Exploration on pharmacological mechanisms of YZP against neuropathic pain via inhibiting spinal inflammation and the rationality of its compatibility.

ETHNOPHARMACOLOGICAL RELEVANCE: Yuanhu Zhitong Prescription (YZP) is a well-known traditional Chinese medicine (TCM) formula for neuropathic pain (NP) therapy with a satisfying clinical efficacy. However, the underlying pharmacological mechanism and its compatibility principle remain unclear. AIM OF THE STUDY: This study aims to investigate the analgesic and compatibility mechanisms of YZP on neuropathic pain (NP) at the gene and biological process levels. MATERIALS AND METHODS: The chronic constriction injury (CCI) rats were intragastrically administrated with extracts of YZP, YH and BZ separately, and then mechanical hypersensitivity were measured to evaluate the analgesic effects between YH and BZ before and after compatibility. Then, RNA-seq and bioinformatics analyses were performed to elucidate the potential mechanisms underlying YZP's analgesia and compatibility. Finally, the expression levels and significant differences of key genes were analyzed. RESULTS: Behaviorally, both YZP and YH effectively alleviated mechanical allodynia in CCI rats, with YZP being superior to YH. In contrast, we did not observe an analgesic effect of BZ. Genetically, YZP, YH, and BZ reversed the expression levels of 52, 34, and 42 aberrant genes in the spinal cord of CCI rats, respectively. Mechanically, YZP was revealed to alleviate NP mainly by modulating the inflammatory response and neuropeptide signaling pathway, which are the dominant effective processes of YH. Interestingly, the effective targets of YZP were especially enriched in leukocyte activation and cytokine-mediated signaling pathways. Moreover, BZ was found to exert an adjunctive effect in enhancing the analgesic effect of YH by promoting skeletal muscle tissue regeneration and modulating calcium ion transport. CONCLUSIONS: YH, as the monarch drug, plays a dominant role in the analgesic effect of YZP that effectively relieves NP by inhibiting the spinal inflammation and neuropeptide signaling pathway. BZ, as the minister drug, not only synergistically enhances analgesic processes of YH but also helps to alleviate the accompanying symptoms of NP. Consequently, YZP exerted a more potent analgesic effect than YH and BZ alone. In conclusion, our findings offer new insights into understanding the pharmacological mechanism and compatibility principle of YZP, which may support its clinical application in NP therapy.

Applications of mass spectrometry in cosmetic analysis: An overview.

Mass spectrometry (MS) is a crucial tool in cosmetic analysis. It is widely used for ingredient screening, quality control, risk monitoring, authenticity verification, and efficacy evaluation. However, due to the diversity of cosmetic products and the rapid development of MS-based analytical methods, the relevant literature needs a more systematic collation of information on this subject to unravel the true potential of MS in cosmetic analysis. Herein, an overview of the role of MS in cosmetic analysis over the past two decades is presented. The currently used sample preparation methods, ionization techniques, and types of mass analyzers are demonstrated in detail. In addition, a brief perspective on the future development of MS for cosmetic analysis is provided.

Metabonomic approaches investigate diosbulbin B-induced pulmonary toxicity and elucidate its underling mechanism in male mice.

Air Potato Yam is widely used in the treatment of many conditions such as cancer, inflammation, and goiter. Diosbulbin B (DIOB) is the primary active component of Air Potato Yam, and it exhibits anti-tumor and anti-inflammatory properties. The main purpose of this study was to determine the mechanism by which DIOB induces lung toxicity, using metabonomics and molecular biology techniques. The results showed that the lung toxicity induced by DIOB may occur because of a DIOB-induced increase in the plasma levels of long-chain free fatty acids and endogenous metabolites related to inflammation. In addition, treatment with DIOB increases the expression of the cyp3a13 enzyme, which leads to enhanced toxicity in a dose-dependent manner. The molecular mechanism underlying toxicity in mouse lung cells is the DIOB-mediated inhibition of fatty acid ß-oxidation, partial glycolysis, and the TCA cycle, but DIOB treatment can also compensate for the low Adenosine triphosphate (ATP) supply levels by improving the efficiency of the last step of the glycolysis reaction and by increasing the rate of anaerobic glycolysis. Using metabonomics and other methods, we identified the toxic effects of DIOB on the lung and clarified the underlying molecular mechanism.

Systems Toxicology Approaches Reveal the Mechanisms of Hepatotoxicity Induced by Diosbulbin B in Male Mice.

