Aronia melanocarpa phenolics and their antioxidant activity

Harvest date affects aronia juice polyphenols, sugars, and antioxidant activity, but not anthocyanin stability

The goal of this work was to characterize how the date of harvest of 'Viking' aronia berry impacts juice pigmentation, sugars, and antioxidant activity. Aronia juice anthocyanins doubled at the fifth week of the harvest, and then decreased. Juice hydroxycinnamic acids decreased 33% from the first week, while proanthocyanidins increased 64%. Juice fructose and glucose plateaued at the fourth week, but sorbitol increased 40% to the seventh harvest week. Aronia juice pigment density increased due to anthocyanin concentration, and polyphenol copigmentation did not significantly affect juice pigmentation. Anthocyanin stability at pH 4.5 was similar between weeks. However, addition of quercetin, sorbitol, and chlorogenic acid to aronia anthocyanins inhibited pH-induced loss of color. Sorbitol and citric acid may be partially responsible for weekly variation in antioxidant activity, as addition of these agents inhibited DPPH scavenging 13-30%. Thus, aronia polyphenol and non-polyphenol components contribute to its colorant and antioxidant functionality.

Modeling and optimization of ultrasound-assisted extraction of polyphenolic compounds from Aronia melanocarpa by-products from filter-tea factory

Aronia melanocarpa by-product from filter-tea factory was used for the preparation of extracts with high content of bioactive compounds. Extraction process was accelerated using sonication. Three level, three variable face-centered cubic experimental design (FCD) with response surface methodology (RSM) was used for optimization of extraction in terms of maximized yields for total phenolics (TP), flavonoids (TF), anthocyanins (MA) and proanthocyanidins (TPA) contents. Ultrasonic power (X₁: 72-216 W), temperature (X₂: 30-70 °C) and extraction time (X₃: 30-90 min) were investigated as independent variables. Experimental results were fitted to a second-order polynomial model where multiple regression analysis and analysis of variance were used to determine fitness of the model and optimal conditions for investigated responses. Three-dimensional surface plots were generated from the mathematical models. The optimal conditions for ultrasound-assisted extraction of TP, TF, MA and TPA were: X₁=206.64 W, X₂=70 °C, X₃=80.1 min; X₁=210.24 W, X₂=70 °C, X₃=75 min; X₁=216 W, X₂=70 °C, X₃=45.6 min and X₁=199.44 W, X₂=70 °C, X₃=89.7 min, respectively. Generated model predicted values of the TP, TF, MA and TPA to be 15.41 mg GAE/ml, 9.86 mg CE/ml, 2.26 mg C3G/ml and 20.67 mg CE/ml, respectively. Experimental validation was performed and close agreement between experimental and predicted values was found (within 95% confidence interval).

Evaluation of sour cherry (Prunus cerasus L.) fruits for their polyphenol content, antioxidant properties, and nutritional components

Nutritional compounds (phenolic compounds, L-ascorbic acid), antioxidant activities, and physicochemical characteristics (fruit weight, dry matter, soluble solids, pH, acidity, total and reducing sugars) of 33 different sour cherry cultivars were studied. Polyphenols were identified by LC-PDA-QTOF/MS and quantified by UPLC-PDA-FL. A total of 41 polyphenolic compounds found were identified and presented as 14 flavan-3-ols, 11 anthocyanins, 5 hydroxycinnamic acids, 10 flavonols, and 1 flavon. The content of total polyphenols (TPs) ranged from 2982.51 ('Wisok' cultivar) to 1539.43 mg/100 g dry weight ('Erdi Nagygyϋmϋscu'cultivar). Flavan-3-ols, the major class of sour cherry polyphenols, represented ∼ 40% of the TP compounds, whereas anthocyanins and hydroxycinnamic acids amounted for about 25% each. The content of l-ascorbic acid did not exceed 22.18 mg/100 g fresh matter. Some polish sour cherry cultivars (especially 'Agat', 'Ametyst', 'Wider', 'Winer', and 'Wisok') may be selected to promote the growth of cultivars with strong nutritional and phytochemical beneficial effects on human health.

