Production Of Quercetin Research Articles

Far infrared irradiation alters total polyphenol, total flavonoid, antioxidant property and quercetin production in tartary buckwheat sprout powder

The effects of far infrared irradiation (FIR) on total polyphenol (TP), total flavonoid (TF) content, antioxidant properties and aglycone quercetin production in tartary buckwheat sprout (TBS) were investigated. The study showed that FIR treatment decreased the total antioxidant capacity and metal chelating property in TBS in a temperature dependent manner, however, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity increased with the temperature. Similarly, TP and TF content also increased with temperature. The HPLC result revealed that quercetin production was directly proportional to the temperature, and the maximum production (average 14.8 mg/g dw) of quercetin was at 120 °C which was 13.5 times higher than the untreated control sample of TBS. Overall, this research is expected to be helpful to improve the nutritional value of tartary buckwheat by optimizing the FIR conditions.

Efficient production of flavonoids in Fagopyrum tataricum hairy root cultures with yeast polysaccharide elicitation and medium renewal process.

Background:Tartary buckwheat (Fagopyrum tataricum), an excellent edible and medicinal crop, has been widely used as a daily diet and traditional medicine for a long time. The major functional components of Fagopyrum tataricum have been demonstrated to be flavonoids (i.e. rutin and quercetin), which had notable andioxidant, antidiabetic, hypocholesterolemic and antitumor activities. Hairy root culture is a convenient and efficient plant tissue culture system for large scale production of bioactive metabolites.Objective:To enhance the functional flavonoids production in hairy root culture of F. tataricum.Materials and Methods:The elicitation treatment in combination with medium renewal strategy was applied for efficient promoting flavonoids production in F. tataricum hairy root cultures.Results:The exogenous yeast polysaccharide (YPS) elicitor notably stimulated the functional metabolites production in F. tataricum hairy root cultures, and the stimulation effect was concentration-dependent. Combination with the YPS elicitation (200 mg/L) and medium renewal process, the maximal flavonoids yield was enhanced to 47.13 mg/L, about 3.2-fold in comparison with the control culture of 14.88 mg/L. Moreover, this research also revealed the accumulation of these bioactive metabolites resulted from the stimulation of the phenylpropanoid pathway by YPS treatment. These results indicated that the F. tataricum hairy root culture could be an effective system for rutin and quercetin production.

Production of quercetin, kaempferol and their glycosidic derivatives from the aqueous-organic extracted residue of litchi pericarp with Aspergillus awamori

Our previous work exhibited Aspergillus awamori fermentation of the litchi pericarp increased significantly antioxidant activity and DNA protection effect. In this present study, the litchi pericarp and its aqueous-organic extracted residues were fermented by A. awamori in order to elucidate the enhanced beneficial effects. The study identified that rutin which present in litchi pericarp could be deglycosylated to form quercetin and quercetin-3-glucoside after the fermentation. Application the standard compounds (rutin, quercetin 3-glucoside, quercetin, kaempferol-3-glucoside and kaempferol) further revealed the effective biotransformation by A. awamori fermentation. It was hypothesised that rutin was initially dehydroxylated to form kaempferol-3-rutinoside and then deglycosylated to form kaempferol-3-glucoside and kaempferol. To our best knowledge, it is the first report on dehydroxylated effect of polyphenols caused by A. awamori fermentation. Thus, A. awamori fermentation can provide an effective way to produce health benefiting value-added products from litchi pericarp in food industry.

