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Special Issue "Flavonoids: From Structure to Health Issues"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products".

Deadline for manuscript submissions: closed (30 September 2016)

Special Issue Editors

Guest Editor
Prof. Dr. Arturo San Feliciano

Faculty of Pharmacy, University of Salamanca, Campus Miguel de Unamuno s/n, 37007 Salamanca, Spain
Website | E-Mail
Interests: alicyclic, aromatic and heterocyclic compounds; alkaloids; coumarins; flavonoids; lignans; quinones; stilbenoids; heterostilbenoids; terpenoids; chemo-modulation and chemo-induction of bioactivity; design and synthesis of bioactive molecules
Guest Editor
Prof. Dr. Celestino Santos-Buelga

Faculty of Pharmacy, University of Salamanca, Campus Miguel de Unamuno s/n, 37007 Salamanca, Spain
Website | E-Mail
Interests: health implications of dietary flavonoids; bioavailability, metabolites and biological activity in humans; stability and reactions of anthocyanins and flavanols and their derived pigments; influence on the definition and stability of colour in food and beverages

Special Issue Information

Dear Colleagues,

Flavonoids are one of the largest groups of plant secondary metabolites. They play relevant roles in plant ecology and plant physiology and are also widely distributed in the human diet, contributing to sensory, technological and health properties of plant-derived foods. Several thousand flavonoids have been identified in natural plant sources and their number increases when considering the flavonoid-derived products that can be formed during processing and storage of foodstuffs, and the metabolites produced in the human organism after their intake. Chemical nature, structural complexity, physicochemical behaviour and concentrations of flavonoids can notably differ among plant, food and biological matrices, making their analysis challenging. A variety of biological activities, such as antioxidant, anti-inflammatory, estrogenic, antimicrobial or antitumor abilities have been reported for flavonoids. However, most of those activities have been shown in vitro, whilst studies on their actual effects in the human body and the involved mechanisms of action are scarcer. Most flavonoids are little bioavailable and largely biotransformed in the organism. In these circumstances, the ability to detect, identify and determine metabolites is crucial to understand absorption, metabolism and biological effects of flavonoids. One difficulty that has prevented progress in that knowledge is the lack of commercial flavonoid metabolites, so that the development of processes for their convenient synthesis is needed in order to be used in activity and mechanistic studies, as well as to be employed as standards in the analysis of biological samples.

Main, but not exclusive, topics to be dealt with in this Special Issue are the following:

  • current trends in the analysis of flavonoid and metabolites in plants, food and biological samples; advanced methodologies
  • structural characterization and synthesis of new compounds
  • implications in human health and validation of uses
  • biological activities, bioavailability and mechanisms of action; novel approaches to their study

We would like to invite you to participate in this Special Issue on “Flavonoids: From Structure to Health Issues” by submitting a contribution in your field of expertise. Both original research papers and global or specialized critical reviews are welcome, although the subject matter of these must be previously agreed with us.

We hope you are interested in accepting this invitation, please send an e-mail by 15 April 2016 to the Molecules Editorial Office (molecules@mdpi.com) indicating the type of contribution (research article or review) you wish to publish online, and a tentative title of your contribution, as well as its scope and coverage in the case of reviews, so as to prevent possible overlapping. The deadline for full manuscript submission is September 30th, 2016

Prof. Dr. Arturo San Feliciano
Prof. Dr. Celestino Santos-Buelga
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • new compounds
  • natural metabolites
  • flavonoid derivatives and analogues
  • advanced analysis
  • improved synthesis
  • bioactivity
  • bioavailability and pharmacokinetics
  • mechanisms of action
  • new methodologies and procedures

Published Papers (31 papers)

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Editorial

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Open AccessEditorial Flavonoids: From Structure to Health Issues
Molecules 2017, 22(3), 477; doi:10.3390/molecules22030477
Received: 16 March 2017 / Revised: 16 March 2017 / Accepted: 16 March 2017 / Published: 17 March 2017
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(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)