Diosbulbin B (DIOB) is an effective component of air potato yam with antitumor and anti-inflammatory activities, and it is the main toxic component leading to hepatotoxicity. However, the mechanism of its hepatotoxicity remains unclear. In this study, we aimed to systematically elucidate the molecular action of DIOB on liver metabolic function through systems toxicology approaches. C57BL/6 mice were orally treated with DIOB (10, 30, 60 mg/kg) for 28 days, and the liver metabonomics and histopathology, molecular docking, mRNA expression levels, and activities of enzymes were analyzed. The results illustrated that DIOB could affect fatty acid and glucose metabolism, block the TCA cycle, and DIOB also could disorder bile acid synthesis and transport and promote the occurrence of hyperbilirubinemia. In addition, DIOB increased Cyp3a11 expression in a dose-dependent manner. Thus, these results provide new insights into the mechanism of hepatotoxicity caused by DIOB.

Metabonomics reveals bisphenol A affects fatty acid and glucose metabolism through activation of LXR in the liver of male mice.

Bisphenol-A (BPA) is a representative environmental endocrine disrupting chemical that is widely used in the production of polycarbonate plastics and epoxy resins. Many studies have confirmed BPA to be closely associated with metabolic diseases, reproductive system diseases, and sex hormone-dependent cancers. In this study, we aimed to systematically elucidate the molecular action of BPA on liver fatty acid and glucose metabolism and the reasons for BPA-induced hypoglycemia through a metabonomics approach. C57BL/6 mice were orally treated with BPA (1, 10, 50, 250 µg/kg) for 35 days and the liver metabonomics and histopathology, molecular docking, mRNA expression levels and activities of enzymes were analyzed. Based on the high-resolution mass spectrometry (MS) for metabonomics and on various software and bioinformatic analysis methods, we found that BPA could affect fatty acid and glucose metabolism, block the TCA cycle, and BPA also regulated the nuclear receptor LXR caused hypoglycemia, thereby affecting the normal metabolic functions of the liver.

Untargeted LC-MS-based metabonomics revealed that aristolochic acid I induces testicular toxicity by inhibiting amino acids metabolism, glucose metabolism, ß-oxidation of fatty acids and the TCA cycle in male mice.

As the main toxic component of aristolochic acid, aristolochic acid I (AAI) is primarily found in Aristolochiaceae plants such as Aristolochia, Aristolochia fangchi and Caulis aristolochiae manshuriensis. AAI has been proven to be carcinogenic, mutagenic and nephrotoxic. Although the role of AAI in testicular toxicity has been reported, its mechanism of action is unknown. Using metabonomics and molecular biology techniques, we tried to identify the differential endogenous metabolites of AAI that may affect the changes in testicular function in mice, map the network of metabolic pathways, and systematically reveal the molecular mechanism of AAI-induced testicular toxicity. We found that AAI inhibited amino acid metabolism in mouse testicular cells, impeded the uptake and oxidative decomposition of fatty acids, prevented normal glucose uptake by testicular cells, which inhibited glycolysis and gluconeogenesis, affected the mitochondrial tricarboxylic acid (TCA) cycle, which impaired the ATP energy supply, decreased the number of spermatogenic cells and sperm in the testes, induced changes in the mitochondrial state of spermatogonial cells, and ultimately led to physiological and pathological changes in the testes. AAI also regulated the testicular physiological activity by regulating the androgen receptor and hormone levels. This study used metabonomics and other methods to elucidate the mechanism of AAI-induced testicular toxicity from a new angle.

Quadrupole Orbitrap Mass Spectrometer-Based Metabonomic Elucidation of Influences of Short-Term Di(2-ethylhexyl) phthalate Exposure on Cardiac Metabolism in Male Mice.

Di(2-ethylhexyl) phthalate (DEHP) can cause severe environmental pollution. Effects of DEHP on cardiac metabolism have been reported, but its mechanism(s) of action is not fully clear. Here, we used high-resolution mass spectrometry for metabonomics and molecular biological methods to identify the different endogenous metabolites affected by DEHP that might cause changes in cardiac metabolism in mice, map the network of metabolic pathways, and reveal (at the molecular level) how DEHP affects cardiac metabolism. The results showed that DEHP could inhibit the ß-oxidation of fatty acids and gluconeogenesis, promote glycolysis, and inhibit the tricarboxylic acid cycle in cardiomyocytes. DEHP caused mitochondrial dysfunction by inhibiting the synthesis and transport of fatty acids and, thus, inhibiting the synthesis and breakdown of adenosine triphosphate in mitochondria. Pathology revealed that DEHP could change the normal structures and functions of the heart and bodies of mice. DEHP can interfere with the physiological and metabolic function of the heart in mice by disrupting the endogenous metabolite and gene levels.

