activities and phytochemical profile of A. glabra, an important source of health-promoting phytochemicals.

Phytochemistry and Antioxidant Activity of Aerial Parts of Phagnalon sordidum L.

One new natural monoterpene, 5-O-β-d-glucopyranosyl-2-hydroxy-p-cymene (1: ), and 11 known compounds were isolated through a biologically oriented approach from the aerial parts of Phagnalon sordidum L. The most active extract and fractions were selected using 3 complementary antioxidant activity assays. Results and the different methods were compared by relative antioxidant capacity index. In addition, the most active extract of P. sordidum was subjected to liquid chromatography coupled with electrospray ionization hybrid linear ion trap quadrupole Orbitrap mass spectrometry to quantify secondary metabolites. Antioxidant activities of ethyl acetate extract, and purified 3,4-dihydroxyacetophenone (3: ) and nebrodenside A (7: ) were demonstrated by in vitro cell free model assays, and their protective effect against H2O2-induced oxidative stress in a HepG2 (human hepatocellular carcinoma) cell line was established.

Comparison between Organic and Conventional Spelt and Wheatgrass juice

This work is aimed to compare antioxidant and scavenger properties of conventionally and organically produced speltgrass. Moreover, the antioxidant status of spelt was compared with wheatgrass. Three spelt varieties were analyzed:Nirvana, Ebners–Rotkorn variety and Eco-10. Antioxidant enzymes, superoxide-dismutase and guiacol-peroxidase, were determined as well as ferric reducing antioxidant power and DPPH-antiradical power. Total soluble proteins and total phenols were determined and also lipid peroxidation as a parameter of oxidative stress. The organically produced spelt was exposed to the higher levels of oxidative stress than conventionally produced spelt, and also DPPH antiradical power was induced by conventional production, which is also demonstrated using the relative antioxidant capacity index. The best antioxidant properties, better than wheat, showed organically produced spelt genotype Ebners–Rotkorn which is determined by the highest phenol content, superoxide-dismutase activity, DPPH antiradical power and ferric reduced antioxidant power and consequently with the lowest lipid peroxidation intensity.

Influence of shading treatment on yield, morphological traits and phenolic profile of sweet basil (Ocimum basilicum L.)

We investigated the roles of different shading strategies on plant growth, antioxidant activity and phenolic profile of sweet basil (Ocimum basilicum L.), a widely used herb with culinary and medicinal properties. Sweet basil plants were cultivated in a commercial multi-span tunnel-greenhouse covered with an EVAC plastic film, shaded from solar radiation in five different ways: n. 1, by calcium hydroxide whitening; n. 2, installing up - or n. 3, under - the greenhouse roof, a PE-HD white reflective net with 36% shading factor; n. 4, installing up - or n. 5, under - the greenhouse roof, a PE-HD white reflective net with 58% shading factor. The remaining part of the greenhouse (n. 6 - control) was unshaded. In each trial, yield traits, antioxidant activity and contents of phenolics of sweet basil plants were assessed to evaluate the influence of the shading strategy on these parameters. The antioxidant capacity was evaluated by using three different in vitro assays: DPPH scavenging activity, reducing power (FRAP) and lipid peroxidation inhibition (BCB). To compare the data obtained by the different chemical methods, the relative antioxidant capacity index (RACI) was calculated. The yield was highest in unshaded plants. The control trial, in which the incoming solar radiation was filtered only by the film which covers the greenhouse, showed the highest RACI value (0.98), indicating that the antioxidant capacity was probably influenced by higher light and temperature conditions. Phenolic quantification, determined by HPLC-DAD, enabled to observe a correlation between the antioxidant power and the identified metabolites.

