Polyphenolic apple juice extracts and their major constituents reduce oxidative damage in human colon cell lines

Apple juice containing high amounts of antioxidative polyphenols might protect the intestine against oxidative cell damage. We investigated the preventive effectiveness of polyphenolic juice extracts of different origins (cider and table apples) in comparison to their major constituents in human colon cell lines (Caco-2, HT29). Parameters studied were (oxidative) DNA damage (Comet assay), glutathione level (photometric kinetic assay), cellular redox status (dichlorofluorescein assay) and antioxidant capacity. The extracts (50-250 microg/mL) modulated DNA damage and redox status in a concentration-dependent manner at 24-h incubation. The pomace extraction technology, applied for juice preparation, and the preferential selection of cider apple varieties influenced the polyphenolic pattern and increased the biological effectiveness of the extracts. The preventive potential of major juice constituents (1-100 microM, 24 h) strongly differed: rutin, epicatechin and caffeic acid clearly reduced (oxidative) DNA damage (Caco-2), chlorogenic acid efficiently decreased cellular reactive oxygen species level (HT29, Caco-2). The aglyca quercetin and phloretin exhibited the highest preventive/antioxidant capacity in all assays. The stability of the compounds inversely correlated with their preventive effectiveness and might contribute to the observed cell specific sensitivities. In conclusion, apple juice extracts distinctly reduce oxidative cell damage in human colon cell lines, an effect, which in part can be accounted for by their major constituents.     

Oxidative stability of whole wheat bread during storage

The oxidative stability was examined in whole wheat bread packed in modified atmosphere (nitrogen) using vacuum grade plastic bags and stored for up to 5 weeks. Small, but significant, differences in oxidative stability developed with time for whole wheat bread crumb and crust. The samples were evaluated by direct electron spin resonance (ESR) spectroscopy for detection of free radicals, peroxide value (POV), overall antioxidative capacity using Trolox equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC) assays, and by the content of tocopherols as determined by HPLC. The overall antioxidative capacity was reduced during storage with an accumulation of lipid hydroperoxides peaking after 2-3 weeks of storage. Bread crust was generally found to be more oxidative stable when compared to crumb. Quality of bread with extended shelf life may accordingly be improved minimising oxidation.     

Fluctuations in the phenolic content and antioxidant capacity of dark fruit juices in refrigerated storage

The changes in total phenol content and antioxidant capacity were monitored in six industrial dark fruit juices during 29-day refrigerated storage. The initial total phenol values ranged from 1302.1 mg/L GAE (strawberry) to 1919.8 mg/L GAE (black currant) with a mean of 1573.3 mg/L GAE. All juices exhibited fluctuations in TP values with a marked increase after 48 hours in refrigerated storage, and a greater overall TP content in 5/6 studied juices after 29 days. Antioxidant capacity was evaluated using the DPPH radical scavenging assay and cyclic voltammetry (CV) and expressed as Trolox equivalent antioxidant capacity (TEAC). Black currant juice exhibited the highest TEAC values according to both CV (2.42 mM Trolox) and the DPPH assay (5.68 mM Trolox), while cranberry juice antioxidants exhibited the greatest storage stability and the smallest antioxidant capacity decrease on day 29, 20% (CV) and 15% (DPPH assay). At the end of 29-day storage 5/6 juices exhibited a significant loss in antiradical activity and all 6 juices exhibited a significant loss in TEAC derived from CV measurements. Significant linear correlation was observed between the results of CV measurements and the DPPH antiradical activity (r² = 0.62).     

Effect of preliminary processing, method of drying and storage temperature on the level of antioxidants in kale (Brassica oleracea L. var. acephala) leaves

The levels of vitamin C, polyphenol constituents and Trolox equivalent antioxidant activity (TEAC) were analyzed in raw kale leaves, blanched leaves and dried leaves obtained using air and freeze-drying methods. 100 g of raw kale leaves contained 683 mg vitamin C and 2236 mg polyphenols (identified using the HPLC method); the level of antioxidative activity was 71 μM Trolox/1 g dry matter. Compared with the raw material, blanching before drying brought about significant decreases of 15% in vitamin C, 32% in polyphenols and13% in TEAC. After 12-month storage, air-dried material retained 30-37% polyphenols; 43-57% vitamin C; and 41-50% of the initial TEAC level; the corresponding values for freeze-dried material were 40-47%; 50-65% and 54-66% depending on the type of sample. Freeze-dried kale leaves contained higher levels of antioxidants than air-dried material: polyphenols, vitamin C and TEAC were respectively 36%, 15%and 33% higher.     

