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

Targeting neutrophils extracellular traps, a promising anti-thrombotic therapy for natural products from traditional Chinese herbal medicine

Thrombi are the main cause of vascular occlusion and contribute significantly to cardiovascular events and death. Neutrophils extracellular traps (NETs)-induced thrombosis plays a vital role in thrombotic complications and it takes the main responsibility for the resistance of fibrinolysis. However, the conventional anti-thrombotic therapies are inadequate to treat NETs-induced thrombotic complications but carry a high risk of bleeding. Consequently, increased attention has shifted towards exploring novel anti-thrombotic treatments targeting NETs. Interestingly, accumulating evidences prove that natural products from traditional Chinese herbal medicines have a great potential to mitigate thrombosis through inhibiting generous NETs formation and degrading excessive NETs. In this review, we elaborated the formation and degradation of NETs and highlighted its pivotal role in immunothrombosis through interactions with platelets and coagulation factors. Since available anti-thrombotic drugs targeting NETs are deficient, we further summarized the natural products and compounds from traditional Chinese herbal medicines which exert effective actions on regulating NETs formation and also have anti-thrombotic effects. Our findings underscore the diverse effects of natural products in targeting NETs, including relieving inflammation and oxidative stress of neutrophils, inhibiting neutrophils activation and DNA efflux, suppressing granule proteins release, reducing histones and promoting DNA degradation. This review aims to highlight the significance of natural medicines in anti-thrombotic therapies through targeting NETs and to lay a groundwork for developing novel anti-thrombotic agents from traditional Chinese herbal medicines.

A highly sensitive and specific fluorescent probe for thrombin detection and high-throughput screening of thrombin inhibitors in complex matrices

Thrombin plays a critical role in hemostasis and hemolysis, and is a significant biomarker for blood-related diseases. Detection and inhibitors screening of thrombin are essential in medical research. In this study, we developed a fluorescent sensor based on the interaction between quantum dots (QDs) and fibrinogen (Fib) for thrombin detection and its inhibitors screening. Upon the presence of thrombin, the fibrinogen of soluble QDs-Fib were converted into insoluble fibrin precipitate, causing a change of fluorescence intensity in the supernatant. Under optimized conditions, our method exhibited an excellent linearity (R2 ≥0.99) over the range of 2∼100 U/L with a limit of detection (LOD) as low as 0.29 U/L. Moreover, we employed this method to screen for thrombin inhibitors using dabigatran as an exemplary direct thrombin inhibitor (DTI), even at concentrations as low as 1 nM. Finally, the established method was successfully used to screen thrombin inhibitors in 23 different extracts from Eupolyphaga sinensis walker. The method provided not only a sensitive, specific and high throughput assay for the detection of thrombin activity in biological samples, but also a reliable strategy for the screening of thrombin inhibitors in complex matrices.

Non-clinical investigations about cytotoxic and anti-platelet activities of gamma-terpinene