The effects of strawberry, black currant, and chokeberry extracts in a grain dietary fiber matrix on intestinal fermentation in rats

The objective of this work was to study the composition, hydration properties and oil holding capacity, antioxidant properties and the physiological effects on the digestive system of dietary preparations containing wheat or oat fiber enriched with polyphenol extracts from strawberry, chokeberry, and black currant pomace. By the addition of black currant, strawberry and chokeberry polyphenol extracts to grain fibers preparations with corresponding polyphenol content of 0.7%-0.8%, 1.1%-1.2%, and 2.5%-2.9% were obtained. The preparations were used as part (8%) of a modified AIN-93 diet given to growing Wistar rats (8 animals per group) over a period of 4weeks. The highest antioxidant potential had grain-chokeberry preparations with the greatest polyphenol content, while grain-black currant preparations exhibited the lowest antioxidant potential with the smallest polyphenol content. The addition of strawberry and chokeberry extracts caused a decrease in the activity of bacterial β-glucosidase and α-galactosidase, while black currant extract led to increased activity of β-galactosidase and β-glucuronidase. The production of short chain fatty acids (SCFAs) in the caecum of rats fed the grain-strawberry preparation, rich in ellagitannins, was considerably higher than the grain-black currant preparation, rich in proanthocyanidins and anthocyans, or the grain-chokeberry preparation with the highest polyphenol content (78.3 vs. 64.7 vs. 56.3μmol/100g body weight, p=0.012). In comparison to preparations without polyphenols only chokeberry extract significantly decreased SCFA concentration. The grain-strawberry preparations were characterized by a higher antioxidant potential per unit of polyphenol content and exhibited a more beneficial influence on the fermentation processes in the caecum of rats than the grain-black currant and grain-chokeberry preparations.

Novel strategy to create hypoallergenic peanut protein-polyphenol edible matrices for oral immunotherapy

Peanut allergy is an IgE-mediated hypersensitivity. Upon peanut consumption by an allergic individual, epitopes on peanut proteins bind and cross-link peanut-specific IgE on mast cell and basophil surfaces triggering the cells to release inflammatory mediators responsible for allergic reactions. Polyphenolic phytochemicals have high affinity to bind proteins and form soluble and insoluble complexes with unique functionality. This study investigated the allergenicity of polyphenol-fortified peanut matrices prepared by complexing various polyphenol-rich plant juices and extracts with peanut flour. Polyphenol-fortified peanut matrices reduced IgE binding to one or more peanut allergens (Ara h 1, Ara h 2, Ara h 3, and Ara h 6). Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) suggested changes in secondary protein structure. Peanut protein-cranberry polyphenol fortified matrices triggered significantly less basophil degranulation than unmodified flour in an ex vivo assay using human blood and less mast cell degranulation when used to orally challenge peanut-allergic mice. Polyphenol fortification of peanut flour resulted in a hypoallergenic matrix with reduced IgE binding and degranulation capacity, likely due to changes in protein secondary structure or masking of epitopes, suggesting potential applications for oral immunotherapy.

Evaluation of antioxidant activity, polyphenolic compounds, amino acids and mineral elements of representative genotypes of Lonicera edulis

The aim of this study was to evaluate the bioactive substances in 19 berry cultivars of edible honeysuckle (Loniceraedulis). A statistical evaluation was used to determine the relationship between the content of selected bioactive substances and individual cultivars. Regarding mineral elements, the content of sodium was measured using potentiometry and spectrophotometry. The content of selected polyphenolic compounds with high antioxidant activity was determined by a HPLC–UV/ED method. The total amount of polyphenols was determined by the Folin-Ciocalteu method. The antioxidant activity was determined using five methods (DPPH, FRAP, ABTS, FR and DMPD) that differ in their principles. The content of 13 amino acids was determined by ion-exchange chromatography. The experimental results obtained for the different cultivars were evaluated and compared by statistical and bioinformatic methods. A unique feature of this study lies in the exhaustive analysis of the chosen parameters (amino acids, mineral elements, polyphenolic compounds and antioxidant activity) during one growing season.

Changes in chokeberry (Aronia melanocarpa L.) polyphenols during juice processing and storage

Chokeberries are an excellent source of polyphenols, but their fate during juice processing and storage is unknown. The stability of anthocyanins, total proanthocyanidins, hydroxycinnamic acids, and flavonols at various stages of juice processing and over 6 months of storage at 25 °C was determined. Flavonols, total proanthocyanidins, and hydroxycinnamic acids were retained in the juice to a greater extent than anthocyanins, with losses mostly due to removal of seeds and skins following pressing. Anthocyanins were extensively degraded by thermal treatments during which time levels of protocatechuic acid and phloroglucinaldehyde increased, and additional losses occurred following pressing. Flavonols, total proanthocyanidins, and hydroxycinnamic acids were well retained in juices stored for 6 months at 25 °C, whereas anthocyanins declined linearly. Anthocyanin losses during storage were paralleled by increased polymeric color values, indicating that the small amounts of anthocyanins remaining were present in large part in polymeric forms.

