• Biomolecules & Therapeutics
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• v.4 no.2
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• pp.122-126
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• 1996

In vitro inhibitory effect of aspalatone ((3-(2-methyl-4-pyronyl)]-2-acetyloxybenzoate) on collagen-, ADP-, and epinephrine-induced platelet aggregation in human platelet rich plasma (PRP) was compared with the effects of reference drugs (acetylsalicylic acid, cilostazol and ticlopidine). Aspalatone inhibited time and dose dependently human platelet aggregation induced by collagen; relative potency was in the order of cilostazol>acetylsalicylic acid>aspalatone>ticlopidine. Aspalatone, like acetylsalicylic acid, potently inhibited only the secondary phase of ADP-and epinephrine-induced aggregation. Thromboxane $B^2$ production evoked by collagen in human PRP was inhibited significantly and concentration-dependently by aspalatone and acetylsalicylic acid. These results were in agreement with the earlier studies in which the antiplatelet action of aspalatone was indicated to be due to the inhibition of platelet cyclooxygenase activity (Han et al., Arzneim. Forsch./Drug Res. 44(II), 1122, 1994; Suh and Han, Yakhak Hoeji 39, 565, 1995). In addition, the inhibitory activity of aspalatone on the platelet aggregation appears to be inversely related to the rate of nonspecific deacetylation of the drug in plasma.

• Biomolecules & Therapeutics
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• v.23 no.2
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• pp.149-155
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• 2015

Our previous study demonstrated that yuzu has an anti-platelet effect in rat blood. In the present study, we examined whether the anti-platelet effect of yuzu can be extended to human blood by investigating its ability to inhibit aggregations induced by various agonists in human platelet rich plasma (PRP). This study also investigated the underlying mechanism of yuzu focusing on ADP granule secretion, $TXB_2$ formations, and $PLC{\gamma}$/Akt signaling. The results from this study showed that ethanolic yuzu extract (YE), and its components, hesperidin and naringin, inhibited human platelet aggregation in a concentration-dependent manner. YE, hesperidin and naringin also inhibited $TXB_2$ formation and ADP release. The phosphorylation of $PLC{\gamma}$ and Akt was significantly inhibited by YE, heperidin and naringin. Furthermore, we demonstrated that YE, heperidin and naringin has anti-platelet effects in rat ex vivo studies, and lower side effects in mice tail bleeding time studies. The results from this study suggest that YE, hesperidin and naringin can inhibit human platelet aggregation, at least partly through the inhibition of $PLC{\gamma}$ and Akt, leading to a decrease in $TXB_2$ formation and granule secretion.

• Biomedical Science Letters
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• v.10 no.1
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• pp.9-13
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• 2004

We have investigated the effects of hypha-water extracts (HWE), fruit body-water extracts (FWE) and cordycepin from Cordyceps militaris on serotonin release out of human platelets and human platelet aggregation. HWE and FWE inhibited the release of [$^3H$]-serotonin from human platelet stimulated by thrombin (2 U/ml) or collagen (20$\mu$g/ml) in a dose-dependent manner. Furthermore, cordycepin, a major component of Cordyceps militaris, inhibited the human platelet aggregation induced by collagen (10$\mu$g/ml) in a dose-dependent manner. These results suggest that cordycepin containing in HWE and FWE may inhibit the serotonin release by suppressing the collagen-induced human platelet aggregation. Accordingly, our data demonstrate that HWE and FWE containing much cordycepin might have antithrombotic and antimigrainous functions.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1998.11a
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• pp.177-177
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• 1998

In the previous report, tetrandrine (TET) and fangchinoline (FAN) showed antithrombotic and antiplatelet aggregation activities. The present study was undertaken to investigate the effects of tetrandrine and fangchinoline on human platelet aggregation, formation of thromboxane B$_2$ and coagulation of platelet poor plasma. TET and FAN inhibited platelet activating factor (PAF) induced human platelet aggregation, but didn't inhibit the specific binding of PAF to its receptor. Meanwhile, TET and FAN also inhibited PAF, thrombin and arachidonic acid induced thromboxane B$_2$ formation in human washed platelets. In addition, neither TET nor FAN showed any anticoagulation activities in the measurement of the activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) using human platelet poor plasma. These results suggest that antithrombotic effects of TET and FAN in mice may be mainly related to the antiplatelet aggregation activities, and the antiplatelet aggregation effects may be related to the intracellular messenger system such as TXA$_2$ formation etc., but not to the binding of PAF to PAF-receptor on the platelet membrane directly.

