Antioxidant activity of rye bran alkylresorcinols and extracts from whole-grain cereal products

The antioxidant properties of rye bran alkylresorcinols (C15:0–C25:0) and extracts from whole-grain cereal products were evaluated using their radical-scavenging activity on DPPH and the chemiluminescence method (CL). DPPH radical reduction varied from ∼10% to ∼60% for the alkylresorcinol homologues at concentrations from 5 to 300 μM and was not dependent on the length of the alkyl side chain of the particular homologue. Differences in the EC₅₀ values for the studied compounds were not statistically significant, the values varying from 157 μM for homologue C23:0 to 195 μM for homologue C15:0. Moreover, values of EC₅₀ for all the alkylresorcinol homologues were significantly higher than those for Trolox and α-, δ-, and γ-tocopherols, compounds with well-defined antioxidant activity and used as positive controls. CL inhibition was evaluated for all the tested alkylresorcinol homologues at concentrations of 5 and 10 μM and varied from ∼27% to ∼77%. Similar to the DPPH method, the slight differences in CL inhibition suggest that the length of the alkyl side chain had no major impact on their antioxidant properties. The extracts from whole-grain products were added to the DPPH and CL reaction systems and their antioxidant activities were tested and compared with the total amount of alkylresorcinols evaluated in the extracts. DPPH radical and CL reduction for the whole-grain products varied from ∼7% to ∼43% and from ∼37% to ∼91%, respectively. A clear relationship between DPPH radical and CL reduction levels and the amount of total alkylresorcinols was obtained for whole-grain breakfast cereals, in which the reduction level decreased in the order rye > wheat > mixed > barley. Therefore it may be considered that the antioxidant activity of alkylresorcinols could be of potential importance to the food industry, which is continuously searching for natural antioxidants for the protection of food products during their processing and storage.     

ORAC and TEAC assays comparison to measure the antioxidant capacity of food products

Oxygen radical antioxidant capacity (ORAC) and trolox equivalent antioxidant capacity (TEAC) assays were compared to estimate the total antioxidant capacity (TAC) of orange juice, milk, and an orange juice-milk beverage. When the TEAC method was used with this beverage, an increase in the concentration of orange juice corresponded to an increase in TAC, but increasing the percentage of milk did not increase the TAC value. When the ORAC method was applied, it was seen that increased concentrations of juice or milk corresponded to greater antioxidant capacity. An evaluation was also made of the influence of certain compounds (ascorbic acid, gallic acid, β-carotene, lutein, zeaxanthin and albumin) with antioxidant capacity that were present in the samples studied.     

Dual effect of milk on the antioxidant capacity of green,Darjeeling, and English breakfast teas

Past studies present contradictory results regarding the effect of milk on the antioxidant capacities of teas, possibly because of the different methods used. Here, we re-address the question by using three complementary assays, ABTS⁺ free radical scavenging, voltammetry, and lipid peroxidation inhibition, to estimate how milk affects the antioxidant capacities of green, Darjeeling, and English breakfast teas. We observed that milk decreased the antioxidant capacities of Darjeeling (−8.3%), green (−6.0%), and English breakfast (−19.6%) teas, estimated with the ABTS⁺ method. These inhibitions were four times larger using voltammetry. In contrast, milk enhanced the chain-breaking antioxidant capacity of teas in the lipid peroxidation method by 19%, 12%, and 10%, for green, English breakfast, and Darjeeling teas, respectively. Therefore, milk can have dual effects on the tea antioxidant capacity, an inhibitory effect for reactions occurring in solution or at a solid–liquid interface and an enhancing effect for those in oil-in-water emulsion. The mechanisms responsible for these different milk–tea interactions are discussed.     

