Yueming Ma

Identification of the toxic constituents in Rhizoma Coptidis

AIM OF THE STUDY Rhizoma Coptidis (Huanglian) is a widely used Traditional Chinese Medicine. However, it causes human as well as animal toxicities. In this study, we aimed to ascertain the toxic constituents in Rhizoma Coptidis. MATERIALS AND METHODS The acute toxicity of both the total extract and the alkaloid-rich extract of Rhizoma Coptidis were tested in mice. The dose related tissue concentration of the Rhizoma Coptidis alkaloids in mice was determined using high performance liquid chromatography with ultraviolet detection. The influence of phenobarbital sodium [a non-selective hepatic enzyme (P450) inducer] on the acute toxicity of Rhizoma Coptidis as well as the tissue concentration of the alkaloids was investigated. The cytotoxicity of the Rhizoma Coptidis alkaloids was tested in six cell lines using the MTT assay. RESULTS The median acute oral lethal dose of the total extract of Rhizoma Coptidis was 2.95g/kg in mice. The alkaloid-rich extract was much more toxic than the total extract of Rhizoma Coptidis. Four Rhizoma Coptidis alkaloids were detected in brain, heart, and lung tissues of mice that received the oral total extract of Rhizoma Coptidis. Tissue concentration increased nonlinearly with higher doses. Phenobarbital sodium decreased the tissue concentration of every alkaloid as well as the toxicity of Rhizoma Coptidis. All alkaloids, especially berberine, showed dose and time dependent cytotoxicity. CONCLUSIONS The toxic constituents of Rhizoma Coptidis were the alkaloids, mainly berberine.

Super elastic strain limit in metallic glass films

On monolithic Ni-Nb metallic glass films, we experimentally revealed 6.6% elastic strain limit by in-situ transmission electron microscopy observations. The origin of high elastic strain limit may link with high free volume in the film, causing the rearrangement of loosely bonded atomic clusters (or atoms) upon elastic deformation. This high elastic limit of metallic glass films will shed light on new application fields for metallic glasses, and also trigger more studies for deformation mechanism of amorphous materials in general.

Pharmacokinetics of anthraquinones in Xiexin decoction and in different combinations of its constituent herbs

Xiexin decoction (XXD), a classic pyretolysis formula, is composed of Rhei Rhizoma (DH), Radix Scutellaria (HQ) and Coptis Chinensis (HL) and is commonly used in the clinical setting. The aim of this study was to investigate the pharmacokinetic differences of the five anthraquinones in rats after oral administration of XXD and different combinations of its constituent herbs. Twenty rats were randomly divided into four groups and were administered one of the four extracts: DH, DH‐HQ, DH‐HL and XXD (DH‐HQ‐HL) via intragastric gavage. Anthraquinone concentrations in plasma were determined by an HPLC technique. Pharmacokinetic parameters were calculated from the plasma concentration–time data. Compared with DH alone, the DH‐HL combination decreased Cmax of all five anthraquinones and AUC of four anthraquinones (except physcion), and the DH‐HQ combination decreased AUC of aloe‐emodin and Cmax of rhein. Finally, XXD increased AUC of all five anthraquinones compared with DH‐HL combination. These results showed that the oral bioavailabilities of five anthraquinones were decreased significantly by combining DH with HL, whereas HQ weakened the effect of HL that inhibited the absorption of anthraquinones. Copyright

Simultaneous quantification of multiple active components from Xiexin decoction in rat plasma by LC‐ESI‐MS/MS: application in pharmacokinetics

A sensitive and specific liquid chromatography-electrospray ionization-tandem mass spectrometric (LC-ESI-MS/MS) method was developed and validated to simultaneously quantify 11 active compounds (coptisine, jatrorrhizine, berberine, palmatine, baicalin, baicalein, wogonoside, wogonin, rhein, emodin and aloeemodin) from Xiexin decoction (XXD) in rat plasma. Plasma samples extracted by a single-step protein precipitation procedure were separated using the gradient mode on a Dikma ODS-C₁₈ column. Selected reaction monitoring scanning was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. Calibration curves offered satisfactory linearity (r > 0.995) at linear range of 0.47-60 ng/mL for coptisine, jatrorrhizine, berberine and palmatine, 15-1930 ng/mL for baicalin, 20-2560 ng/mL for baicalein, 14-1790 ng/mL for wogonoside, 0.57-72.8 ng/mL for wogonin, 10-1280 ng/mL for rhein, 0.6-76.8 ng/mL for emodin and 3.0-384 ng/mL for aloeemodin. The intra- and interday precisions were less than 10.2% in terms of relative standard deviation (RSD), and the accuracies were within ±10.84% in terms of relative error (RE). It was successfully applied to the evaluation of pharmacokinetics after single oral doses of XXD were administered to rats.