Nitric oxide-scavenging and antioxidant effects of Uraria crinita root

The antioxidant activity and the nitric oxide-scavenging effect of methanol extracts (MEUR), and their ethyl acetate fraction (EAF), from Uraria crinita root, were investigated. The results of the comet assay indicated that both MEUR and EAF could inhibit DNA damage in macrophage induced by sodium nitroprusside at a concentration of 25–200 μg/ml. The antioxidant activity of the extracts was determined using the Trolox equivalent antioxidant capacity (TEAC) assay. The TEAC values of MEUR and EAF were 0.2 and 0.4, respectively, at a concentration of 200 μg/ml. The antioxidant activity and nitric oxide-scavenging effect of MEUR and EAF showed concentration-dependence. In addition, the results also showed a decreasing effect on nitric oxide production of lipopolysaccharide-induced RAW 264.7, for both extracts. One of the major antioxidative components was isolated from EAF and was identified as genistein, on the basis of UV-vis spectral, IR, MS and NMR analyses. Thus, the traditional edible plant, Uraria crinita, may have potential as an antioxidant and as a nitric oxide-scavenging agent.     

Influence of Different Extraction Media on Phenolic Contents and Antioxidant Capacity of Defatted Dabai (<Emphasis Type="Italic">Canarium odontophyllum</Emphasis>) Fruit

Dabai (Canarium odontophyllum) is a potential “functional fruit”. Future commercialization of dabai fat as healthy oil may result in the accumulation of defatted dabai as a by-product. This study was carried out to determine the total phenolics and antioxidant capacity of defatted dabai parts as a new source of functional food and nutraceutical ingredient. In this study, defatted dabai parts were extracted using different extraction media (methanol, ethanol, ethyl acetate, acetone, and water) and analyzed for total phenolics, total flavonoids, total anthocyanins, and antioxidant capacity (ABTS⁺ radical scavenging and ferric-reducing antioxidant power assays) using spectrophotometric and high-performance liquid chromatography methods. Major phenolics in defatted dabai peel extracted using methanol were catechin and epigallocatechin while in water extract, major phenolic acid was ellagic acid. Defatted dabai peel also had higher anthocyanidin content than its pulp. The peel of a defatted dabai fruit extracted using methanol contained a high total phenolics and Trolox equivalent antioxidant capacity (TEAC). Ethyl acetate extract of defatted dabai parts had the least phenolics compared in ethanol and acetone extracts. Higher total phenolics and TEAC values were observed in water extract of a defatted dabai peel than ethanol, acetone, and ethyl acetate extracts. Hence, methanol extract of a defatted dabai peel could probably be used as a natural antioxidant.     

Antioxidant effectiveness of coffee extracts and selected constituents in cell‐free systems and human colon cell lines