Drug Promiscuity in PDB: Protein Binding Site Similarity Is Key

Drug repositioning applies established drugs to new disease indications with increasing success. A pre-requisite for drug repurposing is drug promiscuity (polypharmacology) – a drug’s ability to bind to several targets. There is a long standing debate on the reasons for drug promiscuity. Based on large compound screens, hydrophobicity and molecular weight have been suggested as key reasons. However, the results are sometimes contradictory and leave space for further analysis. Protein structures offer a structural dimension to explain promiscuity: Can a drug bind multiple targets because the drug is flexible or because the targets are structurally similar or even share similar binding sites? We present a systematic study of drug promiscuity based on structural data of PDB target proteins with a set of 164 promiscuous drugs. We show that there is no correlation between the degree of promiscuity and ligand properties such as hydrophobicity or molecular weight but a weak correlation to conformational flexibility. However, we do find a correlation between promiscuity and structural similarity as well as binding site similarity of protein targets. In particular, 71% of the drugs have at least two targets with similar binding sites. In order to overcome issues in detection of remotely similar binding sites, we employed a score for binding site similarity: LigandRMSD measures the similarity of the aligned ligands and uncovers remote local similarities in proteins. It can be applied to arbitrary structural binding site alignments. Three representative examples, namely the anti-cancer drug methotrexate, the natural product quercetin and the anti-diabetic drug acarbose are discussed in detail. Our findings suggest that global structural and binding site similarity play a more important role to explain the observed drug promiscuity in the PDB than physicochemical drug properties like hydrophobicity or molecular weight. Additionally, we find ligand flexibility to have a minor influence.

Rapid screening and identification of metabolites of quercitrin produced by the human intestinal bacteria using ultra performance liquid chromatography/quadrupole-time-of-flight mass spectrometry

Ultra performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/Q-TOF MS) technique combined with Metabolynx™ software was used for analysis of the metabolites of quercitrin by the isolated human intestinal bacteria from the human feces. Four metabolites of quercitrin were detected and tentatively identified based on the characteristics of their protonated ions. The metabolites were metabolized by four main metabolic pathways including hydroxylation, demethylation, deglycosylation and ring-cleavage. Quercitrin was metabolized to the hydroxyquercitrin and desmethylquercitrin by the majority of the isolated intestinal bacteria such as Bacteroides sp. 54, and was degraded to the deglycosylated product quercetin by rhamnosidase and further ring-cleavage metabolite 3,4-dihydroxybenzoic acid by the minority of the isolated bacteria such as Bacteroides sp. 45. The metabolic pathways and most of the metabolites of quercitrin were reported for the first time.

A chip-type thin-layer electrochemical cell coupled with capillary electrophoresis for online separation of electrode reaction products

A coupling technique of thin-layer electrolysis with high-performance capillary electrophoresis/UV–vis technique(EC/HPCE/UV–vis) is developed for online separation and determination of electrode reaction products. A chip-type thin-layer electrolytic (CTE) cell was designed and fabricated, which contains a capillary channel and a background electrolyte reservoir, allowing rapid electrolysis, direct sampling and online electrophoretic separation. This chip-type setup was characterized based on an electrophoresis expression of Nernst equation that was applied to the redox equilibrium of o-tolidine at different potentials. The utility of the method was demonstrated by separating and determining the electro-oxidation products of quercetin in different pH media. Two main products were always found in the studied time, potential and pH ranges. The variety of products increased not only with increasing potential but also with increasing pH value, and in total, at least 13 products were observed in the electropherograms. This work illustrates a novel example of capillary electrophoresis used online with thin-layer electrolysis to separate and detect electrode reaction products.

Production of Bioactive Flavonol Rhamnosides by Expression of Plant Genes in Escherichia coli

Biotransformation of flavonoids using Escherichia coli harboring specific glycosyltransferases is an excellent method for the regioselective synthesis of flavonoid glycosides. Flavonol rhamnosides have been shown to contain better antiviral and antibacterial activities compared to flavonol aglycones. To synthesize flavonoid rhamnoside, a strain of E. coli expressing UDP-rhamnose flavonol glycosyltransferase (AtUGT78D1) from Arabidopsis thaliana was used to produce quercetin 3-O-rhamnoside. The biotransformation of quercetin using this E. coli transformant resulted in the production of quercetin 3-O-rhamnoside as a major product. A strain of E. coli rfbD (encoding dTDP-4-dehydrorhamnose reductase) expressing AtUGT78D1, which is involved in the final step of thymidine diphosphate rhamnose (TDP-rhamnose) biosynthesis, did not produce quercetin 3-O-rhamnoside, meaning that AtUGT78D1 used endogenous TDP-rhamnose as a sugar donor to produce quercetin 3-O-rhamnoside. The production of quercetin 3-O-rhamnoside could be increased by up to 160% by co-expressing AtUGT78D1 and rhamnose synthase gene 2 (RHM2), which catalyzes the conversion of UDP-glucose into UDP-rhamnose. Using an E. coli strain harboring AtUGT78D1 and RHM2, 150 mg/L quercetin 3-O-rhamnoside and 200 mg/L kaempferol 3-O-rhamnoside were produced in 48 h.