• Journal of Ginseng Research
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• v.45 no.4
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• pp.490-497
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• 2021

Background and objective: Synthetic ginsenoside compounds G-Rp (1,3, and 4) and natural ginsenosides in Panax ginseng 20(S)-Rg3, Rg6, F4 and Ro have inhibitory actions on human platelets. However, the inhibitory mechanism of ginsenoside Rk1 (G-Rk1) is still unclear thus, we initiated investigation of the anti-platelet mechanism by G-Rk1 from Panax ginseng. Methodology: Our study focused to investigate the action of G-Rk1 on agonist-stimulated human platelet aggregation, inhibition of platelet signaling molecules such as fibrinogen binding with integrin α_IIbβ₃ using flow cytometry, intracellular calcium mobilization, fibronectin adhesion, dense granule secretion, and thromboxane B2 secretion. Thrombin-induced clot retraction was also observed in human platelets. Key Results: Collagen, thrombin, and U46619-stimulated human platelet aggregation were dose-dependently inhibited by G-Rk1, while it demonstrated a more effective suppression on collagen-stimulated platelet aggregation using human platelets. Moreover, G-Rk1 suppressed collagen-induced elevation of Ca²⁺ release from endoplasmic reticulum, granule release, and α_IIbβ₃ activity without any cytotoxicity. Conclusions and implications: These results indicate that G-Rk1 possess strong anti-platelet effect, proposing a new drug candidate for treatment and prevention of platelet-mediated thrombosis in cardiovascular disease.

• Biomedical Science Letters
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• v.10 no.1
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• pp.1-8
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• 2004

Cordycepin separated from Cordyceps militaris is a major physiologic active component in Cordyceps militaris. The platelet aggregation is stimulated by $Ca^{2+}$, which is either mobilized from intracellular endoplasmic reticulum or transported from extracellular space. cGMP antagonizes the actions of $Ca^{2+}$. Based on these facts, we have investigated the effects of cordycepin on the mobilization of $Ca^{2+}$ and the production of cGMP on collagen ($10\mu$g/ml)-induced human platelet aggregation. Cordycepin potently stimulated the human platelet aggregation induced by collagen ($10\mu$g/ml) in a dose-dependent manner. Cordycepin (500 $\mu$M) inhibited also the collagen-induced human platelet aggregation in the presence both 1 mM and 2 mM of $CaCl_2$. These are in accord with the results that cordycepin inhibited the $Ca^{2+}$- influx on collagen-induced human platelet aggregation. These results suggest that cordycepin decrease the intracellular $Ca^{2+}$ concentration to inhibit collagen-induced human platelet aggregation. Besides, cordycepin increased the level of cGMP on collagen-induced human platelet aggregation. This result is related with the decrease of intracellular $Ca^{2+}$ concentration, because cGMP inhibits the mobilization of $Ca^{2+}$. In addition, cordycepin inhibited the human platelet aggregation induced by LY -83583, inhibitor of guanylate cyclase. This result suggested that cordycepin inhibit the platelet aggregation by stimulating the activity of guanylate cyclase. In conclusion, we demonstrated that cordycepin might have the antiplatelet function by inhibiting $Ca^{2+}$-mobilization via the stimulation of the production of cGMP.

• Korean Journal of Pharmacognosy
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• v.52 no.3
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• pp.127-133
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• 2021

Platelet activation plays a major role in cardiovascular disorders (CVDs). Thus, disrupting platelet activation represents an attractive therapeutic target on CVDs. Esculetin, a bioactive 6,7-dihydroxy derivative of coumarin, possesses pharmacological activities against obesity, diabetes, renal failure, and CVDs. In other report, the effect of esculetin has been examined in human platelet activation and experimental mouse models, and esculetin inhibited collagen- and arachidonic acid-induced platelet aggregation in washed human platelets. However, it had no effects on other agonists such as thrombin and U46619, and its mechanism is not also clearly known. This study investigated the effect of esculetin on collagen-induced human platelet aggregation, and we clarified the mechanism. Esuletin has effects on the down regulation of PI3K/Akt and MAPK, phosphoproteins that act in the signaling process in platelet aggregation. The effects of esculetin reduced of TXA₂ production and phospholipase A₂ activation, and intracellular granule secretion including ATP and serotonin, leading to inhibit platelet aggregation. These results clearly clarified the effect of esculetin in inhibiting platelet activity and thrombus formation in humans.

