Glycosaminoglycan from Apostichopus japonicus Improves Glucose Metabolism in the Liver of Insulin Resistant Mice.

Holothurian glycosaminoglycan isolated from Apostichopus japonicus (named AHG) can suppress hepatic glucose production in insulin resistant hepatocytes, but its effects on glucose metabolism in vivo are unknown. The present study was conducted to investigate the effects of AHG on hyperglycemia in the liver of insulin resistant mice induced by a high-fat diet (HFD) for 12 weeks. The results demonstrated that AHG supplementation apparently reduced body weight, blood glucose level, and serum insulin content in a dose-dependent manner in HFD-fed mice. The protein levels and gene expression of gluconeogenesis rate-limiting enzymes G6Pase and PEPCK were remarkedly suppressed in the insulin resistant liver. In addition, although the total expression of IRS1, Akt, and AMPK in the insulin resistant liver was not affected by AHG supplementation, the phosphorylation of IRS1, Akt, and AMPK were clearly elevated by AHG treatment. These results suggest that AHG could be a promising natural marine product for the development of an antihyperglycemic agent.

Ionic liquid-based headspace in-tube liquid-phase microextraction coupled with capillary electrophoresis for sensitive detection of phenols.

An ionic liquid-based headspace in-tube liquid-phase microextraction (IL-HS-ITLPME) in-line coupled with capillary electrophoresis (CE) is proposed. The method is capable of quantifying trace amounts of phenols in environmental water samples. In the newly developed method, simply by placing a capillary injected with IL in the HS above the aqueous sample, volatile phenols were extracted into the IL acceptor phase in the capillary. After extraction, electrophoresis of the phenols in the capillary was carried out. Extraction parameters such as the extraction time, extraction temperature, ionic strength, volume of the sample solution and IL types were systematically investigated. Under the optimized conditions, enrichment factors for four phenols were from 1510 to 1985. The proposed method provided a good linearity, low limits of detection (below 5.0 ng mL-1 ), and good repeatability of the extractions (RSDs below 6.7%, n = 6). This method was then utilized to analyze two real environmental samples of Xiaoxi Lake and tap water, obtaining acceptable recoveries and precisions. Compared with the usual HS-ITLPME for CE, IL-HS-ITLPME-CE is a simple, low-cost, fast and environmentally friendly pre-concentration technique. This article is protected by copyright. All rights reserved.

Immunoenhancement Effects of Glycosaminoglycan from Apostichopus japonicus: In Vitro and In Cyclophosphamide-Induced Immunosuppressed Mice Studies.

In this study, the immunomodulatory activities of Apostichopus japonicus glycosaminoglycan (AHG) on the nature killer (NK) cells, cytotoxic T lymphocytes (CTLs) and cyclophosphamide (CY)-treated mice were investigated. After stimulation with multiple concentrations of AHG (0-100 µg/mL), NK cells and CTLs displayed outperformance against YAC-1 and B16 cells, respectively. Furthermore, the mitogen-induced splenic lymphocyte proliferation in CY-induced immunosuppressed mice was significantly promoted by AHG. In addition, the administration of AHG dramatically increased the splenocytes Ca2+ concentration and the delayed-type hypersensitivity (DTH) reaction in a dose-dependent manner. Besides, AHG could strongly increase the total antioxidant capacity (T-AOC), the activities of superoxidase dismutase (SOD), catalase (CAT) as well as glutathione peroxidase (GSH-PX), and could decrease the malondialdehyde (MDA) level in the heart, kidney and liver. These findings indicated that AHG played an important role in the immune enhancement and protection against CY-induced immunosuppression and oxidative damage. Our findings provide experimental evidence for further research and possible immunostimulatory applications of AHG in clinical practice.

Absorption and Transport of Sea Cucumber Saponins from Apostichopus japonicus.