Anti-inflammatory effect of quercetin in a whole orbital tissue culture of Graves' orbitopathy

PurposeThe authors previously reported that quercetin significantly inhibits interleukin (IL)-1β-induced increases of proinflammatory cytokines in cultured primary orbital fibroblasts from Graves' orbitopathy (GO). This study investigated the inhibitory effect of...

Isolation and screening of strains producing high amounts of rutin degrading enzymes from Fagopyrum tataricum seeds

The rutin degrading enzyme (RDE) was isolated and purified from tartary buckwheat seeds. The RDE was purified about 11.34-fold and its final yield was 3.5%, which was very low, due to our purification strategy of giving priority to purity over yield. The RDE molecular weight was estimated to be about 60 kDa. When rutin was used as substrate, an optimal enzyme activity was seen at around pH 5.0 and 40 °C. Strains isolation strategy characterized by the use of rutin as sole carbon source in enrichment cultures was used to isolate RDE-producing strains. Then the active strains were identified by morphology characterization and 18s rDNA-ITS (Internal Transcribed Spacer) gene sequencing. Three isolates coded as B3, W2, Y2 were successfully isolated from fusty Fagopyrum tataricum flour cultures. Strain B3 possessed the highest unit activity among these three strains, and its total activity reached up to 171.0 Unit. The active isolate (B3) could be assigned to Penicillium farinosum. When the Penicillium farinosum strains were added to tartary buckwheat flour cultures at pH 5.0, 30 °C after 5 days fermentation, the quercetin production raised up to 1.78 mg/l, almost 5.1 times higher than the fermentation without the above active strains. Hence, a new approach was available to utilize microorganism-aided fermentation for effective quercetin extraction from Fagopyrum tataricum seeds.

Production of a Novel Quercetin Glycoside through Metabolic Engineering of Escherichia coli

Most flavonoids exist as sugar conjugates. Naturally occurring flavonoid sugar conjugates include glucose, galactose, glucuronide, rhamnose, xylose, and arabinose. These flavonoid glycosides have diverse physiological activities, depending on the type of sugar attached. To synthesize an unnatural flavonoid glycoside, Actinobacillus actinomycetemcomitans gene tll (encoding dTDP-6-deoxy-L-lyxo-4-hexulose reductase, which converts the endogenous nucleotide sugar dTDP-4-dehydro-6-deoxy-L-mannose to dTDP-6-deoxytalose) was introduced into Escherichia coli. In addition, nucleotide-sugar dependent glycosyltransferases (UGTs) were screened to find a UGT that could use dTDP-6-deoxytalose. Supplementation of this engineered strain of E. coli with quercetin resulted in the production of quercetin-3-O-(6-deoxytalose). To increase the production of quercetin 3-O-(6-deoxytalose) by increasing the supplement of dTDP-6-deoxytalose in E. coli, we engineered nucleotide biosynthetic genes of E. coli, such as galU (UTP-glucose 1-phosphate uridyltransferase), rffA (dTDP-4-oxo-6-deoxy-d-glucose transaminase), and/or rfbD (dTDP-4-dehydrorahmnose reductase). The engineered E. coli strain produced approximately 98 mg of quercetin 3-O-(6-deoxytalose)/liter, which is 7-fold more than that produced by the wild-type strain, and the by-products, quercetin 3-O-glucose and quercetin 3-O-rhamnose, were also significantly reduced.