Research

Jump to: Editorial, Review

Open AccessArticle Inhibitory Effects of Constituents from the Aerial Parts of Rosmarinus officinalis L. on Triglyceride Accumulation
Molecules 2017, 22(1), 110; doi:10.3390/molecules22010110
Received: 10 November 2016 / Revised: 26 December 2016 / Accepted: 8 January 2017 / Published: 17 January 2017
Cited by 3 | PDF Full-text (4157 KB) | HTML Full-text | XML Full-text
Abstract
Sixteen flavonoids (116) including two new ones, named officinoflavonosides A (1) and B (2) were obtained from the aerial parts of Rosmarinus officinalis. Among the known ones, 6, 10, and 13 were
[...] Read more.
Sixteen flavonoids (116) including two new ones, named officinoflavonosides A (1) and B (2) were obtained from the aerial parts of Rosmarinus officinalis. Among the known ones, 6, 10, and 13 were isolated from the rosmarinus genus for the first time. Their structures were elucidated by chemical and spectroscopic methods. Moreover, the effects on sodium oleate-induced triglyceride accumulation (TG) in HepG2 cells of the above-mentioned compounds and 16 other isolates (1732) reported previously to have been obtained in the plant were analyzed. Results show that eight kinds of flavonoids (compounds 1, 2, 3, 69 and 11) and seven kinds of other known isolates (compounds 1720, 23, 26 and 31) possessed significant inhibitory effects on intracellular TG content in HepG2 cells. Among them, the activities of compounds 1 and 20 were comparable to that of orlistat, which suggested that these compounds in this plant might be involved in lipid metabolism. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Banana Passion Fruit (Passiflora mollissima (Kunth) L.H. Bailey): Microencapsulation, Phytochemical Composition and Antioxidant Capacity
Molecules 2017, 22(1), 85; doi:10.3390/molecules22010085
Received: 27 October 2016 / Revised: 23 December 2016 / Accepted: 27 December 2016 / Published: 17 January 2017
Cited by 3 | PDF Full-text (1791 KB) | HTML Full-text | XML Full-text
Abstract
Passiflora mollissima (Kunth) L.H. Bailey is an exotic fruit native to South America, known as taxo in Ecuador. This paper characterizes its flavonoid and carotenoid composition and antioxidant capacity and evaluates the effect of the spray-drying process on its phytochemical composition and antioxidant
[...] Read more.
Passiflora mollissima (Kunth) L.H. Bailey is an exotic fruit native to South America, known as taxo in Ecuador. This paper characterizes its flavonoid and carotenoid composition and antioxidant capacity and evaluates the effect of the spray-drying process on its phytochemical composition and antioxidant capacity. A total of 18 flavonoid compounds, nine proanthocyanidins and nine flavan-3-ol monomers, were identified and quantified. Glycosides of (epi)-afzelechin stood out as the most abundant flavonoid. Three carotenoids were identified, with β-carotene having the highest concentration. The DPPH· and ORAC assay methods indicated a high antioxidant capacity. Furthermore, the bioactive content showed a positive and direct correlation with antioxidant capacity. On the other hand, the spray-drying process produced a stable phytochemical composition and antioxidant activity of taxo. These results demonstrate the potential applicability of microencapsulated taxo as a functional ingredient in the food industry. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Kaempferol and Chrysin Synergies to Improve Septic Mice Survival
Molecules 2017, 22(1), 92; doi:10.3390/molecules22010092
Received: 16 November 2016 / Revised: 19 December 2016 / Accepted: 30 December 2016 / Published: 6 January 2017
Cited by 1 | PDF Full-text (2391 KB) | HTML Full-text | XML Full-text
Abstract
Previously, we reported the role of synergy between two flavonoids—namely, chrysin and kaempferol—in inhibiting the secretion of a few major proinflammatory mediators such as tumor necrosis factor-alpha (TNF-α), prostaglandin E2 (PGE2), and nitric oxide (NO) from lipopolysaccharide (LPS)-induced
[...] Read more.
Previously, we reported the role of synergy between two flavonoids—namely, chrysin and kaempferol—in inhibiting the secretion of a few major proinflammatory mediators such as tumor necrosis factor-alpha (TNF-α), prostaglandin E2 (PGE2), and nitric oxide (NO) from lipopolysaccharide (LPS)-induced RAW 264.7 cells. The present study aims to evaluate the effects of this combination on a murine model of polymicrobial sepsis induced by cecal ligation and puncture (CLP). Severe sepsis was induced in male ICR mice (n = 7) via the CLP procedure. The effects of chrysin and kaempferol combination treatment on septic mice were investigated using a 7-day survival study. The levels of key proinflammatory mediators and markers—such as aspartate aminotransferase (AST), TNF-α, and NO—in the sera samples of the septic mice were determined via ELISA and fluorescence determination at different time point intervals post-CLP challenge. Liver tissue samples from septic mice were harvested to measure myeloperoxidase (MPO) levels using a spectrophotometer. Moreover, intraperitoneal fluid (IPF) bacterial clearance and total leukocyte count were also assessed to detect any antibacterial effects exerted by chrysin and kaempferol, individually and in combination. Kaempferol treatment improved the survival rate of CLP-challenged mice by up to 16%. During this treatment, kaempferol expressed antibacterial, antiapoptotic and antioxidant activities through the attenuation of bacterial forming units, AST and NO levels, and increased polymorphonuclear leukocyte (PMN) count in the IPF. On the other hand, the chrysin treatment significantly reduced serum TNF-α levels. However, it failed to significantly improve the survival rate of the CLP-challenged mice. Subsequently, the kaempferol/chrysin combination treatment significantly improved the overall 7-day survival rate by 2-fold—up to 29%. Kaempferol and chrysin revealed some synergistic effects by acting individually upon multiple pathophysiological factors involved during sepsis. Although the kaempferol/chrysin combination did not exhibit significant antibacterial effects, it did exhibit anti-inflammatory and antioxidant activities, which translate to significant improvement in the survival rate of septic animals. These findings suggest the potential application of this combination treatment as a beneficial adjuvant supplement strategy in sepsis control. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Targeted Metabolomic Analysis of Polyphenols with Antioxidant Activity in Sour Guava (Psidium friedrichsthalianum Nied.) Fruit
Molecules 2017, 22(1), 11; doi:10.3390/molecules22010011
Received: 25 October 2016 / Revised: 13 December 2016 / Accepted: 16 December 2016 / Published: 23 December 2016
Cited by 1 | PDF Full-text (571 KB) | HTML Full-text | XML Full-text
Abstract
Psidium is a genus of tropical bushes belonging to the Myrtaceae family distributed in Central and South America. The polar extract of Psidium friedrichsthalianum Nied. was partitioned with ethyl ether, ethyl acetate, and n-butanol, and the total phenolic content and antioxidant activity
[...] Read more.
Psidium is a genus of tropical bushes belonging to the Myrtaceae family distributed in Central and South America. The polar extract of Psidium friedrichsthalianum Nied. was partitioned with ethyl ether, ethyl acetate, and n-butanol, and the total phenolic content and antioxidant activity were measured by Folin-Ciocalteu and ABTS assays, respectively. The ethyl acetate fraction exhibited both the highest phenolic content and antioxidant activity. Due to the complexity of this fraction, an analytical method for the comprehensive profiling of phenolic compounds was done by UPLC-ESI/QqQ in MRM (multiple reaction monitoring) mode. In this targeted analysis, 22 phenolic compounds were identified, among which several hydroxybenzoic, phenylacetic, and hydroxycinnamic acid derivatives were found. This is the first time that (+)-catechin, procyanidin B1, procyanidin B2, and (−)-epicatechin have been reported as constituents of sour guava. A fractionation by exclusion size, C18-column chromatography, and preparative RRLC (rapid resolution liquid chromatography) allowed us to confirm the presence of ellagic acid and isomeric procyanidins B, well-known bioactive compounds. The content of phenolic compounds in this fruit shows its potential for the development of functional foods. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Antioxidant Activities and Chemical Constituents of Flavonoids from the Flower of Paeonia ostii
Molecules 2017, 22(1), 5; doi:10.3390/molecules22010005
Received: 10 September 2016 / Revised: 14 December 2016 / Accepted: 16 December 2016 / Published: 23 December 2016
Cited by 1 | PDF Full-text (1084 KB) | HTML Full-text | XML Full-text
Abstract
Paeonia ostii is a traditional medicinal plant popularly used in China. This study intended to evaluate the antioxidant properties and the chemical components of the flavonoid-rich extracts from the flowers of P. ostii. The results showed that the flavonoid-rich extracts from the
