Flavonol profiles of Vitis vinifera white grape cultivars

The flavonol profiles of a wide set of Vitis vinifera white grape cultivars were determined by HPLC–DAD–ESI-MSⁿ in order to confirm the presence of isorhamnetin-type flavonols and also to evaluate their ability for cultivar authenticity and differentiation. Only 3-O-glycoside derivatives of kaempferol, quercetin and isorhamnetin were identified as grape flavonols. The 3-O-glucosides and 3-O-galactosides of kaempferol, quercetin, and isorhamnetin, and also the 3-O-glucuronides of kaempferol and quercetin, were detected in all the grape varieties. In addition, traces of isorhamnetin 3-O-glucuronide and rutin (quercetin 3-O-(6″-rhamnosyl)-glucoside) were detected in some cases. Flavonol profiles of white grapes are dominated by quercetin-type flavonols. However, the preliminary results have shown remarkable differences (Principal Component Analysis) in the contribution of kaempferol-type flavonols to the characteristic white grape flavonol profiles, which could suggest their use for cultivar authenticity and differentiation purposes. In addition, some white grape cultivars (e.g., Pedro Ximénez, Gewürztraminer, Verdejo, Albillo, and Riesling) were characterised by relatively high and significantly different proportions of the newly reported, usually very minor, isorhamnetin-type flavonols.     

Phenolic composition of fruits from different cultivars of red and black raspberries grown in Poland

Fruits of 11 varieties of Rubus idaeus and 1 variety of Rubus occidentalis cultivated in Poland, were analyzed in terms of phenolic composition. The qualitative and quantitative determination of phenolics was performed by means of HPLC-DAD coupled with ESI–MS detector. Quantitative determination of anthocyanins, revealed significant differences in the levels of major anthocyanins in most red raspberry varieties, of which cyanidin 3-O-sophoroside was the most prevalent one. Black raspberries displayed 4–11 times more anthocyanin content compared to red raspberries, with the dominating anthocyanins being cyanidin 3-O-rutinoside and cyanidin 3-O-xylosyl-rutinoside.Sanguiin H-6 was the main ellagitannin identified in all varieties, with ‘Beskid’, ‘Laszka’, ‘Polana’ and ‘Litacz’ standing out as the richest sources of sanguiin H-6. Ellagic acid was at similar, low concentrations, with the highest levels observed in ‘Willamette’. A number of other compounds belonging to flavonols, flavan-3-ols and phenolic acids, were found at much lower levels than anthocyanins and ellagitannins, with the presence of procyanidins B₁ and B₂ being reported for the first time in the fruits of black raspberries. Data obtained on the variation in content of major and minor phenolic compounds between raspberry varieties highlights the most valuable cultivars to be used as a dietary source of phenolic compounds.     

Diversity of anthocyanins and other phenolic compounds among tropical root crops from Vanuatu, South Pacific

To study the composition and amounts of phenolic compounds in ten tropical root crop species consumed daily worldwide and particularly in South Pacific, acidified aqueous extracts were analyzed. Among 134 samples, 78 components were found. Among total peaks detected from these fractions, 3 anthocyanins (peonidin-caffeoyl-feruloylsophoroside-5-glucoside, petunidin-3-glucoside and pelargonidin-3-glucoside), 5 flavonols (hyperoside, isorhamnetin-3-glucoside, kaempferol-3-glucoside, quercetin-3-glucopyranoside and quercetin-3′-glucoside,6′-acetate), 3 flavanols (catechin, epicatechin and epicatechin-3-gallate), and 3 phenolic acids (caffeic acid, chlorogenic acid and 3,5-dicaffeoylquinic acid) were tentatively identified by HPLC-DAD. Although many compounds remain to be identified, results suggest that these tropical root crops are good sources of anthocyanins and phenolic compounds. The greater yam (Dioscorea alata) had the highest anthocyanin content (up to 93.3 mg CGE/100 g DW), while taro (Colocasia esculenta) had the widest range of flavonols (up to 326.7 mg QGE/100 g DW). Cultivars of these staples should be exploited in breeding programs for the development of varieties with enhanced health and nutritional benefits.     

