Interactions Between Thrombin with Flavonoids from Abelmoschus manihot (L.) Medicus by CZE

Rubus chingii Hu: an overview of botany, traditional uses, phytochemistry, and pharmacology

Rubus chingii Hu, a member of the rosaceae family, is extensively distributed in China and Japan. Its unripe fruits (Fupenzi in Chinese) have a long history of use as an herbal tonic in traditional Chinese medicine for treating various diseases commonly associated with kidney deficiency, and they are still in use today. Phytochemical investigations on the fruits and leaves of R. chingii indicate the presence of terpenoids, flavonoids, steroids, alkaloids, phenylpropanoids, phenolics, and organic acids. Extracts or active substances from this plant are reported to have various pharmacological properties, including antioxidant, anti-inflammatory, antitumor, antifungal, antithrombotic, antiosteoporotic, hypoglycemic, and central nervous system-regulating effects. This review provides up-to-date information on the botanical characterizations, traditional usages, chemical constituents, pharmacological activities, toxicity, and quality control of R. chingii. Possible directions for future research are also briefly proposed. This review aims to supply fundamental data for the further study of R. chingii and contribute to the development of its clinical use.

The antithrombotic activity of the active fractions from the fruits of Celastrus orbiculatus Thunb through the anti-coagulation, anti-platelet activation and anti-fibrinolysis pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine Celastrus orbiculatus Thunb (C. orbiculatus) with peel and seeds is mainly composed of flavonoids, sesquiterpenes and tripenes. According to the Traditional Chinese medicine standard of Liaoning province (2009), it has been long used to invigorate blood circulation.

AIM OF THE STUDY

To identify the antithrombus fraction and components of C. orbiculatus, and to investigate the underlying mechanisms.

MATERIALS AND METHODS

The antithrombus effects of C. orbiculatus fractions were evaluated in vitro by plasma recalcification time (PRT). The antithrombus effect of NST-50, the most effective fraction, was further investigated in acute pulmonary embolism (APE) mice and FeCl₃-induced carotid arterial thrombus rats. Bleeding assessment was also carried out to assess the side effects of NST-50. In addition, the content of total flavonoids and active components of NST-50 was also quantified.

RESULTS

Nine flavonoids were detected in NST-50 as main components with the content of 44.70%. Next, NST-50 was found with significant anticoagulation activity by prolonging the plasma recalcification time (PRT), activated partial thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT) and decreasing the content of fibrinogen (FIB). Furthermore, NST-50 administration markedly suppressed the level of TXB₂ and PAI-1, while significantly up-regulated the level of 6-keto-PGF_1a and t-PA (p < 0.05).

CONCLUSION

The results demonstrated that NST-50 could be valuable in clinical application against acute coronary syndrome, venous thromboembolisms and cerebrovascular thrombosis. It was possible that the anticoagulation action of NST-50 could be related to the regulation of TXA₂ - PGI₂ and t-PA - PAI-1 pairs.

Metabolic profiles of the Flos Abelmoschus manihot extract by intestinal bacteria from the normal and CKD model rats based on UPLC-Q-TOF/MS

Flos Abelmoschus manihot is a traditional herbal medicine widely used in clinical practice to tackle chronic kidney disease (CKD) for thousands of years. Nowadays, many studies indicate that gut bacteria are closely related to the progression of CKD and CKD-related complications. In this study, a UPLC-Q-TOF/MS method coupled with the MetaboLynx™ software was established and successfully applied to investigate the metabolites and metabolic profile of Flos A. manihot extract by intestinal bacteria from normal and CKD rats. Eight parent components and eight metabolites were characterized by their protonated ions. Among these compounds, 15 were detected in the two group samples while M16 was only determined in the CKD model samples. Compared with the quercetin-type glycosides, fewer myricetin-type and gossypetin-type metabolites were obtained in the two group samples. These metabolites suggested that deglycosylation and methylation are the major metabolic pathways of Flos A. manihot extract. Few differences of metabolite classes were observed in the two group samples. However, the concentrations of aglycones such as quercetin, myricetin and gossypetin in the normal samples were notably higher than those in the CKD model samples. The results are important in unravelling the pharmacological effects of A. manihot and clarifying its mechanism of action in vivo.