Scope: Epidemiological studies suggest that coffee can reduce the risk of degenerative diseases such as diabetes type 2, cardiovascular disease and cancer. These beneficial effects have partly been attributed to the antioxidant activity of coffee. We determined composition and antioxidant potential of differentially roasted coffee extracts and investigated the impact of selected original constituents and roast products. Methods and results: Parameters studied were direct antioxidant activity (trolox equivalent antioxidant capacity/oxygen radical absorbing capacity), cellular reactive oxygen species (ROS) level, DNA damage and protein expression of NAD(P)H: quinone oxidoreductase, γ‐glutamylcysteine ligase and glutathione reductase in HT‐29/Caco‐2 cells at 24‐h incubation. All extracts showed distinct direct antioxidant activity: medium roasts>light roast AB1 (caffeoylquinic acid (CQA)‐rich Arabica Brazil extract); dark roast AB2 (N‐methylpyridinium (NMP)‐rich Arabica Brazil extract), and diminished t‐butylhydroperoxide‐induced ROS level in HT‐29 cells (AB2>medium roasts>AB1). NAD(P)H:quinone oxidoreductase 1 expression and γ‐glutamylcysteine ligase expression were distinctly induced by AB1 and 5‐CQA, but not by AB2 and NMP. 5‐CQA and caffeic acid exhibited highest trolox equivalent antioxidant capacity/oxygen radical absorbing capacity values (5‐CQA: 1.3/3.5 mM and caffeic acid: 1.3/3.9 mM trolox); ROS level was distinctly diminished by 5‐CQA (≥3 μM), catechol (30 μM) and trigonelline (≥30 μM), whereas menadione‐induced DNA damage in Caco‐2 cells was reduced by NMP compounds (1–30 μM). Conclusion: The results emphasize that both original constituents and roast products contribute to the cellular antioxidant effectiveness of coffee.     

Influence of origin source, different fruit tissue and juice extraction methods on anthocyanin, phenolic acid, hydrolysable tannin and isolariciresinol contents of pomegranate (Punica granatum L.) fruits and juices

To gain more comprehensive knowledge of pomegranate (Punica granatum L.) fruit composition and its impact on juice features, fruits and juices produced from fruits of eleven different provenances were investigated by HPLC–DAD-ESI/MSⁿ for their monomeric phenolic and lignan profiles. Total phenolics and antioxidant capacity were monitored by the Folin-Ciocalteu, ferric reducing antioxidative power and Trolox equivalent antioxidant capacity assays. Peels, mesocarp, seeds and juices obtained from isolated arils (PJAs) as well as from entire fruits were separately analyzed. Ellagitannins were found to be the predominant phenolics in all samples except in PJAs. However, due to the low lignan amounts, only isolariciresinol could be quantitated in peels and mesocarp. The peels and mesocarp revealed highest contents of hydrolyzable tannins (27–172 g/kg and 32–263 g/kg, respectively) and isolariciresinol (4.9–19.8 mg/kg and 5.0–13.6 mg/kg, respectively). To the best of our knowledge, a systematic investigation of monomeric phenolic compounds and isolariciresinol considering diverse pomegranate fruits has been performed for the first time. The study demonstrates that raw material and extraction process have significant impact on juice composition and thus must be carefully selected. Furthermore, pomegranate processors should select juice extraction processes according to the final designation of the product, that is, distinguish between dietary products being rich in phenolic compounds having an astringent taste, and juices for consumption having an appealing taste but lower amounts of phenolics, respectively. This study may further contribute to facilitate authenticity control of diverse pomegranate products and help predict sensory and biofunctional characteristics of pomegranate juices.     

Physico-chemical characteristics of juice extracted by blender and mechanical press from pomegranate cultivars grown in Georgia

Pomegranate juice is consumed widely for its possible health benefits. The aril juice from 15 pomegranate cultivars grown in Georgia were analysed for juice yield based on fresh weight (FW) and physico-chemical properties, using blender and mechanical press extraction. Blender had a higher juice yield (42.04% FW) compared to mechanical press (38.05% FW). Total phenolics and antioxidant capacity was determined by Folin–Ciocalteau method and ferric reducing antioxidant power (FRAP), Trolox equivalent antioxidant capacity (TEAC), and oxygen radical absorbance capacity (ORAC) assays, respectively. Total monomeric anthocyanins were determined by pH differential method and RP-HPLC. The major anthocyanin was delphinidin 3-glucoside. High negative and significant (p ? 0.05) correlations were found between pH and titratable acidity (TA). The total soluble solids content (TSS) averaged 15.59 in blender and 14.94 °Brix in mechanical press. Chemical analysis of juice showed significant differences among cultivars and extraction methods. Overall, blender was more efficient than mechanical press juice extraction.     