Thermo-treatment affects Quercus cerris L. wood properties and the antioxidant activity and chemical composition of its by-product extracts

Nowadays, there is an increasing interest on thermo-treatment and its effects on wood structure and extraction processes, connected to the wood use for industrial application and for its use as biorefinery. The present investigation aimed to provide the main changes on wood properties (mass loss, color variation and modulus of elasticity) and a comparative analysis of the antioxidant properties and GC–MS profile of the extracts from Turkey oak (Quercus cerris L.) wood. Untreated and thermo-treated wood (170 °C x 3 h) samples were compared. Thermo-treatment induced a mass loss (5.1%) in wood, a darkening of color surface (ΔE = 7.6) and a decrease of MOE (4.1%). Moreover samples were extracted using different techniques: maceration (ME), ultrasound assisted extraction (UAE) and accelerated solvent extraction (ASE). Extracts were tested to evaluate the content of polyphenols and flavonoids along with the in vitro antioxidant activity. Results showed that extracts obtained from thermo-treated wood reported the highest Relative Antioxidant Capacity Index and extraction techniques affected the value in the following rating: UAE > ME > ASE. Qualitative and quantitative measurements of chemical compounds were carried out by GC–MS system. Taking into account the thermo-treatment and extraction techniques, principal component analysis (PCA) was performed also in order to evaluate the relationships among principal chemical compounds. According to results obtained, thermo-treatment and extraction technique had a determinant role in the antioxidant efficiency and, consequently, on the potential application of extracts.

Evaluation of Phytochemical econtents and antioxidant activity of Korean common bean (<i>Phaseolus vulgaris</i> L) landraces

The Korean common bean (Phaseolus vulgaris L.) has been receiving increased attention as a functional food. The objective of this study was to reveal the phytochemicals genetic variation and antioxidant activity of 209 Korean common bean landraces. Antioxidant activity was evaluated with the DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate), ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), ferric reducing antioxidant power (FRAP), and superoxide dismutase (SOD) assay. Antioxidant activities among common bean accessions showed wide variation. Four flavonoids (kaempferol, myricetin, quercetin, and naringenin) of the 209 Korean common bean landraces were measured using HPLC. Among them, kaempferol had the highest phytochemicals compared to the other three flavonoids. Using the relative antioxidant capacity index (RACI), it was found out that the IT104587 had the highest antioxidant activity. Meanwhile, in clustering analysis, the Korean common bean landraces were classified into three clusters. Among them, cluster II contained 64 landraces with higher antioxidant activities and phytochemicals than the other clusters, except DPPH. The results could provide information on the valuable Korean common bean landraces for the development of new common bean varieties.

Potential Application of Prunus armeniaca L. and P. domestica L. Leaf Essential Oils as Antioxidant and of Cholinesterases Inhibitors.

The aim of this work is to investigate the in vitro acetylcholinesterase (AChE) and butyrycholinesterase (BChE) inhibitory activities of essential oils obtained by hydrodistillation from the leaves of Prunus armeniaca and P. domestica in relation to their composition, analysed by Gas Chromatography–Flame Ionization Detector (GC-FID) and Gas Chromatography-Mass Spectrometry (GC-MS) analyses, at different times. Moreover, considering the role of free radicals in the progression of neurodegenerative disorders, the antioxidant properties of essential oils were investigated by using, 2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and β-carotene bleaching tests. The relative antioxidant capacity index (RACI) was used to achieve more comprehensive comparison between analysed antioxidant effects of essential oils. P. armeniaca oils were more active than P. domestica oils against AChE. Against BChE, the most active was the essential oil from P. domestica leaves collected in August with an IC50 value of 95.80 μg/mL. This oil exerted the highest inhibitory activity of lipid peroxidation with IC50 values of 11.15 and 11.39 μg/mL after 30 and 60 min of incubation, respectively. All samples demonstrated a remarkable ABTS radicals scavenging activity, with IC50 values in the range 0.45–0.57 μg/mL in comparison to the positive control, ascorbic acid.