Development of Orally Active Thrombin Inhibitors for the Treatment of Thrombotic Disorder Diseases

Thrombotic disorders represent the major share of the various cardiovascular diseases, and significant progress has been made in the development of synthetic thrombin inhibitors as new anticoagulants. In addition to the development of highly potent and selective inhibitors with improved safety and suitable half-life, several allosteric inhibitors have been designed and synthesized, that did not fully nullify the procoagulant signal and thus could result in reduced bleeding complications. Furthermore, natural products with thrombin inhibitory activity have been isolated, and some natural products have been modified in order to improve their inhibitory activity and metabolic stability. This review summarizes the development of orally active thrombin inhibitors for the treatment of thrombotic disorder diseases, which could serve as a reference for the interested researchers.

Metabolism-based synthesis, biologic evaluation and SARs analysis of O-methylated analogs of quercetin as thrombin inhibitors

In blood, quercetin is mainly found in metabolized forms. In order to study the activities of these quercetin metabolites in cardiovascular disease, 17 methylquercetin derivatives were synthesized based on metabolism in vivo, their thrombin inhibition activity were evaluated through the analyzation of prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and fibrinogen (FIB). The results showed that 6 methylquercetin derivatives had stronger inhibitory activities than that of quercetin. Preliminary SARs analysis showed that hydroxyl groups at C-3' and C-4' position in the B-ring and hydroxyl group at C-3 position in the C-ring played key roles in the thrombin inhibitory activity. The findings of this study would provide information for the exploitation and utilization of quercetin as thrombin inhibitor for thrombotic disease treatment.

Screening of chemokine receptor CCR4 antagonists by capillary zone electrophoresis

CC chemokine receptor 4 (CCR4) is a kind of G-protein-coupled receptor, which plays a pivotal role in allergic inflammation. The interaction between 2-(2-(4-chloro-phenyl)-5-{[(naphthalen-1-ylmethyl)-carbamoyl]-methyl}-4-oxo-thiazolidin-3-yl)-N-(3-morpholin-4-yl-propyl)-acetamide (S009) and the N-terminal extracellular tail (ML40) of CCR4 has been validated to be high affinity by capillary zone electrophoresis (CZE). The S009 is a known CCR4 antagonist. Now, a series of new thiourea derivatives have been synthesized. Compared with positive control S009, they were screened using ML40 as target by CZE to find some new drugs for allergic inflammation diseases. The synthesized compounds XJH-5, XJH-4, XJH-17 and XJH-1 displayed the interaction with ML40, but XJH-9, XJH-10, XJH-11, XJH-12, XJH-13, XJH-14, XJH-3, XJH-8, XJH-6, XJH-7, XJH-15, XJH-16 and XJH-2 did not bind to ML40. Both qualification and quantification characterizations of the binding were determined. The affinity of the four compounds was valued by the binding constant, which was similar with the results of chemotactic experiments. The established CEZ method is capable of sensitive and fast screening for a series of lactam analogs in the drug discovery for allergic inflammation diseases.

A series of natural flavonoids as thrombin inhibitors: structure-activity relationships

A series of natural flavonoids has been evaluated as potential inhibitors of thrombin using the optimized method of thrombin time. Myricetin and quercetin have shown to be the best thrombin inhibitors tested. In order to investigate the thrombin recognition of the most active and selective compounds, a molecular modeling study has been performed using available Protein Data Bank (PDB) structures as receptor models for docking experiments. Structure-activity relationships of flavonoids (SARs) on thrombin would facilitate the design of chemical compounds with higher potency to serve as potential thrombin inhibitors, and provide information for the exploitation and utilization of flavonoids as thrombin inhibitors for thrombotic disease treatment.

