Zhanguo Wang

Pharmacokinetic profile of total quercetin after single oral dose of tartary buckwheat extracts in rats.

As an important edible and medicinal material, tartary buckwheat ( Fagopyrum tataricum Gaertn.) is commonly used as a kind of food or drug in eastern Asian countries. To investigate the pharmacokinetic profile of total quercetin after a single oral dose of tartary buckwheat extract in rats, a sensitive, simple, and accurate HPLC-UV method was developed to determine total quercertin following plasma enzyme hydrolysis with glucuronidase/sulfatase. Eighteen male Wistar rats were randomly assigned into three groups, which were given three different doses of tartary buckwheat extract. The pharmacokinetic results showed that the area under the plasma concentration-time curve (AUC) of total quercetin after single oral doses of tartary buckwheat extract presented a linear relationship. The peak plasma concentrations (C(max)) of total quercetin afte plasma enzyme hydrolysis with glucuronidase/sulfatase were 0.55 ± 0.26, 1.10 ± 0.53, and 2.05 ± 0.26 μg/mL; the peak times (T(max)) were 2.33 ± 1.94, 2.75 ± 3.67, and 2.50 ± 1.82 h; the areas under the curves (AUC(0-36h)) were 5.29 ± 1.35, 10.02 ± 4.43, and 22.51 ± 3.05 μg·mL(-1)·h(-1) for three doses of tartary buckwheat extract (60, 120, and 240 mg/kg). The present study has provided a basic pharmacokinetic profile of total quercetin after a single oral dose of tartary buckwheat extract in rats.

Reduced system exposures of total rhein and baicalin after combinatory oral administration of rhein, baicalin and berberine to beagle dogs and rats

ETHNOPHARMACOLOGICAL RELEVANCE Rhein (Rh), baicalin (BG) and berberine (Be) are important coexisted constituents of San-Huang-Xie-Xin-Tang, which was widely used in traditional Chinese medicine for the treatment of gastritis, hypertension, gastric bleeding and peptic ulcers, etc. AIM OF THE STUDY Based on the extensive phase II conjugation reactions of polyphenols (Rh and BG) in vivo, the aims of the present study were to investigate the effects of combination (Rh, BG and Be) on the system exposures of total Rh and BG involving the phase II conjugates metabolites and its possible mechanism. MATERIALS AND METHODS A 3×3 Latin square single heavy design was used to investigate the pharmacokinetics influence of total Rh and BG after combination of Be by treating plasma samples with β-glucuronidase/sulfatase both in beagle dogs and Wistar rats. In vitro and in situ experiment models including in situ rat intestinal perfusion, Caco-2 cell monolayer transport and small intestinal flora incubation system were used to discuss the possible mechanism. RESULTS The results of pharmacokinetic interactions showed that combination significantly reduced the system exposures of total Rh and BG. Compared with Rh or BG alone, the mean area under concentration-time curves (AUC(0-t)) of total Rh and BG reduced by 31% and 77% in beagle dog experiment. In Wistar rat experiment, the AUC(0-t) of total Rh and BG reduced by 22% and 21%. Subsequently, the results of in situ rat intestinal perfusion and small intestinal flora incubation system tests revealed that combination may decrease the absorption and metabolism of BG. However, combination could not affect the transport profile of BG across the Caco-2 cell. Moreover, combination did not affect the absorption or metabolism profile of Rh in all three in situ/in vitro experiments. CONCLUSIONS It was deduced that the possible mechanism of the reduction of the system exposures of total Rh and BG was related to that combination decreased the metabolism of BG to B or the phase II conjugates of Rh/BG excreted from liver/bile duct to their free aglycones in vivo by inhibiting intestinal flora. The potent effects of combination on the phase II conjugates of Rh and B in pharmacokinetics, shown in this paper, indicated that more attention should be paid to the phase II conjugates metabolites of these polyphenols (undergo extensive phase II conjugation reactions in vivo) when applied herbal products composed of these coexist compounds.

Metabolic profiling assisted quality assessment of Rhodiola rosea extracts by high-performance liquid chromatography

In this work, fast and sensitive high-performance liquid chromatography (HPLC) coupled with multivariate analysis was utilized to assist the quality assessment of Rhodiola rosea extracts (RREs). 131 peaks were separated and detected in RREs on a fused-core C18 column. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) of the chromatographic data demonstrated that 10 batches of RREs could be well-differentiated and categorized into three groups which were closely related to the origins of RREs. Partial least square-discriminant analysis (PLS-DA) showed that the quality differentiation might be explained by at least 6 components, in which rosavin was characterized by an external reference, rosiridine was identified by liquid chromatography-mass spectrometry (LC-MS), and the mass spectra of the others were provided. The observation that the level of rosavin was more relevant to the multivariate chromatographic data than the ones of salidroside and tyrosol, the other two components commonly used to standardize RREs, was confirmed by the PLS prediction models. Results of the present study not only indicated that rosavin was a rational marker to represent the quality of RREs, but also demonstrated the power of HPLC-based metabolic profiling in the quality assessment of herbal extracts.

