Xiaohui Zheng

Screening the bioactive compounds in aqueous extract of Coptidis rhizoma which specifically bind to rabbit lung tissues β2-adrenoceptor using an affinity chromatographic selection method.

A receptor affinity chromatographic selection method was developed for screening the bioactive compounds binding to beta(2)-adrenoceptor (beta(2)-AR) in Coptidis rhizome. The bioactive compounds were analyzed by molecular recognition with a beta(2)-AR affinity column. The retention compounds eluted from the beta(2)-AR column were separated online with reverse-phase high-performance liquid chromatography by column switching technology, and identified by a coupled ion-trap mass spectrometer. Four compounds were screened as the bioactive compounds of Coptidis rhizome and identified as 2,9,10-trimethoxy-3-hydroxyl-protoberberine (jateorhizine), 2,3-methylenedioxy-9-methoxy-protoberberine, 2,3,9,10-tetramethoxy-protoberberine (palmatine) and 2,3-methylenedioxy-9,10-dimethoxy-protoberberine (berberine). The association constants of jatrorrhizine, palmatine and berberine to the beta(2)-AR were determined by the zonal elution method with standards. Berberine and palmatine had only one type of binding site on the immobilized beta(2)-AR. Their association constants were (2.28+/-0.11)x10(4)/M and (3.00+/-0.10)x10(4)/M, respectively. Jatrorrhizine had at least two type of binding sites on the immobilized beta(2)-AR, and the corresponding association constants were (2.20+/-0.09)x10(-4)/M and (6.78+/-0.001)x10(5)/M.

A metabolite of Danshen formulae attenuates cardiac fibrosis induced by isoprenaline, via a NOX2/ROS/p38 pathway

Cardiac fibrosis is a common feature of advanced coronary heart disease and is characteristic of heart disease. However, currently available drugs against cardiac fibrosis are still very limited. Here, we have assessed the role of isopropyl 3‐(3,4‐dihydroxyphenyl)‐2‐hydroxylpropanoate (IDHP), a new metabolite of Danshen Dripping Pills, in cardiac fibrosis mediated by the β‐adrenoceptor agonist, isoprenaline, and its underlying mechanisms.

Affinity chromatographic methodologies based on immobilized voltage dependent anion channel isoform 1 and application in protein-ligand interaction analysis and bioactive compounds screening from traditional medicine

Voltage dependent anion channel isoform 1 (VDAC-1) serves as an attractive target of anti-cancer drugs by mediating the entry and exit of metabolites between cytoplasm and mitochondria. This work reports on the preparation of a VDAC-1-based bioaffinity chromatographic stationary phase by linking the protein on lecithin modified microspheres. An assay of chromatographic methods including frontal analysis, zonal elution, injection dependent analysis and nonlinear chromatography were utilized to investigate the bindings of ATP, NADH and NADPH to VDAC-1. Electrostatic interactions were found to be main forces during these bindings. The calculated association constants of the three ligands to VDAC-1 showed good agreements between diverse chromatographic methods. Validated application of the stationary phase was performed by screening anti-cancer compounds of Rheum officinale Baill. using high performance affinity chromatography coupled with electrospray ionization-quadrupole time of flight mass spectrometry. Chrysophanol, emodin, rhein, aloe-emodin and catechin were identified as the bioactive components of the herb. These compounds targeted VDAC-1 through Thr207 and the N-terminal region of the protein. Taken together, the current stationary phase was possible to become a promising tool for protein-ligand interaction analysis and anti-cancer drug screening from complex matrices.

Identifying the antiasthmatic target of doxofylline using immobilized β2 -adrenoceptor based high-performance affinity chromatography and site-directed molecular docking.

As a xanthine derivative, doxofylline is believed to be dominant for fighting against asthma in practice. Unlike other xanthines, the antiasthmatic effects of doxofylline lack any definite proof of target and mediating mechanism according to previous reports. In this work, the interaction between doxofylline and β2‐AR was investigated by high performance affinity chromatography using frontal analysis and nonlinear model. The methodology involved the immobilization of β2‐AR on the silica gel by a random linking method, the determination of the binding parameters by frontal analysis and nonlinear chromatography and the exploration of the binding mechanism by site‐directed molecular docking. The association constant for doxofylline binding to immobilized β2‐AR was determined to be 7.70 × 104 M−1 by nonlinear chromatography and 5.91 × 104 M−1 by frontal analysis. Ser169 and Ser173 were the binding sites for the receptor–drug interaction on which hydrogen bond was believed to be the main driven force during the interaction. These results indicated that the antiasthmatic effects of doxofylline may be behind the mediating mechanism of β2‐AR. High performance affinity chromatography based on immobilized receptor has potential to become an alternative for drug target confirmation and drug–receptor interaction analysis. Copyright