Effects of Long-Term Administration of Freeze-Dried Chokeberry Juice to Rats

Polyphenolics can act as prooxidants leading to the generation of reactive oxygen species and electrophilic metabolites which bind to DNA, protein and glutathione. The aim of the present study was to evaluate potential adverse effects of the long-term dietary administration of freeze-dried chokeberry juice to rats.Groups of 8 males and 8 females were exposed via diet to 0; 2; 6; 10 g juice/kg feed for 90 days. Mean food consumption and mean body weight gain of treated animals were comparable with controls. Changes in some hematological parameters were sporadic and non-dose-responsive. Several statistically significant changes in clinical chemistry parameters were considered no toxicologically relevant since they were of small magnitude and lacked correlating findings in histopathology. Histopathological examination did not reveal any changes that could be attributed to chokeberry juice intake. Determination of oxidative damage markers in the liver demonstrated no damage of lipids, proteins and DNA. Chokeberry juice intake improved antioxidant status of rats as evidenced by a decrease in the level of lipid peroxidation, an increase in reduced glutathione concentration and an increase in some antioxidant enzymes activity.It could be concluded that freeze-dried chokeberry juice is safe at doses tested and can be used as a component of food supplements.

Dietary supplementation with polyphenol-rich chokeberry juice improves skin morphology in cellulite

The aim of our study was to investigate possible beneficial effects of organic chokeberry juice (OCJ) consumption in the treatment of cellulite. Twenty-nine women aged 25-48 with a cellulite grade 2 according to the Nurnberger-Muller scale were included. Anthropometric and biochemical parameters were measured. Skin structure was analyzed by ultrasonography. All subjects consumed 100 mL of OCJ per day, during 90 days. Measurements of investigated parameters were performed at 0, 45, and 90 days of the study. A marked reduction in the subcutaneous tissue thickness was observed in all subjects, with the average reduction of 1.9 mm. The length of subcutaneous tissue fascicles (ScTFL) was reduced in 97% (28 out of 29) of subjects, with the average value of 1.18 mm. After 45 days of chokeberry juice consumption, reduction of edema was observed in 55.2% of the subjects with edema at the baseline, while at the endpoint of the study, edemas were not observed in any of the subjects involved in the study. OCJ could have beneficial effects on the cellulite condition, including the length of ScTFL, subcutaneous tissue, and dermis thickness as well as on edema reduction.

Oxidative stability of the meat of broilers supplemented with rosemary leaves, rosehip fruits, chokeberry pomace, and entire nettle, and effects on performance and meat quality

Prevention of lipid oxidation needs special attention because a high proportion of fatty acids in broiler meat are unsaturated. A feeding experiment was conducted to evaluate the antioxidant effect of dietary addition of rosemary, chokeberry pomace, rosehip, or nettle in comparison with vitamin E. Male Ross PM3 broilers caged in groups of 6 (4 replicated cages per treatment) were fed a balanced diet supplemented with 25 g/kg of herbal additive, 200 IU of α-tocopheryl acetate/kg, or without supplementation from d 7 to 35. Intake, performance, and with the help of excreta samples, apparent fiber digestibility, ME content, and metabolizability of nitrogen and energy were recorded per cage. Feed was analyzed for total phenols and tocopherols. In each bird (n = 24 per treatment), carcass weight and relative organ weights were recorded, and skin and liver color were assessed. Abdominal fat was analyzed for induction time (h) of lipid oxidation (Rancimat). Breast meat was analyzed for total tocopherol content (mg/kg) and development of TBA reactive substances (TBARS; μg of MDA/kg) over 9 d of storage. Data were subjected to ANOVA considering treatment and, where applicable, storage time. Rosemary supplementation reduced oxidation (TBARS d 9: 201; induction time: 2.48) and elevated tocopherol content (5.72) of the meat compared with control (470, 1.87, and 3.53, respectively). Rosemary-treated birds had a slightly lower carcass weight and a reduced nitrogen and energy metabolizability. Rosehip addition numerically decreased TBARS (319) and enhanced carcass weight (1.71 kg) compared with rosemary-treated birds (1.54 kg). Only a trend in antioxidant activity could be ascribed to chokeberry pomace, although dietary phenolic content was highest. Nettle did not improve oxidative stability (TBARS: 506; induction time: 1.91), although tocopherol content was elevated (6.51). Nettle treatment strongly intensified skin yellowness (b* of 20.6) compared with the control treatment (10.8). Clearly, rosemary is the most suitable dietary antioxidant investigated in this study, yet chokeberry and rosehip also exhibited interesting properties.

Effects of Aronia melanocarpa constituents on biofilm formation of Escherichia coli and Bacillus cereus

Many bacteria growing on surfaces form biofilms. Adaptive and genetic changes of the microorganisms in this structure make them resistant to antimicrobial agents. Biofilm-forming organisms on medical devices can pose serious threats to human health. Thus, there is a need for novel prevention and treatment strategies. This study aimed to evaluate the ability of Aronia melanocarpa extracts, subfractions and compounds to prevent biofilm formation and to inhibit bacterial growth of Escherichia coli and Bacillus cereusin vitro. It was found that several aronia substances possessed anti-biofilm activity, however, they were not toxic to the species screened. This non-toxic inhibition may confer a lower potential for resistance development compared to conventional antimicrobials.