Phenolic ripeness assessment of grape skin by texture analysis

The elaboration of high quality red wines requires the assessment of grape phenolic maturity by the determination of phenolic compound concentration and their extractability during winemaking process. The main aim of this work was to ascertain whether simple texture parameters, like the grape skin hardness and thickness, account for phenolic maturity of berry skin. Furthermore, the function of these grape mechanical properties in the differentiation of 13 grapevine varieties from Galicia (northwest of Spain) was studied during both 2005 and 2006 vintages. An Universal Testing Machine TAxT2i Texture Analyzer was used to carry out the texture test. Total anthocyanin concentration varied from 191 to 2660 mg kg⁻¹ fresh berry weight, while extractable anthocyanin concentration ranged from 116 to 1453 mg kg⁻¹ fresh berry weight, respectively, found in Merenzao and Loureira Tinta varieties. A significant regression was found between anthocyanin extractability, berry skin break force and thickness. Berry skin break force and energy represent meaningful variables for varietal characterization and differentiation. The toughest berry skin corresponded to the Sousón variety, while Mouratón cultivar indeed was the weakest berry skin.     

Characterization of microbial metabolism of Syrah grape products in an in vitro colon model using targeted and non-targeted analytical approaches

Purpose

Syrah red grapes are used in the production of tannin-rich red wines. Tannins are high molecular weight molecules, proanthocyanidins (PAs), and poorly absorbed in the upper intestine. In this study, gut microbial metabolism of Syrah grape phenolic compounds was investigated.

Methods

Syrah grape pericarp was subjected to an enzymatic in vitro digestion model, and red wine and grape skin PA fraction were prepared. Microbial conversion was screened using an in vitro colon model with faecal microbiota, by measurement of short-chain fatty acids by gas chromatography (GC) and microbial phenolic metabolites using GC with mass detection (GC–MS). Red wine metabolites were further profiled using two-dimensional GC mass spectrometry (GCxGC-TOFMS). In addition, the effect of PA structure and dose on conversion efficiency was investigated by GC–MS.

Results

Red wine exhibited a higher degree of C1–C3 phenolic acid formation than PA fraction or grape pericarp powders. Hydroxyphenyl valeric acid (flavanols and PAs as precursors) and 3,5-dimethoxy-4-hydroxybenzoic acid (anthocyanin as a precursor) were identified from the red wine metabolite profile. In the absence of native grape pericarp or red wine matrix, the isolated PAs were found to be effective in the dose-dependent inhibition of microbial conversions and short-chain fatty acid formation.

Conclusions

Metabolite profiling was complementary to targeted analysis. The identified metabolites had biological relevance, because the structures of the metabolites resembled fragments of their grape phenolic precursors or were in agreement with literature data.     

Development and validation of ultrasound assisted extraction (UAE) and HPLC-DAD method for determination of polyphenols in dry beans (Phaseolus vulgaris)

An analytical method for extraction and quantitative determination of the main phenolic compounds (hydroxycinnamic acids and derivatives, anthocyanins and flavonols) in dry beans (Phaseolus vulgaris) is described. The best extraction conditions were: 100% sonication amplitude, 10.3 min extraction, 46% ethanol, 1.5 g dry bean flour and 30 mL of solvent. The developed method was validated in terms of accuracy and precision. Good linearity was obtained, with correlation coefficients exceeding 0.999 and the quantification limits ranged from 0.25 μg/g (p-coumaric acid) to 1.38 μg/g (kaempferol). The accuracy ranged between 88 and 92% and the reproducibility of the method was always < 5.8% (RSD). The method was applied to a set of 17 accessions with different phenotypes. Results showed a greater presence, in all cases, of ferulic acid derivatives, compared to the sinapic acid and p-coumaric acid derivatives. Except for the white variety Xana, flavonoids were detected in all samples. Higher levels of anthocyanins were detected in Black Turtle Soup, a black bean, characterized by a higher content of delphinidin 3-O-glucoside, petunidin 3-O-glucoside and malvidin 3-O-glucoside. The flavonols showed a remarkable diversity, the 3-glucoside derivatives being the most abundant in all samples.     