[...] Read more.
Paeonia ostii is a traditional medicinal plant popularly used in China. This study intended to evaluate the antioxidant properties and the chemical components of the flavonoid-rich extracts from the flowers of P. ostii. The results showed that the flavonoid-rich extracts from the flowers of P. ostii had strong scavenging capacities on 2,2′-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS), hydroxyls, superoxide anions, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals in a dose-dependent manner. Five flavonoids, dihydrokaempferol (1), apigenin-7-O-β-d-glucoside (2), apigenin-7-O-β-d-neohesperidoside (3), kaempferol-7-O-β-d-glucopyranoside (4), and kaempferol-3-O-β-d-glucopyranosyl-7-O-β-d-glucopyranoside (5), were isolated from the flavonoid-rich extracts of the flowers of P. ostii. High-performance liquid chromatography (HPLC) analysis revealed that compounds 3 and 4 were abundant in the P. ostii flower and in flavonoid-rich extracts. The main components of the flower of P. ostii are flavonoids. The high antioxidant activity of the flavonoid-rich extracts may be attributed to the high content of flavonoids. The five isolated flavonoids were the primary antioxidant ingredients, and may play important roles in the strong antioxidant activities of this flower. Based on the obtained results, the flower of P. ostii could be a potential source of natural antioxidants in food and pharmaceutical applications. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Effects of Quercetin in a Rat Model of Hemorrhagic Traumatic Shock and Reperfusion
Molecules 2016, 21(12), 1739; doi:10.3390/molecules21121739
Received: 6 October 2016 / Revised: 30 November 2016 / Accepted: 7 December 2016 / Published: 20 December 2016
Cited by 2 | PDF Full-text (1331 KB) | HTML Full-text | XML Full-text
Abstract
Background: We hypothesized that treatment with quercetin could result in improved hemodynamics, lung inflammatory parameters and mortality in a rat model of hemorrhagic shock. Methods: Rats were anesthetized (80 mg/kg ketamine plus 8 mg/kg xylazine i.p.). The protocol included laparotomy for 15 min
[...] Read more.
Background: We hypothesized that treatment with quercetin could result in improved hemodynamics, lung inflammatory parameters and mortality in a rat model of hemorrhagic shock. Methods: Rats were anesthetized (80 mg/kg ketamine plus 8 mg/kg xylazine i.p.). The protocol included laparotomy for 15 min (trauma), hemorrhagic shock (blood withdrawal to reduce the mean arterial pressure to 35 mmHg) for 75 min and resuscitation by re-infusion of all the shed blood plus lactate Ringer for 90 min. Intravenous quercetin (50 mg/kg) or vehicle were administered during resuscitation. Results: There was a trend for increased survival 84.6% (11/13) in the treated group vs. the shock group 68.4% (13/19, p > 0.05 Kaplan–Meier). Quercetin fully prevented the development of lung edema. The activity of aSMase was increased in the shock group compared to the sham group and the quercetin prevented this effect. However, other inflammatory markers such as myeloperoxidase activity, interleukin-6 in plasma or bronchoalveolar fluid were similar in the sham and shock groups. We found no bacterial DNA in plasma in these animals. Conclusions: Quercetin partially prevented the changes in blood pressure and lung injury in shock associated to hemorrhage and reperfusion. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessFeature PaperArticle Phytochemical Profiling of Flavonoids, Phenolic Acids, Terpenoids, and Volatile Fraction of a Rosemary (Rosmarinus officinalis L.) Extract
Molecules 2016, 21(11), 1576; doi:10.3390/molecules21111576
Received: 26 October 2016 / Revised: 11 November 2016 / Accepted: 17 November 2016 / Published: 19 November 2016
Cited by 4 | PDF Full-text (1025 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a comprehensive analysis of the phytochemical profile of a proprietary rosemary (Rosmarinus officinalis L.) extract rich in carnosic acid. A characterization of the (poly)phenolic and volatile fractions of the extract was carried out using mass spectrometric techniques. The (poly)phenolic
[...] Read more.
This paper presents a comprehensive analysis of the phytochemical profile of a proprietary rosemary (Rosmarinus officinalis L.) extract rich in carnosic acid. A characterization of the (poly)phenolic and volatile fractions of the extract was carried out using mass spectrometric techniques. The (poly)phenolic composition was assessed by ultra-high performance liquid chromatography-electrospray ionization-mass spectrometry (UHPLC-ESI-MSn) and a total of 57 compounds were tentatively identified and quantified, 14 of these being detected in rosemary extract for the first time. The rosemary extract contained 24 flavonoids (mainly flavones, although flavonols and flavanones were also detected), 5 phenolic acids, 24 diterpenoids (carnosic acid, carnosol, and rosmanol derivatives), 1 triterpenoid (betulinic acid), and 3 lignans (medioresinol derivatives). Carnosic acid was the predominant phenolic compound. The volatile profile of the rosemary extract was evaluated by head space solid-phase microextraction (HS-SPME) linked to gas chromatography-mass spectrometry (GC-MS). Sixty-three volatile molecules (mainly terpenes, alcohols, esters, aldehydes, and ketones) were identified. This characterization extends the current knowledge on the phytochemistry of Rosmarinus officinalis and is, to our knowledge, the broadest profiling of its secondary metabolites to date. It can assist in the authentication of rosemary extracts or rosemary-containing products or in testing its bioactivity. Moreover, this methodological approach could be applied to the study of other plant-based food ingredients. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle The Use of Grape Seed Byproducts Rich in Flavonoids to Improve the Antioxidant Potential of Red Wines
Molecules 2016, 21(11), 1526; doi:10.3390/molecules21111526
Received: 30 September 2016 / Revised: 2 November 2016 / Accepted: 8 November 2016 / Published: 12 November 2016
Cited by 3 | PDF Full-text (1281 KB) | HTML Full-text | XML Full-text
Abstract
The influence of adding seeds from grape pomace during Syrah wine fermentation in a warm climate has been studied. Seeds of Pedro Ximenez variety were rich in phenolic compounds, mainly flavonoids such as catechin and procyanidins. Changes in total phenolic content (TPC), total
[...] Read more.
The influence of adding seeds from grape pomace during Syrah wine fermentation in a warm climate has been studied. Seeds of Pedro Ximenez variety were rich in phenolic compounds, mainly flavonoids such as catechin and procyanidins. Changes in total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of red wines were observed. These changes depended on the vinification stage and the amount of seeds (SW: 450 g or DW: 900 g seeds/150 kg grapes) applied. In general, antioxidant activity was greater when a simple dose (SW) was considered. Results indicate that seeds rich in flavonoids could be used as wine additives, which could improve the antioxidant potential of red wines in a warm climate. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Chemistry and Photochemistry of Anthocyanins and Related Compounds: A Thermodynamic and Kinetic Approach
Molecules 2016, 21(11), 1502; doi:10.3390/molecules21111502
Received: 28 September 2016 / Revised: 2 November 2016 / Accepted: 3 November 2016 / Published: 10 November 2016
Cited by 4 | PDF Full-text (3880 KB) | HTML Full-text | XML Full-text
Abstract
Anthocyanins are identified by the respective flavylium cation, which is only one species of a multistate of different molecules reversibly interconverted by external inputs such as pH, light and temperature. The flavylium cation (acidic form) is involved in an apparent acid-base reaction, where
[...] Read more.
Anthocyanins are identified by the respective flavylium cation, which is only one species of a multistate of different molecules reversibly interconverted by external inputs such as pH, light and temperature. The flavylium cation (acidic form) is involved in an apparent acid-base reaction, where the basic species is the sum of quinoidal base, hemiketal and cis- and trans-chalcones, their relative fraction depending on the substitution pattern of the flavylium cation. The full comprehension of this complex system requires a thermodynamic and kinetic approach. The first consists in drawing an energy level diagram where the relative positions of the different species are represented as a function of pH. On the other hand, the kinetic approach allows measuring the rates of the reactions that interconnect reversibly the multistate species. The kinetics is greatly dependent on the existence or not of a high cis-trans isomerization barrier. In this work, the procedure to obtain the energy level diagram and the rates of inter-conversion in the multistate in both cases (low or high isomerization barrier) are described. Practical examples of this approach are presented to illustrate the theory, and recently reported applications based on host–guest complexes are reviewed. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Flavonoids-Rich Orthosiphon stamineus Extract as New Candidate for Angiotensin I-Converting Enzyme Inhibition: A Molecular Docking Study