Underutilized chokeberry (Aronia melanocarpa, Aronia arbutifolia, Aronia prunifolia) accessions are rich sources of anthocyanins, flavonoids, hydroxycinnamic acids, and proanthocyanidins

Polyphenols from underutilized black, purple, and red aronia (Aronia melanocarpa, Aronia prunifolia, and Aronia arbutifolia) and 'Viking' (Aronia mitschurinii) berries were characterized. Anthocyanin and nonanthocyanin flavonoids were quantitated by UHPLC-DAD-MS and proanthocyanidins by normal-phase HPLC. On a dry weight basis, anthocyanins were mainly cyanidin-3-galactoside, highest in black aronia (3.4-14.8 mg/g) and lowest in red aronia (0.5-0.8 mg/g) as cyandin-3-galactoside equivalents. Berries from 'Viking' and the red accession UC021 had substantially more proanthocyanidins than the other accessions, with 3.3 and 3.8 mg catechin equiv/g, respectively. Chlorogenic acids and quercetin glycosides were most abundant in purple UC047 berries, at 17.3 and 1.3 mg/g, respectively. In contrast to anthocyanin content, total phenol values were highest in berries from red and purple accessions and attributed to phenolic acid and proanthocyanin content. Thus, red, purple, and black aronia berries are rich sources of polyphenols with various levels of polyphenol classes.

Aronia melanocarpa juice, a rich source of polyphenols, induces endothelium-dependent relaxations in porcine coronary arteries via the redox-sensitive activation of endothelial nitric oxide synthase

This study examined the ability of Aronia melanocarpa (chokeberry) juice, a rich source of polyphenols, to cause NO-mediated endothelium-dependent relaxations of isolated coronary arteries and, if so, to determine the underlying mechanism and the active polyphenols. A. melanocarpa juice caused potent endothelium-dependent relaxations in porcine coronary artery rings. Relaxations to A. melanocarpa juice were minimally affected by inhibition of the formation of vasoactive prostanoids and endothelium-derived hyperpolarizing factor-mediated responses, and markedly reduced by N(ω)-nitro-l-arginine (endothelial NO synthase (eNOS) inhibitor), membrane permeant analogs of superoxide dismutase and catalase, PP2 (Src kinase inhibitor), and wortmannin (PI3-kinase inhibitor). In cultured endothelial cells, A. melanocarpa juice increased the formation of NO as assessed by electron paramagnetic resonance spectroscopy using the spin trap iron(II)diethyldithiocarbamate, and reactive oxygen species using dihydroethidium. These responses were associated with the redox-sensitive phosphorylation of Src, Akt and eNOS. A. melanocarpa juice-derived fractions containing conjugated cyanidins and chlorogenic acids induced the phosphorylation of Akt and eNOS. The present findings indicate that A. melanocarpa juice is a potent stimulator of the endothelial formation of NO in coronary arteries; this effect involves the phosphorylation of eNOS via the redox-sensitive activation of the Src/PI3-kinase/Akt pathway mostly by conjugated cyanidins and chlorogenic acids.

Characterisation of Aronia powders obtained by different drying processes

Nowadays, food industry is facing challenges connected with the preservation of the highest possible quality of fruit products obtained after processing. Attention has been drawn to Aronia fruits due to numerous health promoting properties of their products. However, processing of Aronia, like other berries, leads to difficulties that stem from the preparation process, as well as changes in the composition of bioactive compounds. Consequently, in this study, Aronia commercial juice was subjected to different drying techniques: spray drying, freeze drying and vacuum drying with the temperature range of 40-80 °C. All powders obtained had a high content of total polyphenols. Powders gained by spray drying had the highest values which corresponded to a high content of total flavonoids, total monomeric anthocyanins, cyaniding-3-glucoside and total proanthocyanidins. Analysis of the results exhibited a correlation between selected bioactive compounds and their antioxidant capacity. In conclusion, drying techniques have an impact on selected quality parameters, and different drying techniques cause changes in the content of bioactives analysed. Spray drying can be recommended for preservation of bioactives in Aronia products. Powder quality depends mainly on the process applied and parameters chosen. Therefore, Aronia powders production should be adapted to the requirements and design of the final product.

Clonal differences in antioxidant activity and bioactive constituents of hardy kiwifruit (Actinidia arguta) and its year-to-year variability

BACKGROUND

Hardy kiwifruit (Actinidia arguta) is a new species, commercially grown in recent years. Total phenolics (TPC), vitamin C (TAA) content, antioxidant activity (AA) and their year-to-year variability in seven hardy kiwifruit clones were evaluated. TPC was determined using the Folin-Ciocalteu reagent assay. TAA was estimated by determination of l-ascorbic acid and l-dehydroascorbic acid levels using high-performance liquid chromatography. AA was measured using diphenyl-1-picryl-hydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and OH radicals.

