Hai Long Li

Could the gut microbiota reconcile the oral bioavailability conundrum of traditional herbs

ETHNOPHARMACOLOGICAL RELEVANCEnA wealth of information is emerging about the impact of gut microbiota on human health and diseases such as cardiovascular diseases, obesity and diabetes. As we learn more, we find out the gut microbiota has the potential as new territory for drug targeting. Some novel therapeutic approaches could be developed through reshaping the commensal microbial structure using combinations of different agents. The gut microbiota also affects drug metabolism, directly and indirectly, particularly towards the orally administered drugs. Herbal products have become the basis of traditional medicines such as traditional Chinese medicine and also been being considered valuable materials in modern drug discovery. Of note, low oral bioavailability but high bioactivity is a conundrum not yet solved for some herbs. Since most of herbal products are orally administered, the herbs constituents are inevitably exposed to the intestinal microbiota and the interplays between herbal constituents and gut microbiota are expected. Emerging explorations of herb-microbiota interactions have an opportunity to revolutionize the way we view herbal therapeutics. The present review aims to provide information regarding the health promotion and/or disease prevention by the interplay between traditional herbs with low bioavailability and gut microbiota through gut microbiota via two different types of mechanisms: (1) influencing the composition of gut microbiota by herbs and (2) metabolic reactions of herbal constituents by gut microbiota.nnnMATERIALS AND METHODSnThe major data bases (PubMed and Web of Science) were searched using gut microbiota, intestinal microbiota, gut flora, intestinal flora, gut microflora, intestinal microflora, herb, Chinese medicine, traditional medicine, or herbal medicine as keywords to find out studies regarding herb-microbiota interactions. The Chinese Pharmacopoeia (2010 edition, Volume I) was also used to collect the data of commonly used medicinal herbs and their quality control approaches.nnnRESULTSnAmong the 474 monographs of herbs usually used in the Chinese Pharmacopoeia, the quality control approach of 284 monographs is recommended to use high-performance liquid chromatography approach. Notably, the major marker compounds (>60%) for quality control are polyphenols, polysaccharides and saponins, with significant oral bioavailability conundrum. Results from preclinical and clinical studies on herb-microbiota interactions showed that traditional herbs could exert heath promotion and disease prevention roles via influencing the gut microbiota structure. On the other hand, herb constituents such as ginsenoside C-K, hesperidin, baicalin, daidzin and glycyrrhizin could exert their therapeutic effects through gut microbiota-mediated bioconversion.nnnCONCLUSIONSnHerb-microbiota interaction studies provide novel mechanistic understanding of the traditional herbs that exhibit poor oral bioavailability. Microbiota availability could be taken consideration into describing biological measurements in the therapeutic assessment of herbal medicine. Our review should be of value in stimulating discussions among the scientific community on this relevant theme and prompting more efforts to complement herb-microbiota interactions studies.

Different Accumulation Profiles of Multiple Components Between Pericarp and Seed of Alpinia oxyphylla Capsular Fruit as Determined by UFLC-MS/MS

Plant secondary metabolites are known to not only play a key role in the adaptation of plants to their environment, but also represent an important source of active pharmaceuticals. Alpinia oxyphylla capsular fruits, made up of seeds and pericarps, are commonly used in traditional East Asian medicines. In clinical utilization of these capsular fruits, inconsistent processing approaches (i.e., hulling pericarps or not) are employed, with the potential of leading to differential pharmacological effects. Therefore, an important question arises whether the content levels of pharmacologically active chemicals between the seeds and pericarps of A. oxyphylla are comparable. Nine secondary metabolites present in A. oxyphylla capsular fruits, including flavonoids (e.g., tectochrysin, izalpinin, chrysin, apigenin-4,7-dimethylether and kaempferide), diarylheptanoids (e.g., yakuchinone A and B and oxyphyllacinol) and sesquiterpenes (e.g., nootkatone), were regarded as representative constituents with putative pharmacological activities. This work aimed to investigate the abundance of the nine constituents in the seeds and pericarps of A. oxyphylla. Thirteen batches of A. oxyphylla capsular fruits were gathered from different production regions. Accordingly, an ultra-fast high performance liquid chromatography/quadrupole tandem mass spectrometry (UFLC-MS/MS) method was developed and validated. We found that: (1) the nine secondary metabolites were differentially concentrated in seeds and fruit capsules; (2) nootkatone is predominantly distributed in the seeds; in contrast, the flavonoids and diarylheptanoids are mainly deposited in the capsules; and (3) the content levels of the nine secondary metabolites occurring in the capsules varied greatly among different production regions, although the nootkatone levels in the seeds were comparable among production regions. These results are helpful to evaluating and elucidating pharmacological activities of A. oxyphylla capsular fruits. Additionally, it may be of interest to elucidate the mechanisms involved in the distinct accumulation profiles of these secondary metabolites between seeds and pericarps.

