3-methylquercetin and isoquercitrin

A simple and sensitive LC-MS/MS method has been developed and validated for the determination of rutin, isoquercitrin, astragalin, quercetin, kaempferol and isorhamnetin in rat plasma using naringin as the internal standard (IS). The plasma samples were pretreated and extracted by liquid-liquid extraction. Chromatographic separation was accomplished on a C18 column with a 10 min gradient elution using acetonitrile and 0.1% formic acid aqueous solution as mobile phase at a flow rate of 0.3 mL min(-1). A tandem mass spectrometric detection was conducted using multiple reaction monitoring (MRM) via an electrospray ionization (ESI) source and operating in the negative ionization mode. The lower limit of quantitation (LLOQ) of each analyte was lower than 1 ng mL(-1). Intra-day and inter-day precisions were less than 11.9%. The relative errors of accuracy were in the range of -9.2% to 6.1%. The mean recoveries of flavonoids and IS were higher than 53.8%. The proposed method was further applied to investigate the pharmacokinetics of all analytes after a single oral administration of total flavonoids from mulberry leaves to rats.

Topics: Animals; Chromatography, Liquid; Flavonoids; Kaempferols; Liquid-Liquid Extraction; Morus; Plant Extracts; Plant Leaves; Plasma; Quercetin; Rats; Rats, Sprague-Dawley; Rutin; Tandem Mass Spectrometry

To investigate the chemical constituents from Commelina communis, fifteen compounds were separated and purified by silica gel, Sephadex LH-20, and ODS column chromatography, and semi-preparative HPLC. By analyses of NMR and MS data as well as their physical and chemical properties, the structures of these compounds were identified as chrysoeriol-7-O-beta-D-glucoside( 1), methyl gallate(2), p-coumaric acid(3), protocatechuic acid(4), caffeic acid(5), p-hydroxybenzoic acid(6), 2-phenethyl-beta-D-gly-cosidase(7) , rhaponticin(8) , (7S, 8R) -dihydrodehydrodiconiferyl alcohol-9-O-beta-D-glucoside (9), isovitexin (10) , isofurcatain (11), isorhamnetin-3-O-beta-D-glucoside(12) , quercetin-3-O-alpha-L-rhamnoside (13) , isoquercitrin (14) , and 1, 2-dihydro-6, 8-dime-thoxy-7-1-(3, 5-dimethoxy-4-hydroxyphenyl) -N1, N2-bis-[2-( 4-hydroxyphenyl) ethyl] -2, 3-naphthalene dicarboxamide (15). Compounds 2, 5-9, 11, 13 were obtained from the genus Commelina for the first time.

Topics: Caffeic Acids; Chromatography, High Pressure Liquid; Commelina; Glucosides; Hydroxybenzoates; Quercetin

The complete and unambiguous (1)H NMR assignments of ten marker constituents of Ginkgo biloba are described. The comprehensive (1)H NMR profiles (fingerprints) of ginkgolide A, ginkgolide B, ginkgolide C, ginkgolide J, bilobalide, quercetin, kaempferol, isorhamnetin, isoquercetin, and rutin in DMSO-d(6) were obtained through the examination of 1D (1)H NMR and 2D (1)H,(1)H-COSY data, in combination with (1)H iterative full spin analysis (HiFSA). The computational analysis of discrete spin systems allowed a detailed characterization of all the (1)H NMR signals in terms of chemical shifts (δ(H)) and spin-spin coupling constants (J(HH)), regardless of signal overlap and higher order coupling effects. The capability of the HiFSA-generated (1)H fingerprints to reproduce experimental (1)H NMR spectra at different field strengths was also evaluated. As a result of this analysis, a revised set of (1)H NMR parameters for all ten phytoconstituents was assembled. Furthermore, precise (1)H NMR assignments of the sugar moieties of isoquercetin and rutin are reported for the first time.