Molecules 2016, 21(11), 1500; doi:10.3390/molecules21111500
Received: 22 August 2016 / Revised: 26 October 2016 / Accepted: 28 October 2016 / Published: 9 November 2016
Cited by 1 | PDF Full-text (3547 KB) | HTML Full-text | XML Full-text
Abstract
This study aims to evaluate the in vitro angiotensin-converting enzyme (ACE) inhibition activity of different extracts of Orthosiphon stamineus (OS) leaves and their main flavonoids, namely rosmarinic acid (RA), sinensetin (SIN), eupatorin (EUP) and 3′-hydroxy-5,6,7,4′-tetramethoxyflavone (TMF). Furthermore, to identify possible mechanisms of action
[...] Read more.
This study aims to evaluate the in vitro angiotensin-converting enzyme (ACE) inhibition activity of different extracts of Orthosiphon stamineus (OS) leaves and their main flavonoids, namely rosmarinic acid (RA), sinensetin (SIN), eupatorin (EUP) and 3′-hydroxy-5,6,7,4′-tetramethoxyflavone (TMF). Furthermore, to identify possible mechanisms of action based on structure–activity relationships and molecular docking. The in vitro ACE inhibition activity relied on determining hippuric acid (HA) formation from ACE-specific substrate (hippuryl-histidyl-leucine (HHL)) by the action of ACE enzyme. A High Performance Liquid Chromatography method combined with UV detection was developed and validated for measurement the concentration of produced HA. The chelation ability of OS extract and its reference compounds was evaluated by tetramethylmurexide reagent. Furthermore, molecular docking study was performed by LeadIT-FlexX: BioSolveIT’s LeadIT program. OS ethanolic extract (OS-E) exhibited highest inhibition and lowest IC50 value (45.77 ± 1.17 µg/mL) against ACE compared to the other extracts. Among the tested reference compounds, EUP with IC50 15.35 ± 4.49 µg/mL had highest inhibition against ACE and binding ability with Zn (II) (56.03% ± 1.26%) compared to RA, TMF and SIN. Molecular docking studies also confirmed that flavonoids inhibit ACE via interaction with the zinc ion and this interaction is stabilized by other interactions with amino acids in the active site. In this study, we have demonstrated that changes in flavonoids active core affect their capacity to inhibit ACE. Moreover, we showed that ACE inhibition activity of flavonoids compounds is directly related to their ability to bind with zinc ion in the active site of ACE enzyme. It was also revealed that OS extract contained high amount of flavonoids other than RA, TMF, SIN and EUP. As such, application of OS extract is useful as inhibitors of ACE. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle A Fast and Robust UHPLC-MRM-MS Method to Characterize and Quantify Grape Skin Tannins after Chemical Depolymerization
Molecules 2016, 21(10), 1409; doi:10.3390/molecules21101409
Received: 30 September 2016 / Revised: 18 October 2016 / Accepted: 19 October 2016 / Published: 21 October 2016
Cited by 4 | PDF Full-text (2288 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A rapid, sensitive, and selective analysis method using ultra high performance liquid chromatography coupled with triple-quadrupole mass spectrometry (UHPLC-QqQ-MS) has been developed for the characterization and quantification of grape skin flavan-3-ols after acid-catalysed depolymerization in the presence of phloroglucinol (phloroglucinolysis). The compound detection
[...] Read more.
A rapid, sensitive, and selective analysis method using ultra high performance liquid chromatography coupled with triple-quadrupole mass spectrometry (UHPLC-QqQ-MS) has been developed for the characterization and quantification of grape skin flavan-3-ols after acid-catalysed depolymerization in the presence of phloroglucinol (phloroglucinolysis). The compound detection being based on specific MS transitions in Multiple Reaction Monitoring (MRM) mode, this fast gradient robust method allows analysis of constitutive units of grape skin proanthocyanidins, including some present in trace amounts, in a single injection, with a throughput of 6 samples per hour. This method was applied to a set of 214 grape skin samples from 107 different red and white grape cultivars grown under two conditions in the vineyard, irrigated or non-irrigated. The results of triplicate analyses confirmed the robustness of the method, which was thus proven to be suitable for high-throughput and large-scale metabolomics studies. Moreover, these preliminary results suggest that analysis of tannin composition is relevant to investigate the genetic bases of grape response to drought. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Flavonoid Interaction with a Chitinase from Grape Berry Skin: Protein Identification and Modulation of the Enzymatic Activity
Molecules 2016, 21(10), 1300; doi:10.3390/molecules21101300
Received: 1 September 2016 / Revised: 20 September 2016 / Accepted: 22 September 2016 / Published: 28 September 2016
Cited by 2 | PDF Full-text (2725 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In the present study, an antibody raised against a peptide sequence of rat bilitranslocase (anti-peptide Ab) was tested on microsomal proteins obtained from red grape berry skin. Previously, this antibody had demonstrated to recognize plant membrane proteins associated with flavonoid binding and transport.
[...] Read more.
In the present study, an antibody raised against a peptide sequence of rat bilitranslocase (anti-peptide Ab) was tested on microsomal proteins obtained from red grape berry skin. Previously, this antibody had demonstrated to recognize plant membrane proteins associated with flavonoid binding and transport. Immuno-proteomic assays identified a number of proteins reacting with this particular antibody, suggesting that the flavonoid binding and interaction may be extended not only to carriers of these molecules, but also to enzymes with very different functions. One of these proteins is a pathogenesis-related (PR) class IV chitinase, whose in vitro chitinolytic activity was modulated by two of the most representative flavonoids of grape, quercetin and catechin, as assessed by both spectrophotometric and fluorimetric assays in grape microsomes and commercial enzyme preparations. The effect of these flavonoids on the catalysis and its kinetic parameters was also evaluated, evidencing that they determine a hormetic dose-dependent response. These results highlight the importance of flavonoids not only as antioxidants or antimicrobial effectors, but also as modulators of plant growth and stress response. Implications of the present suggestion are here discussed in the light of environment and pesticide-reduction concerns. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Analysis of Flavonoids in Rhamnus davurica and Its Antiproliferative Activities
Molecules 2016, 21(10), 1275; doi:10.3390/molecules21101275
Received: 28 July 2016 / Revised: 18 September 2016 / Accepted: 21 September 2016 / Published: 23 September 2016
Cited by 5 | PDF Full-text (1748 KB) | HTML Full-text | XML Full-text
Abstract
Rhamnus davurica Pall. (R. davurica) has been used as a traditional medicinal herb for many years in China and abroad. It has been well documented as a rich source of flavonoids with diversified structures, which in turn results in far-ranging biological
[...] Read more.
Rhamnus davurica Pall. (R. davurica) has been used as a traditional medicinal herb for many years in China and abroad. It has been well documented as a rich source of flavonoids with diversified structures, which in turn results in far-ranging biological activities, such as anti-inflammation, anticancer, antibacterial and antioxidant activities. In order to further correlate their anticancer potentials with the phytochemical components, the fingerprint profile of R. davurica herb from Dongbei was firstly investigated using HPLC-ESI-MS/MS. Thirty two peaks were detected and identified, 14 of which were found in R. davurica for the first time in this work. Furthermore, a total of 23 peaks were resolved as flavonoids, which are the major components found in R. davurica. Meanwhile, the antiproliferative activities against human cancer cells of HT-29 and SGC-7901 in vitro exhibited distinct inhibitory effects with IC50 values at 24.96 ± 0.74 and 89.53 ± 4.11 μg/mL, respectively. Finally, the general toxicity against L-O2 cells displayed a much higher IC50 at 229.19 ± 8.52 μg/mL, which suggested very low or no toxicity on hepatic cell viability. The current study revealed for the first time the correlations between the flavonoids of R. davurica with their antiproliferative activities, which indicated that the fingerprint profile of flavonoids and their anticancer activities could provide valuable information on the quality control for herbal medicines and their derived natural remedies from this valuable medicinal plant. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle The Use of Mass Spectrometric Techniques to Differentiate Isobaric and Isomeric Flavonoid Conjugates from Axyris amaranthoides