Gamma-terpinene (γ-TPN) is a cyclohexane monoterpene isolated from plant essential oils, such as tea tree (Melaleuca alternifolia), oregano (Origanum vulgare), rosemary (Rosmarinus officinalis L.), thyme (Thymus vulgaris Marchand), and eucalyptus (Eucalyptus sp.). Terpenes are widely studied molecules pharmacologically active on the cardiovascular system, hemostasis, and antioxidant actions. Herein, it was investigated the cytotoxic and antiplatelet activity of γ-TPN using different non-clinical laboratory models. For in silico evaluation, the PreADMET, SwissADME, and SwissTargetPrediction softwares were used. Molecular docking was performed using the AutoDockVina and BIOVIA Discovery Studio databases. The cytotoxicity of γ-TPN was analyzed by the MTT assay upon normal murine endothelial SVEC4-10 and fibroblast L-929 cells. Platelet aggregation was evaluated with platelet-rich (PRP) and platelet-poor (PPP) plasma from spontaneously hypertensive rats (SHR), in addition to SVEC4-10 cells pre-incubated with γ-TPN (50, 100, and 200 µM) for 24 h. SHR animals were pre-treated by gavage with γ-TPN for 7 days and divided into four groups (negative control, 25, 50, and 100 mg/kg). Blood samples were collected to measure nitrite using the Griess reagent. Gamma-TPN proved to be quite lipid-soluble (Log P = +4.50), with a qualified profile of similarity to the drug, good bioavailability, and adequate pharmacokinetics. It exhibited affinity mainly for the P2Y12 receptor (6.450 ± 0.232 Kcal/mol), moderate cytotoxicity for L-929 (CC50 = 333.3 µM) and SVEC 4-10 (CC50 = 366.7 µM) cells. The presence of γ-TPN in SVEC 4-10 cells was also able to reduce platelet aggregation by 51.57 and 44.20% at lower concentrations (50 and 100 µM, respectively). Then, γ-TPN has good affinity with purinergic receptors and an effect on the reversal of platelet aggregation and oxidative stress, being promising and safe for therapeutic targets and subsequent studies on the control of thromboembolic diseases.

Celastrus orbiculatus Extract Inhibits Immune Inflammatory Thrombotic State of B-Lymphoma

OBJECTIVE

To investigate the inhibitory effect of Celastrus orbiculatus extracts (COE) on the proliferation of lymphoma cells and the immune regulation ability on inflammation and thrombophilia in vivo.

METHODS

The 38B9 lymphoma cells were treated with COE (160 µ g/mL) and CTX (25 µ mol/L). The apoptosis rate and cell cycle of each group were detected by flow cytometry. The secretion of inflammatory factors, including interleukin (IL)-6, IL-10, and tumor necrosis factor α (TNF-α), in cell supernatant was detected by enzyme-linked immunosorbent assay (ELISA). In vivo, BALB/c mice were subcutaneously injected with 38B9 lymphoma cells to establish lymphoma model. COE (3 mg·kg-1·d-1) and CTX (40 mg·kg-1·d-1) were administered to the model mice, respectively. The expression of plasma inflammatory factors (IL-6, IL-10 and TNF-α) and thrombus indexes, including D-dimer (D-D), von Willebrand factor (vWF) and tissue factor (TF), were detected by ELISA before tumor bearing (1 d), after tumor formation (14 d) and after intervention (21 d). PicoGreen dsDNA was used to detect the level of serum neutrophil extracellular traps (NETs). Flow cytometry was used to detect the expression of platelet activation marker calcium-dependent lectin-like receptor 2 (CLEC-2). The tumor growth and survival of mice were recorded.

RESULTS

The 38B9 lymphoma cells were apoptotic after the intervention of COE and CTX. The ratio of G2-M phase cells decreased in COE intervented cells compared with the control cells (P<0.05), and S phase cells decreased in CTX intervented cells (P<0.05). Also, the secretion level of IL-6 was significantly reduced after COE or CTX intervention (P<0.05), and IL-10 was significantly increased (P<0.05). Furthermore, the tumor mass was reduced, and the median survival time was longer in COE and CTX intervented tumor-bearing mice than in non-intervented mice. The significantly lower levels of TNF-α, IL-6, NETs, TF, DD and CLEC-2, as well as higher IL-10 were observed in COE and CTX treatment mice in comparision with the control mice (P<0.05).

CONCLUSION

COE has a mild and stable anti-tumor effect, which can reduce the secretion of inflammatory factors by lymphoma cells and regulate thrombophilic state caused by tumor inflammatory microenvironment.

Betulinic acid, a major therapeutic triterpene of Celastrus orbiculatus Thunb., acts as a chemosensitizer of gemcitabine by promoting Chk1 degradation

ETHNOPHARMACOLOGICAL RELEVANCE

Celastrus orbiculatus Thunb., also called as oriental bittersweet vine or climbing spindle berry, a traditional Chinese herbal medicine has been used to treat a spectrum of painful and inflammatory diseases for centuries. Explored for their unique medicinal properties, C.orbiculatus offers additional therapeutic effects on cancerous diseases. The effect of single-agent gemcitabine on survival has not long been encouraging, combination therapies provide patients multiple chances of benefit for improved clinical response.