RESULTS

The highest content of vitamin C, in all seasons, was found in D11 (1447-2181 mg kg(-1) fresh weight) and phenolics for D11 and M1 clones (2583-3312 and 2228-3414 mg gallic acid equivalents kg(-1) fresh weight, respectively). TPC and TAA content showed significant differences between hardy kiwifruit clones and showed significant year-to-year variability. Each year, the level of AA was significantly higher for D11 (DPPH, ABTS). AA was strongly correlated with TPC and TAA content in Actinidia fruit.

CONCLUSION

Hardy kiwifruit are an important source of vitamin C and phenolics, which resulted in their good antioxidant potential. A significantly higher content of these compounds was found in fruit of hybrid origin, which suggests that A. purpurea × A. arguta clones may be useful genetic resources for further interspecific hybridization.

Extracts, anthocyanins and procyanidins from Aronia melanocarpa as radical scavengers and enzyme inhibitors

Extracts, subfractions, isolated anthocyanins and isolated procyanidins B2, B5 and C1 from the berries and bark of Aronia melanocarpa were investigated for their antioxidant and enzyme inhibitory activities. Four different bioassays were used, namely scavenging of the diphenylpicrylhydrazyl (DPPH) radical, inhibition of 15-lipoxygenase (15-LO), inhibition of xanthine oxidase (XO) and inhibition of α-glucosidase. Among the anthocyanins, cyanidin 3-arabinoside possessed the strongest and cyanidin 3-xyloside the weakest radical scavenging and enzyme inhibitory activity. These effects seem to be influenced by the sugar units linked to the anthocyanidin. Subfractions enriched in procyanidins were found to be potent α-glucosidase inhibitors; they possessed high radical scavenging properties, strong inhibitory activity towards 15-LO and moderate inhibitory activity towards XO. Trimeric procyanidin C1 showed higher activity in the biological assays compared to the dimeric procyanidins B2 and B5. This study suggests that different polyphenolic compounds of A. melanocarpa can have beneficial effects in reducing blood glucose levels due to inhibition of α-glucosidase and may have a potential to alleviate oxidative stress.

Improved stability of chokeberry juice anthocyanins by β-cyclodextrin addition and refrigeration

Chokeberry anthocyanins are susceptible to degradation during processing and storage of processed products. This study determined the effects of three pH levels (2.8, 3.2, and 3.6) and four β-cyclodextrin (BCD) concentrations (0, 0.5, 1, and 3%) alone and in combination on the stability of chokeberry juice anthocyanins before and after pasteurization and over 8 months of storage at 4 and 25 °C. Lowering the pH from 3.6 to 2.8 in the absence of BCD provided marginal protection against anthocyanin losses during processing and storage. Addition of 3% BCD at the natural chokeberry pH of 3.6 resulted in excellent protection of anthocyanins, with 81 and 95% retentions after 8 months of storage at 25 and 4 °C, respectively. The protective effect of BCD was lessened with concentrations <3% and reduction in pH, indicating changes in anthocyanin structure play an important role in BCD stabilization of anthocyanins.

In vivo influence of extract from Aronia melanocarpa on the erythrocyte membranes in patients with hypercholesterolemia

Background

Hypercholesterolemia increases cholesterol concentration in erythrocyte membranes, which results in decrease of membrane fluidity and decreases the deformability of red blood cells. The fruits of Arona melanocarpa contains many of polyphenols and other compounds that have beneficial health effects.

Material/Methods

The aim of the study was to estimate the influence of 2-month supplementation of extract from Aronia melanocarpa (100 mg Aronox, three times per day) on cholesterol concentration, lipid peroxidation, membrane fluidity, level of thiol groups and activity of ATPase in erythrocytes from patients with hypercholesterolemia. The study involved 25 patients with hypercholesterolemia without pharmacological treatment and 20 healthy individuals as a control group. Blood samples were collected before, and after 1 and 2 months of Aronia administration.

Results

The 2-month Aronia supplementation resulted in a decrease of cholesterol concentration (by 22%) and a decrease of lipid peroxidation (by 40%), and an increase of membrane fluidity. No statistically significant increase of the concentration of thiol groups and of ATPase activity were observed.

Conclusions

Our study shows that supplementation of extract from Aronia melanocarpa has a beneficial effect on rheological properties of erythrocytes.

