Screening bioactive components of Glycyrrhiza uralensis Fisch. with isolated perfused lung extraction and HPLC-ESI-MSn analysis.

The isolated perfused rat lung (IPL), coupled with high performance liquid chromatography\tandem mass spectrometry analysis (HPLC-ESI-MSn), has been developed as a tool for screening bioactive components in Glycyrrhiza uralensis Fisch. (GU). First, IPL was perfused with the water extract of GU (EGU), the bioactive components in the EGU would selectively combine to the receptors or channels of lung. By changing the pH of perfused solution, the combined components were eluated and then detected by HPLC-ESI-MSn. Four compounds were detected in the desorption eluate of IPL, among these compounds, liquiritin (1), ononin (2) and glycyrrhizic acid (4) were identified by comparing with the chromatography of the standards, while licorice-saponin G2 (3) were determined by analysis of the structure clearage characterization of mass spectrometry. Then, due to the lack of compound 3 sample, compounds 1, 2 and 4 with respective concentrations of 50 µM, 5 µM, 500 nM, 50 nM and 5 nM were applied to evaluate the protective effect of pulmonary epithelial cells (PEC, A549 cell) injury induced by lipopolysaccharide (LPS) for anti-inflammatory activity assessment. The results showed that except the 5 nM group of compound 1, 5 nM and 50 nM groups of compound 2, all other groups could remarkably inhibit the PEC injury (vs LPS group, 2-500 nM groups: p < 0.05; other groups: p < 0.01), all compound showed the dose-dependent effect. In conclusion, IPL coupled with HPLC-ESI-MSn was successfully used to screen the anti-inflammatory components of GU for the first time. The application of IPL coupled with HPLC-ESI-MSn for screening bioactive components of TCMs is rapid, convenient and reliable, and the isolated perfused technology could be extended to isolated heart, liver, kidney, and so on.

The C-terminal tails of 4,4'-diphenylmethane-bis(methyl) carbamate are essential for binding to receptor for advanced glycation end products to attenuate advanced glycation end products-induced inflammation and apoptosis responses in human umbilical vein endothelial cells.

OBJECTIVES: A novel compound 4,4'-diphenylmethane-bis(methyl) carbamate (CM1) was shown to possess preventive activity on AGEs-induced human umbilical vein endothelial cells (HUVECs) damage via binding to RAGE. However, the underlying structural basis of CM1 on binding to RAGE was not fully understood. METHODS: In the present study, CM1 analogues were designed and synthesized to compare the activity differences on inhibiting AGEs-induced inflammatory response including TGF-ß1, RAGE protein expression in HUVECs, and macrophages migration and adhesion to HUVECs. In addition, the cell viability and anti-apoptosis activities of CM1 analogues were also examined. KEY FINDINGS: These results indicated that CM1 had higher activities on preventing AGEs-induced HUVECs damage (inflammation, cell viability and apoptosis) than other analogues. The bioaffinity assay was conducted by CMC and demonstrated that the IC50 and dissociation equilibrium constants (Kd) of CM1 were lower whereas the Bmax was higher than other analogues. The incubation of RAGE protein with CM1 analogues by equilibrium dialysis method showed CM1 had a stronger binding rate than other CM1 analogues. CONCLUSION: Our findings suggested that the C-terminal tails (methoxycarbonyl groups) of CM1 were the active groups for binding to RAGE and then led to the attenuation on RAGE-mediated endothelial dysfunction.

Pre-column incubation followed by fast liquid chromatography analysis for rapid screening of natural methylglyoxal scavengers directly from herbal medicines: case study of Polygonum cuspidatum.

Methylglyoxal (MGO), a very reactive metabolite of glucose, plays a pivotal role in the pathogenesis of several chronic diseases associated with diabetes, and it has been validated as an attractive target for them. In the present study, a simple and effective method, namely pre-column incubation followed by fast high performance liquid chromatography based on superficially porous particles (shell), coupled with diode array detection and tandem mass spectrometry (UHPLC-DAD-MS(n)), was proposed for rapid and high-throughput screening of natural MGO scavengers directly from the crude extract of Polygonum cuspidatum Sieb. et Zucc, a well-known traditional Chinese medicine which was used for treatment of diabetic complications. The hypothesis is that upon reaction with MGO, the peak areas of components with MGO scavenging potency in the chromatogram will be significantly reduced or disappear, and the structural characterization could be achieved by UHPLC-DAD-MS(n) hyphenated technique. First of all, 12 compounds in P. cuspidatum were well separated within shorter time (~12 min) than previous methods and identified, and two of them, i.e. 3,5,4'-trihydroxystilbene-3-O-(6″-galloyl)-glucoside (3) and emodin-8-O-(6'-malonyl)-glucoside (8) were firstly reported ingredients. After incubation with MGO, four stilbene derivatives were demonstrated to possess potential MGO trapping activities. Furthermore, it was proved that both polydatin (piceid) and resveratrol exhibited effective MGO-trapping capacity by UHPLC analysis, and they could significantly inhibit the formation of advanced glycation end products (AGEs) in the human serum albumin (HSA)-MGO assay, indicating that they were potential candidate agents for delaying and preventing diabetic complications. Additionally, MGO trapping mechanism exploration by UHPLC-MS(n) showed that the positions 2 and 4 of the A ring of stilbene were major active sites for trapping MGO to form both mono- and di-MGO adducts, however, the glucosylation of the hydroxyl group would significantly decrease the trapping efficiency. Collectively, the current work provides a very promising method for rapid discovery of natural MGO scavengers directly from complex matrices such as herbal medicines with huge resources.