Antioxidant and free radical scavenging potential of Achillea santolina extracts

The antioxidative activities of hydroalcoholic extract of Achillea santolina were investigated employing various established in vitro systems including total antioxidant activity in linoleic acid emulsion system, 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals scavenging, reducing power, and inhibitory effect on protein oxidation as well as the inhibition of Fe²⁺/ascorbate induced lipid peroxidation in rat liver homogenate. Total phenolic and flavonoid content of A. santolina extract (ASE) was also determined by a colorimetric method. The results revealed that ASE has notable inhibitory activity on peroxides formation in linoleic acid emulsion system along with concentration-dependent quenching of DPPH and superoxide radicals. Furthermore, the extract showed both nonsite-specific (Fe²⁺ + H₂O₂ + EDTA) and site-specific (Fe²⁺ + H₂O₂) hydroxyl radical scavenging suggesting potent hydroxyl radical scavenging and chelating ability for iron ions in deoxyribose degradation model. A linear correlation between ASE and the reducing power was also observed (r² = 0.9981). ASE prevents thiobarbituric acid reactive substances formation in Fe²⁺/ascorbate induced lipid peroxidation in rat liver tissue in a dose-dependent manner. Moreover, free radical induced protein oxidation was suppressed significantly by the addition of ASE over a range of concentration. These results clearly demonstrated that A. santolina extract possess a marked antioxidant activity.     

Antioxidant activity of various extracts and fractions of Chenopodium quinoa and Amaranthus spp. seeds

The antioxidant potency of various extracts and fractions from Chenopodium quinoa and Amaranthus sp. was evaluated using three established methods, specifically the DPPH scavenging activity, FRAP, and β-carotene bleaching assays. Satisfying results were obtained, which lead to expect the use of these seeds as health-promoting ingredients. The antioxidant activity was less correlated to the phenolics content suggesting that non-phenolic compounds might play major free radicals scavenging activity in studied plant materials.     

The antioxidant properties of the cherimoya (Annona cherimola) fruit

Annona cherimola is an exotic fruit from the genus Annona, native to the Andean highlands in western South America. The cherimoya skin, flesh and juice were isolated and analyzed for antioxidant content using the oxygen radical absorbance capacity (ORAC) assay. The juice showed the highest antioxidant activity, while the flesh exhibited the lowest. The cherimoya skin, flesh and juice extracts were also incubated with Raji (Burkitt's Lymphoma) and HT-29 (colon cancer) cell lines, and the antioxidant uptake of cells was measured. Both cell lines, when subjected to cherimoya juice, showed the highest antioxidant uptake. The cells were then exposed to AAPH, a radical initiator, to simulate the conditions of cells under oxidative stress, and then subjected to cherimoya skin, flesh and juice extracts. Both cell lines absorbed more antioxidants after being pre-exposed to AAPH, indicating that cells under stress have the ability to import antioxidants.     

Antioxidative properties of aqueous and aroma extracts of squid miso prepared with Aspergillus oryzae-inoculated koji

To evaluate the antioxidative properties of a newly developed fermented paste (squid miso) prepared from squid mantle flesh with Aspergillus oryzae-inoculated koji, we used in vitro models, including 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, nitric oxide (NO) and carbon-centered radical-scavenging activity (RSA), reducing power ability (RPA), and linoleic acid oxidation. The antioxidant activity of volatile compounds, which were extracted from squid miso by dichloromethane, was confirmed based on the results obtained by the oxidation models consisting of carotene linoleate and hexanal. The RSA of the miso against several radicals, including DPPH, hydroxyl, nitric oxide and carbon-centered radicals measured by ESR spectrometry increased gradually through the fermentation period. On the other hand, the RPA increased rapidly in early stages of fermentation. Proteins were hydrolyzed to peptides and amino acids during fermentation. Certain peptides of low molecular mass significantly contributed to RSA. 4-Ethylguaiacol in the RSA active fraction, which was obtained by column chromatography, was the most potent antioxidative in the volatile extract. Analysis of phenolics in ethyl acetate fraction clearly suggested that 4-ethylguaiacol in the squid miso is possibly a bioconversion product of ferulic acid derived from koji. However, the aqueous extracts containing antioxidative peptides contributed more remarkably to radical scavenging than heterocyclic volatiles and phenolics.     

Antioxidant stability of small fruits in postharvest storage at room and refrigerator temperatures

Strawberries (Fragaria ananassa), raspberries (Rubus idaeus) and red currants (Ribes rubrum), as well as two drupes, cherries (Prunus avium), and sour cherries (Prunus cerasus), were subjected to two storage temperatures (4 °C and 25 °C) and phytochemicals concentrations (total phenols, flavonoids and anthocyanins) as well as antioxidant capacity (DPPH, ABTS and FRAP assays) were monitored until the fruit visually spoiled. Red currants and strawberries exhibited the highest initial total phenol (TP) contents (322.40 ± 5.56 and 335.47 ± 6.12 mg GAE/100 g FW, respectively) and maintained the highest TP contents throughout storage at both temperatures. Storage of at 25 °C as opposed to 4 °C, facilitated faster spoilage of analyzed fruits. In addition, most fruits stored at 4 °C, exhibited slightly higher antioxidant activity values at the end of storage according to all three antioxidant activity assays as opposed to fruits stored at 25 °C. The dynamic evolution of antioxidant capacity at both temperatures reflected the transient changes in phytochemical composition of small fruits in storage.     