Molecules 2016, 21(9), 1229; doi:10.3390/molecules21091229
Received: 27 July 2016 / Revised: 1 September 2016 / Accepted: 8 September 2016 / Published: 19 September 2016
Cited by 1 | PDF Full-text (2026 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Flavonoids are a group of compounds that are commonly found in various plants, where they play important roles in many processes, including free radical scavenging and UV protection. These compounds can also act as chemical messengers, physiological regulators or protectants against pathogens in
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Flavonoids are a group of compounds that are commonly found in various plants, where they play important roles in many processes, including free radical scavenging and UV protection. These compounds can also act as chemical messengers, physiological regulators or protectants against pathogens in the defense reactions of plants. Flavonoid activity is regulated by the addition of various substituents, usually mono- or oligosaccharides of common sugars, such as glucose, rhamnose or galactose. In some plants, glucuronic acid is attached, and this sugar is often acylated by phenylpropanoic acids. Identification of these compounds and their derivatives is of great importance to understanding their role in plant metabolism and defense mechanisms; this research is important because flavonoids are frequently a significant constituent of the human diet. In this study, we identify the flavonoid conjugates present in Axyris amaranthoides L. extracts and demonstrate the usefulness of high-resolution mass spectrometry (HRMS) analyzers for the differentiation of isobaric compounds and the utility of fragmentation spectra for the differentiation of isomeric structures. According to our knowledge, some of the structures, especially dehydrodiferulated conjugates of tricin, whose structures are proposed here have been found for the first time in plant material. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Screening of Potential Xanthine Oxidase Inhibitors in Gnaphalium hypoleucum DC. by Immobilized Metal Affinity Chromatography and Ultrafiltration-Ultra Performance Liquid Chromatography-Mass Spectrometry
Molecules 2016, 21(9), 1242; doi:10.3390/molecules21091242
Received: 22 August 2016 / Accepted: 13 September 2016 / Published: 17 September 2016
Cited by 3 | PDF Full-text (3680 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this study, a new method based on immobilized metal affinity chromatography (IMAC) combined with ultrafiltration-ultra performance liquid chromatography-mass spectrometry (UF-UPLC-MS) was developed for discovering ligands for xanthine oxidase (XO) in Gnaphalium hypoleucum DC., a folk medicine used in China for the treatment
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In this study, a new method based on immobilized metal affinity chromatography (IMAC) combined with ultrafiltration-ultra performance liquid chromatography-mass spectrometry (UF-UPLC-MS) was developed for discovering ligands for xanthine oxidase (XO) in Gnaphalium hypoleucum DC., a folk medicine used in China for the treatment of gout. By IMAC, the high flavonoid content of G. hypoleucum could be determined rapidly and efficiently. UF-UPLC-MS was used to select the bound xanthine oxidase ligands in the mixture and identify them. Finally, two flavonoids, luteolin-4′-O-glucoside and luteolin, were successfully screened and identified as the candidate XO inhibitors of G. hypoleucum. They were evaluated in vitro for XO inhibitory activity and their interaction mechanism was studied coupled with molecular simulations. The results were in favor of the hypothesis that the flavonoids of G. hypoleucum might be the active content for gout treatment by inhibiting XO. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessCommunication Three New Isoprenylated Flavonoids from the Root Bark of Morus alba
Molecules 2016, 21(9), 1112; doi:10.3390/molecules21091112
Received: 12 July 2016 / Revised: 16 August 2016 / Accepted: 19 August 2016 / Published: 24 August 2016
Cited by 2 | PDF Full-text (797 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Phytochemical investigation of the root bark of Morus alba has led to the isolation and identification of three new isoprenylated flavonoids, namely sanggenon U (1), sanggenon V (2), and sanggenon W (3), along with four known isoprenylated
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Phytochemical investigation of the root bark of Morus alba has led to the isolation and identification of three new isoprenylated flavonoids, namely sanggenon U (1), sanggenon V (2), and sanggenon W (3), along with four known isoprenylated flavonoids: euchrenone a7 (4), sanggenon J (5), kuwanon E (6), and kuwanon S (7). All compounds were isolated by repeated silica gel (SiO2), octadecyl SiO2 (ODS), and Sephadex LH-20 open column chromatography. The structure of the compounds were determined based on spectroscopic analyses, including nuclear magnetic resonance (NMR), mass spectrometry (MS), circular dichroism (CD), and infrared (IR). In addition, compounds 14 were isolated for the first time from the root bark of M. alba in this study. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Neuroprotective Effects of a Standardized Flavonoid Extract from Safflower against a Rotenone-Induced Rat Model of Parkinson’s Disease
Molecules 2016, 21(9), 1107; doi:10.3390/molecules21091107
Received: 22 April 2016 / Revised: 16 June 2016 / Accepted: 16 August 2016 / Published: 24 August 2016
Cited by 7 | PDF Full-text (4336 KB) | HTML Full-text | XML Full-text
Abstract
Parkinson’s disease (PD) is a major age-related neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra par compacta (SNpc). Rotenone is a neurotoxin that is routinely used to model PD to aid in understanding the mechanisms of neuronal death.
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Parkinson’s disease (PD) is a major age-related neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra par compacta (SNpc). Rotenone is a neurotoxin that is routinely used to model PD to aid in understanding the mechanisms of neuronal death. Safflower (Carthamus tinctorius. L.) has long been used to treat cerebrovascular diseases in China. This plant contains flavonoids, which have been reported to be effective in models of neurodegenerative disease. We previously reported that kaempferol derivatives from safflower could bind DJ-1, a protein associated with PD, and that a flavonoid extract from safflower exhibited neuroprotective effects in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced mouse model of PD. In this study, a standardized safflower flavonoid extract (SAFE) was isolated from safflower and found to primarily contain flavonoids. The aim of the current study was to confirm the neuroprotective effects of SAFE in rotenone-induced Parkinson rats. The results showed that SAFE treatment increased body weight and improved rearing behavior and grip strength. SAFE (35 or 70 mg/kg/day) treatment reversed the decreased protein expression of tyrosine hydroxylase, dopamine transporter and DJ-1 and increased the levels of dopamine and its metabolite. In contrast, acetylcholine levels were decreased. SAFE treatment also led to partial inhibition of PD-associated changes in extracellular space diffusion parameters. These changes were detected using a magnetic resonance imaging (MRI) tracer-based method, which provides novel information regarding neuronal loss and astrocyte activation. Thus, our results indicate that SAFE represents a potential therapeutic herbal treatment for PD. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Optimization of the Ultrasonic-Assisted Extraction of Bioactive Flavonoids from Ampelopsis grossedentata and Subsequent Separation and Purification of Two Flavonoid Aglycones by High-Speed Counter-Current Chromatography
Molecules 2016, 21(8), 1096; doi:10.3390/molecules21081096
Received: 28 June 2016 / Revised: 8 August 2016 / Accepted: 16 August 2016 / Published: 20 August 2016
Cited by 3 | PDF Full-text (3016 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The fermented leaf of Ampelopsis grossedentata has been used as a beverage and folk medicine called “vine tea” in the southern region of China. In this paper, the optimum extraction conditions for the maximum recovery amounts of total flavonoids (TF), dihydromyricetin (DMY), myricitrin