Biological synthesis of quercetin 3-O-N-acetylglucosamine conjugate using engineered Escherichia coli expressing UGT78D2

Biotransformation of flavonoids using Escherichia coli harboring nucleotide sugar-dependent uridine diphosphate-dependent glycosyltransferases (UGTs) commonly results in the production of a glucose conjugate because most UGTs are specific for UDP-glucose. The Arabidopsis enzyme AtUGT78D2 prefers UDP-glucose as a sugar donor and quercetin as a sugar acceptor. However, in vitro, AtUGT78D2 could use UDP-N-acetylglucosamine as a sugar donor, and whole cell biotransformation of quercetin using E. coli harboring AtUGT78D2 produced quercetin 3-O-N-acetylglucosamine. In order to increase the production of quercetin 3-O-N-acetylglucosamine via biotransformation, two E. coli mutant strains deleted in phosphoglucomutase (pgm) or glucose-1-phosphate uridylyltransferase (galU) were created. The galU mutant produced up to threefold more quercetin 3-O-N-acetylglucosamine than wild type, resulting in the production of 380-mg/l quercetin 3-O-N-acetylglucosamine and a negligible amount of quercetin 3-O-glucoside. These results show that construction of bacterial strains for the synthesis of unnatural flavonoid glycosides is possible through rational selection of the nucleotide sugar-dependent glycosyltransferase and engineering of the nucleotide sugar metabolic pathway in the host strain.

Quercetin production from rutin by a thermostable β-rutinosidase from Pyrococcus furiosus

Pyrococcus furiosus β-glucosidase converted rutin to quercetin and rutinose disaccharide with a ratio of 1:1, with no glucose, L-rhamnose, and isoquercitrin, indicating that the enzyme is a β-rutinosidase. The specific activity for flavonoid glycosides followed the order of isoquercitrin > quercitrin > rutin. The conversion of rutin to quercetin was optimal at pH 5.0 and 95°C in the presence of 0.5% dimethyl sulfoxide with a half-life of 101 h, a k(cat) of 1.6 min(-1), and a K(m) of 0.3 mM. Under the improved conditions, the enzyme produced 6.5 mM quercetin from 10 mM rutin after 150 min, with a molar yield of 65% and a productivity of 2.6 mM/h. This productivity is the highest reported thus far among enzymatic transformations.

Quercetin Inhibits IL-1β-Induced Inflammation, Hyaluronan Production and Adipogenesis in Orbital Fibroblasts from Graves' Orbitopathy

Management of Graves' orbitopathy (GO) is challenging, as no reliable, specific, and safe medical therapeutic agents have yet been developed. We investigated the effect of quercetin in primary cultured orbital fibroblasts from GO, targeting pathways of inflammation, aberrant accumulation of extracellular matrix macromolecules, and adipose tissue expansion. Quercetin significantly attenuated intercellular adhesion molecule-1 (ICAM-1), interleukin (IL) -6, IL-8, and cyclooxygenase (COX) -2 mRNA expression, and inhibited IL-1β-induced increases in ICAM-1, IL-6, and IL-8 mRNA. Increased hyaluronan production induced by IL-1β or tumor necrosis factor-α was suppressed by quercetin in a dose- and time-dependent manner. Treatment with noncytotoxic doses of quercetin inhibited accumulation of intracytoplasmic lipid droplets and resulted in a dose-dependent decrease in expression of peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein (C/EBP) α, and C/EBPβ proteins. In conclusion, inhibition of inflammation, hyaluronan production, and adipogenesis by the natural plant product quercetin in vitro provides the basis for further study of its potential use in the treatment of GO.

Production of adventitious root biomass and secondary metabolites of Hypericum perforatum L. in a balloon type airlift reactor

The effects of inoculum density, aeration volume and culture period on accumulation of biomass and secondary metabolites in adventitious roots of Hypericum perforatum in balloon type airlift bioreactors (3l capacity) were investigated. The greatest increment of biomass as well as metabolite content occurred at an inoculum density of 3gl−1 and an aeration volume of 0.1vvm. After 6weeks of culture, an approximately 50-fold increase in biomass was recorded containing 60.11mgg−1 dry weight (DW) of phenolics, 42.7mgg−1 DW of flavonoids and 0.80mgg−1 DW of chlorogenic acid. Liquid chromatography–mass spectroscopy/mass spectroscopy demonstrated that the presence of quercetin and hyperoside in adventitious roots at a level of 1.33 and 14.01μgg−1 DW, respectively after 6weeks of culture. The results suggest scale-up of adventitious root culture of H. perforatum for the production of chlorogenic acid, quercetin and hyperoside is feasible.