AIMS OF THIS STUDY

This study aims at expounding the chemopotentiating effects and underlying mechanisms of betulinic acid, a primary therapeutic triterpene of C. orbiculatus in combination with gemcitabine chemotherapy.

MATERIALS AND METHODS

The preparation of betulinic acid was optimized using ultrasonic-assisted extraction method. Gemcitabine-resistant cell model was established by induction of the cytidine deaminase. MTT, colony formation, EdU incorporation and Annexin V/PI staining assays were used to evaluate cytotoxicity, cell proliferation and apoptosis in BxPC-3 pancreatic cancer cell line and H1299 non-small cell lung carcinoma cell line. Comet assay, metaphase chromosome spread and γH2AX immunostaining were applied for DNA damage assessment. Western blot and co-immunoprecipitation was used to detect the phosphorylation and ubiquitination of Chk1. Mode of action of gemcitabine in combination with betulinic acid was further captured in BxPC-3-derived mouse xenograft model.

RESULTS

We noticed that the extraction method had an impact on the thermal stability of C. orbiculatus. Ultrasound-assisted extraction at room temperature in shorter processing time could maximize the overall yields and biological activities of C. orbiculatus. The major constituent was identified as betulinic acid, and the pentacyclic triterpene represented the prominent anticancer activity of C. orbiculatus. Forced expression of cytidine deaminase conferred acquired resistance to gemcitabine, while betulinic acid displayed equivalent cytotoxicity toward gemcitabine-resistant and sensitive cells. A combination therapy of gemcitabine with betulinic acid produced synergistic pharmacologic interaction on cell viability, apoptosis and DNA double-strand breaks. Moreover, betulinic acid abrogated gemcitabine-triggered Chk1 activation by destabilizing Chk1 loading via proteasomal degradation. The combination of gemcitabine and betulinic acid significantly retarded BxPC-3 tumor growth in vivo compared to single-agent gemcitabine treatment alone, accompanied with reduced Chk1 expression.

CONCLUSIONS

These data provide evidence that betulinic acid is a potential candidate for chemosensitization as a naturally occurring Chk1 inhibitor and warrants further preclinical evaluation.

Sodium dehydroacetate-induced disorder of coagulation function in broiler chickens and the protective effect afforded by vitamin K

Sodium dehydroacetate (S-DHA) is used widely as a preservative in several products, including poultry feed. The anticoagulation effect of 200 mg/kg S-DHA in rats has been reported to accompany a reduction in hepatic expression of vitamin K epoxide reductase complex 1 (VKORC1). Poultry and mammals have different physiology and coagulation systems, and species differences in VKORC1 expression have been found. The effect of S-DHA on blood clotting of poultry has not been studies deeply. S-DHA was given to yellow-plumage broilers (YBs) as single and multiple administrations. Vitamin K3 (VK₃) was injected into YBs 2 wk after S-DHA administration. Then, the prothrombin time (PT), partial activated prothrombin time (APTT), plasma levels of vitamin K (VK), factor IX (FIX), and S-DHA, and hepatic expression of VKORC1 were obtained. Chicken hepatocellular carcinoma (LMH) cells were also exposed to S-DHA, and the cell activity, VK level, and FIX level were measured. S-DHA prolonged the PT or APTT significantly, decreased levels of VK and FIX in blood, and inhibited hepatic expression of VKORC1. The maximum changes were 1.15-fold in the PT, 1.42-fold in the APTT, 0.8-fold in the VK level, 0.7-fold in the FIX level, and 0.35-fold in VKORC1 expression compared with controls. The cell activity, VK level, FIX level, and VKORC1/VKORC1L1 expression of LMH cells were reduced significantly at S-DHA doses of 2.0 to 10.0 mM. Prolongation of the PT/APTT and lower levels of VK/FIX in YBs or the lower cell activity and VK/FIX levels in LMH cells induced by S-DHA therapy were resisted significantly by VK₃ treatment. We demonstrated that S-DHA could induce a disorder in coagulation function in YBs or in LMH cells via reduction of VKORC1/VKORC1L1 expression, and that VK could resist this anticoagulation effect.