Antioxidant capacity and the relationship with polyphenol and Vitamin C in Actinidia fruits

Fruit of eight Actinidia genotypes were evaluated for antioxidant potential by several assays (DPPH, ABTS, ORAC, FRAP, SASR and MCC) and tested for their polyphenol composition and vitamin C contents. The significance analysis demonstrated that the antioxidant capacity of Actinidia eriantha and Actinidia latifolia fruits were significantly higher than that of other genotypes, which was about 3.3–8.7-fold higher than the Actinidia deliciosa cv. Hayward assayed in ABTS, DPPH, ORAC and FRAP methods. The total polyphenols and vitamin C contents showed a great variety amongst Actinidia genotypes and highly correlation with the total antioxidant capacity. It is concluded that significant genotypic difference exists in the total antioxidant capacity of Actinidia fruits. The wild A. eriantha and A. latifolia species have significantly higher antioxidant capacity than the cultivars of A. chinensis and A. deliciosa. Both total polyphenols and vitamin C are major contributors to the total antioxidant capacity in Actinidia fruit.     

Antioxidant and antimicrobial activity of Cynara cardunculus extracts

The whole, fresh involucral bracts of cardoon, Cynara cardunculus L. (Compositae), were extracted with EtOH and an aqueous suspension of the obtained EtOH extract was partitioned successively with CHCl₃, EtOAc and n-BuOH, leaving a residual water extract. All obtained extracts were evaluated for their antioxidant and antimicrobial properties. The antioxidant potential was evaluated using following in vitro methods: FRAP (ferric reducing antioxidant power) assay, and scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. Antimicrobial activity was estimated using a microdilution technique against food-borne, mycotoxin producers and human pathogenic bacteria and micromycetes. The following bacteria were tested: Salmonella typhimurium, Escherichia coli, Bacillus subtilis, Staphylococcus epidermidis, Staphylococcus aureus, as well as micromycetes: Aspergillus niger, Aspergillus ochraceus, Aspergillus flavus, Penicillium ochrochloron, Penicillium funiculosum, Trichoderma viride, Fusarium tricinctum and Alternaria alternata. Results showed that all extracts possessed concentration-dependent antioxidant activity. In biological assays, C. cardunculus extracts showed antimicrobial activity comparable with standard antibiotics.     

Metabolic profile and biological activities of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco: Studies on the essential oil and polar extracts

We investigated the metabolic profile and biological activities of the essential oil and polar extracts of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco collected in south Portugal. Gas chromatography–mass spectrometry (GC–MS) analysis revealed that oxygen-containing monoterpenes was the principal group of compounds identified in the essential oil. Camphor (40.6%) and fenchone (38.0%) were found as the major constituents. High-performance liquid chromatography with diode array detection (HPLC–DAD) analysis allowed the identification of hydroxycinnamic acids (3-O-caffeoylquinic, 4-O-caffeoylquinic, 5-O-caffeoylquinic and rosmarinic acids) and flavones (luteolin and apigenin) in the polar extracts, with rosmarinic acid being the main compound in most of them. The bioactive compounds from L. pedunculata polar extracts were the most efficient free-radical scavengers, Fe²⁺ chelators and inhibitors of malondialdehyde production, while the essential oil was the most active against acetylcholinesterase. Our results reveal that the subspecies of L. pedunculata studied is a potential source of active metabolites with a positive effect on human health.     