Identification of known chemicals and their metabolites from Alpinia oxyphylla fruit extract in rat plasma using liquid chromatography/tandem mass spectrometry (LC-MS/MS) with selected reaction monitoring

Alpinia oxyphylla (Yizhi) capsularfruits are commonly used in traditional medicine. Pharmacological studies have demonstrated that A. oxyphylla capsularfruits have some beneficial roles. Besides volatile oil, sesquiterpenes, diarylheptanoids and flavonoids are main bioactive constituents occurring in the Yizhi capsularfruits. The representative constituents include tectochrysin, izalpinin, chrysin, apigenin-4,7-dimethylether, kaempferide, yakuchinone A, yakuchinone B, oxyphyllacinol and nootkatone. Their content levels in the fruit and its pharmaceutical preparations have been reported by our group. The nine phytochemicals are also the major components present in the Yizhi alcoholic extracts, which have anti-diarrheal activities. However, the fates of these constituents in the body after oral or intravenous administration remain largely unknown. In the present study, we focus on these phytochemicals albeit other concomitant compounds. The chemicals and their metabolites in rat plasma were identified using liquid chromatography/tandem mass spectrometry with selected reaction monitoring mode after orally administered Yizhi extract to rats. Rat plasma samples were treated by methanol precipitation, acidic or enzymatic hydrolysis. This target analysis study revealed that: (1) low or trace plasma levels of parent chemicals were measured after p.o. administration of Yizhi extract, Suoquan capsules and pills to rats; (2) flavonoids and diarylheptanoids formed mainly monoglucuronide metabolites; however, diglucuronide metabolites for chrysin, izalpinin and kaempferide were also detected; (3) metabolic reduction of Yizhi diarylheptanoids occurred in rats. Yakuchinone B was reduced to yakuchinone A and then to oxyphyllacinol in a stepwise manner and subsequently glucuronidated by UDP-glucuronosyl transferase. Further research is needed to characterize the UDP-glucuronosyl transferase and reductase involved in the biotransformation of Yizhi chemicals.

Quantitative analysis of the major constituents in Chinese medicinal preparation SuoQuan formulae by ultra fast high performance liquid chromatography/quadrupole tandem mass spectrometry.

BackgroundThe SuoQuan formulae containing Fructus Alpiniae Oxyphyllae has been used to combat the urinary incontinence symptoms including frequency, urgency and nocturia for hundreds of years in China. However, the chemical information was not well characterized. The quality control marker constituent only focused on one single compound in the current Chinese Pharmacopeia. Hence it is prudent to identify and quantify the main constituents in this herbal product. This study aimed to analyze the main constituents using ultra-fast performance liquid chromatography coupled to tandem mass spectrometry (UFLC-MS/MS).ResultsFourteen phytochemicals originated from five chemical classes constituents were identified by comparing the molecular mass, fragmentation pattern and retention time with those of the reference standards. A newly developed UFLC-MS/MS was validated demonstrating that the new assay was valid, reproducible and reliable. This method was successfully applied to simultaneously quantify the fourteen phytochemicals. Notably, the content of these constituents showed significant differences in three pharmaceutical preparations. The major constituent originated from each of chemical class was isolinderalactone, norisoboldine, nootkatone, yakuchinone A and apigenin-4’,7-dimethylther, respectively. The variation among these compounds was more than 1000 times. Furthermore, the significant content variation between the two different Suoquan pills was also observed.ConclusionThe proposed method is sensitive and reliable; hence it can be used to analyze a variety of SuoQuan formulae products produced by different pharmaceutical manufacturers.

Differential systemic exposure to galangin after oral and intravenous administration to rats