Bioactive compounds and functional foods as coadjuvant therapy for thrombosis

Cardiovascular diseases (CVDs) are the leading cause of death. The most common cardiovascular pathologies are thromboembolic diseases. Antithrombotic therapy prevents thrombus formation or dissolves that previously constituted. However, it presents a high rate of accidents such as gastric bleeding and cerebrovascular embolism. Plant foods and their secondary metabolites have been reported to regulate blood hemostasis. This review article aims to propose plant foods and their metabolites as adjuvant therapy for the management of thromboembolic diseases. Various databases were consulted, using antiplatelet, anticoagulant, and fibrinolytic as key terms. In total, 35 foods and 24 secondary metabolites, via in vitro, in vivo, and clinical studies, have been reported to regulate platelet aggregation, blood coagulation, and fibrinolysis. According to the studies presented in this review, plant foods with effects at concentrations less than 50 μg mL^-1 and secondary metabolites with IC₅₀ less than 100 μM can be considered agents with high antithrombotic potential. This review suggests that plant foods and their secondary metabolites should be used to develop foods, ingredients and nutraceuticals with functional properties. The evidence presented in this review shows that plant foods and their bioactive compounds could be used as adjuvants for the treatment and prevention of thrombotic complications. However, further in vivo and clinical trials are required to establish effective and safe doses.

A Novel Polysaccharide from AuriculariaAuricula Alleviates Thrombosis Induced by Carrageenan in Mice

The increasing incidence of cardiovascular diseases has created an urgent need for safe and effective antithrombotic agents. In this study, we aimed to elucidate the structural characteristics and antithrombotic activity of a novel polysaccharide isolated from Auriculariaauricula fruiting bodies. The purified polysaccharide AAP-b2 (12.02 kDa) was composed of mannose, glucuronic acid, glucose and xylose, with a molar ratio of 89.25:30.50:4.25:1.00. Methylation and NMR analyses showed that AAP-b2 primarily consisted of →2,3)-Manp-(1→, →3)-Manp-(1→, →4)-GlcAp-(1→ and Manp-(1→. A thrombus mouse model induced by carrageenan was used in this research to evaluate its antithrombotic effect. AAP-b2 significantly inhibited platelet aggregation, reduced the black tail length and prolonged the coagulation time, including activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT), exerting a good inhibitory effect on thrombosis in mice. The antithrombotic activity of AAP-b2 was found to be related to the inhibition of platelet activation by regulation of endothelial nitric oxide synthases (eNOs), endothelin-1 (ET-1), prostacyclin (PGI2) and thromboxane B2 (TXB2), along with the enhancement of anticoagulant activity by affecting antithrombin III (AT-III) and protein C (PC) pathways.

A Linarin Derivative Protects against Ischemia-Induced Neuronal Injury in Mice by Promoting Cerebral Blood Flow Recovery via KDELR-Dependent CSPG4 Activation