The present study is focused on the intestinal absorption of sea cucumber saponins. We determined the pharmacokinetic characteristics and bioavailability of Echinoside A and Holotoxin A1; the findings indicated that the bioavailability of Holotoxin A1 was lower than Echinoside A. We inferred that the differences in chemical structure between compounds was a factor that explained their different characteristics of transport across the intestine. In order to confirm the absorption characteristics of Echinoside A and Holotoxin A1, we examined their transport across Caco-2 cell monolayer and effective permeability by single-pass intestinal perfusion. The results of Caco-2 cell model indicate that Echinoside A is transported by passive diffusion, and not influenced by the exocytosis of P-glycoprotein (P-gp, expressed in the apical side of Caco-2 monolayers as the classic inhibitor). The intestinal perfusion also demonstrated well the absorption of Echinoside A and poor absorption of Holotoxin A1, which matched up with the result of the Caco-2 cell model. The results demonstrated our conjecture and provides fundamental information on the relationship between the chemical structure of these sea cucumber saponins and their absorption characteristics, and we believe that our findings build a foundation for the further metabolism study of sea cucumber saponins and contribute to the further clinical research of saponins.

High-density extraction solvent-based solvent de-emulsification dispersive liquid-liquid microextraction combined with MEKC for detection of chlorophenols in water samples.

For the first time, the high-density solvent-based solvent de-emulsification dispersive liquid-liquid microextraction (HSD-DLLME) was developed for the fast, simple, and efficient determination of chlorophenols in water samples followed by field-enhanced sample injection with reverse migrating micelles in CE. The extraction of chlorophenols in the aqueous sample solution was performed in the presence of extraction solvent (chloroform) and dispersive solvent (acetone). A de-emulsification solvent (ACN) was then injected into the aqueous solution to break up the emulsion, the obtained emulsion cleared into two phases quickly. The lower layer (chloroform) was collected and analyzed by field-enhanced sample injection with reverse migrating micelles in CE. Several important parameters influencing the extraction efficiency of HSD-DLLME such as the type and volume of extraction solvent, disperser solvent and de-emulsification solvent, sample pH, extraction time as well as salting-out effects were optimized. Under the optimized conditions, the proposed method provided a good linearity in the range of 0.02-4 µg/mL, low LODs (4 ng/mL), and good repeatability of the extractions (RSDs below 9.3%, n = 5). And enrichment factors for three phenols were 684, 797, and 233, respectively. This method was then utilized to analyze two real environmental samples from wastewater and tap water and obtained satisfactory results. The obtained results indicated that the developed method is an excellent alternative for the routine analysis in the environmental field.

Simultaneous determination of chito-oligosaccharides in rat plasma by the LC-MS/MS method: application to a pharmacokinetic study.

A simple and sensitive method for the simultaneous determination of chito-oligosaccharides (COSs) with degrees of polymerization (DPs) from 2 to 7 was developed and used for COS quantification in rat plasma. Samples were separated on a Waters XBridge Amide column (3.5 µm, 2.1 × 150 mm) by isometric elution with 10 mM aqueous ammonium acetate (pH = 9) in acetonitrile and 10 mM aqueous ammonium acetate (pH = 9) (v/v, 50 : 50) employing multiple reaction monitoring (MRM) detection. Analytes and internal standards (IS) were extracted from rat plasma by protein precipitation with acetonitrile. The assay was linear over a concentration range of 20-10 000 ng mL-1 for COS2-7. The intra-day and inter-day precision of the investigated components exhibited an RSD within 15%, and the accuracy (RE%) ranged from -7.3% to 7.6%. The extraction recoveries of the six constituents were determined to be between 82.5% and 94.3%. No significant matrix effects for COS2-7 were observed in rat plasma. COS in plasma remained stable for 24 h at room temperature (short-term), after freeze-thaw cycles, and 30 days in a -40 °C freezer. In comparison to reported COS quantitation methods, this method is simple, sensitive and cost-effective and could be used for the simultaneous quantitation of COS2-7. This method meets the Food and Drug Administration guidelines and had been successfully applied to the analysis of pharmacokinetic samples collected from rats.

On-line concentration by field-enhanced sample injection with reverse migrating micelles in micellar electrokinetic capillary chromatography for the analysis of coumarins from traditional Chinese medicine and human serum.