AbstractBackgroundGalangin (3,5,7-trihydroxyflavone) is present in high concentrations in herbal medicine such as Alpinia officinarum Hance. Galangin shows multifaceted in vitro and in vivo biological activities. The number and position of hydroxyl groups in this molecule play an important role in these biological activities. However, these hydroxyl groups undergo glucuronidation and sulfation in in vitro assay system. However, the systemic exposure to galangin after dosing in animals and/or humans remains largely unknown. Thus it is not clear whether the galangin exists in the body at concentrations high enough for the biological effects. Furthermore, the metabolite identification and the corresponding plasma pharmacokinetics need to be characterized.ResultsTwo LC-MS/MS methods were developed and validated and successfully applied to analyze the parent drug molecules and aglycones liberated from plasma samples via β-glucuronidase hydrolysis. Our major findings were as follows: (1) The routes of administration showed significant influences on the systemic exposure of galangin and its metabolites. (2) Galangin was preferentially glucuronidated after p.o. dosing but sulfated after i.v. medication. (3) Kaempferol conjugates were detected demonstrating that oxidation reaction occurred; however, both glucuronidation and sulfation were more efficient. (4) Oral bioavailability of free parent galangin was very low.ConclusionsSystemic exposure to galangin and its metabolites was different in rat plasma between oral and intravenous administration. Further research is needed to characterize the structures of galangin conjugates and to evaluate the biological activities of these metabolites.n Graphical abstractGalangin was preferentially glucuronidated after p.o. dosing but sulfated after i.v. medication.

Validated method to measure yakuchinone A in plasma by LC-MS/MS and its application to a pharmacokinetic study in rats

BackgroundYakuchinone A has a plethora of beneficial biological effects. However, the pharmacokinetic (PK) data of yakuchinone A still remain unknown so far. Furthermore, the quantification of yakuchinone A in biological samples has not been reported in the literature. Therefore, in the present study we aimed to develop a new method for the fast, efficient and accurate assessment of yakuchinone A concentration in plasma, as a means for facilitating the PK evaluation of yakuchinone A.ResultsA liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method was developed and validated for the determination of yakuchinone A in rat plasma. Mass spectrometric and chromatographic conditions were optimized. Plasma samples were pretreated by protein precipitation with methanol. LC separation was performed on a Phenomenex Luna C18 column with gradient elution using a mobile phase consisting of methanol–water containing 0.5xa0mM formic acid (HCOOH) at a flow rate of 0.28xa0mL/min. ESI-MS spectra were acquired in positive ion multiple reaction monitoring mode (MRM). The precursor-to-product ion pairs used for MRM of yakuchinone A and yakuchinone B were m/z 313.1u2009→u2009137.0 and 311.2u2009→u2009117.1, respectively. Low concentration of HCOOH reduced the ion suppression caused by matrix components and clearly improved the analytical sensitivity. Yakuchinone A showed good linearity over a wide concentration range (ru2009>u20090.99). The accuracy, precision, stability and linearity were found to be within the acceptable criteria. This new method was successfully applied to analyze the rat plasma concentration of parent yakuchinone A after a single oral administration of SuoQuan capsules. Low systemic exposure to parent yakuchinone A was observed.ConclusionThe proposed method is sensitive and reliable. It is hoped that this new method will prove useful for the future PK studies.

A sensitive and cost-effective LC-ESI-MS/MS method for quantitation of euscaphic acid in rat plasma using optimized formic acid concentration in the mobile phase

Euscaphic acid, a triterpene acid, exists ubiquitously in medicinal plants and demonstrates various pharmacological activities. This active compound is often used as a marker compound for quality control. Hitherto, the pharmacokinetic (PK) information is relatively scarce; therefore, it remains open to question whether the euscaphic acid reaches the target sites in the body at concentrations high enough for the claimed biological effects. A robust analytical method is prerequisite for obtaining enough PK information of euscaphic acid, which is useful for interpreting its pharmacological effects. In this study, we developed and validated a rapid liquid chromatographic tandem mass spectrometric (LC-MS/MS) method for the measurement of euscaphic acid in rat plasma. The rat plasma samples were precipitated with acetonitrile and the resulting supernatants were separated by a 4 min pulse gradient method on a Synergi Fusion-RP C18 column (4 μm, 2.0 mm i.d. × 50 mm). Ursolic acid was used as an internal standard for quantification of euscaphic acid. Deprotonated euscaphic acid and its internal standard were generated in negative electrospray ionization (ESI) mode and their precursor-to-product ion pairs (m/z 487.4→469.3 and 455.5→455.4, respectively) were used for measurement. Notably, the commonly used concentration of formic acid (HCOOH; 1‰ and 5‰, v/v) in the mobile phase seriously suppressed the signal intensity, but this mobile phase additive at a much lower concentration level (0.1‰ and 0.2‰) could overcome the matrix effects and therefore increase the sensitivity of MS detection of euscaphic acid. The newly developed bioanalytical assay possessed favorable accuracy and precision with a lower limit of quantification of 2.0 ng mL−1 and was successfully applied to PK studies in rats. The experimental strategies presented herein may be helpful for measurement of other triterpene acids in biological matrices.