The cerebral ischemic microvascular response and collateral circulation compensatory capacity are important for the outcome of ischemic stroke. Here, we sought to evaluate the effect of a linarin derivate 4′-benzylapigenin-7-β-rutinoside (BLR) on neurological function and cerebral blood flow restoration in ischemic stroke. A mouse model of middle cerebral artery occlusion (30 min) with reperfusion (24 h) was used to mimic ischemic stroke in vivo, and 2,3,5-triphenyltetrazolium chloride (TTC) staining, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays, and immunofluorescence microscopy were used to assess the protective effects of BLR on infarct volume, neurological function, neuronal apoptosis, and inflammatory damage. Cerebral blood flow was assayed by laser speckle contrast imaging. Double immunostaining of GFAP-collagen IV and brain lucidification were performed to determine the protective effects of BLR on the disruption of brain vasculature. Differential gene expression was assessed by RNA sequencing. Coimmunoprecipitation and western blotting were used to explore the mechanism of BLR-induced neuroprotection. The results of in vivo experiments showed that BLR administration after reperfusion onset reduced infarct volume, improved neurological function, and decreased the neural cell apoptosis and inflammatory response in the ischemic brain, which was accompanied by increased cerebral blood flow and reduced detachment of astrocyte endfeet from the capillary basement membrane. The RNA sequencing data showed that BLR promoted the upregulation of extracellular matrix and angiogenesis pathway-related genes; in particular, BLR significantly increased the expression of the chondroitin sulfate proteoglycan 4 (CSPG4) gene, enhanced the membrane location of CSPG4, and promoted its downstream signaling protein expression, which is associated with KDEL receptor (KDELR) activation. In addition, activated KDELR further increased the phosphorylation of mitogen-activated protein kinases after BLR treatment. Taken together, our data showed that BLR could protect against ischemic brain injury and may serve as a new promising therapeutic candidate drug for ischemic stroke, and that KDELR might act as both a sensor and effector to activate CSPG4 to increase cerebral blood flow.

New Insights into the Biological Activity of Lichens: Bioavailable Secondary Metabolites of Umbilicaria decussata as Potential Anticoagulants

This study reports the in vitro anticoagulation activity of acetonic extract (AE) of 42 lichen species and the identification of potential bioavailable anticoagulant compounds from Umbilicaria decussata as a competent anticoagulant lichen species. Lichens' AEs were evaluated for their anticoagulant activity by monitoring activated partial thromboplastin time (APTT) and prothrombin time (PT) assays. A strong, positive correlation was observed between total phenolics concentration (TPC) of species and blood coagulation parameters. U. decussata was the only species with the longest clotting time in both APTT and PT assays. The research was moved forward by performing in vivo assays using rats. The results corroborated the dose-dependent impact of U. decussata's AE on rats' clotting time. Major secondary metabolites of U. decussata and their plasma-related bioavailability were also investigated using LC-ESI-MS/MS. Atranol, orsellinic acid, D-mannitol, lecanoric acid, and evernic acid were detected as possible bioavailable anticoagulants of U. decussata. Our findings suggest that U. decussata might be a potential anticoagulant lichen species that can be used for the prevention or treatment of coagulation-related issues such as cardiovascular diseases (CVDs).

Novel Pheretima guillelmi-derived antithrombotic protein DPf3: Identification, characterization, in vitro evaluation and antithrombotic mechanisms investigation

In this study, the antithrombotic protein, named DPf3, was purified from Pheretima guillelmi by ion-exchange chromatography. The protein pattern of DPf3 was mainly at 26-34 kDa; its two main proteins, DPf3 ID NO.1 and NO.2, were detected to be 36,121.745 Da and 24,485.004 Da consisting of 329 and 241 amino acids, respectively; the full covered protein sequences were consistent with Ac44553_g1_i1_1 and Dc43026_g1_i1_2 in our previous constructed P. guillelmi local database. The secondary structure of DPf3 is the mixture of α-helix (0.19), β-sheet (0.30) and random coil (0.51). DPf3 was predicted to possess a direct effect on fibrin, fibrinogen and plasminogen by protein-protein docking analysis, which was further confirmed by in vitro and ex vivo study. DPf3 was determined to possess antithrombotic ability by showing outstanding direct-hydrolysis ability on fibrin, fibrinogen and blood clot, and slight plasminogen activation activity. DPf3 could significantly prolong APTT and decrease fibrinogen content, indicating that DPf3 exerted antithrombotic activity via the intrinsic and/or common pathway, and the third coagulation phase. By this approach, the functional protein DPf3 was fully revealed and found to confer excellent anticoagulant and thrombolytic activity, and could be developed into a promising antithrombotic agent.