Antioxidative activities of mao feng tea (Camellia spp.) and kamtae (Ecklonia cava) extracts and their effects on structured lipid from corn and perilla oil

In the study, solvent extracts of kamtae (Ecklonia cava) and mao feng tea (Camillia sinensis) were used for obtaining different fractions of organic solvents (diethyl ether, butanol, and ethyl acetate) and the extracted fractions were studied for their antioxidative activities. The total phenolic contents of the mao feng tea ranged from 1.44 to 5.97 mM GAE/g while kamtae ranged from 1.13 to 4.41 mM GAE/g, respectively. Among them, ethyl acetate fraction showed the highest content of phenolic compounds, resulting in Trolox equivalent antioxidant capacity (TEAC) values as 1,554.54 (from mao feng tea) and 1,097.63 mM Trolox E/g (from kamtae). Also, ethyl acetate fractions from mao feng tea showed the highest DPPH (89.27 RSC%), superoxide anion scavenging activity (46.58%), and ferric reducing antioxidant power (FRAP) (242.2 mg GAE/g) while ethyl acetate fractions from kamtae (K-EA) showed the highest DPPH (82.23 RSC%), superoxide anion scavenging activity (28.82%), and FRAP (162.43 mg GAE/g) among the obtained fractions.     

Phenolic content and antioxidative capacity of green and white tea extracts depending on extraction conditions and the solvent used

The efficiencies of different solvents in the extraction of phenolics from bagged and loose leaves of white and green tea, after different extraction times, as well as the antioxidative capacity of the obtained extracts, were investigated. The developed HPLC method has the potential to separate and determinate 17 phenolics widely distributed in plants, but in investigated tea extracts only four catechins and traces of three flavonols and one flavone were separated and detected based on comparison with authentic standards. The extraction efficiency of phenolics depended strongly on the time of extraction and the solvents used. The extraction of catechins from green tea was significantly affected by the form (bagged or loose) of the tea, whereas this effect was shown not to be statistically significant for white tea. Green tea was a richer source of phenolics than was white tea. The extraction of phenolics from white tea by water could be accelerated by the addition of lemon juice. Aqueous ethanol (40%) was most effective in the prolonged extraction of catechins. The antioxidative capacity of the investigated tea extracts correlated with their phenolic content.     

Antioxidant properties and total phenolics content of green and black tea under different brewing conditions

 The antioxidant activity and the total phenolics content of various tea extracts were analysed. Green and black tea were brewed from 0.5 min up to 10 min under different brewing conditions (stirring the extract, chopping the tea leaves before brewing). For measuring the antioxidant activity, the Trolox equivalent antioxidant capacity (TEAC) test and the low density lipoprotein (LDL) oxidation test were used. In all cases the antioxidant activity as well as the content of the phenolics increased with the brewing time. In black tea (brewed without stirring or chopping), the total phenolics increased from 33.8 mg/100 ml after 0.5 min up to 68.4 mg/100 ml after 10 min brewing time. Stirring during brewing led to higher phenolic yields in the extract. Thus, phenolics in stirred black tea ranged from 44.5 mg/100 ml (0.5 min) to 96.7 mg/100 ml (10 min). Chopping the tea leaves resulted in the highest content of phenolics. Antioxidant activity was well correlated with the corresponding total phenolics content. The results of the LDL oxidation test varied more than those of the TEAC test. Received: 27 May 1998 / Revised version: 15 July 1998     

Effect of preliminary processing and method of preservation on the content of selected antioxidative compounds in kale (Brassica oleracea L. var. acephala) leaves

Vitamin C and polyphenol content as well as total antioxidative activity were investigated in fresh leaves of kale; in leaves after blanching or cooking; and in frozen and canned leaves. In 100 g fresh matter, kale leaves contained 384.9 mg polyphenols and 112.1 mg vitamin C, with a Trolox equivalent antioxidant capacity (TEAC) level of 1175 μM Trolox. Of the polyphenols identified in kale leaves, ferulic acid occurred in the highest amount (240.44 mg/100 g, constituting 62% of total polyphenols). Freezing was a better method of preserving kale leaves since the loss of nutritive constituents was lower than in the case of canning. Depending on preliminary processing and storage temperature, after one-year storage frozen leaves contained 82.9–171.3 mg polyphenols and 39.3–65.4 mg vitamin C, with TEAC at the level of 501–681 μM Trolox in 100 g. In canned leaves these values were: 91.3–94.1 mg polyphenols, 16.1–19.3 mg vitamin C and 268–293 μM Trolox.     