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The fermented leaf of Ampelopsis grossedentata has been used as a beverage and folk medicine called “vine tea” in the southern region of China. In this paper, the optimum extraction conditions for the maximum recovery amounts of total flavonoids (TF), dihydromyricetin (DMY), myricitrin (MYG) and myricetin (MY) from natural Ampelopsis grossedentata leaves subjected to ultrasonic-assisted extraction (UAE) were determined and optimized by using response surface methodology. The method was employed by the Box–Behnken design (BBD) and Derringer’s desirability function using methanol concentration, extraction time, liquid/solid ratio as factors and the contents of TF, DMY, MYG and MY as responses. The obtained optimum UAE conditions were as follows: a solvent of 80.87% methanol, an extraction time of 31.98 min and a liquid/solid ratio of 41.64:1 mL/g. Through analysis of the response surface, it implied that methanol concentration and the liquid/solid ratio had significant effects on TF, DMY, MYG and MY yields, whereas extraction time had relatively little effects. The established extraction and analytical methods were successfully applied to determine the contents of the total flavonoids and three individual flavonoids in 10 batches of the leaf samples of A. grossedentata from three counties in Fujian Province, China. The results suggested the variability in the quality of A. grossedentata leaves from different origins. In addition, high purities of dihydromyricetin and myricetin were simultaneously separated and purified from the extract subjected to optimized UAE, by high-speed counter-current chromatography using a solvent system of N-hexane–ethyl acetate–methanol–water (1:3:2:4; v/v/v/v). In a single operation, 200 mg of the extract were separated to yield 86.46 mg of dihydromyricetin and 3.61 mg of myricetin with the purity of 95.03% and 99.21%, respectively. The results would be beneficial for further exploiting the herbal products and controlling the quality of the herb and its derived products. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Rapid Isolation and Determination of Flavones in Biological Samples Using Zinc Complexation Coupled with High-Performance Liquid Chromatography
Molecules 2016, 21(8), 1067; doi:10.3390/molecules21081067
Received: 16 June 2016 / Revised: 2 August 2016 / Accepted: 9 August 2016 / Published: 16 August 2016
Cited by 2 | PDF Full-text (1935 KB) | HTML Full-text | XML Full-text
Abstract
Chlorophyll-type contaminants are commonly encountered in the isolation and determination of flavones of plant aerial plant parts. Heme is also a difficult background substance in whole blood analysis. Both chlorophyll and heme are porphyrin type compounds. In this study, a rapid method for
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Chlorophyll-type contaminants are commonly encountered in the isolation and determination of flavones of plant aerial plant parts. Heme is also a difficult background substance in whole blood analysis. Both chlorophyll and heme are porphyrin type compounds. In this study, a rapid method for isolating flavones with 5-hydroxyl or ortho-hydroxyl groups from biological samples was developed based on the different solubilities of porphyrin-metal and flavone-metal complexes. It is important that other background substances, e.g., proteins and lipids, are also removed from flavones without an additional processing. The recoveries of scutellarin, baicalin, baicalein, wogonoside and wogonin, which are the primary constituents of Scutellaria baicalensis (skullcaps) were 99.65% ± 1.02%, 98.98% ± 0.73%, 99.65% ± 0.03%, 97.59% ± 0.09% and 95.19% ± 0.47%, respectively. As a sample pretreatment procedure, this method was coupled to high-performance liquid chromatography (HPLC) with good separation, sensitivity and linearity and was applied to determine the flavone content in different aerial parts of S. baicalensis and in dried blood spot samples. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Synthesis of Natural Homoisoflavonoids Having Either 5,7-Dihydroxy-6-methoxy or 7-Hydroxy-5,6-dimethoxy Groups
Molecules 2016, 21(8), 1058; doi:10.3390/molecules21081058
Received: 14 July 2016 / Revised: 8 August 2016 / Accepted: 9 August 2016 / Published: 13 August 2016
Cited by 2 | PDF Full-text (1142 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Naturally occurring homoisoflavonoids containing either 5,7-dihydroxy-6-methoxy or 7-hydroxy-5,6-dimethoxy groups such as the antiangiogenic homoisoflavanone, cremastranone, were synthesized via three or four linear steps from the known 4-chromenone. This facile synthesis includes chemoselective 1,4-reduction of 4-chromenone and selective deprotection of 3-benzylidene-4-chromanone a containing C7-benzyloxy
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Naturally occurring homoisoflavonoids containing either 5,7-dihydroxy-6-methoxy or 7-hydroxy-5,6-dimethoxy groups such as the antiangiogenic homoisoflavanone, cremastranone, were synthesized via three or four linear steps from the known 4-chromenone. This facile synthesis includes chemoselective 1,4-reduction of 4-chromenone and selective deprotection of 3-benzylidene-4-chromanone a containing C7-benzyloxy group. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Nobiletin Induces Protective Autophagy Accompanied by ER-Stress Mediated Apoptosis in Human Gastric Cancer SNU-16 Cells
Molecules 2016, 21(7), 914; doi:10.3390/molecules21070914
Received: 10 May 2016 / Revised: 6 July 2016 / Accepted: 8 July 2016 / Published: 14 July 2016
Cited by 9 | PDF Full-text (1416 KB) | HTML Full-text | XML Full-text
Abstract
Nobiletin, a major component of citrus fruits, is a polymethoxyflavone derivative that exhibits anticancer activity against several forms of cancer, including SNU-16 human gastric cancer cells. To explore the nobiletin-induced cell death mechanism, we examined the changes in protein expression caused by nobiletin
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Nobiletin, a major component of citrus fruits, is a polymethoxyflavone derivative that exhibits anticancer activity against several forms of cancer, including SNU-16 human gastric cancer cells. To explore the nobiletin-induced cell death mechanism, we examined the changes in protein expression caused by nobiletin in human gastric cancer SNU-16 cells by means of two-dimensional gel electrophoresis (2-DGE), followed by peptide mass fingerprinting (PMF) analysis. Seventeen of 20 selected protein spots were successfully identified, including nine upregulated and eight downregulated proteins. In nobiletin-treated SNU-16 cells the glucose-regulated protein 78 kDa (GRP78) mRNA level was induced most significantly among six proteins related to cell survival and death. Western blot analysis was used to confirm the expression of GRP78 protein. We detected increases in the levels of the ER-stress related proteins inositol requiring enzyme 1 alpha (IRE1-α), activating transcription factor 4 (ATF-4), and C/EBP homology protein (CHOP), as well as GRP78, in response to nobiletin in SNU-16 cells. Furthermore, the ER stress-mediated apoptotic protein caspase-4 was proteolytically activated by nobiletin. Pretreatment with chloroquine, an autophagy inhibitor, strongly augmented apoptosis in SNU-16 cells, as evidenced by decreased cell viability, an increased number of sub-G1 phase cells and increased levels of cleaved PARP. Our results suggest that nobiletin-induced apoptosis in SNU-16 cells is mediated by pathways involving intracellular ER stress-mediated protective autophagy. Thus, the combination of nobiletin and an autophagy inhibitor could be a promising treatment for gastric cancer patients. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
Open AccessArticle Myricitrin Attenuates High Glucose-Induced Apoptosis through Activating Akt-Nrf2 Signaling in H9c2 Cardiomyocytes
Molecules 2016, 21(7), 880; doi:10.3390/molecules21070880
Received: 12 May 2016 / Revised: 26 June 2016 / Accepted: 27 June 2016 / Published: 5 July 2016
Cited by 9 | PDF Full-text (3173 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Hyperglycemia, as well as diabetes mellitus, has been shown to trigger cardiac cell apoptosis. We have previously demonstrated that myricitrin prevents endothelial cell apoptosis. However, whether myricitrin can attenuate H9c2 cell apoptosis remains unknown. In this study, we established an experiment model in
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Hyperglycemia, as well as diabetes mellitus, has been shown to trigger cardiac cell apoptosis. We have previously demonstrated that myricitrin prevents endothelial cell apoptosis. However, whether myricitrin can attenuate H9c2 cell apoptosis remains unknown. In this study, we established an experiment model in H9c2 cells exposed to high glucose. We tested the hypothesis that myricitrin may inhibit high glucose (HG)-induced cardiac cell apoptosis as determined by TUNEL staining. Furthermore, myricitrin promoted antioxidative enzyme production, suppressed high glucose-induced reactive oxygen species (ROS) production and decreased mitochondrial membrane potential (MMP) in H9c2 cells. This agent significantly inhibited apoptotic protein expression, activated Akt and facilitated the transcription of NF-E2-related factor 2 (Nrf2)-mediated protein (heme oxygenase-1 (HO-1) and quinone oxidoreductase 1 (NQO-1) expression as determined by Western blotting. Significantly, an Akt inhibitor (LY294002) or HO-1 inhibitor (ZnPP) not only inhibited myricitrin-induced HO-1/NQO-1 upregulation but also alleviated its anti-apoptotic effects. In summary, these observations demonstrate that myricitrin activates Nrf2-mediated anti-oxidant signaling and attenuates H9c2 cell apoptosis induced by high glucose via activation of Akt signaling. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Variation of the Phytochemical Constituents and Antioxidant Activities of Zingiber officinale var. rubrum Theilade Associated with Different Drying Methods and Polyphenol Oxidase Activity