Macrophage biospecific extraction and HPLC-ESI-MSn analysis for screening immunological active components in Smilacis Glabrae Rhizoma.

A cell-permeable membrane, as typified by Transwell insert Permeable Supports, permit accurate repeatable invasion assays, has been developed as a tool for screening immunological active components in Smilacis Glabrae Rhizoma (SGR). In this research, components in the water extract of SGR (ESGR) might conjugate with the receptors or other targets on macrophages which invaded Transwell inserts, and then the eluate which contained components biospecific binding to macrophages was identified by HPLC-ESI-MS(n) analysis. Six compounds, which could interact with macrophages, were detected and identified. Among these compounds, taxifolin (2) and astilbin (4) were identified by comparing with the chromatography of standards, while the four others including 5-O-caffeoylshikimic acid (1), neoastilbin (3), neoisoastilbin (5) and isoastilbin (6), were elucidated by their structure clearage characterizations of tandem mass spectrometry. Then compound 1 was isolated and purified from SGR, along with 2 and 4, was applied to the macrophage migration and adhesion assay in HUVEC (Human Umbilical Vein Endothelial Cells) -macrophages co-incultured Transwell system for immunological activity assessment. The results showed that compounds 1, 2 and 4 with concentration of 5µM (H), 500nM (M) and 50nM (L) could remarkably inhibit the macrophage migration and adhesion (Vs AGEs (Advanced Glycation End Produces) group, 1-L, 2-H and 4-L groups: p<0.05; other groups: p<0.01). Moreover, 1 and 4 showed satisfactory dose-effect relationship. In conclusion, the application of macrophage biospecific extraction coupled with HPLC-ESI-MS(n) analysis is a rapid, simple and reliable method for screening immunological active components from Traditional Chinese Medicine.

Development of self-microemulsifying drug delivery system for oral bioavailability enhancement of berberine hydrochloride.

The purpose of this study was to develop a self-microemulsifying drug delivery system (SMEDDS) to improve the oral bioavailability of Berberine hydrochloride (BBH), an important bioactive compound from Chinese Medicines with poor water solubility. Pseudoternary phase diagrams were constructed using oil, surfactant and co-surfactant types to identify the efficient self-microemulsification region. SMEDDS was characterized by morphological observation, droplet size, zeta-potential determination, stability, in vitro release and in vivo bioavailability study. The optimal formulation with the best self-microemulsifying and solubilization ability consisted of 40% (w/w) of ethyl linoleate and oleic acid (2:1), 35% (w/w) Tween-80 and 25% (w/w) glycerol. The SMEDDS of BBH could exhibit good stability. In vitro release test showed a complete release of BBH from SMEDDS was in 5 h. In vivo results indicated that the peak plasma concentration (C(max)) and the area under the curve (AUC(0→12 h)) of SMEDDS of BBH were higher than the commercial tablet by 163.4% and 154.2%, respectively. The relative bioavailability of SMEDDS of BBH was enhanced about 2.42-fold compared with the commercial tablet in rats. The study confirmed that the SMEDDS formulation could be used as a possible alternative to traditional oral formulations of BBH to improve its bioavailability.

Preventative effects of 4,4'-diphenylmethane-bis(methyl) carbamate isolated from cortex mori on human umbilical vein endothelial cell dysfunction induced by advanced glycation end products.

Advanced glycation end-products (AGEs) have been regarded as an initial motivating factor in the pathogenesis of endothelial dysfunction in diabetic complications. 4,4'-Diphenylmethane-bis(methyl) carbamate (DMPC), a carbamate compound, was isolated from Cortex Mori and its prevention effects against AGEs-induced endothelial dysfunction were studied. 4,4'-Diphenylmethane-bis(methyl) carbamate significantly reduced cell apoptosis to normal level at 10⁻9 mol/L concentration. Advanced glycation end-products up-regulated the expression of Bad and Bax and down-regulated Bcl-2 proteins, and pretreatment with DMPC significantly down-regulated Bad and Bax while up-regulating Bcl-2 expressions. In addition, ICAM (intercellular adhesion molecule)-1 and TGF (transforming growth factor)-ß1 expressions in human umbilical vein endothelial cell (HUVEC) were significantly enhanced by AGEs. More importantly, these increases of ICAM-1 and TGF-ß1 expressions were reduced meaningfully with the pretreatment of DMPC. All the results showed DMPC had prevention effects against the progression of AGE-induced endothelial dysfunction, and this compound might be a promising agent against endothelial dysfunction in diabetic vascular complications.