Topics: Cyclopentanes; Furans; Ginkgo biloba; Ginkgolides; Kaempferols; Lactones; Magnetic Resonance Spectroscopy; Molecular Structure; Protons; Quercetin; Reference Standards; Rutin; Stereoisomerism

In the present study, over a period of 8 days 12 mg/kg/d quercetin aglycone and 18 mg/kg/d isoquercitrin were orally given to rats, respectively. Four hours after administration, plasma samples were taken as well as tissue samples of liver, lung, heart, kidney and the brain sections hippocampus, cerebellum, striatum, cortex and the remaining brain. A HPLC-FD method with in-line post-column complexation was employed to quantify the quercetin metabolites (QM) in plasma and tissues. Compared to the quercetin gavage the isoquercitrin gavage consistently produced higher levels of QM in tissues (double to five-fold) as well as in plasma (double to three-fold). In body tissues, the highest amounts of QM were observed in the lung. In brain tissue, the highest levels of QM were found in the cerebellum, while the striatum contained the lowest levels of QM. In conclusion, this study clearly demonstrates that orally given isoquercitrin leads to higher levels in plasma and in all investigated tissue than quercetin aglycone.

Topics: Administration, Oral; Animals; Biological Availability; Brain; Chromatography, High Pressure Liquid; Hypnotics and Sedatives; Male; Quercetin; Rats; Rats, Wistar; Reference Standards; Tissue Distribution

Obesity, which is related to metabolic syndrome and is associated with liver disease, represents an epidemic problem demanding effective therapeutic strategies. Evidence shows that the Wnt/β-catenin pathway is closely associated with obesity and that small molecules regulating the Wnt/β-catenin pathway can potentially control adipogenesis related to obesity. Eleven plant extracts activating the Wnt/β-catenin pathway were screened by using HEK 293-TOP cells retaining the Wnt/β-catenin signaling reporter gene. An extract of Persicaria hydropiper (L.) Spach was found to activate Wnt/β-catenin signaling. P. hydropiper is grown worldwide in temperate climates and is found widely in Southeast Asia. The P. hydropiper extract inhibited the differentiation of adipocyte 3T3-L1 cells. Isoquercitrin and isorhamnetin, constituents of P. hydropiper, also activated Wnt/β-catenin signaling and suppressed the differentiation of 3T3-L1 cells. These results indicate that isoquercitrin in P. hydropiper suppresses the adipogenesis of 3T3-L1 cells via the inhibition of Wnt/β-catenin signaling. P. hydropiper and isoquercitrin may therefore be potential therapeutic agents for obesity and its associated disorders.

Topics: 3T3-L1 Cells; Adipogenesis; Animals; beta Catenin; Cell Differentiation; Flavonols; HEK293 Cells; Humans; Mice; Polygonaceae; Quercetin; Signal Transduction; Wnt Proteins

To study the chemical constituents of flowers of Prunus mume.. Compounds were separated by silica gel. Their structures were identified and elucidated by spectral analysis and chemical methods.. Eight compounds were obtained and identified as benzoic acid (I), isorhamnetin (II), quercetin (III), kaempferol-3-O-beta-D-galactopyranoside (IV), isorhamnetin-3-O-beta-D-glucopyranoside (V), isoquercitrin (VI), hypericin (VII) and rutin (VIII).. Among them, II-VII are isolated from this plant for the first time.

Topics: Anthracenes; Benzoic Acid; Flavonols; Flowers; Molecular Structure; Perylene; Plants, Medicinal; Prunus; Quercetin

Moderate consumption of red wine has been associated with beneficial effects on human health, and this has been attributed to the flavonoid content. Factors that influence the bioavailability of this group of polyphenolic compounds are therefore important. Using the rat cannulated everted jejunal sac technique, we have investigated the effect of alcohol on the intestinal absorption of quercetin and its 3-O-glucoside from red wine. Tissue preparations were incubated in whole or dealcoholised red wine, diluted 1 : 1 with Krebs buffer for 20 min at 37 degrees C, after which the mucosa was removed and processed for HPLC analysis. Tissues exposed to red wine had significantly higher amounts of both quercetin (x 3; P < 0.001) and quercetin-3-O-glucoside (x 1.5; P < 0.01) associated with them, compared with sacs incubated in the dealcoholised equivalent. In addition, both tamarixetin (T) and isorhamnetin (I), in the mucosal tissue from sacs exposed to the whole wine, were significantly elevated approximately two fold (P < 0.05; P < 0.01, respectively). Similar results were obtained when sacs were incubated in Krebs buffer containing a mixture of pure quercetin and quercetin-3-O-glucoside with or without alcohol, and, although effects on the apparent absorption of Q and Q-3-G were not so marked, concentrations of the metabolites quercetin-3-O-glucuronide and I were significantly increased by the presence of alcohol (P < 0.01 and P < 0.001, respectively). It is therefore plausible that the moderate alcohol content of red wine contributes to its beneficial health effects in humans by both increasing the absorption of quercetin and quercetin-3-O-glucoside and by channelling their metabolism towards O-methylation to yield compounds (T and I), which have potential protective effects against cancer and cardiovascular diseases.