An Essential Difference between the Flavonoids MonoHER and Quercetin in Their Interplay with the Endogenous Antioxidant Network

Antioxidants can scavenge highly reactive radicals. As a result the antioxidants are converted into oxidation products that might cause damage to vital cellular components. To prevent this damage, the human body possesses an intricate network of antioxidants that pass over the reactivity from one antioxidant to another in a controlled way. The aim of the present study was to investigate how the semi-synthetic flavonoid 7-mono-O-(β-hydroxyethyl)-rutoside (monoHER), a potential protective agent against doxorubicin-induced cardiotoxicity, fits into this antioxidant network. This position was compared with that of the well-known flavonoid quercetin. The present study shows that the oxidation products of both monoHER and quercetin are reactive towards thiol groups of both GSH and proteins. However, in human blood plasma, oxidized quercetin easily reacts with protein thiols, whereas oxidized monoHER does not react with plasma protein thiols. Our results indicate that this can be explained by the presence of ascorbate in plasma; ascorbate is able to reduce oxidized monoHER to the parent compound monoHER before oxidized monoHER can react with thiols. This is a major difference with oxidized quercetin that preferentially reacts with thiols rather than ascorbate. The difference in selectivity between monoHER and quercetin originates from an intrinsic difference in the chemical nature of their oxidation products, which was corroborated by molecular quantum chemical calculations. These findings point towards an essential difference between structurally closely related flavonoids in their interplay with the endogenous antioxidant network. The advantage of monoHER is that it can safely channel the reactivity of radicals into the antioxidant network where the reactivity is completely neutralized.

ChemInform Abstract: Synthesis and Protein-Tyrosine Kinase Inhibitory Activities of Flavonoid Analogues.

Treatment of o-hydroxyacetophenones 2a-e with excess lithium bis(trimethylsilyl)amide followed by dialkyl carbonates gave alkyl 3-(2-hydroxyaryl)-3-oxopropanoates 3a-e. The latter substances were transformed through the reaction of their magnesium chelates with benzoyl chlorides into a series of 3-(alkoxycarbonyl)-2-arylflavones, which were subsequently elaborated into a variety of flavonoids. These compounds were tested for their abilities to inhibit the in vitro protein-tyrosine kinase activity of p56lck, an enzyme which is thought to play a key role in mediating signal transduction from the CD4 receptor during lymphocyte activation. All of the active compounds had either an amino or a hydroxyl substituent at the 4'-position of the 2-aryl ring. The most active substance prepared in this study is compound 17c, which is approximately 1 order of magnitude more potent than the natural product quercetin (1). Compound 17c was a competitive inhibitor of p56lck with respect to ATP and was highly selective for the inhibition of protein-tyrosine over protein-serine/threonine kinases.

UVA and UVB radiation-induced oxidation products of quercetin

The flavonol quercetin is believed to provide protection against ultraviolet (UV) radiation-induced damage in plants. As part of our investigations into the potential for quercetin to protect skin against UV radiation-induced damage we have investigated the products of quercetin exposed to UV radiation in vitro. UVA (740 μW cm −2 at 365 nm) or UVB (1300 μW cm −2 at 310 nm) irradiation of quercetin in methanol results in a small conversion (less than 20%) to C-ring breakdown products over 11 h. When the triplet sensitizer benzophenone is added, greater than 90% conversion by UVA or UVB occurs within 1 h. The major photoproducts from either UVA or UVB radiation are 2,4,6-trihydroxybenzaldehyde ( 1), 2-(3′,4′-dihydroxybenzoyloxy)-4,6-dihydroxybenzoic acid ( 2) and 3,4-dihydroxyphenylethanol ( 3). Product 2 has previously been observed as a product of oxidative metabolism of quercetin, however products 1 and 3 appear to be the result of a unique UV-dependent pathway. In conclusion we have determined that quercetin undergoes slow decomposition to a mixture of C-ring-opened products, two of which to our knowledge have not been previously observed for quercetin decomposition, and that the presence of a triplet sensitizer greatly increases UV radiation-mediated quercetin decomposition. The presence of endogenous photosensitizers in the skin could potentially affect the UV stability of quercetin, suggesting that further study of quercetin for both its photoprotective properties and photostabilty in skin are warranted.