Competitive binding between 4,4'-diphenylmethane-bis(methyl) carbamate and RAGE ligand MG-H1 on human umbilical vein endothelial cell by cell membrane chromatography.

The compound 4,4'-diphenylmethane-bis(methyl) carbamate (CM1) has a protective activity on AGEs-induced endothelial dysfunction on human umbilical vein endothelial cell (HUVEC) in our previous study. It suggested that CM1 which may act as a competitive antagonist to the blockade of AGEs to receptor of AGEs (RAGE) and attenuate the HUVEC damage. In order to testify that hypothesis, the cell membrane chromatography (CMC) combined with high performance liquid chromatography (HPLC) was developed for analyzing the competitive binding properties on RAGE of HUVEC between CM1 and MG-H1, the agonist of RAGE. The results from saturation binding of CM1 and MG-H1 on cells demonstrated that dissociation equilibrium constants (K(d)) of CM1 and MG-H1 were 3.653 nM and 4.12 nM, respectively; while maximum binding capacity (B(max)) of CM1 and MG-H1 were 30.08 and 18.72 fmol/mg protein, respectively. In competition experiments, IC50 of CM1 with pre-incubation 10⁻¹° M and 10⁻9 M MG-H1 were 1.37 × 10⁻9 M and 4.56 × 10⁻8 M, respectively. The present findings indicated that CM1 conjugated competitively to cells with RAGE ligand MG-H1. The primary study illustrated that CMC combined with HPLC analysis method could be an alternative, rapid and efficient approach for the interaction of drug molecule and receptor, and that CM1 intervene the AGEs inducing HUVEC damage may via the competitively block the AGEs-RAGE path way.

Isolated perfused lung extraction and HPLC-ESI-MS(n) analysis for predicting bioactive components of Saposhnikoviae Radix.

A novel strategy for predicting bioactive components in traditional Chinese material herb was proposed, using isolated perfused rat lung (IPL) extraction and high performance liquid chromatography\tandem mass spectrometry (HPLC-MS(n)) analysis. The hypothesis is that when the IPL is perfused with the extract of Saposhnikoviae Radix (ESR), the potential bioactive components in the ESR should selectively combine with the receptor or channel of lung, by changing the pH of perfused liquid, the combining components would be eluated and then detected by HPLC-ESI-MS(n). Five compounds were detected in the desorption eluate of IPL; among these compounds, two potential bioactive compounds, prim-O-glucosylcimifugin (2) and 4'-O-ß-D-glucosyl-5-O-methylvisamminol (4) were identified by comparing with the chromatography of the standard sample, and three other compounds, i.e. cimifugin (1), 5-O-methylvisamminol (3) and sec-O-glucosylhamaudol (5) were determined by analysis of the structure clearage characterization of mass spectrometry. The application of IPL extraction coupled with HPLC-ESI-MS(n) for predicting potential bioactive components of TCMs is rapid, convenient, operational, economic and reliable.

Inhibitory effects of two major isoflavonoids in Radix Astragali on high glucose-induced mesangial cells proliferation and AGEs-induced endothelial cells apoptosis.

Radix Astragali, the dried roots of Astragalus membranaceus var. mongholicus, is well known to have a protective effect on diabetic nephropathy. However, the effects of isoflavonoids in Radix Astragali on glomerular cells, which play a key role in the development of diabetic vascular complications, remain largely unknown. Thus, the purpose of this study was to investigate in vitro the effect of calycosin and calycosin-7-O-ß-D-glucoside, two major isoflavonoids in Radix Astragali, on high glucose-induced rat mesangial cells proliferation and AGEs-induced human glomerular endothelial cell apoptosis. The results indicated that both calycosin and calycosin-7-O-ß-D-glucoside (10-100 µM) could inhibit high glucose-induced mesangial cell early proliferation. Additionally, AGEs-mediated cell apoptosis was also attenuated by treatment of glomerular endothelial cells with either calycosin or calycosin-7-O-ß-D-glucoside (1-100 µM). Therefore, the results obtained in this study suggest that both calycosin and calycosin-7-O-ß-D-glucoside have a significant therapeutic potential to modulate the development and/or progression of diabetic nephropathy.