In this work, a simple, reproducible and sensitive micellar electrokinetic chromatography method was developed for the separation and determination of three coumarins, imperatorin (IM), isoimperatorin (IO) and osthole (OS) from traditional Chinese medicine and human serum. Field-enhanced sample injection with reverse migrating micelles was used for on-line concentration of the coumarins. The optimum buffer contained 50 mM H(3)PO(4), 160 mM sodium dodecyl sulfate, 20% acetonitrile and 15% 2-propanol, and the pH of buffer was 2.0. The sample solution was diluted with water containing 5 mM sodium dodecyl sulfate and injected for 15 s with -8 kV after injection of 2 s water plug. The effects of concentrations of sodium dodecyl sulfate and organic modifier, the sample matrix, the injection time of water plug, the injection voltage and injection time of sample on the separation and stacking efficiency were investigated. Under the optimum conditions, the analytes were well separated and by optimizing the stacking conditions, about 93, 195 and 136 fold improvement in the detection sensitivity was obtained for IM, IO and OS. The contents of three coumarins in Angelica dahurica Benth, Radix Angelicae Pubescentis and Fructus Cnidii were successfully determined with satisfactory repeatability and recovery. The possibilities of using this method for the determination of three coumarins in spiked human serum were also tested.

Determination of fluoroquinolones in milk, honey and water samples by salting out-assisted dispersive liquid-liquid microextraction based on deep eutectic solvent combined with MECC.

A simple and sensitive salting out-assisted dispersive liquid-liquid microextraction method using deep eutectic solvent combined with back extraction and micellar electrokinetic capillary chromatography (SO-DLLME-DES-BE-MECC) was developed for the determination of fluoroquinolones in milk, honey and water samples. Several parameters affecting the extraction efficiency including DES volume, vortex time, centrifugation time, salt type and amount, sample pH and volume, etc. were investigated. Good linearity were obtained for fluoroquinolones in a range of 0.020-3.200 µg mL-1 and 0.030-4.800 µg mL-1 with LODs less than 0.010 µg mL-1. The recoveries were in the ranges of 95.0-104.9%, 90.1-110.2% and 87.8-114.1% for water, honey and milk samples, respectively. The relative standard deviations for reproducibility were all below 7.6%. Under the optimized conditions, the enrichment factors for analytes were achieved in the range from 531 to 858 folds. The presented method was successfully applied for the determination of fluoroquinolones in milk, honey and water samples.

Glycosaminoglycan from Apostichopus japonicus induces immunomodulatory activity in cyclophosphamide-treated mice and in macrophages.

This study was designed to systematically elucidate the immunomodulation effect of glycosaminoglycan from Apostichopus japonicus (AHG) in cyclophosphamide (CY)-induced immunosuppression model and potential mechanism responsible for the activation of macrophages. The results showed that the treatment with AHG could increase natural killer (NK) cell cytotoxicity, carbon clearance and marker enzymes activities in CY-induced immunosuppression mice, indicating that the innate immunity experienced recovery to some extent. Moreover, CY-induced reductions in thymus and spleen indices, serum levels of cytokines, immunoglobulins and hemolysin, as well as the ratio of spleen lymphocyte subsets were recovered by AHG, suggesting that AHG could improve the adaptive immunity through cellular immunity and humoral immunity. Delightedly, it was found that AHG at 10 mg/kg body weight could restore the CY-induced immunosuppression in mice to normal level on both innate and adaptive immunity. Furthermore, AHG also promoted both the expression of NO, TNF-α, IL-6, IL-1ß, IL-18 and MCP-1 protein and related mRNA in macrophages. It was revealed that AHG activated macrophages through the phosphorylation of mitogen-activated protein kinase (MAPK) and nuclear factor-B (NF-κB). In conclusion, AHG exerts remarkable immunomodulatory activities in both innate and adaptive immune system. These findings should have great value for further study on the immunopotentiating mechanisms of this biomacromolecule.

Glycosaminoglycan from Apostichopus japonicus inhibits hepatic glucose production via activating Akt/FoxO1 and inhibiting PKA/CREB signaling pathways in insulin resistant hepatocytes.