Antioxidant and quinone reductase-inducing constituents of black chokeberry (Aronia melanocarpa) fruits

Using in vitro hydroxyl radical-scavenging and quinone reductase-inducing assays, bioactivity-guided fractionation of an ethyl acetate-soluble extract of the fruits of the botanical dietary supplement, black chokeberry (Aronia melanocarpa), led to the isolation of 27 compounds, including a new depside, ethyl 2-[(3,4-dihydroxybenzoyloxy)-4,6-dihydroxyphenyl] acetate (1), along with 26 known compounds (2-27). The structures of the isolated compounds were identified by analysis of their physical and spectroscopic data ([α](D), NMR, IR, UV, and MS). Altogether, 17 compounds (1-4, 9, 15-17, and 19-27) showed significant antioxidant activity in the hydroxyl radical-scavenging assay, with hyperin (24, ED(50) = 0.17 μM) being the most potent. The new compound (1, ED(50) = 0.44 μM) also exhibited potent antioxidant activity in this assay. Three constituents of black chokeberry fruits doubled quinone reductase activity at concentrations <20 μM, namely, protocatechuic acid [9, concentration required to double quinone reductase activity (CD) = 4.3 μM], neochlorogenic acid methyl ester (22, CD = 6.7 μM), and quercetin (23, CD = 3.1 μM).

Antioxidant activities of chokeberry extracts and the cytotoxic action of their anthocyanin fraction on HeLa human cervical tumor cells

The present study evaluates the antioxidant activity of two Aronia melanocarpa cultivars-Viking and Aron-and of Aronia prunifolia hybrid in relationship with their phytochemical composition regarding the contents of total phenolics, flavonoids, procyanidins, and monomeric anthocyanins. The antioxidant capacity of the mentioned extracts of chokeberries was evaluated through five complementary assays: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), H(2)O(2) scavenging potential, oxygen radical absorbance capacity, ferric reducing antioxidant power, and cupric ion reducing antioxidant capacity. A. prunifolia hybrid was found to have the highest antioxidant activity and to be the richest in polyphenols, procyanidins, and anthocyanins compared with the A. melanocarpa cultivars. A good correlation was observed between antioxidant activity and total procyanidin and anthocyanin content. Cyanidin glycosides inhibited HeLa human cervical tumor cell proliferation and increased generation of reactive oxygen species after 48 h of treatment, suggesting that they could be responsible for the antiproliferative activity. These results may be significant for industry concerning food quality and disease prevention.

Phytochemical profile of a blend of black chokeberry and lemon juice with cholinesterase inhibitory effect and antioxidant potential

In this study, black chokeberry concentrate was added (5% w/v) to lemon juice, since previous reports suggested potential health benefits of this blend. The phytochemical composition, antioxidant capacity (scavenging of DPPH, superoxide and hydroxyl radicals, and hypochlorous acid), and inhibitory activity against cholinesterase of the new blend were determined and compared with those of lemon juice and chokeberry in citric acid (5%). The chokeberry concentrate, rich in cyanidin-glycosides, quercetin derivatives, and 3-O-caffeoylquinic acid, and lemon juice, possessing flavones, flavanones, quercetin derivates, and hydroxycinnamic acids, were characterised. The new drink showed a higher antioxidant effect than the chokeberry or lemon controls for all the tested methods, except for hypochlorous acid, in which lemon juice displayed higher activity. Both the lemon juice and chokeberry controls inhibited acetylcholinesterase and butyrylcholinesterase, and this effect was increased in the new mixtures. The results of the different radical scavenging assays indicate that the lemon-black chokeberry (5% w/v) mixture was more antioxidative than the respective controls separately. Moreover, their inhibition of cholinesterase is of interest regarding neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, or senile dementia.

High performance liquid chromatography analysis of anthocyanins in bilberries (Vaccinium myrtillus L.), blueberries (Vaccinium corymbosum L.), and corresponding juices

In the present study the anthocyanin content of commercially available bilberry juices and fresh fruits were quantified by using 15 authentic anthocyanin standards via high performance liquid chromatography with an ultra-violet detector (HPLC-UV/VIS). Delphinidin-3-O-glucopyranoside, delphinidin-3-O-galactopyranoside, and cyanidin-3-O-arabinopyranoside were the major anthocyanins found in juices, nectar, and fresh bilberries. In contrast, fresh blueberries had higher concentrations of malvidin-3-O-arabinopyranoside and petunidin-3-O-galactopyranoside. Up to 438 mg anthocyanins per 100 g fresh weight (2762 mg/100 g dry weight (DW)) were detected in blueberries from various sources, whereas bilberries contained a maximum of 1017 mg anthocyanins per 100 g fresh weight (7465 mg/100 g DW). Commercially available bilberry and blueberry juices (n= 9) as well as nectars (n= 4) were also analyzed. Anthocyanin concentrations of juices (1610 mg/L to 5963 mg/L) and nectar from bilberries (656 mg/L to 1529 mg/L) were higher than those of blueberry juices (417 mg/L) and nectar (258 mg/L to 386 mg/L). We conclude that using several authentic anthocyanin references to quantify anthocyanin contents indicated them to be up to 53% and 64% higher in fresh bilberries and blueberries, respectively, than previously reported using cyanidin-3-O-glucoside. This study has also demonstrated that commercially available juices produced from bilberries contain much higher anthocyanin concentrations than those from blueberries.