Interactions between thrombin and natural products of Millettia nitita var. hirsutissima using capillary zone electrophoresis

A sensitive and selective high-performance analytical method based on capillary zone electrophoresis (CZE) was developed for investigating interactions between natural products isolated from Millettia nitita var. hirsutissima and thrombin qualitatively and quantitatively for the first time. The results showed that, compared with positive and negative control, the compounds ZYY-5 (genistein-8-C-beta-d-apiofuranosyl-(1-->6)-O-beta-d-glucopyranoside), ZYY-6 (calycosin), ZYY-8 (isoliquiritigenin), ZYY-9 (formononetin), ZYY-12 (gliricidin), ZYY-13 (8-O-methylretusin), FJ-2 (dihydrokaempferol), FJ-3 (biochanin), FJ-5 (afromosin) and XC-2 (hirsutissimiside F) interacted with thrombin, while ZYY-1 (sphaerobioside), ZYY-2 (formononetin-7-O-beta-d-apiofuranosyl-(1-->6)-O-beta-d-glucopyranoside), ZYY-3 (genistein-5-methylether-7-O-alpha-l-rhamnopyranosyl-(1-->6)-O-beta-d-glucopyranoside), ZYY-4 (retusin-7,8-O-beta-d-diglucopyranoside), ZYY-7 (symplocoside), ZYY-10 (ononin), ZYY-11 (genistin), ZYY-14 (afromosin-7-O-beta-d-glucopyranoside), ZYY-15 (lanceolarin), FJ-1 (liquiritigenin), FJ-4 (7,2-dihydroxy,4-methoxyisoflavan) and XC-1 (sphaerobioside) had no binding to thrombin. This indicated that the reported CZE method for the determination of compound-thrombin interactions is powerful, sensitive and fast, and requires less amounts of reagents, and further, it can be employed as a reliable alternative to other methods.

Studies on the interactions between lactam analogs and theN-terminal extracellular tail of CC chemokine receptor 4 by CZE

CC chemokine receptor 4 (CCR4) is a kind of G-protein-coupled receptors with a characteristic seven-transmembrane structure and selectively expressed on Th2-type CD4+ T-cells, which play a pivotal role in allergic inflammation. In this study, the interactions between 2-(2-(2,4-dichloro-phenyl)-4-{[(2-methyl-3-chloro-phenyl)-1-ylmethyl]-carbamoyl}-methyl)-5-oxo-pyrrole-1-yl)-N-(3-piperidinyl-propyl)-acetamide (compound A), a known CCR4 antagonist, and ML40 were studied by CZE for the first time. Both qualitative and quantitative characterizations of the drug-peptide binding were determined. The binding constant of the interaction between the trans-diastereomer of compound A and ML40, calculated from the Scatchard plot by regression, was (1.06 +/- 0.11)x10(5)/M. Also, it was confirmed that the trans-diastereomer was more potent affinity with CCR4 than its cis-counterpart. The experimental results show that this reported method by CZE for the determination of the compound A and ML40 interactions is powerful, sensitive, and fast, requires less amounts of reagents, and further, it can be employed as one of the reliable screening methods to a series of lactam analogs in the drug discovery for allergic inflammation diseases.

Determination of binding constant and binding region of programmed cell death 5-heparin by capillary zone electrophoresis

A sensitive and selective high-performance analytical method based on capillary zone electrophoresis (CZE) was developed for investigating interactions between heparin and programmed cell death 5 (PDCD5) qualitatively and quantitatively. The binding constant of the interaction between PDCD5 and heparin calculated by Scatchard analysis was 4.17x10(4) M(-1) and the binding sites located in the C-terminal region of PDCD5 (residues 109-115). The precisions of migration times, peak heights and binding constants, expressed as the relative standard deviation, were less than 2.4%, 1.1% and 5.7%, respectively.

Studies on interactions of programmed cell death 5 (PDCD5) and its related peptides with heparin by capillary zone electrophoresis

Capillary zone electrophoresis (CZE) was used to investigate interactions between heparin and programmed cell death 5 (PDCD5), and between heparin and PDCD5-related peptides. Samples containing PDCD5, PDCD5-related peptides, and heparin at various ratios were incubated at room temperature and then separated by CZE with tris-acetate buffer at pH 7.2. Both qualitative and quantitative characterizations of the binding of PDCD5 and PDCD5-related peptides to heparin were determined. The changes in the signals of PDCD5 and PDCD5-related peptides were monitored by comparing the electropherograms of the mixtures containing PDCD5 and heparin and PDCD5-related peptides and heparin with that of PDCD5 or PDCD5-related peptides only. The binding constant of the interaction between PDCD5 and heparin was calculated as 4.17 x 10(4) M(-1) by Scatchard analysis. Our investigations show that it is possible to characterize the interaction between PDCD5 and heparin quantitatively and the interaction between PDCD5-related peptides and heparin qualitatively using CZE.