The aim of this study was to elucidate the effect and the underlying mechanism of glycosaminoglycan from Apostichopus japonicus (AHG) on hepatic glucose production (HGP) in insulin resistant hepatocytes. Insulin resistance was induced with high glucose (HG) for 24 h in primary hepatocytes. The results showed that AHG exhibited hypoglycemic activity at a relatively low concentration (1 µg mL-1) and revealed non-toxic activity to insulin resistant hepatocytes even at 500 µg mL-1 concentration. The HGP test showed that the treatment of AHG (10 µg mL-1) for 3 h decreased HGP by 25% in insulin resistant hepatocytes. Quantitative PCR and western blot analysis revealed that AHG also ameliorated phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). The data revealed the mechanism of AHG in alleviating HGP via activating the Akt/FoxO1 signaling pathway and suppressing the PKA/CREB signaling pathway in insulin resistant hepatocytes. This finding suggests that AHG could be a potential marine natural product for the treatment of dysregulating glucose homeostasis.

Bioanalysis and pharmacokinetics of chitosan ester in rabbit serum by HPLC with postcolumn fluorescence derivatization.

Interest in antiatherosclerotic activity of chitosan ester (PS916) with a new form of sulfate amino polysaccharide derived from marine chitin has necessitated the development of a sensitive and specific method to study its pharmacokinetics. A sensitive and reproducible high-performance liquid chromatography (HPLC) with postcolumn fluorescence derivatization method was developed and validated for the determination of PS916 in rabbit serum. Chromatography was carried out using a C8 reversed-phase column with an isocratic mobile phase consisting of methanol-water (20:80, v/v) at a flow rate of 0.2 ml/min. The derivatization procedure involved postcolumn reaction with guanidine hydrochloride in an alkaline medium at 110 degrees C. The fluorometric detector was operated at 250 nm (excitation) and 435 nm (emission). The assay was linear over the concentration range of 5-100 microg/ml. The lower limit of detection (LLOD) was found to be 1.0 microg/ml. The proposed method was successfully applied for a pharmacokinetic study of PS916 in rabbits.

Determination of kava lactones and flavonoid glycoside in Scorzonera austriaca by capillary zone electrophoresis.

A capillary zone electrophoretic method has been developed for the quantitative analysis of three active comppounds, 12-hydroxy-desmethoxyyangonin (HD), 12-beta-d-glucopyranoside-desmethoxyyangonin (GD) and luteolin 3'-(6-E-p-coumaroyl-beta-d-glucopyranoside) (LG) in Scorzonera austriaca with UV detection at 254 nm. The applied voltage was 25 kV and the capillary temperature was kept constant at 25 degrees C. The effect of buffer pH, the concentration of electrolyte and organic modifier on migration were studied systematically. Optimum separation was achieved with 20 mM borate buffer at pH 10.00 containing 10% (v/v) methanol. Daphnetin was used as internal standard for quantification. Regression equations revealed good linear relationship between the ratios of the peak area of each compound and its the ratios of concentration. All the correlation coefficients were higher than 0.9990. The relative standard deviations of migration time and the peak area were <1.46% and 5.13% (inter-day), and <1.65% and 5.16% (intra-day), respectively. The contents of the three compounds in S. austriaca were successfully determined with satisfactory repeatability and recovery.

Extending the structure-activity relationship study of marine natural ningalin B analogues as P-glycoprotein inhibitors.

In the present study, a total of 25 novel ningalin B analogues were synthesized and evaluated for their P-gp modulating activity in a P-gp overexpressed breast cancer cell line LCC6MDR. Preliminary structure-activity study shows that A ring and its two methoxy groups are important pharmacophores for P-gp inhibiting activity. Among all derivatives, 23 is the most potent P-gp modulator with EC50 of 120-165 nM in reversing paclitaxel, DOX, vinblastine and vincristine resistance. It is relatively safe to use with selective index at least greater than 606 compared to verapamil. Mechanistic study demonstrates that compound 23 reverses P-gp mediated drug resistance by inhibiting transport activity of P-gp, thereby restoring intracellular drug accumulation. In summary, our study demonstrates that ningalin B analogue 23 is a non-cytotoxic and effective P-gp chemosensitizer that can be used in the future for reversing P-gp mediated clinical cancer drug resistance.

Separation of plant hormones from biofertilizer by capillary electrophoresis using a capillary coated dynamically with polycationic polymers.