Comparative Chemical Composition and Bioactivity of Opuntia ficus‐indica Sanguigna and Surfarina Seed Oils Obtained by Traditional and Ultrasound‐Assisted Extraction Procedures

This study investigates the seed oils obtained from two different varieties of Opuntia ficus‐indica (Sanguigna and Surfarina) growing in Sicily, Italy. Soxhlet and ultrasound‐assisted extraction procedures are used to obtain the seed oils. The fatty acid profile, γ‐tocopherols, carotenoid content, and the bioactivity in terms of the antioxidant effects (using ABTS, DPPH, FRAP, and β‐carotene bleaching tests), and carbohydrate‐hydrolysing enzyme inhibitory activity (α‐amylase and α‐glucosidase) are determined. The extraction procedure does not significantly affect the fatty acid composition of the oil, but it does affect the tocopherol and carotenoid contents, as well as the antioxidant and inhibitory activities. All the oil samples are rich in polyunsaturated fatty acids, especially linoleic, and oleic acids. Soxhlet extraction proves to be the best extraction procedure to enrich the oils in γ‐tocopherol. Relative antioxidant capacity index (RACI) and global antioxidant score (GAS) analyses are applied to evaluate the antioxidant potential of the Sanguigna variety oil extracted with the Soxhlet apparatus that is shown to be the most active. The same oil also shows the highest α‐amylase inhibitory activity (IC50 value of 40.9 μg mL−1), which is better than that reported for acarbose used as a positive control.Practical Applications: This study is the first to evaluate the effect of oil extraction technologies on the bioactive compound levels and antioxidant and hypoglycaemic activities of cactus pear seed oil, which is a by‐product of fruit processing. The findings will contribute to the valorization of food by‐products. The results provide useful information to select the most valuable technological conditions for oil extraction to preserve the bioactive compounds and the biological activity of the vegetable by‐product extracts, such as seed oil. Cactus pear seed oil obtained by the traditional extraction procedure (Soxhlet) represents a promising source of healthy compounds, particularly of carotenoids and γ‐tocopherol, used not only as antioxidants to preserve lipid components in food preparation but also as functional ingredients due to their hypoglycaemic effect.Effect of extraction procedure on chemical composition, antioxidant potential, and hypoglycaemic activity of cactus pear seed oils.

Antioxidant Capacity of Nettle Leaves During Osmotic Treatment

Osmotic treatment (OT) of nettle leaves was assessed in various osmotic solutions (sugar beet molasses – SBM and ternary aqueous solution – TAS), at temperatures of 20, 35 and 50 °C, under the atmospheric pressure. The influence of the kind of utilized osmotic solution, process temperature and osmotic time on the antioxidant activity (AOC), expressed with the spectrophotometric assays (ABTS, FRAP and DPPH), as well as two direct current polarographic assays, Hydroxo Perhydroxo Mercury (II) complex assay, based on the decrease of anodic current and assay based on the decrease of a cathodic current of Hg (II) reduction. For determination of the total phenolic content Folin-Ciocalteu assay was used. The Relative Antioxidant Capacity Index (RACI), obtained by setting equal weight for every involved assay was applied in order to get an extensive comparison among analyzed samples and between the used assays. Based on these results, after the OT of nettle leaves in TAS, the AOC decreased, while the OT in SBM increased AOC values. The phenolic antioxidant coefficients (PAC), calculated as the ratio between particular AO capacity and TPC, were used to achieve a more comprehensive comparison between analysed samples, as well as applied assays. The results of RACI evaluation revealed that the most favorable osmotic treatment is the one performed for 5h at 35 °C.

Antioxidant Activity and Phytochemical Characterization of Senecio clivicolus Wedd.

