Search Results

You are looking at 1 - 4 of 4 items for

  • Author or Editor: H. Du x
  • Refine by Access: Content accessible to me x
Clear All Modify Search

Summary

Cleavage of glucosinolates with myrosinase yields thioglycosidic compounds which have cancer chemoprevention activity. In this paper, glucosinolates in an extract (2.0 g) of broccoli seeds (Brassica oleracea var. italica) were separated by high-speed countercurrent chromatography (HSCCC) with the solvent system n-butanol-acetonitrile-10% ammonium sulfate solution 1:0.5:2.2 (v/v) to yield five glucosinolate compounds after desalting and decolorizing by MCI column chromatography. The five compounds, 7-methylsulfinylheptyl glucosinolate (22.4 mg), 4-pentenyl glucosinolate (33.6 mg), 3-butenyl glucosinolate (24.0 mg), 4-methylsulfinylbutyl glucosinolate (161.4 mg), and 3-methylsulfinylpropyl glucosinolate (29.6 mg), were identified by ESI-MS, 1H NMR and 13C NMR. The purity of the products was >98%, and 7-methylsulfinylheptyl glucosinolate was obtained from broccoli seeds for the first time.

Full access

Summary

The method of high-performance liquid chromatography (HPLC) with diode array detector (DAD) was used and validated for the simultaneous determination of nine flavonoids (rutin, myricetin, quercitrin, quercetin, luteolin, genistein, kaempferol, apigenin, and isorhamnetin) in beagle dog plasma. Plasma sample was pre-treated with acetonitrile (containing 0.05% formic acid). Chromatographic separation was performed on a kromasil C18 column (250 × 4.6 mm, 5 µm) maintained at 35 °C. The mobile phase was a mixture of methanol and 0.2% formic acid with a step linear gradient. At 1.0 mL min−1 flow rate, the eluent of other eight flavonoids was detected simultaneously at 360 nm with good separation except genistein (detected at 254 nm). Under optimum conditions, the correlation coefficient between the peak area and the concentrations for each analyte was all above 0.999. The intra-day and inter-day precisions were less than 10% for all analytes. The limit of detection and the limit of quantification for the selected nine flavonoids were 0.006–0.03 and 0.02–0.12 g mL−1, respectively. The extracted recoveries of selected nine flavonoids were 74.02%–99.37%. The assay has been successfully applied to determine concentrations of nine flavonoids in plasma from beagle dog after being intravenously administrated Ginkgo biloba extract.

Full access

Summary

An efficient ionic liquid-based microwave-assisted (IL-MAE) method has been developed for extraction of dehydrocavidine from Corydalis saxicola Bunting (C. saxicola) for subsequent rapid analysis by high-performance liquid chromatography (HPLC). The yield of dehydrocavidine reached 9.446 mg g−1 within 10 min under the optimum IL-MAE conditions (1.5 mol L−1 [hmim]Br as extraction solvent, liquid-to-solid ratio 20:1 (mL:g), and extraction temperature 70°C). Compared with conventional procedures, the proposed IL-MAE method has many advantages, for example high extraction yield, short extraction time, low solvent consumption, no use of volatile organic solvents, and no further sample clean-up before HPLC analysis. The method was validated for limit of detection (LOD) and quantification (LOQ), linearity, precision, recovery, and reproducibility. The calibration range was 5.0–200 mg L−1 and the correlation coefficient, r, was 0.9996. The LOD and LOQ were 0.035 and 0.12 mg L−1, respectively. The relative standard deviations of intra-day and inter-day assays were below 2.6% and 6.5%, respectively. Recovery was between 93.8% and 109.3% with RSD values below 5.0%. The method can be used for rapid and effective extraction and analysis of active components from medicinal plants.

Full access

Bee pollen is a health food with a wide range of nutritional and therapeutic properties. However, the bioactive compounds of bee pollen have not been extensively revealed due to low efficacy in separation. High-speed counter-current chromatography (HSCCC) and solvent extraction were applied to separate tyrosinase inhibitors from camellia pollen in this study. The camellia pollen extracts prepared with petroleum ether, ethyl acetate, and n-BuOH have tyrosinase inhibitory activity. Acidic hydrolysis could promote the tyrosinase inhibitory activity of crude sample. Three fractions with tyrosinase inhibitory activity were separated from the hydrolysate by a one-step HSCCC procedure. Among the fractions, two chemicals were sufficiently purified and identified to be levulinic acid (LA) and 5-hydroxymethylfurfural (5-HMF). The recovery was 0.80 g kg−1 pollen for LA and 1.75 g kg−1 pollen for 5-HMF; and their purity was all over 98%. The study demonstrates that HSCCC method is powerful for preparative separation of tyrosinase inhibitors from camellia pollen.

Open access