Simultaneous quantification of seventeen bioactive components in rhizome and aerial parts of Alpinia officinarum Hance using LC-MS/MS

The rhizomes of Alpinia officinarum Hance (Zingiberaceae family) have been used as antiemetics, stomachics and analgesics in Asia for centuries. Unfortunately, the aerial parts were thrown away as waste whilst harvesting the rhizomes of A. officinarum. Recently, scientists reported that the ethanol extract of the aerial parts displayed anti-proliferation activity through mitochondrial pathway-induced cell apoptosis. However, the chemical composition of this extract remained largely unknown. We have identified sixteen chemicals including twelve flavonoids and four diarylheptanoids from the methanol extract of A. officinarum leaves using liquid chromatography/tandem mass spectrometry (LC-MS/MS). In order to better explore the potential value of the aerial parts, we need to know what the main constituents occurring in the aerial parts are and how the content of these chemicals is influenced by growing period. In the present study, a LC-MS/MS method was developed and validated for determination of seventeen compounds occurring both in the aerial parts and rhizomes sampled at different growing periods. The validation indices evaluated were satisfactory and the method was successfully employed to analyze the above-mentioned plant samples. Notably, we found that the content of these compounds, except for quercetin, was higher in rhizomes than in aerial parts. The six major constituents both in the aerial parts and rhizomes were galangin, kaempferide, hexahydrocurcumin, pinocembrin, chrysin and isorhamnetin. Moreover, the trends of change in content along with the sample period for most of the monitored phytochemicals were almost similar between the aerial parts and rhizomes. Our study should be of value in arousing everyones interest to make the best use of the aerial parts of A. officinarum in the future.

LC-MS/MS-based method for simultaneous quantification of known chemicals and metabolites of Alpiniae oxyphyllae Fructus extract in rat plasma and its application in a pharmacokinetic study

Alpiniae oxyphyllae Fructus (Yizhi in Chinese) is commonly used for the treatment of diarrhea, intestinal disorders and urinary incontinence symptoms. To date, little information is available on the pharmacokinetic (PK) properties of this herb. We have identified the known active chemicals (including nootkatone, yakuchinone A, yakuchinone B, oxyphyllacinol, tectochrysin, chrysin, izalpinin, apigenin-4′,7-dimethylether, and kaempferide) and their metabolites (phase II metabolites and oxidized product such as kaempferol) from Yizhi extract in rat plasma using liquid chromatography/tandem mass spectrometry (LC-MS/MS) with selected reaction monitoring. In the present study, an LC-MS/MS-based method was developed and validated for the simultaneous quantitation of the Yizhi chemicals and their metabolites in rat plasma after enzymatic treatment. A mixture of β-glucuronidase and sulfatase was used to liberate parent chemicals from their phase II metabolites. A post-extraction spike method, as well as a post-column infusion method, was conducted to investigate matrix-effects. Particularly, the ion suppression effect for all the analytes was overcome through combining a liquid–liquid extraction method for clean-up, elution gradient optimization for separation and inclusion of very low concentration of HCOOH into the mobile phase. Mean accuracies were obtained in the range of 84.7–112% at three different quality control levels for the ten analytes, with intra- and inter-day variations within 13.6% (1.76–13.6%). This validated method was successfully applied to a PK investigation in rats after a single oral administration of Yizhi extract. These results supply a suitable reference for further PK studies of the Yizhi chemicals and their metabolites in the future.

Determination of α-hederin in rat plasma using liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) and its application to a pharmacokinetic study

The evaluation of efficacy and safety should be paralleled with the assessment of comprehensive pharmacokinetic (PK) properties for a drug candidate, and a robust bioanalytical method is a prerequisite for obtaining PK information. α-Hederin is reported to have various in vitro and in vivo activities; however, very little is known about its PK and metabolic characteristics. In this study, we have developed an efficient LC-ESI(−)-MS/MS assay for α-hederin and its sapogenin hederagenin in rat plasma. Sample cleanup involved methanol precipitation for identification analysis and liquid–liquid extraction with ethyl acetate for quantification assay. LC analysis was performed under reversed-phase conditions in the modified “pulse gradient elution” mode. Analyte identification and quantification were conducted using multiple reaction monitoring (MRM) mode with euscaphic acid as the internal standard. Under these conditions, deglycosylated metabolites and their sulfate conjugates were detected; however, hederagenin was not detected in rat plasma samples after both oral and intravenous treatments. The mean plasma clearance (CL), volume of distribution (VSS) and elimination half-life (t1/2) of α-hederin were 0.24 L h−1 kg−1, 0.25 L kg−1 and 2.67 h, respectively. The oral bioavailability (F) of α-hederin in rats was about 0.14%, which might result from the poor intestinal absorption and/or extensive biliary excretion. It is hoped that this validated method will be useful for future PK studies of α-hederin.