(2S)-taxifolin is an important flavonoid that has anti-inflammatory and anti-oxidation effects. It is widely used in pharmaceutical and nutraceutical industries. Flavone 3-hydroxylase (F3H) can catalyze the synthesis of (2S)-taxifolin and other 3-hydroxylated flavonoids from (2S)-eriodictyol. Due to the low catalytic efficiency of F3H, the titer of many 3-hydroxyflavones, such as taxifolin, synthesized by microbial method is relatively low. In this study, a SmF3H was identified from the transcriptome of Silybum marianum (L.) Gaertn. The results of fermentation showed that SmF3H can catalyze the flavone 3-hydroxylation reaction, and its catalytic efficiency was significantly higher than that of commonly used SlF3H from Solanum lycopersicum. Six promoters with different transcription strength were selected to optimize the synthesis pathway from the flavonoid precursor (2S)-naringenin to (2S)-taxifolin. The results showed that the highest titer of (2S)-taxifolin (695.90 mg/L in shake flask) could be obtained when the P(GAL7) promoter was used to control the expression of SmF3H. The titer of (2S)-taxifolin was further improved to 3.54 g/L in a 5-L fermenter, which is the highest titer according to current available literatures.
Antioxidants ; Flavonoids ; Milk Thistle ; Quercetin/analogs & derivatives*

OBJECTIVETo study the water soluble constituents from Amomum villosum.

METHODThe constituents were separated and purified with chromatographic methods, identified by NMR, MS, UV and IR.

RESULTTwo quercetin glycosides: quercitrin (quercetin-3-O-alpha-L-rhamnoside I) and isoquercitrin (quercetin-3-O-beta-D-glucoside II) were isolated and identified.

CONCLUSIONI and II were isolated for the first time from A. villosum.

Amomum ; chemistry ; Fruit ; chemistry ; Plants, Medicinal ; chemistry ; Quercetin ; analogs & derivatives ; chemistry ; isolation & purification

OBJECTIVETo investigate the chemical constituents from the aerial parts of Hyperricum monogynum.

METHODCompounds were isolated by various column chromatography and identified by spectral analysis.

RESULTTen compounds were isolated and identified as quercetin, quercitrin, hyperoside, rutin, (-)-epicatechin, 3,5-dihydroxy-1-methoxy-xanthone, 3,4-O-isopropylidenyl shikimic acid, shikimic acid, daucosterol, and oleanoic acid.

CONCLUSIONAll compounds were isolated from this plant for the first time.

Hypericum ; chemistry ; Plant Components, Aerial ; chemistry ; Plants, Medicinal ; chemistry ; Quercetin ; analogs & derivatives ; chemistry ; isolation & purification

OBJECTIVETo study the chemical constituents of the seeds of Cuscuta chinensis.

METHODThe separation was carried out by polyamide and silica gel chromatography, and the compounds were identified by means of physico-chemical and spectroscopic methods.

RESULTSEight compounds were isolated from the plant and identified as quercetin 3-O-beta-D-galactoside-7-O-beta-D-glucoside (I), quercetin 3-O-beta-D-apiofuranosyl-(1-->2)-beta-D-galactoside (II), hyperoside (III), isorhamnetin (IV), kaempferol (V), quercetin (VI), d-sesamin (VII) and 9(R)-hydroxy-d-sesamin (VIII).

CONCLUSIONCompounds IV and VII were isolated from Cuscuta for the first time, and I, II and VIII were characteristic constituents for this vegetable drug.

Cuscuta ; chemistry ; Flavonols ; Plants, Medicinal ; chemistry ; Quercetin ; analogs & derivatives ; chemistry ; isolation & purification ; Seeds ; chemistry

OBJECTIVETo develop an HPLC method for fingerprint study of both Senecio scandens and S. scandens.

METHODFingerprints of the two Senecio herbs were compared. And the concentrations of main peaks in them were semi-quantified as chlorogenic acid or hyperoside. Chromatography was performed on a Shiseido Capcell Pak MG II C18 (4.6 mm x 250 mm, 5 microm) column using a gradient elution of acetonitrile-water containing 0.2% acetic acid. And detection wavelength was 360 nm.

RESULTSignificant difference was found in the fingerprint of the two herbs. Eleven peaks were picked out for the evaluation of S. scandens and S. scandens, respectively. They were identified to be either organic acid compounds or flavones by HPLC-UV and LC-ESI-MS analysis. And semi-quantification of them showed the concentrations of organic acid compounds and flavones in S. scandens were 2.29- and 15.56- folds of those in S. scandens, respectively.

CONCLUSIONThe developed HPLC method is suitable for the fingerprint study for both of S. scandens and S. scandens. It is robust and producible enough to be used for the quality evaluation on S. scandens.

Chlorogenic Acid ; analysis ; Chromatography, High Pressure Liquid ; methods ; Quercetin ; analogs & derivatives ; analysis ; Senecio ; chemistry

OBJECTIVETo investigate the chemical constituents of Epimedium brevicornum.