PRACTICAL APPLICATION

We have investigated the contents of a special class of antioxidants, namely anthocyanins in blueberry and billberry fruits and juices commercially available in Germany. To achieve reliable data we have used authentic standards for the first time. We think that our results are important in the field of nutritional intake of this important class of polyphenols and fruit juice companies get a closer insight in the occurrence of these antioxidants in market samples to be used in food composition databases and for nutritional survey.

Interaction between plant polyphenols and the erythrocyte membrane

The purpose of these studies was to determine the effect of polyphenols contained in extracts from apple, strawberry and blackcurrant on the properties of the erythrocyte membrane, treated as a model of the biological membrane. To this end, the effect of the substances used on hemolysis, osmotic resistance and shape of erythrocytes, and on packing order in the hydrophilic region of the erythrocyte membrane was studied. The investigation was performed with spectrophotometric and fluorimetric methods, and using the optical microscope. The hemolytic studies have shown that the extracts do not induce hemolysis at the concentrations used. The results obtained from the spectrophotometric measurements of osmotic resistance of erythrocytes showed that the polyphenols contained in the extracts cause an increase in the resistance, rendering them less prone to hemolysis in hypotonic solutions of sodium chloride. The fluorimetric studies indicate that the used substances cause a decrease of packing order in the hydrophilic area of membrane lipids. The observations of erythrocyte shapes in a biological optical microscope have shown that, as a result of the substances' action, the erythrocytes become mostly echinocytes, which means that the polyphenols of the extracts localize in the outer lipid monolayer of the erythrocyte membrane. The results obtained indicate that, in the concentration range used, the plant extracts are incorporated into the hydrophilic area of the membrane, modifying its properties.

Protective effect of chokeberry on chemical-induced oxidative stress in rat

Male Wistar rats were treated with chokeberry juice per os, 10 mL/kg/day, for 28 days and a single intraperitoneal (i.p.) dose of N-nitrosodiethylamine (NDEA), 150 mg/kg, or carbon tetrachloride (CCl(4)), 2 ml/kg. The level of hepatic microsomal lipid peroxidation, expressed as thiobarbituric acid reactive substances (TBARS), was increased in animals dosed with NDEA and CCl(4). Juice pretreatment resulted in a significant decrease in TBARS by 53% and 92%, respectively. In rats administered juice alone, 50% decrease in TBARS was noted. The activities of all antioxidant enzymes were decreased in the liver of rats administered either toxicant by 29%-52% as compared to controls. Juice pretreatment resulted in an increase in the activity of catalase, glutathione peroxidase and glutathione reductase by 117%, 56% and 44%, respectively, only in rats challenged with NDEA. Although no response of plasma protein carbonyls to both toxicants was observed, the pretreatment with juice caused a 55% decrease of this parameter in CCl(4)-dosed rats. DNA damage in blood leukocytes induced by either toxicant was slightly reduced, by 24%, in the rats pretreated with juice and administered NDEA. The results of the study showed that pretreatment with chokeberry juice confers some protection against chemical-induced oxidative stress.

Chokeberry (Aronia melanocarpa) juice modulates 7,12-dimethylbenz[a]anthracene induced hepatic but not mammary gland phase I and II enzymes in female rats

Chokeberry is a rich source of procyanidins known to have several types of biological activity including anticarcinogenic potential in experimental models. In this study we examined the effect of chokeberry juice on the hepatic and mammary gland carcinogen metabolizing enzyme expression altered by the polycyclic aromatic hydrocarbon, 7,12-dimethylbenz[a]anthracene (DMBA). Sprague-Dawley rats were gavaged with chokeberry juice (8 ml/kg b.w.) for 28 consecutive days. DMBA was administered i.p. on the 27th and the 28th days. Pretreatment with chokeberry juice reduced the activity of CYP1A1 and increased that of CYP2B involved in metabolic activation/detoxication of DMBA in rat liver, as well as expression and activity of phase II enzymes. Chokeberry juice had no effect on these parameters in the mammary gland and DMBA induced DNA damage in rat blood cells. These results together with our earlier observations indicate that metabolic alterations induced by chokeberry feeding are tissue specific and depend on the class of carcinogen.