A new, simple and rapid capillary electrophoresis (CE) method, using hexadimethrine bromide (HDB) as electroosmotic flow (EOF) modifier, was developed for the identification and quantitative determination of four plant hormones, including gibberellin A3 (GA3), indole-3-acetic acid (IAA), alpha-naphthaleneacetic acid (NAA) and 4-chlorophenoxyacetic acid (4-CA). The optimum separation was achieved with 20 mM borate buffer at pH 10.00 containing 0.005% (w/v) of HDB. The applied voltage was -25 kV and the capillary temperature was kept constant at 25 degrees C. Salicylic acid was used as internal standard for quantification. The calibration dependencies exhibited good linearity within the ratios of the concentrations of standard samples and internal standard and the ratios of the peak areas of samples and internal standard. The correlation coefficients were from 0.9952 to 0.9997. The relative standard deviations of migration times and peak areas were < 1.93 and 6.84%, respectively. The effects of buffer pH, the concentration of HDB and the voltage on the resolution were studied systematically. By this method, the contents of plant hormone in biofertilizer were successfully determined within 7 min, with satisfactory repeatability and recovery.

Novel branch patterns and anticoagulant activity of glycosaminoglycan from sea cucumber Apostichopus japonicus.

A novel glucosidic pattern of fucose branches was found in the glycosaminoglycan from the sea cucumber Apostichopus japonicus in China. The methylation of desulfated/carboxyl-reduced polysaccharides and analysis of unsaturated disaccharides generated from the enzymolysis of the defucosed polysaccharides demonstrated that the branch is formed by one fucopyranosyl residue, 46.5% of which is linked through the O-3 position of ß-D-glucuronic acid, while 8.7% and 43.9% are linked through the O-6 and O-4 positions of the N-acetylgalactosamine moiety. The ß-D-glucuronic acid, N-acetyl-ß-D-galactosamine, α-L-fucose and sulfate ester with the molecular ratio of 0.97:1.00:1.13:3.85 composed the backbone → 4)GlcUAß(1 → 3)GalNAcß(1 → and sulfated fucose branches. The sulfation patterns of fucose branches and the linkage pattern of the backbone structure were determined by 1/2 dimension NMR. The most abundant branch species were 2,4-di-O-sulfated and 3,4-di-O-sulfated fucose, but 4-mono-O-sulfated residue was also present. The structure of presently obtained glycosaminoglycan is different from that previously obtained from Stichopus japonicus (Kariya et al., Carbohyd. Res. 297 (1997) 273-279), which suggests that the structures of glycosaminoglycans from the same species of different regions somehow differ. The anticoagulant assay indicated that the polysaccharide possessed a high anticoagulant activity and the sulfated fucose branches were essential to the activity.

Depolymerized glycosaminoglycan and its anticoagulant activities from sea cucumber Apostichopus japonicus.

A controlled Cu(2+) catalytic free-radical depolymerization process of fucosylated chondroitin sulfate from sea cucumber Apostichopus japonicus was established. The results showed a good linear relationship between 1/Mw and time during the depolymerization. A series of fractions with different molecular weight were obtained, and the physicochemical properties of them were investigated and compared utilizing the chemical method, IR spectra and NMR spectra. The results showed no significant variations of the backbone and branches structures during the depolymerization. Furthermore, the anticoagulant activities of the depolymerized fractions were evaluated by the activated partial thromboplastin time (APTT). The APTT decreases in proportion to the molecular weight following a linear relationship and the prolongation of APTT activity requires at least oligosaccharide of 4 trisaccharide units (about 4000 Da). Their anticoagulant activity of low molecular weight fraction (Mw = 24,755 Da) is similar to LMWH with significantly less bleeding risk. The results suggest that the low molecular weight fraction could be used as a novel anticoagulant with less undesired side effects.

Separation and determination of phenylpropanoid glycosides from Pedicularis species by capillary electrophoresis.

Capillary zone electrophoresis, using 30 mM borate buffer (pH 9.00) with 10% (v/v) methanol, was established for the identification and determination of four phenylpropanoid glycosides (PPGs)--echinocoside (ECH), verbascoside (VER), pedicularioside M (PED-M) and pedicularioside A (PED-A)--in extracts of Pedicularis longiflora var tubiformis, Pedicularis longiflora and Pedicularis Kansuensis. Regression equations revealed linear relationships (correlation coefficients: 0.9993-0.9999) between the peak area of each compound (ECH, VER, PED-M and PED-A) and its concentration. The relative standard deviations of the migration times and peak areas were <1.93 and 4.54%, respectively. The recoveries of four PPGs ranged between 95.6 and 108.4%. The effects of several CE parameters on the resolutions were studied systematically.