Graphene Enhances Cellular Proliferation through Activating the Epidermal Growth Factor Receptor.

Graphene has promising applications in food packaging, water purification, and detective sensors for contamination monitoring. However, the biological effects of graphene are not fully understood. It is necessary to clarify the potential risks of graphene exposure to humans through diverse routes, such as foods. In the present study, graphene, as the model nanomaterial, was used to test its potential effects on the cell proliferation based on multiple representative cell lines, including HepG2, A549, MCF-7, and HeLa cells. Graphene was characterized by Raman spectroscopy, particle size analysis, atomic force microscopy, and transmission electron microscopy. The cellular responses to graphene exposure were evaluated using flow cytometry, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, and alamarBlue assays. Rat cerebral astrocyte cultures, as the non-cancer cells, were used to assess the potential cytotoxicity of graphene as well. The results showed that graphene stimulation enhanced cell proliferation in all tested cell cultures and the highest elevation in cell growth was up to 60%. A western blot assay showed that the expression of epidermal growth factor (EGF) was upregulated upon graphene treatment. The phosphorylation of EGF receptor (EGFR) and the downstream proteins, ShC and extracellular regulating kinase (ERK), were remarkably induced, indicating that the activation of the mitogen-activated protein kinase (MAPK)/ERK signaling pathway was triggered. The activation of PI3 kinase p85 and AKT showed that the PI3K/AKT signaling pathway was also involved in graphene-induced cell proliferation, causing the increase of cell ratios in the G2/M phase. No influences on cell apoptosis were observed in graphene-treated cells when compared to the negative controls, proving the low cytotoxicity of this emerging nanomaterial. The findings in this study revealed the potential cellular biological effect of graphene, which may give useful hints on its biosafety evaluation and the further exploration of the bioapplication.

Single and 14-day repeated dose inhalation toxicity studies of hexabromocyclododecane in rats.

Limited toxicological information is available for hexabromocyclododecane (HBCD),a widely used additive brominated flame retardant. Inhalation is a major route of human exposure to HBCD. The aim of this study was to determine the acute inhalation toxicity and potential subchronic inhalation toxicity of HBCD in Sprague-Dawley rats exposed to HBCD only through inhalation. The acute inhalation toxicity of HBCD was determined using the limit test method on five male and five female Sprague-Dawley rats at a HBCD concentration of 5000 mg/m(3). Repeated-dose toxicity tests were also performed, with 20 males and 20 females randomly assigned to four experimental groups (five rats of each sex in each group). There were three treatment groups (exposed to HBCD concentrations of 125,500, and 2000 mg/m(3)) and a blank control group (exposed to fresh air). In the acute inhalation toxicity study, no significant clinical signs were observed either immediately after exposure or during the recovery period. Gross pathology examination revealed no evidence of organ-specific toxicity in any rat. The inhalation LC50(4 h) for HBCD was higher than 5312 ± 278 mg/m3 for both males and females. In the repeated dose inhalation study, daily head/nose-only exposure to HBCD at 132 ± 8.8, 545.8 ± 35.3, and 2166.0 ± 235.9 mg/m(3) for 14 days caused no adverse effects. No treatment-related clinical signs were observed at any of the test doses. The NOAEL for 14-day repeated dose inhalation toxicity study of HBCD is 2000 mg/m(3).

Optimal method to stimulate cytokine production and its use in immunotoxicity assessment.