Antioxidant phytochemicals play a key role in oxidative stress control and in the prevention of related disorders, such as premature aging, degenerative diseases, diabetes, and cancer. The aim of this study was to investigate the potential antioxidant activity and the phytochemical profile of Senecio clivicolus Wedd., a perennial shrub, belonging to the Asteraceae family. Despite the wide interest of this family, this specie has not been investigated yet. S. clivicolus aerial parts were extracted with 96% ethanol. Then, the ethanol extract was fractionated by liquid/liquid extraction using an increasing solvents polarity. Total polyphenol and terpenoid contents were measured. Moreover, the antioxidant activity was evaluated by six different complementary in vitro assays. The Relative Antioxidant Capacity Index (RACI) was used to compare data obtained by different tests. The sample showing the highest RACI was subjected to characterization and quantitation of its phenolic composition using LC-MS/MS analysis. The ethyl acetate fraction, investigated by LC-MS/MS analysis, showed 30 compounds, most of them are chlorogenic acid and flavonoid derivatives. To the best of our knowledge, this is the first report about the evaluation of antioxidant activity and phytochemical profile of S. clivicolus, underlying the importance of this species as a source of health-promoting phytochemicals.

Chemical and biological evaluation of essential oil from Saussurea costus (Falc.) Lipsch. from Garhwal Himalaya collected at different harvesting periods

The purpose of this study is the determination of chemical composition and antioxidant activity of essential oils (EOs) from Saussurea costus (Falc.) Lipsch. Roots have been collected on December of the first plant year (IY) and in April, August and December of the third plant year (I, 6B, D7). A GC analysis was carried out for achieving this purpose. Subsequently, total polyphenol content (TPC) and antioxidant activity measured by DPPH, FRAP and BCB assays were evaluated. Three different statistical methods: Relative Antioxidant Capacity Index (RACI), Pearson’s correlation coefficient (r) and PCA, were used to compare results obtained and underline EO relationships. From the results obtained, it was possible to observe how the collection period of the EO, in particular both the month and the year of collection, influences the metabolite profile.

Daphne striata Tratt. and D. mezereum L.: a study of anti-proliferative activity towards human cancer cells and antioxidant properties

In this study, we investigated for the first time the anti-proliferative and antioxidant properties of D. mezereum and D. striata. The aerial parts were extracted by maceration with n-hexane, dichloromethane, and methanol. MPLC, GC, and GC-MS were used for the phytochemical study. The anti-proliferative activity was tested against MCF-7, A549, LNCaP, ACHN, and C32 cancer human cells. The antioxidant activity was measured by employing β-carotene bleaching, ABTS, DPPH, and FRAP tests. The Relative Antioxidant Capacity Index (RACI) was applied from the perspective of statistics. D. mezereum dichloromethane extract showed a remarkable anti-proliferative with an IC50 of 6.08 μg/mL against LNCaP cells. Experimental data indicate that Daphne species have interesting anti-proliferative and antioxidant properties that deserve more investigations to develop novel antineoplastic drugs.

Chemical and Biological insights of Ouratea hexasperma (A. St.-Hil.) Baill.: a source of bioactive compounds with multifunctional properties

The study aimed to evaluate in vitro antioxidant, anticholinesterase and antidiabetic properties of Ouratea hexasperma (A. St.-Hil.) Baill. The inflorescence methanol extract and the ethyl acetate fraction of leaves and stems reported the highest Relative Antioxidant Capacity Index (RACI), whereas the dichloromethane fraction of leaves was the best inhibitor of α-amylase and α-glucosidase. Trans-3-O-methyl-resveratrol-2-C-β-glucoside, lithospermoside, 2,5-dimethoxy-p-benzoquinone, lup-20(30)-ene-3β,28-diol, 7-O-methylgenistein, apigenin and luteolin and amentoflavone were isolated from O. hexasperma. Resveratrol derivative was isolated for the first time in Ochnaceae family. Luteolin, followed by apigenin, reported the highest Relative Antioxidant Capacity Index and they were also the best inhibitors of α-glucosidase enzyme.