METHODThe chemical constituents were isolated by using silica gel column chromatography and preparative TLC. The structures were identified on the basis of physical-chemical constants and spectral data.

RESULTFive compounds were isolated and identified as hyperoside, icariin, epimedin B, epimedin C, inositol.

CONCLUSIONCompound I and III - V were isolated from the plant for the first time.

Epimedium ; chemistry ; Flavonoids ; chemistry ; isolation & purification ; Plant Components, Aerial ; chemistry ; Plants, Medicinal ; chemistry ; Quercetin ; analogs & derivatives ; chemistry ; isolation & purification

OBJECTIVETo develop an HPLC method for simultaneous determination of rutin, isoquercitrin and chlorogenic acid in Farfarae Flos.

METHODThe analysis was carried out on a Phenomenex Synergi POLAR-RP 80A column (4.6 mm x 250 mm, 4 microm) with gradient elution using methanol-acetonitrile-water (adjusted to pH 2.5 with formic acid) as mobile phase. The flow rate was 1.2 mL x min(-1) and the detection wavelength was at 255 nm.

RESULTThe calibration curves were linear over the range of 0.2-2 000 microg x L(-1) for rutin and isoquercitrin, 10-2 000 microg x L(-1) for chlorogenic acid, respectively. The average recoveries were 99.5% for rutin, 100.1% for isoquercitrin and 99.4% for chlorogenic acid, respectively, with RSD not more than 3.0%.

CONCLUSIONThe described method is reliable and could be used for the quality control of Farfarae Flos.

Calibration ; Chlorogenic Acid ; analysis ; Chromatography, High Pressure Liquid ; methods ; Quercetin ; analogs & derivatives ; analysis ; Rutin ; analysis ; Tussilago ; chemistry

AIMTo study the chemical constituents of Knoxia corymbosa Willd.

METHODSChromatography was used to isolate and purify the chemical constituents, their structures were identified by spectral analysis.

RESULTSFour flavonol glycosides were identified as quercetin-7-O-alpha-L-arabinosyl-3-O-beta-D-6"-acetylglucopyranoside (1), kaempferol-7-O-alpha-L-arabinosyl-3-O-beta-D-glucopyranoside (2), quercetin-3-O-beta-D-glucopyranoside (3), quercetin-3-O-beta-D-6"-acetylglucopyranoside (4).

CONCLUSIONCompound 1 is a new flavonol glycoside. The other flavonol glycosides were isolated from Knoxia corymbosa Willd for the first time.

Glucosides ; chemistry ; isolation & purification ; Molecular Conformation ; Molecular Structure ; Plants, Medicinal ; chemistry ; Quercetin ; analogs & derivatives ; chemistry ; isolation & purification ; Rubiaceae ; chemistry

OBJECTIVETo establish an HPLC method for determination the contents of quercitrin in Polygonum capitatum and Relinqing granules.

METHODThe samples were analyzed on a Diamonsil C18 colunm (4.6 mm x 250 mm, 5 microm) eluted with the mobile phase consisted of methanol-1% HAc-THF. The flow rate was 1.0 mL x min-m. The detection wavelength was set at 258 nm and the column temperature was 25 degrees C.

RESULTThe calibration curve was linear in the range of 0. 081 64-0.4084 microg (r = 0.99997). The average recovery rate of quercitrin in P. capitatum was 102.3% (RSD 0.99%), and was 102.7% (RSD 2.2%) in Relinqing granules.

CONCLUSIONThe method is reliable and specific with good repeatability, and can be used for the quality control of P. capitatum and Relinqing granules. It can provide a science bases for the planting of polygonum capitatum.

Chromatography, High Pressure Liquid ; methods ; Drugs, Chinese Herbal ; analysis ; chemistry ; Polygonum ; chemistry ; Quercetin ; analogs & derivatives ; analysis ; chemistry ; Reproducibility of Results

OBJECTIVETo study the flavonoid constituents in fresh herb of Houttuynia cordata.

METHODVarious column packing materials including Diaion HP - 20, Sephadex LH - 20, ODS and silica gel were employed for the isolation and purification of compounds from H. cordata. The structures of the compounds were identified by physiochemical properties and spectral analysis.

RESULTFive compounds were isolated, and their structures were identified as quercetin-3-O-beta-D-galactoside-7-O-beta-D-glucoside (1), kaempferol-3-O-alpha-L-rhamnopyranosyl-(1 --> 6)-beta-D-glucopyranoside (2), quercitrin (3), hyperin (4), quercetin 3-O-alpha-L-rhamnopyranosyl-7-O-beta-D-glucopyranoside (5).

CONCLUSIONCompounds 1, 2 and 5 were separated from H. cordata for the first time.

Flavonoids ; chemistry ; isolation & purification ; Glycosides ; chemistry ; isolation & purification ; Houttuynia ; chemistry ; Plants, Medicinal ; chemistry ; Quercetin ; analogs & derivatives ; chemistry ; isolation & purification