Molecules 2016, 21(6), 780; doi:10.3390/molecules21060780
Received: 3 May 2016 / Revised: 27 May 2016 / Accepted: 1 June 2016 / Published: 17 June 2016
Cited by 3 | PDF Full-text (526 KB) | HTML Full-text | XML Full-text
Abstract
The effects of different drying methods (freeze drying, vacuum oven drying, and shade drying) on the phytochemical constituents associated with the antioxidant activities of Z. officinale var. rubrum Theilade were evaluated to determine the optimal drying process for these rhizomes. Total flavonoid content
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The effects of different drying methods (freeze drying, vacuum oven drying, and shade drying) on the phytochemical constituents associated with the antioxidant activities of Z. officinale var. rubrum Theilade were evaluated to determine the optimal drying process for these rhizomes. Total flavonoid content (TFC), total phenolic content (TPC), and polyphenol oxidase (PPO) activity were measured using the spectrophotometric method. Individual phenolic acids and flavonoids, 6- and 8-gingerol and shogaol were identified by ultra-high performance liquid chromatography method. Ferric reducing antioxidant potential (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays were used for the evaluation of antioxidant activities. The highest reduction in moisture content was observed after freeze drying (82.97%), followed by vacuum oven drying (80.43%) and shade drying (72.65%). The highest TPC, TFC, and 6- and 8-shogaol contents were observed in samples dried by the vacuum oven drying method compared to other drying methods. The highest content of 6- and 8-gingerol was observed after freeze drying, followed by vacuum oven drying and shade drying methods. Fresh samples had the highest PPO activity and lowest content of flavonoid and phenolic acid compounds compared to dried samples. Rhizomes dried by the vacuum oven drying method represent the highest DPPH (52.9%) and FRAP activities (566.5 μM of Fe (II)/g DM), followed by freeze drying (48.3% and 527.1 μM of Fe (II)/g DM, respectively) and shade drying methods (37.64% and 471.8 μM of Fe (II)/g DM, respectively) with IC50 values of 27.2, 29.1, and 34.8 μg/mL, respectively. Negative and significant correlations were observed between PPO and antioxidant activity of rhizomes. Vacuum oven dried rhizomes can be utilized as an ingredient for the development of value-added food products as they contain high contents of phytochemicals with valuable antioxidant potential. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Antimicrobial Activity of Xanthohumol and Its Selected Structural Analogues
Molecules 2016, 21(5), 608; doi:10.3390/molecules21050608
Received: 30 March 2016 / Revised: 27 April 2016 / Accepted: 5 May 2016 / Published: 11 May 2016
Cited by 5 | PDF Full-text (746 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The objective of this study was to evaluate the antimicrobial activity of structural analogues of xanthohumol 1, a flavonoid compound found in hops (Humulus lupulus). The agar-diffusion method using filter paper disks was applied. Biological tests performed for selected strains of
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The objective of this study was to evaluate the antimicrobial activity of structural analogues of xanthohumol 1, a flavonoid compound found in hops (Humulus lupulus). The agar-diffusion method using filter paper disks was applied. Biological tests performed for selected strains of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, fungi (Alternaria sp.), and yeasts (Rhodotorula rubra, Candida albicans) revealed that compounds with at least one hydroxyl group—all of them have it at the C-4 position—demonstrated good activity. Our research showed that the strain S. aureus was more sensitive to chalcones than to the isomers in which the heterocyclic ring C is closed (flavanones). The strain R. rubra was moderately sensitive to only one compound: 4-hydroxy-4’-methoxychalcone 8. Loss of the hydroxyl group in the B-ring of 4’-methoxychalcones or its replacement by a halogen atom (−Cl, −Br), nitro group (−NO2), ethoxy group (−OCH2CH3), or aliphatic substituent (−CH3, −CH2CH3) resulted in the loss of antimicrobial activity towards both R. rubra yeast and S. aureus bacteria. Xanthohumol 1, naringenin 5, and chalconaringenin 7 inhibited growth of S. aureus, whereas 4-hydroxy-4′-methoxychalcone 8 was active towards two strains: S. aureus and R. rubra. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessArticle Soy Isoflavones Regulate Lipid Metabolism through an AKT/mTORC1 Pathway in Diet-Induced Obesity (DIO) Male Rats
Molecules 2016, 21(5), 586; doi:10.3390/molecules21050586
Received: 22 March 2016 / Revised: 25 April 2016 / Accepted: 29 April 2016 / Published: 3 May 2016
Cited by 3 | PDF Full-text (3781 KB) | HTML Full-text | XML Full-text
Abstract
The pandemic tendency of obesity and its strong association with serious co-morbidities have elicited interest in the underlying mechanisms of these pathologies. Lipid homeostasis, closely involved in obesity, has been reported to be regulated by multiple pathways. mTORC1 is emerging as a critical
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The pandemic tendency of obesity and its strong association with serious co-morbidities have elicited interest in the underlying mechanisms of these pathologies. Lipid homeostasis, closely involved in obesity, has been reported to be regulated by multiple pathways. mTORC1 is emerging as a critical regulator of lipid metabolism. Here, we describe that the consumption of soy isoflavones, with a structural similarity to that of estradiol, could mitigate obesity through an AKT/mTORC1 pathway. Fed with soy isoflavones, the diet-induced obesity (DIO) male rats exhibited decreased body weight, accompanied with suppressed lipogenesis and adipogenesis, as well as enhanced lipolysis and β‑oxidation. The phosphorylation of AKT and S6 were decreased after soy isoflavone treatment in vivo and in vitro, suggesting an inhibition effect of soy isoflavones on mTORC1 activity. Our study reveals a potential mechanism of soy isoflavones regulating lipid homeostasis, which will be important for obesity treatment. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessReview Wine Flavonoids in Health and Disease Prevention
Molecules 2017, 22(2), 292; doi:10.3390/molecules22020292
Received: 22 November 2016 / Accepted: 10 February 2017 / Published: 14 February 2017
Cited by 7 | PDF Full-text (1021 KB) | HTML Full-text | XML Full-text
Abstract
Wine, and particularly red wine, is a beverage with a great chemical complexity that is in continuous evolution. Chemically, wine is a hydroalcoholic solution (~78% water) that comprises a wide variety of chemical components, including aldehydes, esters, ketones, lipids, minerals, organic acids, phenolics,
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Wine, and particularly red wine, is a beverage with a great chemical complexity that is in continuous evolution. Chemically, wine is a hydroalcoholic solution (~78% water) that comprises a wide variety of chemical components, including aldehydes, esters, ketones, lipids, minerals, organic acids, phenolics, soluble proteins, sugars and vitamins. Flavonoids constitute a major group of polyphenolic compounds which are directly associated with the organoleptic and health-promoting properties of red wine. However, due to the insufficient epidemiological and in vivo evidences on this subject, the presence of a high number of variables such as human age, metabolism, the presence of alcohol, the complex wine chemistry, and the wide array of in vivo biological effects of these compounds suggest that only cautious conclusions may be drawn from studies focusing on the direct effect of wine and any specific health issue. Nevertheless, there are several reports on the health protective properties of wine phenolics for several diseases such as cardiovascular diseases, some cancers, obesity, neurodegenerative diseases, diabetes, allergies and osteoporosis. The different interactions that wine flavonoids may have with key biological targets are crucial for some of these health-promoting effects. The interaction between some wine flavonoids and some specific enzymes are one example. The way wine flavonoids may be absorbed and metabolized could interfere with their bioavailability and therefore in their health-promoting effect. Hence, some reports have focused on flavonoids absorption, metabolism, microbiota effect and overall on flavonoids bioavailability. This review summarizes some of these major issues which are directly related to the potential health-promoting effects of wine flavonoids. Reports related to flavonoids and health highlight some relevant scientific information. However, there is still a gap between the knowledge of wine flavonoids bioavailability and their health-promoting effects. More in vivo results as well as studies focused on flavonoid metabolites are still required. Moreover, it is also necessary to better understand how biological interactions (with microbiota and cells, enzymes or general biological systems) could interfere with flavonoid bioavailability. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessReview An Integrated View of the Effects of Wine Polyphenols and Their Relevant Metabolites on Gut and Host Health