Activation of lymphocytes can effectively produce a large amount of cytokines. The types of cytokines produced may depend on stimulating reagents and treatments. To find an optimal method to stimulate cytokine production and evaluate its effect on immunotoxicity assessments, the authors analyzed production of IL-2, IL-4, IL-6, IL-10, IL-13, IFN-γ, TNF-α, GM-CSF, RANTES and TGF-ß in undiluted rat whole blood culture (incubation for 0, 2, 4, 6, 8 or 10 h) with different concentrations of PMA/ionomycin, PHA, Con A, LPS and PWM. We also evaluated the effects of cyclosporin A and azathioprine on cytokine production. The results revealed a rapid increase of IL-2, IFN-γ, TNF-α, RANTES and TGF-ß secretion within 6 h after stimulation with 25 ng/mL PMA and 1 µg/mL ionomycin. The inhibition of these cytokine profiles reflected the effects of immunosuppressants on the immune system. Therefore, the results of this is study recommend the detection of cytokine profiles in undiluted whole blood stimulated 6 h with 25 ng/mL PMA and 1 µg/mL ionomycin as a powerful immunotoxicity assessment method.

The immunotoxicity of dibutyl phthalate on the macrophages in mice.

OBJECTIVE: Dibutyl phthalate (DBP), a widely used phthalate chemical, is commonly used as plasticizer. It is well known that DBP causes reproductive and developmental diseases, but the effect of DBP on the immune system remains to be determined. We assessed the effect of DBP on immune functions of murine macrophages, which constitute a key component in the immune response. MATERIALS AND METHODS: Murine peritoneal exudate macrophages (PEMs) were treated with 0, 1, 5, 10, 50 or 100 µM DBP in vitro for 24 h and then the viability of PEMs were measured by flow cytometry (FCM) and trypan blue count. To investigate the effect of DBP on the functions of PEMs, we treated the PEMs with moderate dose of DBP (0, 1, 5 or 10 µM) in vitro for 24 h. The phenotypes, phagocytosis and cytokine production of PEMs were measured by FCM or real-time PCR. The immunogenicity and antigen presenting capacity of PEMs treated with DBP in vitro were assessed both by the mixed lymphocytereaction (MLR) in vitro assay and through the injection of exposed cells in mice by the delayed-type hypersensitivity (DTH) assay. RESULTS: High dose of DBP (50-100 µM) showed cytotoxicity on PEMs, whereas after the treatment with moderate dose of DBP (1-10 µM) in vitro, PEMs expressed low level of CD36, CD80 and MHC-II molecules, and showed significantly decreased phagocytosis on apoptotic cells and Escherichia coli. In addition, DBP treatment exhibited a decrease in the cytokine production, immunogenicity and antigen-presenting capacity of PEMs. CONCLUSIONS: The present study shows the effects of DBP on macrophages, demonstrating immunogenicity and decreased antigen presentation in vitro.

Cerium oxide nanoparticles induce cytotoxicity in human hepatoma SMMC-7721 cells via oxidative stress and the activation of MAPK signaling pathways.

BACKGROUND: Lanthanide cerium oxide (CeO2) nanoparticles have extensive applications in industrial fields, and concerns regarding their potential toxicity in humans and their environmental impact have increased. We investigated the underlying molecular mechanisms by which CeO2 nanoparticles induce toxicity in human hepatoma SMMC-7721 cells. RESULTS: Our results demonstrated that CeO2 nanoparticles reduced viability, caused dramatic morphological damage, and induced apoptosis in SMMC-7721 cells. CeO2 nanoparticles significantly increased the production of reactive oxygen species (ROS) and malondialdehyde (MDA), and significantly reduced the activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-px) and catalase (CAT). The phosphorylation levels of ERK1/2, JNK and p38 MAPK were significantly elevated after treatment with CeO2 nanoparticles. Pretreatment with the antioxidant N-acetyl-cysteine (NAC): reduced the induction of ROS and MDA by CeO2 nanoparticles; recovered the activity of SOD, GSH-px and CAT; reduced the phosphorylation levels of ERK1/2, JNK and p38; and attenuated CeO2 nanoparticles-induced damage and apoptosis in SMMC-7721 cells. CONCLUSIONS: Our data demonstrated that CeO2 nanoparticles induced damage and apoptosis in human SMMC-7721 cells via oxidative stress and the activation of MAPK signaling pathways.

Liquid chromatographic/mass spectrometry assay of bromotetrandrine in rat plasma and its application to pharmacokinetic study.

