The flavonoid 7-mono-O-(β-hydroxyethyl)-rutoside is able to protect endothelial cells by a direct antioxidant effect

Alfalfa Silage Diet Improves Meat Quality by Remodeling the Intestinal Microbes of Fattening Pigs

Because the demand for pork is increasing, it is crucial to devise efficient and green methods to improve the quality and quantity of meat. This study investigated the improvement in pork quality after the inclusion of alfalfa meal or alfalfa silage in pig diet. Our results indicated that alfalfa silage improved meat quality more effectively in terms of water-holding capacity, drip loss, and marbling score. Besides, an alfalfa silage diet can affect the level of fatty acids and amino acids in pork. Further, alfalfa silage was found to improve meat quality by remodeling intestinal microbiota and altering the level of SCFAs, providing a viable option for improving meat quality through forage.

Flavonoids Seen through the Energy Perspective

In all life forms, opposing forces provide the energy that flows through networks in an organism, which fuels life. In this concept, health is the ability of an organism to maintain the balance between these opposing forces, which creates resilience, and a deranged flow of energy is the basis for diseases. Treatment should focus on adjusting the deranged flow of energy, e.g., by the redox modulating activity of antioxidants. A major group of antioxidants is formed by flavonoids, a group of polyphenolic compounds abundantly present in our diet. The objective here is to review how the redox modulation by flavonoids fits in the various concepts on the mode of action of bioactive compounds, so we can 'see' where there is overlap and where the missing links are. Based on this fundament, we should choose our research path aiming to 'understand' the redox modulating profile of specific flavonoids, so we can ultimately rationally apply the redox modulating power of flavonoids to improve our health.

Chemopreventive effect of troxerutin against hydrogen peroxide-induced oxidative stress in human leukocytes through modulation of glutathione-dependent enzymes

Troxerutin is a natural flavonoid present abundantly in tea, coffee, olives, wheat, and a variety of fruits and vegetables. Due to its diverse pharmacological properties, this flavonoid has aroused interest for treatment of various diseases, and consequently prompted investigation into its toxicological characteristics. The aim of this study was to evaluate the genotoxic and mutagenic effects and chemoprotective activity attributed to troxerutin using human peripheral blood leukocytes (PBLs) through several well-established experimental protocols based upon different parameters. Data demonstrated that troxerutin (100 to 1000 µM) induced no marked cytotoxic effect on PBLs after 24 hr, and did not produce strand breaks and mutagenicity. Regarding chemoprevention, this flavonoid attenuated cytotoxicity, genotoxicity, and mutagenicity initiated by hydrogen peroxide (H₂O₂) in human PBLs. Further, troxerutin demonstrated no marked cytotoxic effect on PBLs and exerted a protective effect against oxidative stress induced by H₂O₂ through modulation of GSH-dependent enzymes.

Investigation of Chemical Composition, Antioxidant Activity, and the Effects of Alfalfa Flavonoids on Growth Performance

The flavonoids were extracted from alfalfa using ethanol assisted with ultrasonic extraction and purified by D101 macroporous resin column chromatography. The chemical composition and content of ethanol elution fractions (EEFs) were assessed by ultrahigh-performance liquid chromatography and hybrid quadrupole time of flight mass spectrometry (UHPLC-Q-TOF-MS) and aluminum nitrate-sodium nitrite-sodium hydroxide colorimetric method. The in vitro antioxidant activity of two EEFs was conducted by scavenging DPPH free radical, and the main antioxidants of 75% EEFs were screened using DPPH-UHPLC. Moreover, the in vivo antioxidant activity of 75% EEFs and the growth performance of broilers were studied. The results showed that the content of 30% and 75% EEFs was 26.20% and 62.57%. Fifteen compounds were identified from 75% EEFs, and five of them were reported in alfalfa for the first time. The scavenging activity of 75% and 30% EEFs (200 μg/mL) against DPPH was 95.51% and 78.85%. The peak area of 5,3',4'-trihydroxyflavone and hyperoside was decreased by 82.69% and 76.04%, which exhibited strong scavenging capacities. The total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-PX) level of three treated groups against the normal control group (NC) fed with basal diet significantly increased by 3.89-24.49%, 0.53-7.39%, and 0.79-11.79%, respectively. While the malondialdehyde (MDA) decreased by 0.47-18.27%. Compared with the NC, the feed to gain ratio (F : G) of three treated groups was lowered by 2.98-16.53% and survival rate of broilers significantly increased. Consequently, 75% EEFs extracted from alfalfa exhibited powerful antioxidant activities and might be a potential feed additive to poultry and livestock.