Proximate composition,phenolic acids,and flavonoids characterization of commercial and wild nopal (Opuntia spp.)

The proximate composition, phenolic acid, and flavonoid characterization of two commercial and eight wild Opuntia spp., as well two processed products, were analyzed. Commercial varieties were obtained from a local market; wild varieties were collected from the Central and High Plateau zones of Mexico, and Opuntia tablets were purchased at a natural commodities store. Spines from fresh cladodes were removed and clean cladodes were freeze-dried and milled to obtain nopal powder. Differences in proximate composition were determined: wild nopal blanco collected from the High Plateau had the highest protein content, while tapon-II had the highest fiber content. Nopal tablets had low protein and carbohydrate content but had the highest ash content. The wild morado, tempranillo, blanco, and cristalino varieties had the highest total phenolic acid content, while the commercial varieties had the highest total flavonoid contents. Very low amounts of flavonoids were found in nopal tablets. LC-MS/MS was used to identify six phenolic acids (gallic, coumaric, 3,4-dihydroxybenzoic, 4-hydroxybenzoic, ferulic, and salicylic acid), and only tapon-II contained all six. The five flavonoids (iso-quercitrin, isorhamnetin-3-O-glucoside, nicotiflorin, rutin, and narcissin) were found in all varieties; nicotiflorin was predominant, followed by narcissin.     

Antiradical potential of ancient Italian apple varieties of Malus × domestica Borkh. in a peroxynitrite-induced oxidative process

Ancient apple cultivars may be an important source of genes for apple breeding programs and for the production of value-added apple cultivars. We evaluated the biochemical properties of six apple varieties grown in the Casentino area (Tuscany, Italy). Two commercial varieties (Golden Delicious and Stark Delicious) and four local varieties (Mora, Nesta, Panaia-red and Ruggine) were selected and their methanolic extracts were analysed for total phenolics and flavonoids. Moreover the content of catechin, epicatechin, rutin, chlorogenic and caffeic acid, five major phenolic constituents, was determined through HPLC-UV analysis. The radical scavenging capacity of the methanolic extracts was assessed using two in vitro tests: the blanching of the stable DPPH radical and the inhibition of tyrosine nitration induced by peroxynitrite. Three of the four local varieties had the highest content of total phenols and flavonoids. Ruggine and Panaia-red apple had the highest content of the five phenolic compounds investigated and the highest antioxidant activity towards both radicals. The commercial varieties were characterized by lower phenolic content and antioxidant activity compared to old varieties. Finally, a significant correlation between phenolic content and antioxidant activity was found.     

Total phenolic contents and free-radical scavenging activities of grape (Vitis vinifera L.) and grape products

Grape is one of the world's largest fruit crops, with an approximate annual production of 58 million metric tons, and it is well known that the grape skins, seeds and stems, waste products generated during wine and grape juice processing, are rich sources of polyphenols. It contains flavonoids, phenolic acids and stilbenes. In this study, we tried to determine antioxidant properties and phenolic contents of grape and grape products (fresh fruit, seed, dried fruit, molasses, pestil, vinegar) of ethanol and water extracts. Antioxidant properties of extracts were investigated by DPPH^√, ABTS^√+, superoxide, H₂O₂ scavenging, reducing power, metal chelating activity and determination of total phenolic contents. The seed extracts revealed highest ABTS^√+, DPPH^√, H₂O₂ scavenging and reducing power activities. Furthermore, these extracts showed higher total phenolic contents than other grape product extracts.     

Changes in the phenolic contents and composition of Persicaria odorata fresh and dried leaves

Leaves of Persicaria odorata (Polygonum odoratum), known also as Vietnamese coriander are used as a pungent additive to dishes of south-eastern Asian cuisine, where it occurs as a native species. Although the essential oil phytochemistry was exhaustively studied, no detailed research on phenolic composition has been conducted. The aim of this research was to investigate what are the main phenolics in dried and fresh leaves with the focus on flavonoids, phenolic acids, and procyanidins. Methanolic-aqueous extracts were analysed with use of HPLC-DAD-MSⁿ validated analytical method. The main compounds identified were methyl gallate (2), (+)-catechin (5), quercetin 3-O-β-D-glucuronide (25), tetrahydroxyflavonol derivative (28), and kaempferol sulfate (33). Comparisons of contents and profile of phenolics were performed.     