Comparative evaluation of petitgrain oils from six Citrus species alone and in combination as potential functional anti-radicals and antioxidant agents

Six Citrus petitgrain oils, namely C. × sinensis (L.) Osbeck., C. × limon (L.) Osbeck., C. × clementina Hort., C. × aurantium L., C. reticulata Blanco and C. × bergamia Risso & Poit. (P1-P6), were characterized by means of gas chromatography equipped with flame ionisation detector (GC-FID) and gas chromatography coupled to mass spectrometry (GC-MS) and evaluated for their food functional-related properties. Antioxidant and radical-scavenging properties were tested by means of 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, β-carotene bleaching test and Ferric Reducing Antioxidant Power (FRAP) assays. The synergistic interactions on antioxidant efficacy of petitgrain oils in combination were studied. The Relative Antioxidant Capacity Index (RACI) was applied from the perspective of statistics by integrating the antioxidant capacity data determined by all used methods. A high content of monoterpenes and a less representative content of sesquiterpenes characterized Citrus petitgrain oils. In the DPPH assay, C. × aurantium showed major effectiveness with an IC50 value of 27.2 μg/ml. Citrus petitgrains oils, a rich source of healthy phytochemicals, should be considered a by-product of interest.

Phytochemical distribution and antioxidant activities of Korean adzuki bean (Vigna angularis) landraces

Total polyphenol content (TPC), total phenolic acid content (TPA), and total flavonoid content (TFC) in 209 Korean adzuki bean landraces were determined by colorimetric methods. Antioxidant effects were evaluated with the DPPH, ABTS, ferric reducing antioxidant power (FRAP), reducing power (RP), and SOD assays. TPC, TPA, and TFC in the 209 Korean adzuki bean landraces ranged from 1.1 to 11.7 mg gallic acid equivalents/g, 0.37 to 5.03 mg caffeic acid equivalents/g, and 0.17 to 0.91 mg quercetin equivalents/g, respectively. Antioxidant activities as assessed by the DPPH, ABTS, FRAP, PR, and SOD assays showed wide variation, ranging from 12.2 to 86.3 (IC50), 0.85 to 5.25 mg ascorbic acid equivalents (ASC)/g, 0.41 to 5.44 mg ASC/g, 0.54 to 1.83 mg ASC/g, and 60.4 to 142.8 (IC50), respectively. Using the relative antioxidant capacity index (RACI), we found that the IT189394 had the highest antioxidant activity. In clustering analysis, 209 Korean adzuki bean landraces were classified into three clusters. Among them, cluster I contained 22 landraces with higher antioxidant activities, TPC, TFC, and TPA and smaller seed sizes than the other clusters. We anticipate that these results will provide useful information for the development of adzuki bean-based functional foods.

Antioxidant efficiency of polyphenols from coffee and coffee substitutes-electrochemical versus spectrophotometric approach.

Antioxidant (AO) capacity of instant, espresso, filter and Turkish/Greek coffee brews, coffee substitutes (roasted chicory root, barley, pea, chickpea, carob and dried fig) and individual compounds (phenolic acids, flavonoids, methylxanthines, N-methyl pyridinium and HMW melanoidins) was assessed using DC polarographic assay based on decrease of anodic current originating from hydroxo-perhydroxo mercury complex formed in alkaline solutions of H2O2 at potential of mercury dissolution, as well as three spectrophotometric assays (DPPH, ABTS and FRAP). A large difference between applied assays ability to recognize various types of individual AOs was noticed. Only according to DC polarographic assay significant AO activity was ascribed to methylxanthines and N-methyl pyridinum. The total content of phenolics (TPC) present in complex samples was determined by FC assay. The highest TPC was ascribed to instant coffees and coffee substitutes while the lowest to decaffeinated filter coffee. Complex samples were grouped based on principal components analysis, phenolics AO coefficient, calculated as the ratio between AO capacity and TPC, and relative AO capacity index (RACI), calculated by assigning equal weight to all applied assays including FC. The highest values of RACI were ascribed to instant coffee brews, followed by substitutes while the lowest to the decaffeinated espresso coffee.