Investigation of Chemical Composition, Antioxidant Activity, and the Effects of Alfalfa Flavonoids on Growth Performance

The flavonoids were extracted from alfalfa using ethanol assisted with ultrasonic extraction and purified by D101 macroporous resin column chromatography. The chemical composition and content of ethanol elution fractions (EEFs) were assessed by ultrahigh-performance liquid chromatography and hybrid quadrupole time of flight mass spectrometry (UHPLC-Q-TOF-MS) and aluminum nitrate-sodium nitrite-sodium hydroxide colorimetric method. The in vitro antioxidant activity of two EEFs was conducted by scavenging DPPH free radical, and the main antioxidants of 75% EEFs were screened using DPPH-UHPLC. Moreover, the in vivo antioxidant activity of 75% EEFs and the growth performance of broilers were studied. The results showed that the content of 30% and 75% EEFs was 26.20% and 62.57%. Fifteen compounds were identified from 75% EEFs, and five of them were reported in alfalfa for the first time. The scavenging activity of 75% and 30% EEFs (200 μg/mL) against DPPH was 95.51% and 78.85%. The peak area of 5,3′,4′-trihydroxyflavone and hyperoside was decreased by 82.69% and 76.04%, which exhibited strong scavenging capacities. The total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-PX) level of three treated groups against the normal control group (NC) fed with basal diet significantly increased by 3.89-24.49%, 0.53-7.39%, and 0.79-11.79%, respectively. While the malondialdehyde (MDA) decreased by 0.47-18.27%. Compared with the NC, the feed to gain ratio (F : G) of three treated groups was lowered by 2.98-16.53% and survival rate of broilers significantly increased. Consequently, 75% EEFs extracted from alfalfa exhibited powerful antioxidant activities and might be a potential feed additive to poultry and livestock.

Haemodynamic effects of the flavonoid quercetin in rats revisited

Background and Purpose

The flavonoid quercetin increased the in vitro potency of the α₁‐antagonist tamsulosin to reduce phenylephrine‐dependent arterial contractions by 10‐fold. To examine if this supplement–drug interaction luxates hypotensive and orthostatic events in vivo, several set of studies were conducted in spontaneously hypertensive (SHR) and normotensive (Wistar Kyoto [WKY]) rats.

Experimental Approach

First, in rats pretreated with quercetin or its vehicle, responses to phenylephrine and tamsulosin were examined. Second, tamsulosin‐induced changes in renal, mesenteric, hindquarter and carotid conductance were compared in quercetin‐ and vehicle‐treated rats instrumented with Doppler flow probes. Animals were also placed on a tilt table to record regional haemodynamic changes to orthostatic challenges. Third, adult SHR were instrumented with telemeters to measure 24‐hr patterns of BP. Recordings were made before and during a 5‐week oral treatment of quercetin. Finally, pre‐hypertensive SHR were treated with quercetin from 4 to 8 weeks of age and arterial pressure was measured at 8 and 12 weeks.

Key Results

Pretreatment with quercetin did not influence the responses to phenylephrine and tamsulosin, in neither WKY nor SHR. While tamsulosin treatment and tilting lowered BP and increased conductance in all vascular beds, effect size was not influenced by pretreatment with quercetin. Prolonged treatment with quercetin, in either prehypertensive SHR or adult SHR with established hypertension did not lower BP.

Conclusions and Implications

Cumulatively, these data demonstrate that quercetin does not amplify haemodynamic effects of tamsulosin or tilting in vivo in rats and has no effect on BP development in SHR.

Modulation of ERK1/2 and Akt Pathways Involved in the Neurotrophic Action of Caffeic Acid Alkyl Esters

Neurodegenerative diseases affect millions of human lives all over the world. The number of afflicted patients is rapidly growing, and disease-modifying agents are urgently needed. Caffeic acid, an important member of the hydroxycinnamic acid family of polyphenols, has considerable neurotrophic effects. We have previously shown how caffeate alkyl ester derivatives significantly promote survival and differentiation in neuronal cells. In this study, the mechanisms by which these ester derivatives exert their neurotrophic effects are examined. A series of eight caffeic acid esters with different alkyl chain lengths, ranging from methyl (CAF1) to dodecyl esters (CAF8), were synthesized and studied for their influence on neurotrophic signaling pathways. Caffeate esters did not induce tropomyosin-receptor kinase A (TrkA) phosphorylation, which was assessed by immunoblotting up to a concentration of 25 µM. NIH/3T3 cells overexpressing TrkA were generated to further examine phosphorylation of this receptor tyrosine kinase. None of the esters induced TrkA phosphorylation in these cells either. Assessment of the effect of caffeate derivatives on downstream neurotrophic pathways by immunoblotting showed that the most potent esters, decyl caffeate (CAF7) and dodecyl caffeate (CAF8) caused extracellular signal-regulated kinase (ERK1/2) and Akt serine threonine kinase phosphorylation in PC12 cells at 5 and 25 µM concentrations. In conclusion, this study shows that caffeate esters exert their neurotrophic action by modulation of ERK1/2 and Akt signaling pathways in neuronal cells, and further demonstrates the potential therapeutic implications of these derivatives for neurodegenerative diseases.