Topics: Animals; Central Nervous System Depressants; Chromatography, High Pressure Liquid; Disaccharides; Ethanol; Flavonols; Hydrogen-Ion Concentration; In Vitro Techniques; Intestinal Absorption; Intestinal Mucosa; Intestines; Jejunum; Male; Phenols; Quercetin; Rats; Rats, Wistar; Sulfur Dioxide; Wine

A comprehensive two-dimensional liquid chromatographic separation system based on the combination of an immobilized liposome chromatographic (ILC) column and an ODS column was developed for the separation of components in Ginkgo biloba, a traditional Chinese medicine. Two columns were coupled by a two-position, eight-port valve equipped with two storage loops, and the system was controlled by a computer. The effluent was detected both by a diode array detector and by an atmospheric pressure chemical ionization (APCI) mass spectrometer. Under the optimization separation conditions with the separation system, more than 41 components in the methanol extract of Ginkgo biloba were resolved. According to their UV and mass spectra, 13 of them were preliminarily identified as ginkgolide B, ginkgolide C, bilobalide, rutin, quercetin, quercetin-3-O-beta-D-glucosyl (1-2)-alpha-L-rhamnoside, quercetin-3-O-beta-D-glucoside, isorhamnetin, kaempferol-3-O-beta-D-glucosyl (1-2)-alpha-L-rhamnoside, isohamnetin-3-O-beta-D-rutinoside, kaempferol-3-O-beta-D-glucoside, kaempferol, kaempferol-3-O-beta-D-rutinoside.

Topics: Chromatography, High Pressure Liquid; Cyclopentanes; Drugs, Chinese Herbal; Flavonols; Furans; Ginkgo biloba; Ginkgolides; Kaempferols; Lactones; Medicine, Chinese Traditional; Monosaccharides; Quercetin; Rutin; Spectrometry, Mass, Electrospray Ionization

Quercetin has antioxidant, anti-inflammatory, antiproliferative and anticarcinogenic properties. In plant foods, quercetin occurs mainly bound to various sugars via a beta-glycosidic link. We hypothesized that lactase phlorizin hydrolase (LPH), an enzyme at the brush border membrane of intestinal cells, is involved in the in vivo intestinal uptake of quercetin-sugars. To study this, we measured the appearance of quercetin metabolites in plasma and perfusate after perfusing the jejunum and ileum with 50 micro mol/L quercetin-3-glucoside in an in situ rat perfusion model. LPH was inhibited by the selective LPH inhibitor N-butyldeoxygalactonojirimycin (0, 0.5, 2 or 10 mmol/L) (n = 5 rats/group). Quercetin in plasma and perfusion buffer was determined by HPLC with CoulArray detection. Results are given as means +/- SEM. In the perfusion buffer, 13.8 +/- 0.7 micro mol/L quercetin-3-glucoside was hydrolyzed during intestinal passage. Co-perfusion with 0.5, 2 and 10 mmol/L N-butyldeoxygalactonojirimycin resulted in 38% (P < 0.05), 50% (P < 0.01) and 67% (P < 0.01) less hydrolysis, respectively. Plasma concentrations of quercetin in the corresponding groups were 36% (P = 0.12), 55% (P < 0.01) and 75% (P < 0.01) lower than in controls (1.23 +/- 0.22 micro mol/L). These data suggest that LPH is a major determinant of intestinal absorption of quercetin-3-glucoside in rats.