Polyphenol metabolic diversity of Chinese peach and nectarine at thinned and ripe stages by UPLC-ESI-Q-TOF-MS combined with multivariate statistical analysis

Peach and nectarine fruits are rich in phenolic compounds, which differ with the varieties and maturity. This study profiled the polyphenol metabolites in 7 Chinese peach and nectarine varieties at thinned and ripe stages by HPLC and UPLC-ESI-Q-TOF-MS. A total of 58 phenolic metabolites were identified in peach and nectarine. Neochlorogenic acid, catechin and chlorogenic acid were the dominant polyphenols in 7 varieties at both thinned and ripe stages. Regarding fruits at the thinned stage, phenolic acids were the major metabolic markers that distinguished 7 different peach and nectarine varieties, whereas flavonoids were the main metabolites differentiated the ripe fruit. Moreover, 3-p-coumaroyl quinic acid, 1-caffeoylquinic acid, myricetin, and kaempferol-3-o-rutinoside were the vital phenolic markers that differentiated thinned young fruit from the ripe one. There were significant differences in the polyphenol metabolic profile in different peach and nectarine varieties in different maturity stages. This work would provide a reference for further peach and nectarine phenolic metabolites investigation.     

Antioxidant activities of some Greek wines and wine phenolic extracts

Antioxidant activities and phenolic composition of eight Greek wines were determined. Red wines scavenged 1,1′-diphenyl-2-picryl-hydrazyl radical (DPPH) to a much greater degree than whites, in proportion to their phenolic contents. Red wines inhibited β-carotene bleaching, while white wines were almost inactive. Red wines were more active than quercetin in DPPH and less active in β-carotene assay. Xinomavro-red must exhibited significant activities in both assays. Roditis-white must scavenged DPPH, and exhibited some activity in β-carotene assay. Young Xinomavro and Roditis wines and their extracts were more active in scavenging DPPH than the respective aged wine and extracts. However, young Xinomavro wine and its extracts were less active than those of aged wine in β-carotene assay. Roditis wine extracts exhibited only limited activity in β-carotene assay. Xinomavro young and aged wine extracts rich in anthocyanins and flavanols were more active than the others in both assays used.     

Sigmoidal kinetics of anthocyanin accumulation during fruit ripening: A comparison between açai fruits (Euterpe oleracea) and other anthocyanin-rich fruits

Anthocyanins are natural colorants with increasing interest. Euterpe oleracea fruits (EOF) (açai) are an interesting phenolic compounds source. They are extremely rich in two anthocyanins: cyanidin-3-glucoside and cyanidin-3-rutinoside. In this study, the anthocyanin content was evaluated in EOF during their ripening, allowing to characterize very important parameters for the post-harvest industry: their maximum accumulation rate, per day, (Δy), their maximum concentration in fruits (CMAX) and the corresponding maturity class (S). Samples of 12 racemes from three plantations were collected twice a month during their ripening process. The maturity class of EOF was recorded at each harvesting and their anthocyanin content was determined by an HPLC method after solvent extraction. Anthocyanin accumulation was described (p < 0.05) by sigmoidal equations and Δy, CMAX and S values were determined. The Δy of EOF reached 35.63 mg kg⁻¹ fruits day⁻¹, whereas CMAX reached 1443 mg kg⁻¹ fruits. On average, in the beginning of maturation, both anthocyanins were present in similar proportions. However, in the last maturity stages, cyanidin-3-glucoside became less abundant than cyanidin-3-rutinoside. On the basis of the data available on strawberries, grapes, pomegranates and lychees, it was possible to verify that the sigmoidal mathematical model of anthocyanin accumulation is transposable.     