A rapid and sensitive liquid chromatography-tandem mass spectrometric method (LC-MS/MS) for the determination of bromotetrandrine in rat plasma has been developed and applied to pharmacokinetic study in Sprague-Dawley (SD) rats after a single oral administration. Sample preparation involves a liquid-liquid extraction with n-hexane-dichlormethane (65:35, containing 1% 2-propanol isopropyl alcohol, v/v). Bromotetrandrine and brodimoprim (internal standard, IS) were well separated by LC with a Dikma C18 column using methanol-ammonium formate aqueous solution (20 mm) containing 0.5% formic acid (60:40, v/v) as mobile phase. Detection was performed on a triple quadrupole mass spectrometer in multiple reaction monitoring mode. The ionization was optimized using ESI+ and selectivity was achieved using MS/MS analysis, m/z 703.0 --> 461.0 and m/z 339.0 --> 281.0 for bromotetrandrine and IS, respectively. The present method exhibited good linearity over the concentration range of 20-5000 ng/mL for bromotetrandrine in rat plasma with a lower limit of quantification of 20 ng/mL. The intra- and inter-day precisions were 2.8-7.5% and 3.2-8.1%, and the intra- and inter-day accuracy ranged from -4.8 to 8.2% and -5.6 to 6.2%, respectively. The method was successfully applied to a pharmacokinetic study after a single oral administration to SD rats with bromotetrandrine of 50 mg/kg.

Liquid chromatography/tandem mass spectrometry method for simultaneous evaluation of activities of five cytochrome P450s using a five-drug cocktail and application to cytochrome P450 phenotyping studies in rats.

A reliable liquid chromatography/tandem mass spectrometry has been developed for simultaneous evaluation of the activities of five cytochrome P450s (CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A) in rat plasma and urine. The five-specific probe substrates/metabolites include phenacetin/paracetamol (CYP1A2), tolbutamide/4-hydroxytolbutamide and carboxytolbutamide (CYP2C9), mephenytoin/4'-hydroxymephenytoin (CYP2C19), dextromethorphan/dextrorphan (CYP2D6), and midazolam/1'-hydroxymidazolam (CYP3A). Internal standards were brodimoprim (for phenacetin, paracetamol, midazolam and 1'-hydroxymidazolam), ofloxacin (for 4'-hydroxymephenytoin, dextromethorphan and dextrorphan) and meloxicam (for tolbutamide, 4-hydroxytolbutamide and carboxytolbutamide). Sample preparation was conducted with solid-phase extraction using Oasis HLB cartridges. The chromatography was performed using a C(18) column with mobile phase consisting of methanol/0.1% formic acid in 20 mM ammonium formate (75:25). The triple-quadrupole mass spectrometric detection was operated in both positive mode (for phenacetin, paracetamol, midazolam, 1'-hydroxymidazolam, brodimoprim, 4'-hydroxymephenytoin, dextromethorphan, dextrorphan and ofloxacin) and negative mode (for tolbutamide, 4-hydroxytolbutamide, carboxytolbutamide and meloxicam). Multiple reaction monitoring mode was used for data acquisition. Calibration ranges in plasma were 2.5-2500 ng/mL for phenacetin, 2.5-2500 ng/mL for paracetamol, 5-500 ng/mL for midazolam, and 0.5-500 ng/mL for 1'-hydroxymidazolam. In urine calibration ranges were 5-1000 ng/mL for dextromethorphan, 0.05-10 microg/mL for dextrorphan and 4'-hydroxymephenytoin, 5-2000 ng/mL for tolbutamide, 0.05-20 microg/mL for 4-hydroxytolbutamide and 0.025-10 microg/mL for carboxytolbutamide. The intra- and inter-day precision were 4.3-12.4% and 1.5-14.8%, respectively for all of the above analytes. The intra- and inter-day accuracy ranged from -9.1 to 8.3% and -10 to 9.2%, respectively for all of the above analytes. The lower limits of quantification were 2.5 ng/mL for phenacetin and paracetamol, 5 ng/mL for midazolam, 0.5 ng/mL for 1'-hydroxymidazolam, 5 ng/mL for dextromethorphan, 50 ng/mL for dextrorphan and 4'-hydroxymephenytoin, 5 ng/mL for tolbutamide, 50 ng/mL for 4-hydroxytolbutamide and 25 ng/mL for carboxytolbutamide. All the analytes were evaluated for short-term (24 h, room temperature), long-term (3 months, -20 degrees C), three freeze-thaw cycles and autosampler (24 h, 4 degrees C) stability. The stability of urine samples was also prepared with and without beta-glucuronidase incubation (37 degrees C) and measured comparatively. No significant loss of the analytes was observed at any of the investigated conditions. The current method provides a robust and reliable analytical tool for the above five-probe drug cocktail, and has been successfully verified with known CYP inducers.