The chemical reactivity of (-)-epicatechin quinone mainly resides in its B-ring

As one of the important dietary antioxidants, (-)-epicatechin is a potent reactive oxygen species (ROS) scavenger involved in the redox modulation of the cell. When scavenging ROS, (-)-epicatechin will donate two electrons and become (-)-epicatechin quinone, and thus take over part of the oxidative potential of the ROS. The aim of the study is to determine where this chemical reactivity resides in (-)-epicatechin quinone. When this reactivity is spread out over the entire molecule, i.e. over the AC-ring and B-ring, this will lead to partial epimerization of (-)-epicatechin quinone to (-)-catechin quinone. In our experiments, (-)-epicatechin quinone was generated with tyrosinase. The formation of (-)-epicatechin quinone was confirmed by trapping with GSH, and identification of (-)-epicatechin-GSH adducts. Moreover, (-)-epicatechin quinone could be detected using Q-TOF/MS despite its short half-life. To detect the epimerization, the ability of ascorbate to reduce the unstable flavonoid quinones into the corresponding stable flavonoids was used. The results showed that the reduction of the formed (-)-epicatechin quinone by ascorbate did not result in the formation of an appreciable amount of (-)-catechin. Therefore it can be concluded that the chemical reactivity of (-)-epicatechin quinone mainly resides in its B-ring. This could be corroborated by quantum chemical calculations. Understanding the stabilization of the (-)-epicatechin quinone will help to differentiate between flavonoids and to select the appropriate compound for a specific disorder.

Effects of alfalfa flavonoids extract on the microbial flora of dairy cow rumen

Objective

The effect of flavonoids from alfalfa on the microbial flora was determined using molecular techniques of 16S ribosome deoxyribonucleic acid (rDNA) analysis.

Methods

Four primiparous Holstein heifers fitted with ruminal cannulas were used in a 4×4 Latin square design and fed a total mixed ration to which alfalfa flavonoids extract (AFE) was added at the rates of 0 (A, control), 20 (B), 60 (C), or 100 (D) mg per kg of heifer BW.

Results

The number of operational taxonomic units in heifers given higher levels of flavonoid extract (C and D) was higher than for the two other treatments. The Shannon, Ace, and Chao indices for treatment C were significantly higher than for the other treatments (p<0.05). The number of phyla and genera increased linearly with increasing dietary supplementation of AFE (p<0.05). The principal co-ordinates analysis plot showed substantial differences in the microbial flora for the four treatments. The microbial flora in treatment A was similar to that in B, C, and D were similar by the weighted analysis. The richness of Tenericutes at the phylum level tended to increase with increasing AFE (p = 0.10). The proportion of Euryarchaeota at the phylum level increased linearly, whereas the proportion of Fusobacteria decreased linearly with increasing AFE supplementation (p = 0.04). The percentage of Mogibacterium, Pyramidobacter, and Asteroleplasma at the genus level decreased linearly with increasing AFE (p<0.05). The abundance of Spirochaeta, Succinivibrio, and Suttonella at the genus level tended to decrease linearly with increasing AFE (0.05<p<0.10).

Conclusion

Including AFE in the diet of dairy cows may alter the microbial composition of the rumen; however its effect on nutrient digestibility remains to be determined.

Modulation of neurotrophic signaling pathways by polyphenols

Polyphenols are an important class of phytochemicals, and several lines of evidence have demonstrated their beneficial effects in the context of a number of pathologies including neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease. In this report, we review the studies on the effects of polyphenols on neuronal survival, growth, proliferation and differentiation, and the signaling pathways involved in these neurotrophic actions. Several polyphenols including flavonoids such as baicalein, daidzein, luteolin, and nobiletin as well as nonflavonoid polyphenols such as auraptene, carnosic acid, curcuminoids, and hydroxycinnamic acid derivatives including caffeic acid phentyl ester enhance neuronal survival and promote neurite outgrowth in vitro, a hallmark of neuronal differentiation. Assessment of underlying mechanisms, especially in PC12 neuronal-like cells, reveals that direct agonistic effect on tropomyosin receptor kinase (Trk) receptors, the main receptors of neurotrophic factors including nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) explains the action of few polyphenols such as 7,8-dihydroxyflavone. However, several other polyphenolic compounds activate extracellular signal-regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K)/Akt pathways. Increased expression of neurotrophic factors in vitro and in vivo is the mechanism of neurotrophic action of flavonoids such as scutellarin, daidzein, genistein, and fisetin, while compounds like apigenin and ferulic acid increase cyclic adenosine monophosphate response element-binding protein (CREB) phosphorylation. Finally, the antioxidant activity of polyphenols reflected in the activation of Nrf2 pathway and the consequent upregulation of detoxification enzymes such as heme oxygenase-1 as well as the contribution of these effects to the neurotrophic activity have also been discussed. In conclusion, a better understanding of the neurotrophic effects of polyphenols and the concomitant modulations of signaling pathways is useful for designing more effective agents for management of neurodegenerative diseases.