Topics: 1-Deoxynojirimycin; Animals; Chromatography, High Pressure Liquid; Enzyme Inhibitors; Flavonols; Hydrolysis; Ileum; Intestines; Jejunum; Lactase-Phlorizin Hydrolase; Male; Microvilli; Quercetin; Rats; Rats, Wistar

The two bacterial species, Eubacterium ramulus and Enterococcus casseliflavus, which had previously been isolated from human faeces using the flavonoid quercetin-3-glucoside as the growth substrate, were tested for their ability to utilize this compound in vivo.. Germ-free rats were associated with Eu. ramulus and subsequently with Ent. casseliflavus and vice versa. Identification and enumeration of the bacterial cell counts in faeces and intestinal contents were performed by whole cell fluorescence in situ hybridization. Eubacterium ramulus and Ent. casseliflavus occurred in caecal and colonic contents at cell counts of up to 10(10) g(-1) dry weight. In the jejunum, only Ent. casseliflavus was found (10(9) g(-1) dry weight). Upon oral administration of 32 micromol quercetin-3-glucoside, quercetin was detected in the faeces and urine of germ-free rats (2.2 x 10(-1)-8.1 x 10(-1) micromol 24-h(-1) faeces collection and 1.0 x 10(-2)-2.8 x 10(-1) micromol 24-h(-1) urine collection, respectively) and of rats monoassociated with Ent. casseliflavus (7.9 x 10(-1)-2.7 micromol 24-h(-1) faeces and 1.0 x 10(-1)-5.9 x 10(-1) micromol 24-h(-1) urine, respectively). In contrast, the faeces and urine of rats associated with Eu. ramulus contained 3,4-dihydroxyphenylacetic acid (4.7 x 10(-2)-3.6 micromol 24-h(-1) faeces and 2.4 x 10(-2)-1.0 micromol 24-h(-1) urine, respectively) but only low, or undetectable, concentrations of faecal quercetin (up to 9.3 x 10(-2) micromol 24-h(-1) faeces; detection limit 2.5 x 10(-2) micromol). Urinary quercetin concentrations varied markedly from undetectable amounts up to 1.0 micromol 24-h(-1) urine (detection limit 1.0 x 10(-2) micromol). Isorhamnetin was found in the urine of all animals independent of their bacterial status. There were no significant differences between the groups (2.0 x 10(-2)-2.8 x 10(-1) micromol 24-h(-1) urine). In complete intestinal tissues of animals, associated with both species, quercetin-3-glucoside and its metabolites were detected by a more sensitive and selective method at concentrations that were two to three orders of magnitude lower than in faeces or urine.. These results indicate that Eu. ramulus may be a key organism for the bacterial transformation of flavonoids in the gut.

Topics: 3,4-Dihydroxyphenylacetic Acid; Animals; Biotransformation; Cecum; Colon; Colony Count, Microbial; Enterococcus; Eubacterium; Feces; Flavonols; Gastrointestinal Contents; Germ-Free Life; Humans; Intestinal Mucosa; Intestines; Jejunum; Quercetin; Random Allocation; Rats; Rats, Inbred Strains

The efficiency of intestinal absorption and metabolic conversion of quercetin aglycone and its glucosides, quercetin-4'-O-beta-D-glucoside (Q4'G), quercetin-3-O-beta-D-glucoside (Q3G), and quercetin-3,4'-di-O-beta-D-glucoside (Q3,4'G), was estimated by using Caco-2 cell monolayers as an intestinal epithelial cell model. Aglycone was significantly lost from the apical side, resulting in the appearance of free and conjugated forms of quercetin and those of isorhamnetin in the cellular extracts. In the basolateral solution, the conjugated form of quercetin was predominant and increased with the elapse of incubation. As compared with quercetin aglycone, none of the quercetin glucosides were absorbed efficiently from apical side. However, Q4'G yielded conjugated quercetin and isorhamnetin in basolateral solution at higher amounts than Q3G or Q3,4'G. Lipophilicity of Q4'G was found to be higher than that of Q3G or Q3,4'G. This suggests that lipophilicity contributes to the relatively efficient absorption of Q4'G. It is likely that the occurrence of hydrolysis enhances the efficiency of intestinal absorption and metabolic conversion of dietary quercetin glucosides.

Topics: Caco-2 Cells; Cell Extracts; Cell Polarity; Flavonols; Humans; Intestinal Absorption; Intestinal Mucosa; Quercetin