[On-line coupling of ionic liquid-based single-drop microextraction and capillary electrophoresis for determination of three bromophenols in water samples].

An ionic liquid-based single-drop microextraction (IL-SDME) procedure using IL as an extractant on-line coupled to capillary electrophoresis (CE) is proposed. The method is capable of quantifying trace amounts of bromophenols in water samples. The extraction parameters such as extraction solvent, extraction time, ionic liquid single-drop volume, ionic strength and organic solvent were systematically investigated. For the SDME of the three bromophenols, a [C4MIM] [ PF6,] microdrop was exposed for 8 min to the aqueous sample with 10% (w/w) NaCI and then was directly injected into a capillary column for analysis. Under the optimal conditions, good linear relationships were obtained in the concentration range of 1 - 100 mg/L with the correlation coefficients of 0. 993 9 - 0. 998 8 for the bromophenols. The detection limits of the three bromophenols were 0. 3 mg/L. The RSDs of peak areas of the standards were 5. 21%- 6.47% (n =6). And the enrichment factors for the three bromophenols were 115.8, 327.0 and 569. 8. The proposed method was applied to the determination of the three bromophenols in tap, river and lake waters with the recoveries of the three bromophenols in the range of 87.8% - 96.7%. The method is suitable for the quantification of bromophenols in water samples.

Identification and analysis of an impurity inducing clinical adverse effect in anti-adhesion carboxymethyl chitosan products.

Controlling and minimizing the adverse effects of drugs are the key issues in ensuring the safety of drug therapy. Carboxymethyl chitosan has been widely used as an anti-adhesion material. However, recently in China there have been several reported instances of conjunctival hyperemia associated with the use of carboxymethyl chitosan containing products. Through MS, FTIR, and GC analysis, an impurity, diglycolic acid, was discovered in carboxylmethyl chitosan products. Pharmacological tests further indicated diglycolic acid has antithrombogenicity properties and induces vasodilation, both of which can cause conjunctival hyperemia. Thus, through these tests it was ascertained that diglycolic acid was the culprit responsible for the adverse clinical effects. Next, emphasis shifted to trying to discover the mechanism responsible for generating the diglycolic acid. Under strong basic conditions, chloroacetic acid can generate glycolic acid, which, upon etherification, can become diglycolic acid. In order to avoid future adverse effects, we have established an HPLC method to detect and determine diglycolic acid in carboxymethyl chitosan products. This method is specific, accurate, and precise, and can be easily implemented into routine monitoring practice. Concurrently, a refined method has also been established in order to eliminate diglycolic acid from carboxymethyl chitosan.

Immobilized capillary tyrosinase microreactor for inhibitor screening in natural extracts by capillary electrophoresis.

A method for creating an immobilized capillary tyrosinase (TRS) reactor based on a layer-by-layer (LBL) assembly for inhibitor screening is described. Tyrosinase was immobilized on the surface of fused-silica capillary via ionic binding technique with cationic polyelectrolyte hexadimethrine bromide (HDB). Then, HDB solution with the same plug length as the TRS was injected again into the capillary to cover the immobilized enzyme by forming HDB-TRS-HDB sandwich-like structure. Then, the substrate of l-tyrosine was introduced into the capillary and on-line enzyme inhibition study was performed by capillary electrophoresis (CE). The enzyme activity was determined by the quantification of peak area of the product of l-DOPA. Enzyme inhibition can be read out directly from the reduced peak area of the product in comparison with a reference electropherogram obtained in the absence of any inhibitor. The immobilized enzyme could withstand 25 consecutive assays by only losing 12% activity. A known TRS inhibitor, kojic acid was employed as a model compound for the validation of the inhibitor screening method. Finally, screening 19 natural extracts of traditional Chinese drugs was demonstrated. The results indicated that inhibition activity could be straightforwardly identified with the system.