Antioxidant potentials of polyphenolic extracts from leaves of trees and fruit bushes

The aim of the work was to determine the antioxidant potential of extracts from leaves of strawberry, blackcurrant and apple in relation to lipids contained in the erythrocyte membrane. The studies performed have shown that the substances used protect membrane lipids against oxidation, clearly reducing the level of free radicals in erythrocyte ghosts suspension. The antioxidant activity of the substances studied follows the sequence: strawberry leaves > apple leaves > blackcurrant leaves. The results of the research on the antioxidant activity when confronted with the contents of polyphenols in the extracts indicates that the antioxidant potentials of the extracts depend both on the quantity and kind of individual polyphenols; in particular, on the kind and quantity of quercetin derivatives that constitute over 60 % of all the phenolic compounds. Moreover, the high antioxidant activity of the extracts may be also due to other, nonphenolic substances that occur in leaves. The extracts exhibit very good properties as free radical scavenges, and can thus be used as cheap, easily available, natural antioxidants in the industries where natural antioxidants in the form of fruit extracts have been used for long.

Fruit polyphenols and CVD risk: a review of human intervention studies

Epidemiological evidence suggests that polyphenols may, in part, explain the cardioprotective properties of fruits. This review aims to summarise the evidence for the effects of fruit polyphenols on four risk factors of CVD: platelet function, blood pressure, vascular function and blood lipids. This review includes human dietary intervention studies investigating fruits and their polyphenols. There was some evidence to suggest that fruits containing relatively high concentrations of flavonols, anthocyanins and procyanindins, such as pomegranate, purple grapes and berries, were effective at reducing CVD risk factors, particularly with respect to anti-hypertensive effects, inhibition of platelet aggregation and increasing endothelial-dependent vasodilation than other fruits investigated. Flavanone-rich fruits, such as oranges and grapefruits, were reported to have hypocholesterolaemic effects, with little impact on other risk factors being examined. However, the evidence was limited, inconsistent and often inconclusive. This is in part due to the heterogeneity in the design of studies, the lack of controls, the relatively short intervention periods and low power in several studies. Details of the polyphenol content of the fruits investigated were also omitted in some studies, negating comparison of data. It is recommended that large, well-powered, long-term human dietary intervention studies investigating a wider range of fruits are required to confirm these observations. Investigations into the potential synergistic effects of polyphenols on a combination of CVD risk markers, dose-response relationships and standardisation in methodology would facilitate the comparison of studies and also provide valuable information on the types of fruits which could confer protection against CVD.

Changes Caused by Fruit Extracts in the Lipid Phase of Biological and Model Membranes

The aim of the study was to determine changes incurred by polyphenolic compounds from selected fruits in the lipid phase of the erythrocyte membrane, in liposomes formed of erythrocyte lipids and phosphatidylcholine liposomes. In particular, the effect of extracts from apple, chokeberry, and strawberry on the red blood cell morphology, on packing order in the lipid hydrophilic phase, on fluidity of the hydrophobic phase, as well as on the temperature of phase transition in DPPC liposomes was studied. In the erythrocyte population, the proportions of echinocytes increased due to incorporation of polyphenolic compounds. Fluorimetry with a laurdan probe indicated increased packing density in the hydrophilic phase of the membrane in presence of polyphenolic extracts, the highest effect being observed for the apple extract. Using the fluorescence probes DPH and TMA-DPH, no effect was noted inside the hydrophobic phase of the membrane, as the lipid bilayer fluidity was not modified. The polyphenolic extracts slightly lowered the phase transition temperature of phosphatidylcholine liposomes. The studies have shown that the phenolic compounds contained in the extracts incorporate into the outer region of the erythrocyte membrane, affecting its shape and lipid packing order, which is reflected in the increasing number of echinocytes. The compounds also penetrate the outer part of the external lipid layer of liposomes formed of natural and DPPC lipids, changing its packing order.

Preparation of dimeric procyanidins B1, B2, B5, and B7 from a polymeric procyanidin fraction of black chokeberry ( Aronia melanocarpa )

A semisynthetic approach has been used for the preparative formation of dimeric procyanidins B1, B2, B5, and B7. As starting material for the semisynthesis, polymeric procyanidins from black chokeberry were applied. These polymers were found to consist almost exclusively of (-)-epicatechin units. Under acidic conditions the interflavanoid linkages of the polymeric procyanidins are cleaved and the liberated (-)-epicatechin can react with nucleophiles, such as (+)-catechin or (-)-epicatechin. In this way, the polymeric procyanidins are degraded while dimeric procyanidins are formed. During this reaction only dimeric procyanidins are formed that contain (-)-epicatechin in the upper unit, that is, B1 [(-)-EC-4beta-->8-(+)-C)], B2 [(-)-EC-4beta-->8-(-)-EC], B5 [(-)-EC-4beta-->6-(-)-EC], and B7 [(-)-EC-4beta-->6-(+)-C]. The reaction mixtures of the semisynthesis can be successfully fractionated with high-speed countercurrent chromatography (HSCCC), and it is possible to isolate pure procyanidins B1, B2, B5, and B7 on a preparative scale.