PAR modulation of the UV-dependent levels of flavonoid metabolites in Arabidopsis thaliana (L.) Heynh. leaf rosettes: cumulative effects after a whole vegetative growth period

Long-term effects of ultraviolet (UV) radiation on flavonoid biosynthesis were investigated in Arabidopsis thaliana using the sun simulators of the Helmholtz Zentrum München. The plants, which are widely used as a model system, were grown (1) at high photosynthetically active radiation (PAR; 1,310 micromol m(-2) s(-1)) and high biologically effective UV irradiation (UV-B(BE) 180 mW m(-2)) during a whole vegetative growth period. Under this irradiation regime, the levels of quercetin products were distinctively elevated with increasing UV-B irradiance. (2) Cultivation at high PAR (1,270 micromol m(-2) s(-1)) and low UV-B (UV-B(BE) 25 mW m(-2)) resulted in somewhat lower levels of quercetin products compared to the high-UV-B(BE) conditions, and only a slight increase with increasing UV-B irradiance was observed. On the other hand, when the plants were grown (3) at low PAR (540 micromol m(-2) s(-1)) and high UV-B (UV-B(BE) 180 mW m(-2)), the accumulation of quercetin products strongly increased from very low levels with increasing amounts of UV-B but the accumulation of kaempferol derivatives and sinapoyl glucose was less pronounced. We conclude (4) that the accumulation of quercetin products triggered by PAR leads to a basic UV protection that is further increased by UV-B radiation. Based on our data, (5) a combined effect of PAR and different spectral sections of UV radiation is satisfactorily described by a biological weighting function, which again emphasizes the additional role of UV-A (315-400 nm) in UV action on A. thaliana.

Indução de metabólitos secundários em plântulas de Hypericum brasiliense Choisy crescendo in vitro

A produção de rutina, quercetina, 1,5-diidroxixantona e ácido betulínico foi investigada em plântulas de H. brasiliense crescendo in vitro, sob a influência de ácido salicílico, polietilenoglicol, NaCl, 24-epibrassinolídeo, benzotiadiazole (BION), metiljasmonato e concentrações aumentadas de boro e nitrogênio no meio líquido de cultura. As avaliações foram feitas após 5 e 10 dias do início dos tratamentos. Os maiores aumentos de conteúdo foram observados com quercetina para boro e ácido salicílico aos 5 dias, e 24-epibrassinolídeo e BION aos 10 dias.

Fructose Induced Leptin Dysfunction and Improvement by Quercetin and Rutin in Rats

To investigate the dysfunction of leptin underlying insulin resistance syndrome in fructose-fed rats and improvement by lowing uric acid with natural products quercetin and rutin. Rats were fed with fructose solution for 8 weeks. At week 4, animals received quercetin and rutin, as well as allopurinol. Serum uric acid and insulin levels were measured before and after drug treatment. Leptin levels in serum and hypothalamus, leptin secretion from adipose tissue were used to evaluate the responses of leptin to hyperuricemia and hyperinsulinemia in rats with insulin resistance syndrome. Triglyceride (TG), high dense lipid (HDL) and low dense lipid (LDL) in serum were examined to evaluate dyslipidemia in fructose-fed rats. Fructose consumption significantly increased serum uric acid, insulin and leptin levels in rats, and induced a significant increase of leptin secretion by upregulating ob gene expression in adipose tissue. Quercetin and rutin, as well as allopurinol reduced hyperleptinemia and inhibited leptin secretion from adipose tissue. Moreover, fructose-fed rats exhibited leptin level increase in hypothalamus accompanying dyslipidemia. Quercetin, rutin and allopurinol attenuated fructose-induced dyslipidemia in rats, but failed to improve leptin insufficiency in hypothalamus. These results indicated that fructose consumption might cause hyperleptinemia and leptin insufficiency in the brain, which might be indirectly mediated by hyperinsulinemia and hypertriglyceridemia in rats. Hopouricemic agents quercetin, rutin and allopurinol improved hyperinsulinemia and dyslipidemia, and subsequently regulated leptin dysfunction in fructose-fed rats. This study provided direct evidence that hyperuricemia was associated with hyperleptinemia during fructose consumption, and another pharmacological explanation for lowing uric acid agents to prevent hyperuricemia and leptin dysfunctions in fructose-induced insulin resistance syndrome in rats.