Binding interactions between prazosin and α1A-adrenoceptor: investigation on the thermodynamic behaviors and the binding mechanism by high performance affinity chromatography

Although the association constant and the number of binding sites of prazosin to α1A-adrenoceptor were determined by high performance affinity chromatography (HPAC) in our previous work, the thermodynamic behaviors and the binding mechanism of the drug to immobilized α1A-adrenoceptor remained unclear. This work intended to address the issue by HPAC and molecular docking. The investigations involved the determination of association constants by frontal analysis at different temperatures, the calculation of enthalpy, entropy and free energy changes, the examination of mobile phase composition on the binding parameters and the site-directed molecular docking. The changes of enthalpy, entropy and free energy during the interaction were −20.79 kJ mol−1, −59.28 J mol−1 K−1 and −2.4 kJ mol−1, respectively. The binding of prazosin to α1A-adrenoceptor was an endothermic process with an increase in entropy. This reaction was mainly driven by hydrogen bonds. The ionic strength of the mobile phase provided a positive response to the values of association constants, while the power of hydrogen and the concentration of isopropyl in the mobile phase showed a negative trend. Ser203 and Ser192 in the fifth transmembrane segment of the receptor were the positions for the formation of hydrogen bonds. It is possible to utilize the immobilized receptor to determine the mechanism of drug–receptor interactions.

Binding of caffeic acid to human serum albumin by the retention data and frontal analysis

A new mathematical model and frontal analysis were used to characterize the binding behavior of caffeic acid to human serum albumin (HSA) based on high-performance affinity chromatography. The experiments were carried out by injecting various mole amounts of the drug onto an immobilized HSA column. They indicated that caffeic acid has only one type of binding site to HSA on which the association constant was 2.75 × 10(4) /m. The number of the binding site involving the interaction between caffeic acid and HSA was 69 nm. The data obtained by the frontal analysis appeared to present the same results for both the association constant and the number of binding sites. This new model based on the relationship between the mole amounts of injection and capacity factors assists understanding of drug-protein interaction. The proposed model also has the advantages of ligand saving and rapid operation.

Traditional Uses, Chemical Constituents and Biological Activities of Plants from the Genus Sanguisorba L.

Plants from the genus Sanguisorba have been treated as medicinal ingredients for over 2000 years. This paper reviews advances in the botanical, phytochemical and pharmacological studies of the genus. To date, more than 120 chemical constituents have been isolated and identified from these plants, especially from S. officinalis and S. minor. Among these compounds, triterpenoids, phenols and flavonoids are the primary biologically active constituents. Triterpenoids can be used as quality control markers to determine the quality of medicinal materials and their preparations. In vivo and in vitro studies have shown that plants from the genus Sanguisorba exhibit a wide range of pharmacological properties, including hemostatic, antibacterial, antitumor, neuroprotective and hypoglycemic activities. In Chinese medical practice, many drugs (e.g., tablets and powders) that contain S. officinalis roots have been used to treat leukopenia, hemorrhaging and burns. However, there is still a multitude of Sanguisorba species that have garnered little or no attention. Indeed, there are few reports concerning the clinical use and toxic effects of these plants. Further attention should be focused on the study of these species in order to gather information on their respective toxicology data, any relevant quality-control measures, and the clinical value of the crude extracts, active compounds, and bioactive metabolites from Genus Sanguisorba.

Design, Synthesis and Evaluation of Novel 2-Hydroxypyrrolobenzodiazepine-5,11-dione Analogues as Potent Angiotensin Converting Enzyme (ACE) Inhibitors