Effect of thermal processing on the profile of bioactive compounds and antioxidant capacity of fermented orange juice

Previously, we reported that alcoholic fermentation enhanced flavanones and carotenoids content of orange juice. The aim of this work was to evaluate the influence of pasteurization on the qualitative and quantitative profile of bioactive compounds and the antioxidant capacity of fermented orange juice. Ascorbic acid (203?mg/L), total flavanones (647?mg/L), total carotenoids (7.07?mg/L) and provitamin A (90.06 RAEs/L) values of pasteurized orange beverage were lower than those of fermented juice. Total phenolic remained unchanged (585?mg/L) and was similar to that of original juice. The flavanones naringenin-7-O-glucoside, naringenin-7-O-rutinoside, hesperetin-7-O-rutinoside, hesperetin-7-O-glucoside and isosakuranetin-7-O-rutinoside, and the carotenoids karpoxanthin and isomer, neochrome, lutein, ζ-carotene, zeaxanthin, mutatoxanthin epimers, β-cryptoxanthin and auroxanthin epimers were the major compounds. Pasteurization produced a decrease in antioxidant capacity of fermented juice. However, TEAC (5.45?mM) and ORAC (6353?μM) values of orange beverage were similar to those of original orange juice. The novel orange beverage could be a valuable source of bioactive compounds with antioxidant capacity and exert potential beneficial effects.     

Phenolic acids,flavonols and anthocyanins in Corema album (L.) D. Don berries

Phenolic compounds of Corema album (Ericaceae) wild edible berries were determined by LC–DAD–MS/MS. Fifteen compounds were identified and quantified, including phenolic acids (2268.1 ± 229.2 mg/kg of dried weight, DW) such as chlorogenic and neochlorogenic acids, flavonols (638.3 ± 80.1 mg/kg DW) including quercetin 3-O-hexoside and rutin, and the anthocyanins (19. 6 ± 2.4 mg/kg DW) cyanidin 3-O-glucoside, cyanidin 3-O-pentoside and delphinidin 3-O-hexoside. Phenolic acids, the main phenolic compounds in this fruit, were fractionated into their free and bound forms, and analysed by GC–MS after hydrolysis. Eleven compounds (benzoic, salicylic, t-cinnamic, p-hydroxybenzoic, vanillic, gentisic, syringic, p-coumaric, gallic, ferulic and caffeic acids) were identified on the basis of GC retention times and simultaneously recorded mass spectra, namely caffeic, benzoic, ferulic and vanillic acids as the major phenolic acids in Corema album berries.     

Catechin, epicatechin, quercetin, rutin and resveratrol in red grape: Content, in vitro antioxidant activity and interactions

The extracts obtained from skin and seeds of 10 native Tuscan and international Vitis vinifera varieties were evaluated for their antioxidant activity, total phenolic and anthocyanin content and subjected to HPLC–UV analysis to quantify the content of five phenolic constituents of biological interest: catechin and epicatechin in seeds and quercetin, rutin and resveratrol in skin extracts. The antioxidant activity of the extracts and pure compounds was assessed by means of two different in vitro tests: scavenging of the stable DPPH radical and of authentic peroxynitrite (ONOO⁻). All the extracts showed significant antiradical capacity: Merlot skin was most active towards both radicals. All the five phenols investigated possessed strong antiradical activity. Quercetin, catechin and epicatechin showed maximum activity (respectively, IC_50(DPPH) 5.5, 6.7 and 6.8 μM, IC_50(ONOO^-) 48.8, 55.7 and 56.7 μM). Potential antiradical interactive effects among the five compounds were also investigated and results indicated possible synergy between quercetin, rutin and resveratrol towards ONOO⁻. The effect was additive for catechin and epicatechin.     

Anthocyanins from the fruits of Rubus croceacanthus and Rubus sieboldii,wild berry plants from Okinawa,Japan

Anthocyanins from the fruits of Rubus croceacanthus and Rubus sieboldii, wild berries from Okinawa, Japan, were extracted using 80% methanol containing 0.5% acetic acid, and the extracts were separated by a DIAION HP-20 column. The major anthocyanins were purified by preparative HPLC and their structures were determined by NMR and MS spectrometry. Cyanidin-3-O-glucoside and pelargonidin-3-O-glucoside were identified from R. croceacanthus, and their contents were 81.44 ± 1.01 mg and 170.02 ± 4.36 mg/100 g fresh weight, respectively. Pelargonidin-3-O-glucoside and pelargonidin-3-O-rutinoside were identified from R. sieboldii, and their contents were 10.04 ± 0.34 mg and 15.08 ± 0.48 mg/100 g fresh weight, respectively. An ORAC assay indicated that the two Okinawan wild berries, especially R. croceacanthus, had potent antioxidant activity compared to raspberry (Rubus idaeus).     