Antioxidant and protective properties of six Tanacetum species against hydrogen peroxide-induced oxidative stress in K562 cell line: A comparative study

The antioxidant activities of ethanolic extract of six species of Tanacetum (T. budjnurdense, T. hololeucum, T. chiliophyllum, T. sonboli, T. tabrisianum, T. kotschyi) from Iran were examined by employing various established in vitro assay systems. The results showed that all Tanacetum extracts displayed antioxidant activities, with IC₅₀ values ranging from 59.55 to 157.24 μg/ml, using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The extract of T. hololeucum, with an IC₅₀ value of 59.55 μg/ml was nearly two or three times more active than the other used Tanacetum extracts. The amounts of total phenolics and total flavonoids were also determined by spectrophotometer. A similar order of the amounts of phenolics and flavonoids in all plant extracts were found. The results showed that the extent of antioxidant activities is in accordance with the amounts of phenolics and flavonoids existing in all plant extracts. Regarding high performance liquid chromatography (HPLC) data, caffeic acid, ferulic acid, luteolin, apigenin and rutin were detected as major phenolic compounds in all the species investigated. Pretreatment of K562 cells with various concentrations of Tanacetum extracts (10–100 μg/ml) for 16 h prevent cell damage and enhanced activity of antioxidant enzymes induced by a treatment with H₂O₂. Moreover, lower level of glutathione caused by hydrogen peroxide in K562 cells were partly recovered by a pretreatment of cells with various Tanacetum species extract. These results may show the significant protection effect of Tanacetum sp. against oxidation of the cells.     

In vitro and in vivo studies on the antioxidant activities of the aqueous extracts of Douchi (a traditional Chinese salt-fermented soybean food)

The aqueous extracts of Douchi were obtained and evaluated for their antioxidant properties. The isoflavones and peptides contents of extracts were determined. Antioxidant activities in vitro of extracts were conducted by determining the α,α-diphenyl-β-pricrylhydrazyl (DPPH) and 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activities, and the chelating ability of ferrous ions, of which IC₅₀ values were found to be 0.658, 0.204 and 206 mg/mL, respectively. Antioxidant enzymatic activities of extracts in cholesterol-fed rats and an index of lipid peroxidation (thiobarbituric acid reactive substances (TBARS)) were determined, and hepatic tissue ultramicrostructure was also observed under transmission electron microscope (TEM). These results showed that, in Douchi extracts groups, superoxide dismutase (SOD) activities in liver and kidney, catalase (CAT) activity in liver, and glutathione peroxidase (GSH-Px) activity in kidney increased significantly compared with the negative control group (p < 0.05). TBARS in liver and kidney of extracts groups decreased significantly (p < 0.05). Less fatty degeneration in hepatocytes of extracts groups was found on TEM photos. The percentage of total isoflavones and peptides contents in aqueous extracts were 0.087% and 40.7%, respectively. These results showed that Douchi extracts had excellent antioxidant activities, might affect the activities of antioxidant enzymes and lipid peroxidation, and mitigate the lipidosis of hepatocytes.     

Strawberry consumption improves plasma antioxidant status and erythrocyte resistance to oxidative haemolysis in humans

Significant increases in the plasma total antioxidant capacity (TAC) have already been reported after acute intake of strawberries. In addition, antihaemolitic effects of strawberry extracts have been recently demonstrated in vitro, revealing that part of the antioxidant properties of strawberry bioactive compounds could lie in their localisation within cell membranes. However, there is a lack of research evidence from in vivo protracted strawberry consumption studies. We carried out a 16-day pilot study where 12 healthy subjects ingested 500 g of antioxidants-rich strawberries daily, and we evaluated the potential effects of fruit consumption on biomarkers of plasma and cellular antioxidant status. A significant increase in fasting plasma TAC and in serum vitamin C concentrations were progressively observed during the period of strawberry supplementation. An enhanced resistance to haemolysis was also observed in both AAPH-treated and untreated erythrocytes, collected during and after the period of strawberry consumption. The results obtained in this work suggest that regular consumption of antioxidant-rich strawberries may exert an improvement on the plasma antioxidant status and an increase on the antihaemolitic defenses of human erythrocytes.     