Under the guidance of combination of traditional Chinese medicine chemistry (CTCMC), this study describes the preparation of a phenolic acid/dipeptide/borneol hybrid consisting of phenolic acid and a bornyl moiety connected to the dipeptide N-terminal and C-terminal respectively. It also evaluates their angiotensin converting enzyme (ACE) inhibitory and synergistic antihypertensive activities. Briefly, a series of novel phenolic acid/dipeptide/borneol hybrids were prepared and investigated for their ability to inhibit ACE. The influence of the phenolic acid and bornyl moiety on subsite selectivity is also demonstrated. Among all the new compounds, two compounds—7a and 7g—reveal good inhibition potency in in vitro ACE-inhibitory tests. Interestingly, favorable binding results in molecular docking studies also supported the in vitro results. Additionally, the bioassay showed that oral administration of the two compounds displayed high and long-lasting antihypertensive activity both in acute antihypertensive tests and in therapeutic antihypertensive tests by non-invasive blood pressure measurements in spontaneously hypertensive rats.Under the guidance of combination of traditional Chinese medicine chemistry (CTCMC), this study describes the preparation of a phenolic acid/dipeptide/borneol hybrid consisting of phenolic acid and a bornyl moiety connected to the dipeptide N-terminal and C-terminal respectively. It also evaluates their angiotensin converting enzyme (ACE) inhibitory and synergistic antihypertensive activities. Briefly, a series of novel 2-hydroxypyrrolobenzodiazepine-5,11-dione analogues were prepared and investigated for their ability to inhibit ACE. The influence of the phenolic acid and bornyl moiety on subsite selectivity is also demonstrated. Among all the new compounds, two compounds-7a and 7g-reveal good inhibition potency in in vitro ACE-inhibitory tests. Interestingly, favorable binding results in molecular docking studies also supported the in vitro results. Additionally, the bioassay showed that oral administration of the two compounds displayed high and long-lasting antihypertensive activity both in acute antihypertensive tests and in therapeutic antihypertensive tests by non-invasive blood pressure measurements in spontaneously hypertensive rats.

Distribution of Metabolites in Root Barks of Seven Tree Peony Cultivars for Quality Assessment Using NMR-based Metabolomics

Abstract Objective To determine the distribution of metabolites in the root barks of different tree peony cultivars for quality assessment. Methods Seven tree peony phenotypic cultivars with different colors were systematically analyzed using NMR-based metabolomics. Results A total of 16 metabolites from their methanol extracts were simultaneously identified and quantified, including one primary metabolite (sucrose) and 15 secondary ones (acetophenones, phenolics, monoterpene glycosides, flavonoids, and unsaturated fatty acids). The quantitative data indicated that sucrose (90-180 mg/g) and acetophenones (15-100 mg/g), and non-phenolics, monoterpene glycosides, flavonoids, and unsaturated fatty acids (2-15 mg/g) were the major metabolites in these tree peony cultivars. The significantly increasing levels of paeonoside with bioactivity were observed in “Xiangyu”, “Wujinyaohui”, “Roufurong”, “Yaohuang”, “Zhaofen”, “Doulű”, and “Yingrihong” in order. Opposite trends in the levels of paeonoside and paeonol were observed in “Xiangyu” and “Yingrihong”, suggesting that the changes of the secondary metabolites in plants were influenced by primary metabolites, such as sucrose/glucose, and the different physiological processes occurred in different tree peony cultivars. Conclusion “Yingrihong” with red flower has the highest medicine quality whereas “Xiangyu” with white flower has the worst one based on the content of paeonoside.

Binding mechanism of nine N-phenylpiperazine derivatives and α1A-adrenoceptor using site-directed molecular docking and high performance affinity chromatography

N-Phenylpiperazine derivatives are widely used as clinical drugs for fighting diseases related to the cardiovascular system by mediating the signal pathway of α1-adrenoceptor. The binding mechanism of nine N-phenylpiperazine derivatives to α1A-adrenoceptor was explored using molecular docking and high performance affinity chromatography. The methodology involved homology modelling of the three dimensional structure of α1A-adrenoceptor, predication of the binding behaviors using LIBDOCK and investigation of the thermodynamic behaviors of the binding by frontal analysis. Molecular docking results showed that Asp106, Gln177, Ser188, Ser192 and Phe193 of the receptor were the main binding sites for the nine N-phenylpiperazine derivatives binding to α1A-adrenoceptor. The binding was driven by formation of hydrogen bonds and electrostatic forces. The affinity of these derivatives for the receptor depended on the functional groups of an ionizable piperazine, hydrogen bond acceptor and hydrophobic moiety in the ligand structures. Frontal analysis indicated that the association constants of these compounds for the receptor were determined by their structural deviations in the above-mentioned functional groups. Thermodynamic studies presented negative enthalpy and Gibbs free energy changes with a positive entropy change, providing proof that the binding of the derivatives to α1A-adrenoceptor was mainly driven by electrostatic forces. This result was in line with the binding mechanism predicted by molecular docking. It is possible to explore the binding mechanism of drug candidates specifically binding to α1A-adrenoceptor using receptor chromatography.