Antioxidant potential of barley as affected by alkaline hydrolysis and release of insoluble-bound phenolics

Phenolic constituents of six barley varieties, namely Falcon, AC Metcalfe, Tyto, Tercel, Phoenix and Peregrine were separated into free, soluble conjugate and insoluble-bound fractions. Soluble conjugates and insoluble-bound phenolics were extracted into diethyl ether after consecutive alkaline hydrolysis for 4 h. Total phenolic content of each of the three fractions was determined by using Folin–Ciocalteau method. Total antioxidant capacity of the phenolic fractions was determined by trolox equivalent antioxidant capacity (TEAC) assay. The extracts were evaluated for their efficacy in scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Oxygen radical scavenging capacity (ORAC_FL) of the extracts was determined using a fluorometric assay. Effectiveness of phenolic extracts in inhibiting oxidation of human LDL cholesterol and radical-induced supercoiled DNA breakage was also evaluated. The contribution of insoluble-bound phenolics toward total phenolic content was significantly (p < 0.05) higher than the soluble phenolics for all barley extracts tested. The ratio of soluble to insoluble phenolics ranged from 1:27 to 1:35. TEAC and ORAC values and DPPH radical scavenging capacity of the insoluble phenolic fraction were significantly (p < 0.05) higher than those of their insoluble counterparts. A similar trend was observed against inhibition of LDL cholesterol oxidation and radical-induced DNA breakage.     

Phenolic Composition,Radical Scavenging Activity and an Approach for Authentication of Aronia melanocarpa Berries,Juice, and Pomace

Aronia melanocarpa is a rich source of phenolic compounds like anthocyanins, chlorogenic acids, quercetin derivatives, and proanthocyanidins possessing strong antioxidative potential. The consumption of A. melanocarpa is actually increasing because of the known bioactivity of its phenolic constituents. A. melanocarpa extracts are used as natural colorants and nutraceuticals. Several attempts of adulteration of aronia products have already been reported. In this study, we investigated changes in phenolic composition from berry to juice by HPLC‐PDA, and HPLC‐ESI‐MSⁿ analyses as well as fingerprint profiles for authentication of commercially available aronia products in order to detect possible adulteration. Additionally, the radical scavenging activity of aronia products was determined by using the TEAC (Trolox® equivalent antioxidant capacity) assay. Aronia pomace, a valuable by‐product of juice production, showed the highest phenolic content and possessed the highest radical scavenging activity.     

Antioxidant properties and total phenolics content of green and black tea under different brewing conditions

 The antioxidant activity and the total phenolics content of various tea extracts were analysed. Green and black tea were brewed from 0.5 min up to 10 min under different brewing conditions (stirring the extract, chopping the tea leaves before brewing). For measuring the antioxidant activity, the Trolox equivalent antioxidant capacity (TEAC) test and the low density lipoprotein (LDL) oxidation test were used. In all cases the antioxidant activity as well as the content of the phenolics increased with the brewing time. In black tea (brewed without stirring or chopping), the total phenolics increased from 33.8 mg/100 ml after 0.5 min up to 68.4 mg/100 ml after 10 min brewing time. Stirring during brewing led to higher phenolic yields in the extract. Thus, phenolics in stirred black tea ranged from 44.5 mg/100 ml (0.5 min) to 96.7 mg/100 ml (10 min). Chopping the tea leaves resulted in the highest content of phenolics. Antioxidant activity was well correlated with the corresponding total phenolics content. The results of the LDL oxidation test varied more than those of the TEAC test.     