Quantitative comparison of phytochemical profile,antioxidant, and anti-inflammatory properties of blackberry fruits adapted to Argentina

The phytochemical profile by HPLC-TOF-MS of three blackberry cultivars (‘Jumbo’, ‘Black Satin’ and ‘Dirksen’), adapted to the central-east of Argentina, was determined. The antioxidant capacity by DPPH and FRAP assays, and the effect of the blackberry extracts on lipopolysaccharide (LPS)-induced nitric oxide (NO) production, reactive oxygen species (ROS) production, and biomarkers of inflammation were also evaluated. ‘Dirksen’ fruits exhibited the highest vitamin C content (24 and 14% higher than values found in ‘Black Satin’ and ‘Jumbo’, respectively). However, ‘Jumbo’ and ‘Black Satin’ fruits presented higher total phenolic contents (more than 15%) than ‘Dirksen’. Cyanidin-3-O-glucoside was the main polyphenolic compound quantified in all samples. ‘Jumbo’ and ‘Black Satin’ cultivars exhibited higher antioxidant capacity, and significantly reduced the release of ROS. The mRNA expression levels of cyclooxygenase-2 (Cox-2) and interleukin-6 (IL-6) were reduced consistently (more than 30%) by extracts of both cultivars, and showed slight suppressions on NO production. However, effective inhibition in the gene expression of interleukin-1β (IL-1β) and nitric oxide synthase (iNOS) was not observed by any extract. These results suggest the potential of blackberries cultivars ‘Black Satin’ and ‘Jumbo’ to contribute to a healthy diet, based on their higher polyphenol content, providing higher antioxidant and anti-inflammatory properties.     

Flavanol–anthocyanin pigments in corn: NMR characterisation and presence in different purple corn varieties

A flavanol–anthocyanin condensed pigment was isolated from a commercial anthocyanin-rich purple corn powder and its structure elucidated by mass spectrometry and ¹H and ¹³C NMR using 1D and 2D techniques (COSY, HSQC, HMBC). The compound was unequivocally identified as the dimer catechin-(4α→8)-cyanidin-3,5-O-diglucoside. In addition, six non-processed samples belonging to different corn varieties were analysed for their anthocyanin profiles, with the aim of checking if similar condensed pigments were present in native corn. The presence of condensed pigments was found in three corn varieties, whose identity was established from their UV and mass spectra and MS² fragmentation patterns. The percentage of condensed pigments ranged between 0.3% and 3.2% of total anthocyanins. The whole of the observations made confirm that flavanol–anthocyanin condensed pigments can occur naturally in corn.     

Dietary Flavonoids Alleviate Inflammation and Vascular Endothelial Barrier Dysfunction Induced by Advanced Glycation End Products In Vitro

The aim of this study was to compare the protective effects of three dietary flavonoids (apigenin-7-O-glucoside (A7G), isorhamnetin-3-O-rutinoside (I3R), and cyanidin-3-O-glucoside (C3G)) on advanced glycation end products (AGEs)-induced inflammation and vascular endothelial dysfunction. Furthermore, the potential mechanisms of varied effects of those three dietary flavonoids were analyzed by molecular docking analysis. Results showed that C3G (40 μM) achieved the best inhibition on inflammatory cytokines (TNF-α, IL-1β, and IL-6) in AGEs-induced RAW264.7 cells, followed by I3R, and A7G was the weakest. The molecular docking results also showed that C3G exhibited the closest binding with the receptor for AGE. However, I3R (40 μM) demonstrated the best effect in improving endothelial dysfunction in AGEs-induced EA.hy926 cells, followed by C3G, and A7G was the weakest, as evidenced by the molecular docking results of flavonoids with profilin-1. This work may provide knowledge and helpful suggestions regarding the benefits of dietary flavonoids in diabetic vascular complications.