Rapid Isolation and Purification of Phorbol Esters from Jatropha curcas by High-Speed Countercurrent Chromatography

In this work, a high-speed countercurrent chromatography (HSCCC) method was established for the preparation of phorbol esters (PEs) from Jatropha curcas. n-Hexane-ethyl acetate-methanol-water (1.5:1.5:1.2:0.5, v/v) was selected as the optimum two-phase solvent system to separate and purify jatropha factor C1 (JC1) with a purity of 85.2%, as determined by HPLC, and to obtain a mixture containing four or five PEs. Subsequently, continuous semipreparative HPLC was applied to further purify JC1 (99.8% as determined by HPLC). In addition, UPLC-PDA and UPLC-MS were established and successfully used to evaluate the isolated JC1 and PE-rich crude extract. The purity of JC1 was only 87.8% by UPLC-UV. A peak (a compound highly similar to JC1) was indentified as the isomer of JC1 by comparing the characteristic UV absorption and MS spectra. Meanwhile, this strategy was also applied to analyze the PE-rich crude extract from J. curcas. It is interesting that there may be more than 15 PEs according to the same quasi-molecular ion peaks, highly similar sequence-specific fragment ions, and similar UV absorption spectrum.

Chemical Fingerprint and Quantitative Analysis for the Quality Evaluation of Docynia dcne Leaves by High-Performance Liquid Chromatography Coupled with Chemometrics Analysis

Docynia dcne leaf from the genus of Docynia Dcne (including three species of Docynia delavayi, Docynia indica and Docynia longiunguis.) is an important raw material of local ethnic minority tea, ethnomedicines and food supplements in southwestern areas of China. However, D. dcne leaves from these three species are usually used confusingly, which could influence the therapeutic effect of it. A rapid and effective method for the chemical fingerprint and quantitative analysis to evaluate the quality of D. dcne leaves was established. The chemometric methods, including similarity analysis, hierarchical cluster analysis and partial least-squares discrimination analysis, were applied to distinguish 30 batches of D. dcne leaf samples from these three species. The above results could validate each other and successfully group these samples into three categories which were closely related to the species of D. dcne leaves. Moreover, isoquercitrin and phlorizin were screened as the chemical markers to evaluate the quality of D. dcne leaves from different species. And the contents of isoquercitrin and phlorizin varied remarkably in these samples, with ranges of 6.41-38.84 and 95.73-217.76 mg/g, respectively. All the results indicated that an integration method of chemical fingerprint couple with chemometrics analysis and quantitative assessment was a powerful and beneficial tool for quality control of D. dcne leaves, and could be applied also for differentiation and quality control of other herbal preparations.

Purified Phlorizin from DocynIa Indica (Wall.) Decne by HSCCC, Compared with Whole Extract, Phlorizin and Non-Phlorizin Fragment Ameliorate Obesity, Insulin Resistance, and Improves Intestinal Barrier Function in High-Fat-Diet-Fed Mice

Natural products generally contain complex and multiple bioactive compounds that are responsible for the effects on health through complicated synergistic and/or suppressive actions. As an important raw material of local ethnic minority tea, ethnomedicines and food supplements in southwestern areas of China, Docynia indica (Wall.) Decne (DID) mainly consists of phlorizin (PHZ), which is the main active component. In this study, the holistic activities and the interactions of components of PHZ, non-phlorizin (NP) in the DID extract (DIDE) were evaluated. A rapid and effective high-speed counter-current chromatography (HSCCC) was performed to knock out PHZ from DIDE and the purity of PHZ was 96.01% determined by HPLC, with a recovery rate of 96.76%. After 13 weeks of treatment course in a high-fat diet (HFD)-induced obese mice model, the results revealed that the DIDE and PHZ significantly decreased weight gain, blood lipid levels, hyperplasia of adipocytes and alleviated inflammation (p < 0.05). Both DIDE and PHZ improves insulin resistance (p < 0.001). Meanwhile, the intestinal barrier function was improved compared to HFD group, through the determination of serum lipopolysaccharides (LPS), glucagon-likepeptide-2 (GLP-2) and hematoxylin-eosin staining of jejunum. Interestingly, after NP treatment, the metabolic syndrome of the HFD-induced obesity appeared to have a similar improvement. All the experiments showed that there is a synergistic weakening phenomenon when PHZ and NP interact with each other in the mixed state. In conclusion, for the PHZ and NP showing a good effect on anti-obesity, anti-inflammation, and intestinal barrier function, DIDE could be a good source of functional food to prevent obesity.