Contribution of low‐molecular‐weight antioxidants to the antioxidant capacity of raw and processed lentil seeds

In this study four cultivars of lentil originating from Spain were examined: cv Paula, cv Agueda, cv Almar and cv Alcor. Since consumption of these seeds after heat treatment and as sprouts has been popularised, the impact of cooking (up to 30 min) and germination process (in dark, at 25°C, for up to 4 days) on peroxyl radical‐trapping capacity (PRTC) and Trolox‐equivalent antioxidant capacity (TEAC) of the processed seeds was addressed. Also, changes in the content of low‐molecular‐weight antioxidants (LMWA) and soluble proteins in the course of cooking and germination were studied. The analyzed LMWA were: total phenolics, tocopherols (α‐T, β‐T, γ‐T, δ‐T( reduced glutathione, and L ‐ascorbic acid. On the basis of the results obtained, the contribution of LMWA and soluble proteins to the PRTC and TEAC of raw, cooked, and germinated lentil seeds was calculated by multiple mean values for the content of investigated compounds and their relative potential with respect to Trolox. The results showed a very high molar percentage contribution of phenolic compounds and low contribution of tocopherols, glutathione, soluble proteins, and ascorbate (only in germinated seeds) to the total TEAC and total PRTC calculated as a sum of data provided for phosphate‐buffered and 80% methanolic extracts of raw and processed lentil seeds.     

SYNERGISM OF CRANBERRY PHENOLICS WITH ELLAGIC ACID AND ROSMARINIC ACID FOR ANTIMUTAGENIC AND DNA PROTECTION FUNCTIONS

Several studies have shown the antimutagenic DNA protective functions of some naturally occurring phenolic phytochemicals. Emerging research also indicates that synergistic functionality of these phytochemicals in whole foods benefits the management of many diseases. Here we have investigated the potential antimutagenic properties of cranberry phenolics, ellagic acid (EA), rosmarinic acid (RA) and their synergistic interactions on enhancing antimutagenic properties in Salmonella typhimurium tester system against mutagens sodium azide and N‐methyl‐N′‐nitro‐N‐nitrosoguanidine. Ability of these phytochemical treatments to protect oxidative damage to DNA was also investigated using the supercoiled DNA strand scission assay. Results showed that EA was most effective in inhibiting the mutations in S. typhimurium system, whereas RA and EA were equally effective in protecting the DNA from oxidative damage. Results also showed that the antimutagenic functionality of cranberry powder (CP) made from juice extracts was significantly enhanced when 30% (w/w) of phenolics in CP was substituted with RA and EA possibly because of synergistic redox modulation that can influence mutagen function. It is also suggested that the synergistic mixture of cranberry phenolics with RA could also be protecting the cell from mutations by modulating DNA repair systems.     

Antioxidant Potential of Pea Beans (Phaseolus vulgaris L.)

ABSTRACT: Four bean varieties ( Phaseolus vulgaris L.) (white kidney, red pinto, Swedish brown, and black kidney) and their hull fractions were extracted with 80% acetone and evaluated for their phenolic contents and antiradical activities. Total phenolic content of bean hulls and whole seed extracts ranged from 6.7 to 270 and 4.9 to 93.6 mg/g extract as catechin equivalents, respectively. Trolox equivalent antioxidant capacity (TEAC) assay revealed that the antioxidant capacity of red, brown, and black whole seed extracts was in the same order of magnitude with little variation. TEAC values of red and brown whole seed extracts were superior to that of black whole seed extract. On the basis of the total phenolic content and TEAC values, it can be deduced that colored beans possess superior antioxidative activity compared with white beans. The hydrogen peroxide scavenging capacity of different bean extracts ranged from 58% to 67% at 50 ppm and 65% to 76% at 100 ppm. The corresponding superoxide radical scavenging capacity was 24% to 29% at 50 ppm and 53% to 60% at 100 ppm. The 2,2–diphenyl-1–picrylhydrazyl (DPPH) radical scavenging capacity of black bean whole seed extracts was 22% at 50 ppm, whereas the other extracts showed 100% scavenging of this radical at both 50 and 100 ppm levels. The hydroxyl radical scavenging capacities of the bean extracts at 50 and 100 ppm were 12% to 29% and 32% to 49%, respectively. All extracts used prevented human low-density lipoprotein (LDL) cholesterol oxidation by 61.4% to 99.9% at 2 to 50 ppm level as catechin equivalents.