Effective constituents in Xiexin Decoction for anti-inflammation.

AIM OF THE STUDY To ascertain the effective constituents in Xiexin Decoction for anti-inflammation and the interactions of these constituents at the pharmacodynamic level. MATERIALS AND METHODS Rats were administered oral Xiexin Decoction 1h before intraperitoneal lipopolysaccharide. Nitric oxide production and Xiexin Decoction constituents in venous serum samples were quantified and the correlation between nitric oxide production and each constituent in serum was calculated. Raw264.7 cells were stimulated with lipopolysaccharide and one or more Xiexin Decoction constituents; cell viability and nitric oxide production was quantified. RESULTS Xiexin Decoction significantly decreased nitric oxide production in vivo, which correlated well with rhein, baicalin, emodin and aloe-emodin. All the typical constituents of Xiexin Decoction, with the exception of physcione and chrysophanol, dose-dependently inhibited nitric oxide production in vitro. In an orthogonal designed in vitro study, rhein was the most powerful constituent, followed by baicalin then berberine and no synergy was found among these constituents. CONCLUSIONS Rhein was the most effective anti-inflammatory constituent in Xiexin Decoction followed by baicalin; no synergy was observed between rhein, baicalin and berberine at the pharmacodynamic level in vitro.

Influence of Coptis Chinensis on pharmacokinetics of flavonoids after oral administration of Radix Scutellariae in rats

Radix Scutellariae (RS) and Coptis Chinensis (CC) are the most popular components in traditional Chinese medicine prescriptions. Flavonoids are the main effective ingredients in RS and berberine is the main effective ingredient in CC. The aim of this study was to determine the influence of CC on the pharmacokinetics of flavonoids following the administration of RS in rats and to investigate the effects of CC on the pharmacokinetic mechanism. Rats were administered RS or RS+CC by intragastric gavage (ig). Plasma concentrations of baicalin (baicalein 7‐glucuronide) and wogonoside (wogonin 7‐glucuronide) were measured by HPLC. Pharmacokinetic parameters were calculated from the plasma concentration time curve. The effect of CC on the metabolism of flavonoids in RS by rat intestinal flora was studied using rat fecal suspensions after ig administration of CC. The effect of berberine on the bi‐directional transport of baicalein and baicalin was studied in Caco‐2 monolayer models. The effect of CC on the metabolism of baicalein and baicalin by the liver was studied using rat liver microsomes after ig administration of CC. Compared to RS alone, RS+CC decreased AUC and Cmax of baicalin and wogonoside. CC decreased the hydrolyzation of baicalin and wogonoside by intestinal flora. Berberine decreased the amount of baicalein transported to the basolateral side and the amount of baicalin which appeared at the basolateral side. The results showed that CC may decrease the bioavailability of baicalin and wogonoside in RS and the mechanism was related to CC decreasing the transport of flavonoid aglycones from the mucosa side to the serosal side and the hydrolyzation of flavonoids by inhibiting intestinal flora. Copyright

Increased Systemic Exposure to Rhizoma Coptidis Alkaloids in Lipopolysaccharide-Pretreated Rats Attributable to Enhanced Intestinal Absorption

Rhizoma coptidis is a rhizome commonly used in traditional Chinese medicine. After oral administration of rhizoma coptidis extract, the plasma concentrations of its effective alkaloid constituents are so low that their systemic therapeutic actions cannot be explained. This study aimed to investigate the influence of lipopolysaccharide (LPS) on the pharmacokinetics of the rhizoma coptidis alkaloids. Pharmacokinetic experiments were performed with rats; both in vitro absorption and efflux experiments were carried out with everted rat gut sacs, whereas in vitro metabolism experiments were conducted with rat liver microsomes and intestinal S9 fractions. Mucosal changes were evaluated with light microscopy and transmission electron microscopy. The results showed that, in rat plasma, LPS pretreatment increased systemic alkaloid exposure. LPS pretreatment increased the in vitro absorption of the alkaloids and decreased their efflux. The efflux of vinblastine and rhodamine 123, P-glycoprotein substrates, also was decreased. The absorption of fluorescein isothiocyanate-labeled dextran (average molecular mass, 4 kDa), a gut paracellular permeability probe, was not influenced. Obvious damage was observed in the mucosa, but the tight junctions between epithelial cells remained intact. Intestinal, rather than hepatic, alkaloid metabolism was decreased. These findings indicated that LPS pretreatment increased systemic exposure to the alkaloids through enhancement of their absorption, which was related to decreased intestinal efflux and metabolism. The results add to the understanding of why rhizoma coptidis is active despite the low plasma concentrations of the rhizoma coptidis alkaloids measured in normal subjects and experimental animals.