Molecules 2017, 22(1), 99; doi:10.3390/molecules22010099
Received: 7 November 2016 / Revised: 30 December 2016 / Accepted: 4 January 2017 / Published: 6 January 2017
Cited by 6 | PDF Full-text (1606 KB) | HTML Full-text | XML Full-text
Abstract
Over the last few decades, polyphenols, and flavonoids in particular, have attracted the interest of researchers, as they have been associated with the health-promoting effects derived from diets rich in vegetables and fruits, including moderate wine consumption. Recent scientific evidence suggests that wine
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Over the last few decades, polyphenols, and flavonoids in particular, have attracted the interest of researchers, as they have been associated with the health-promoting effects derived from diets rich in vegetables and fruits, including moderate wine consumption. Recent scientific evidence suggests that wine polyphenols exert their effects through interactions with the gut microbiota, as they seem to modulate microbiota and, at the same time, are metabolized by intestinal bacteria into specific bioavailable metabolites. Microbial metabolites are better absorbed than their precursors and may be responsible for positive health activities in the digestive system (local effects) and, after being absorbed, in tissues and organs (systemic effects). Differences in gut microbiota composition and functionality among individuals can affect polyphenol activity and, therefore, their health effects. The aim of this review is to integrate the understanding of the metabolism and mechanisms of action of wine polyphenols at both local and systemic levels, underlining their impact on the gut microbiome and the inter-individual variability associated with polyphenols’ metabolism and further physiological effects. The advent of promising dietary approaches linked to wine polyphenols beyond the gut microbiota community and metabolism are also discussed. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessReview Black Crowberry (Empetrum nigrum L.) Flavonoids and Their Health Promoting Activity
Molecules 2016, 21(12), 1685; doi:10.3390/molecules21121685
Received: 30 September 2016 / Revised: 28 November 2016 / Accepted: 28 November 2016 / Published: 7 December 2016
Cited by 3 | PDF Full-text (226 KB) | HTML Full-text | XML Full-text
Abstract
Nowadays, much research attention is focused on underutilized berry crops due to the high antioxidant activity of fruits. Black crowberry (Empetrum nigrum L.) represents an important source of flavonols (quercetin, rutin, myricetin, naringenin, naringin, morin, and kaempferol) and anthocyanins. The fruit components
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Nowadays, much research attention is focused on underutilized berry crops due to the high antioxidant activity of fruits. Black crowberry (Empetrum nigrum L.) represents an important source of flavonols (quercetin, rutin, myricetin, naringenin, naringin, morin, and kaempferol) and anthocyanins. The fruit components could be utilised as natural colourants or as a part of functional foods and, because of the high antioxidant activity, the berries of black crowberry can be used in the treatment of diseases accompanied with inflammation, or as an effective antibacterial and antifungal remedy. Moreover, the reduction of lipid accumulation and total cholesterol as well as an improvement of postprandial hyperglycaemia have been proven. This review summarizes for the first time the main antioxidants (flavonoids) of black crowberry fruits, with a focus on their health promoting activity. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
Open AccessReview Structural Characterization of Flavonoid Glycoconjugates and Their Derivatives with Mass Spectrometric Techniques
Molecules 2016, 21(11), 1494; doi:10.3390/molecules21111494
Received: 30 September 2016 / Revised: 30 October 2016 / Accepted: 31 October 2016 / Published: 8 November 2016
Cited by 3 | PDF Full-text (6485 KB) | HTML Full-text | XML Full-text
Abstract
Mass spectrometry is currently one of the most versatile and sensitive instrumental methods applied to structural characterization of plant secondary metabolite mixtures isolated from biological material including flavonoid glycoconjugates. Resolution of the applied mass spectrometers plays an important role in structural studies of
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Mass spectrometry is currently one of the most versatile and sensitive instrumental methods applied to structural characterization of plant secondary metabolite mixtures isolated from biological material including flavonoid glycoconjugates. Resolution of the applied mass spectrometers plays an important role in structural studies of mixtures of the target compounds isolated from biological material. High-resolution analyzers allow obtaining information about elemental composition of the analyzed compounds. Application of various mass spectrometric techniques, including different systems of ionization, analysis of both positive and negative ions of flavonoids, fragmentation of the protonated/deprotonated molecules and in some cases addition of metal ions to the studied compounds before ionization and fragmentation, may improve structural characterization of natural products. In our review we present different strategies allowing structural characterization of positional isomers and isobaric compounds existing in class of flavonoid glycoconjugates and their derivatives, which are synthetized in plants and are important components of the human food and drugs as well as animal feed. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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Open AccessReview Cyanidin-3-O-glucoside: Physical-Chemistry, Foodomics and Health Effects
Molecules 2016, 21(9), 1264; doi:10.3390/molecules21091264
Received: 15 August 2016 / Revised: 9 September 2016 / Accepted: 13 September 2016 / Published: 21 September 2016
Cited by 10 | PDF Full-text (2279 KB) | HTML Full-text | XML Full-text
Abstract
Anthocyanins (ACNs) are plant secondary metabolites from the flavonoid family. Red to blue fruits are major dietary sources of ACNs (up to 1 g/100 g FW), being cyanidin-3-O-glucoside (Cy3G) one of the most widely distributed. Cy3G confers a red hue to
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Anthocyanins (ACNs) are plant secondary metabolites from the flavonoid family. Red to blue fruits are major dietary sources of ACNs (up to 1 g/100 g FW), being cyanidin-3-O-glucoside (Cy3G) one of the most widely distributed. Cy3G confers a red hue to fruits, but its content in raspberries and strawberries is low. It has a good radical scavenging capacity (RSC) against superoxide but not hydroxyl radicals, and its oxidative potential is pH-dependent (58 mV/pH unit). After intake, Cy3G can be metabolized (phases I, II) by oral epithelial cells, absorbed by the gastric epithelium (1%–10%) and it is gut-transformed (phase II & microbial metabolism), reaching the bloodstream (<1%) and urine (about 0.02%) in low amounts. In humans and Caco-2 cells, Cy3G’s major metabolites are protocatechuic acid and phloroglucinaldehyde which are also subjected to entero-hepatic recycling, although caffeic acid and peonidin-3-glucoside seem to be strictly produced in the large bowel and renal tissues. Solid evidence supports Cy3G’s bioactivity as DNA-RSC, gastro protective, anti-inflammatory, anti-thrombotic chemo-preventive and as an epigenetic factor, exerting protection against Helicobacter pylori infection, age-related diseases, type 2 diabetes, cardiovascular disease, metabolic syndrome and oral cancer. Most relevant mechanisms include RSC, epigenetic action, competitive protein-binding and enzyme inhibition. These and other novel aspects on Cy3G’s physical-chemistry, foodomics, and health effects are discussed. Full article
(This article belongs to the Special Issue Flavonoids: From Structure to Health Issues)
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