Establishment of a liquid chromatographic/mass spectrometry method for quantification of tetrandrine in rat plasma and its application to pharmacokinetic study.

A rapid and sensitive liquid chromatography-tandem mass spectrometric method (LC/MS/MS) for the determination of tetrandrine in rat plasma has been developed, fully validated and successfully applied to pharmacokinetic study in Sprague-Dawley (SD) rats after a single oral administration. Sample preparation involves a liquid-liquid extraction with n-hexane-dichlormethane (65:35, containing 1% 2-propanol isopropyl alcohol, v/v). Tetrandrine and brodimoprim (internal standard) were well separated by LC with a Dikma C(18) column using acetonitrile-methanol-ammonium formate aqueous solution (20mM) containing 0.3% formic acid (20:30:50, v/v/v) as mobile phase. Detection was performed on a triple quadrupole mass spectrometer in multiple reaction monitoring mode. The ionization was optimized using ESI(+) and selectivity was achieved using MS/MS analysis, m/z 623.0-->381.0 and m/z 339.0-->281.0 for tetrandrine and I.S., respectively. The present method exhibited good linearity over the concentration range of 5-2,000 ng/mL for tetrandrine in rat plasma with a lower limit of quantification of 5 ng/mL. The intra- and inter-day precision were 2.0-9.2% and 4.5-9.4%, and the intra- and inter-day accuracy ranged from -7.6 to 10.3% and -6.0 to 5.3%, respectively. No endogenous compounds were found to interfere with the analysis, and tetrandrine was stable during the whole assay period. The method was successfully applied to a pharmacokinetic study after an intragastric administration (i.g.) of tetrandrine to SD rats with a single dose of 50mg/kg. The results confirm that the assay is suitable for the pharmacokinetic study of tetrandrine.

Intestinal permeability of metformin using single-pass intestinal perfusion in rats.

AIM: To characterize the intestinal transport and mechanism of metformin in rats and to investigate whether or not metformin is a substrate for P-glycoprotein (P-gp). METHODS: The effective intestinal permeability of metformin was investigated using single-pass intestinal perfusion (SPIP) technique in male Waster rats. SPIP was performed in three isolated intestinal segments (duodenum, jejunum and ileum) at the same concentration of metformin (50 microg/mL) to test if the intestinal transport of metformin exhibited site-dependent changes, and in a same isolated intestinal segment (duodenal segment) at three different concentrations of metformin (10, 50, 200 microg/mL) to test if the intestinal transport of metformin exhibited concentration-dependent changes. Besides, P-gp inhibitor verapamil (400 microg/mL) was co-perfused with metformin (50 microg/mL) in the duodenum segment to find out if the intestinal absorption of metformin was affected by P-gp exiting along the gastrointestinal track. Stability studies were conducted to ensure that the loss of metformin could be attributed to intestinal absorption. RESULTS: The effective permeability values (P(eff)) of metformin in the jejunum and ileum at 50 microg/mL were significantly lower than those in the duodenum at the same concentration. Besides, P(eff) values in the duodenum at high concentration (200 microg/mL) were found to be significantly lower than those at low and medium concentrations (10 and 50 microg/mL). Moreover the co-perfusion with verapamil did not increase the P(eff) value of metformin at 50 microg/mL in the duodenum. CONCLUSION: Metformin could be absorbed from the whole intestine, with the main absorption site at duodenum. This concentration-dependent permeability behavior in the duodenum indicates that metformin is transported by both passive and active carrier-mediated saturable mechanism. The P(eff) value can not be increased by co-perfusion with verapamil, indicating that absorption of metformin is not efficiently transported by P-gp in the gut wall. Furthermore metformin is neither a substrate nor an inducer of P-gp. Based on the P(eff) values obtained in the present study and using established relationships, the human fraction dose absorbed for metformin is estimated to be 74%-90% along human intestine.

[Advances on biological activities of coumarins].

This paper reviewed the advances on effective constituents and biological activities of coumarins in recent ten years. Coumarins are a group of important natural compounds, and have been found to have multi-biological activities such as anti-HIV, anti-tumor, anti-hypertension, anti-arrhythmia, anti-osteoporosis, assuaging pain, preventing asthma and antisepsis. Therefore, further investigation should emphasize on improving techniques for extraction and separation, searching the effective precursory compound, and synthesizing and screening out courmarin derivatives with high activity and low toxicity.