Pharmacokinetics and metabolism of jatrorrhizine, a gastric prokinetic drug candidate

Jatrorrhizine, a protoberberine alkaloid derived from Coptis chinensis, is currently under investigation as a natural gastric prokinetic drug candidate. In vitro and in vivo studies were conducted to characterize its pharmacokinetics and metabolism. After intravenous administration, the plasma concentration kinetics and major metabolites in rats were investigated. The metabolic kinetics, key cytochrome P450 enzymes and UDP‐glucuronosyltransferase isoforms (UGTs) of jatrorrhizine were studied in rat liver microsomes (RLMs). After intravenous administration, plasma jatrorrhizine concentrations showed a biphasic decline, dose‐independent clearance and half‐life of terminal elimination phase, and a relatively large distribution volume. The metabolic pathway for the conversion of jatrorrhizine was important for its elimination. In addition, the demethylated and glucuronidated products were found to be the major metabolites in rats. The enzyme kinetics for both demethylation and glucuronidation were fitted to the hyperbolic Michaelis‐Menten equation in RLMs. CYP3A1/2 and CYP2D2 were mainly responsible for demethylation, and UGT 1A1 and 1A3 were responsible for glucuronidation in RLMs. The metabolic properties of jatrorrhizine suggest multiple metabolic pathways. These results will contribute to promote further research and development of jatrorrhizine. Copyright

Pharmacokinetics difference of multiple active constituents from decoction and maceration of Fuzi Xiexin Tang after oral administration in rat by UPLC-MS/MS.

Fuzi Xiexin Tang (FXT) is a classic traditional Chinese medicine formula which has been employed in clinical for more than 1800 years. The distinctive preparation method (maceration) recorded in ancient time is different from one in modern clinical practice (decoction). Aim of this study is to investigate the pharmacokinetic difference of alkaloids, flavones and anthraquinones in rats after oral administration of decoction of FXT (DFXT, 30gkg(-1)), maceration of FXT (MFXT, 30gkg(-1)) and decoction of Aconiti Lateralis Radix Preparata (DAR, 6gkg(-1)) by a validated UPLC-MS/MS method. Plasma concentrations and pharmacokinetic parameters of 16 active constituents (aconitine, hypaconitine, mesaconitine, benzoylaconine, benzoylhypaconine, benzoylmesaconine, berberine, palmatine, jatrorrhizine, coptisine, baicalin, wogonin, wogonoside, emodin, aloe-emodin, rhein) in rat were quantified and compared. Different preparative methods resulted in significant difference on exposure and pharmacokinetic characteristics of alkaloids, flavones and anthraquinones from FXT, especially protoberberine alkaloids. Concentrations of monoester-diterpenoid alkaloids were below the LOD in rat plasma after administration of DFXT and MFXT because of the existence of other three herbs from FXT. Maceration could decrease the absorption of flavones while increased the absorption of anthraquinones. Cmax of emodin and rhein were 3.1 and 10.3 times increased, while eliminations of these two constituents were 8.0 and 19.0 times slower after administration of MFXT. Bioavailability of both flavones and anthraquinones increased after administration of MFXT, especially emodin and rhein increasing as much as 13.5 and 20.7 times. Herb-herb interaction between DAR and other three herbs from FXT significantly influenced the exposure of aconitum alkaloids.

UPLC-ESI/MS determination of 17 active constituents in two categorized formulas of traditional Chinese medicine, Sanhuang Xiexin Tang and Fuzi Xiexin Tang: application in comparing the differences in decoctions and macerations.

A rapid and sensitive UPLC-ESI/MS method was established and validated to determine 17 active constituents (aconitine, hypaconitine, mesaconitine, benzoylaconine, benzoylhypaconine, benzoylmesaconine, berberine, palmatine, jatrorrhizine, coptisine, baicalein, wogonin, baicalin, wogonoside, emodin, aloe-emodin and rhein) in Sanhuang Xiexin Tang (SXT) and Fuzi Xiexin Tang (FXT), which are two classic compound recipes from Xiexin Tang categorized formulas in traditional Chinese medicien. The separation was performed on a UPLC BEH C18 column gradient eluted using acetonitrile and 0.1% formic acid as mobile phase. ESI/MS was operated in positive ([M + H](+)) in selected ion recording mode for analysis of alkaloids and flavones, while in negative ([M - H](-)) selected ion recording mode for anthraquinones. All of the 17 constituents exhibited good linearity in a relatively wide concentration ranges with the lowest limits of detection of 0.38 ng/mL. All of the relative standard deviation values of intra- and inter-precisions and stabilities of 17 constituents were within 5%. The method was successfully applied to determine 17 active constituents in decoctions and macerations of SXT and FXT. The results indicated that different preparative methods resulted in significant diversity in concentrations of the 17 analytes. Herb-herb interaction appeared between aconitum alkaloids in Aconiti Lateralis Radix Preparata and another three herbs.