Supercritical fluid extraction and hydrodistillation for the recovery of bioactive compounds from Lavandula viridis L’Hér

The chemical profiles of bioactive essential oil and extracts obtained by hydrodistillation (HD) and supercritical fluid extraction (SFE), respectively, from Lavandula viridis were compared. The SFE was performed at 40 °C and at extraction pressures of 12 or 18 MPa in two different separators. Evaluation of the essential oil and SFE extracts by GC–FID and GC–IT–MS revealed that oxygen-containing monoterpenes were the major constituents in both cases, but there were important differences between the chemical profiles produced by the different extraction techniques. More compounds were isolated by HD but higher yields were achieved by SFE. Camphor was the main component identified in the essential oil (31.59 ± 1.32%), and in extracts from the first (1.61 ± 0.34%) and second SFE separators (22.48 ± 1.49%) at 12 MPa. In contrast, the first separator SFE extract at 18 MPa (heavy compounds) was dominated by myrtenol (5.38 ± 2.04%) and camphor (4.81 ± 1.93%), whereas the second separator SFE extract (volatiles) was dominated by verbenone (13.97 ± 5.27%). The essential oil and heavy compound extracts from the first separator possessed antioxidant and anti-cholinesterase activities. Our data show that phytochemicals from the aerial parts of L. viridis could be developed as natural antioxidant and anti-cholinesterase drugs, with particular applications in the symptomatic treatment of Alzheimer’s disease.     

Inhibitory effects of Chrysanthemum species extracts on formation of advanced glycation end products

The corolla of Chrysanthemum species (C.morifolium R. and C.indicum L.) has long been used to treat eye and inflammatory disease. However, little is known about the antiglycation properties of Chrysanthemum species. Our study sought to characterise their activity against the formation of advanced glycation end products (AGEs) in glycation model reactions. In BSA/glucose (fructose) systems, both Chrysanthemum species strongly inhibited the formation of AGEs and N^ε-(carboxymethyl)lysine (CML). C.morifolium R., not C.indicum L., also acted to inhibit the formation of fluorescent AGEs, including pentosidine. This difference correlated with the values of polyphenol and flavonoid components. We characterised the active components in these plants by liquid chromatography-diode array detector-atmospheric pressure chemical ionisation/mass spectrometry, which showed that C. morifolium R. contains large amounts of chlorogenic acid, flavonoid glucoside varieties, and apigenin, while C.indicum L. contains large amounts of caffeic acid, luteolin, and kaempferol. Our findings raise hopes for the successful treatment of pathogenesis in conditions associated with diabetic complications and aging.     

Suppressive effect of ethyl acetate extract of Teucrium polium on cellular oxidative damages and apoptosis induced by 2-deoxy-d-ribose: Role of de novo synthesis of glutathione

The effect of ethyl acetate (EtOAc) extract of Teucrium polium on 2-deoxy-d-ribose (dRib)-induced oxidative stress and apoptosis in erythroleukemic K562 cells was investigated. K562 cells exposed to dRib (50 mM) exhibited abnormal properties such as overproduction of reactive oxygen species, lipid peroxidation, glutathione (GSH) depletion and biochemical features of apoptosis. Treatment with EtOAc extract (25 and 50 μg/ml) reduced oxidative stress and apoptosis among the dRib-treated K562 cells. To disclose the mode of action, the effect of the extract on the cellular GSH and its synthesis by γ-glutamylcysteine synthetase (γ-GCS), a key rate-limiting enzyme of the GSH synthetic pathway, were evaluated. The results demonstrated that the antioxidant property of EtOAc extract mainly results from increasing the level of cellular GSH by inducing the activity of γ-GCS. It can be concluded that the EtOAc extract of T. polium prevents dRib-induced oxidative stress and apoptosis mostly through antioxidative mechanisms.     

Varietal differences among the phenolic profiles and antioxidant properties of four cultivars of spine grape (Vitis davidii Foex) in Chongyi County (China)

Spine grape (Vitis davidii Foex) is an important wild plant species in South China. To provide sufficient experimental evidence for the strong antioxidant activity of spine grapes, four cultivars from Chongyi County, China, including three red varieties (Junzi #1, Junzi #2, and Liantang) and one white variety (Baiyu) were evaluated. The Junzi #1 had the highest phenolic content (total phenolic, flavonoids, flavanols, and anthocyanins) and the strongest antioxidant capacity (DPPH radical-scavenging capacity, cupric-reducing capacity and hydroxyl radical-scavenging activity) among the four varieties. HPLC analysis of spine grapes revealed that the (+)-catechin was the most abundant phenolics and the hydroxycinnamic acids were the major phenolic acids in the four varieties. Hierarchical cluster analysis showed that the Junzi #1 belongs to the group with high phenolic content and strong antioxidant power. The results suggest the Junzi #1 has the best health promoting properties, and the higher utilization value and potential for development.