• Journal of Applied Biological Chemistry
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• v.64 no.3
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• pp.317-322
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• 2021

Among the different cardiovascular disorders (CVDs), the activation of platelets is a necessary step. Based on this knowledge, therapeutic treatments for CVDs that target the disruption of platelet activation are proving to be worthwhile. One such substance, a bioactive 6,7-dihydroxy derived from coumarin, is 6,7-Dihydroxy-2H-1-benzopyran-2-one (esculetin). This compound has demonstrated several pharmacological effects on CVDS as well as various other disorders including diabetes, obesity, and renal failure. In various reports, esculetin and its effect has been explored in experimental mouse models, human platelet activation, esculetin-inhibited collagen, and washed human platelets exhibiting aggregation via arachidonic acid. Yet, esculetin affected aggregation with agonists like U46619 or thrombin in no way. This study investigated esculetin and how it affected human platelet aggregation activated through U46619. Ultimately, we confirmed that esculetin had an effect on the aggregation of human platelets when induced from U46619 and clarified the mechanism. Esculetin interacts with the downregulation of both phosphoinositide 3-kinase/Akt and mitogen-activated protein kinases, important phosphoproteins that are involved in activating platelets and their signaling process. The effects of esculetin reduced TXA₂ production, phospholipase A₂ activation, and platelet secretion of intracellular granules (ATP/serotonin), ultimately causing inhibition of overall platelet aggregation. These results clearly define the effect of esculetin in inhibiting platelet activity and thrombus formation in humans.

• Korean Journal of Pharmacognosy
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• v.51 no.2
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• pp.100-106
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• 2020

The extract of Cudrania tricuspidata is used in ethnomedicine throughout Eastern Asia in China, Korea and Japan. In Korean traditional medicine, Cudrania tricuspidata has been used to treat eczema, mumps, tuberculosis, contusions, insomnia and acute arthritis. In addition, it has been reported that root extract of Cudrania tricuspidata has anti-platelet effects. Therefore, we investigated which compound in Cudrania tricuspidata has inhibitory effect on platelet aggregation. In this study, we tried to explain the inhibitory mechanism of steppogenin from Cudrania tricuspidata on human platelet aggregation. Collagen-induced human platelet aggregation and [Ca²⁺]_i mobilization were dose-dependently inhibited by steppogenin and we determined the inhibition by steppogenin is due to the down regulation of extracellular-signal-regulated kinase(ERK) and inositol-1,4,5-triphosphate receptor type I(IP₃RI) phosphorylation. In addition, steppogenin inhibited collagen-induced fibronectin adhesion to αIIb/β3 and thromboxane A₂ generation. Thus, in the present study, steppogenin showed an inhibitory effect on human platelet aggregation, suggesting its potential use for preventing platelet-induced cardiovascular disease.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.5
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• pp.980-985
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• 2009

The study was designed to test anti-platelet effect and find out anti-platelet mechanism of extract from Gamisopunghwalheol-tang in vitro. The extract was investigated for the inhibition against the aggregation of human platelet suspensions induced from collagen by aggregometer. And also the extract was investigated for the inhibition against the aggregation of human platelet suspensions who is taking aspirin or clopidogrel induced from collagen by aggregometer. In collagen-induced platelet aggregation test, the extract significantly inhibited collagen-induced platelet aggregation in a concentration-dependent manner(p<0.05). The extract significantly inhibited collagen-induced platelet aggregation of human platelet who is taking aspirin or clopidogrel ing 0 mg/ml concentration(p<0.05). And the extract inhibited more ingpatients who is taking aspirin. These results show that the extract from Gamisopunghwalheol-tang has anti-platelet aggregation effect.