The contribution of the major metabolite 4'-O-methylmonoHER to the antioxidant activity of the flavonoid monoHER

The antioxidant flavonoid 7-mono-O-(β-hydroxyethyl)-rutoside (monoHER) effectively protects against doxorubicin-induced cardiotoxicity in mice. Doxorubicin is a very effective anticancer drug. The clinical use of doxorubicin is limited by severe cardiotoxicity. Free radicals, i.e., hydroxyl and superoxide radicals play a crucial role in this toxicity. In this study the involvement of the major metabolite of monoHER, 4'-O-methylmonoHER (methylmonoHER) in the protective effect of monoHER is studied. MethylmonoHER displayed antioxidant activity i.e., TEAC, hydroxyl and superoxide radical scavenging activity; nevertheless monoHER appeared to be superior compared to methylmonoHER. As a result of scavenging, flavonoids are oxidized and display reactivity towards thiols. Oxidized methylmonoHER, is far less thiol reactive towards creatine kinase than monoHER, which indicates that methylmonoHER is less toxic towards thiol containing enzymes. The thiol-reactivity of oxidized methylmonoHER was also negligible towards KEAP1 compared to monoHER. These results indicate that methylmonoHER hardly protects against radical damage via scavenging or via activating the NRF2 defense system. Also in HUVECs, methylmonoHER provided far less protection against oxidative stress (EC50>100μM) than monoHER which was a very potent protector (EC50=80nM). The results indicate that the contribution of methylmonoHER to the protection against doxorubicin-induced cardiotoxicity by monoHER is relatively low.

WITHDRAWN: The paradox of natural flavonoid C-glycosides and health benefits: When more occurrence is less research

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Liquid chromatography with mass spectrometry method based two-step precursor ion scanning for the structural elucidation of flavonoids

Plant flavonoids are very important secondary metabolites for insect and virus control of their host plant and are potent nutrients for humans. To be able to understand the bioavailability and functions of plant flavonoids, it is necessary to reveal their exact chemical structures. Liquid chromatography with tandem mass spectrometry is a powerful approach for structural elucidation of metabolites. In this report, a two-step precursor ion scanning based liquid chromatography with tandem mass spectrometry method was developed for the structural elucidation of plant flavonoids. The established method consists of the two-step precursor ions scanning for possible flavonoids extraction, MS(2) fragment spectra acquisition and comparison with an online database, liquid chromatography retention rules correction, and commercial standards verification. The developed method was used for the structure elucidation of flavonoids in flowers and leaves of tobacco (Nicotiana tabacum), and 17 flavonoids were identified in the tobacco variety Yunyan 97. Nine of the 17 identified flavonoids were considered to be found in tobacco flowers or/and leaves for the first time based on the available references. This method was proved to be very effective and can be used for the identification of flavonoids in other plants.

Analysis of Antioxidant Properties and Major Components of the Extract of Paulownia tomentosa Steud Flowers

PaulowniatomentosaSteud flowers have been used for many therapeutic purposes in traditional pharmacopeia. The components of the extract ofPaulowniatomentosaSteud flowers were separated using ethanol elution. The antioxidant properties of different components (20% component, 40% component, 60% component, and 80% component) and synthetic antioxidants (BHA and BHT) were evaluated by scavenging DPPH, superoxide anions, and hydroxyl radical methods. All components showed strong antioxidant properties, especially the 60% component, which exhibited excellent antioxidant activity. These components may be developed for use as natural antioxidants. The main compounds in these components were identified using UPLC-TOF-MS/MS and UV spectra analysis. Two compounds, abscisic acid and t-abscisic acid, were found in the 20% component. Five compounds, t-abscisic acid, luteolin, apigenin, tricin, and 4′,5,7-trihydroxy-3′-methoxyflavone, were found in the 40% component. Three compounds, t-abscisic acid, apigenin and 4′,5,7-trihydroxy-3′-methoxyflavone, were found in the 60% component. Six compounds, luteolin, apigenin, 4′,5,7-trihydroxy-3′-methoxyflavone, paulownin, 3'-methyldiplacol, and diplacone, were found in the 80% component. The antioxidant activity of these components can be attributed to the main chemical composition of the components of the extract ofPaulowniatomentosaSteud flowers.