• 대한의생명과학회지
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• 제22권4호
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• pp.127-139
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• 2016

A species of the fungal genus Cordyceps has been used as an ingredient of traditional Chinese medicine. In this study, we prepared cordycepin-enriched WIB-801CE, an ethanol extract from culture solution of Cordyceps militaris-hypha, and evaluated its antiplatelet effects on human platelet aggregation. WIB-801CE dose-dependently inhibited ADP-, collagen-, and thrombin-induced platelet aggregation. These antiplatelet effects by WIB-801CE were associated with the attenuation of thromboxane $A_2$ ($TXA_2$) production and serotonin release by ADP, collagen, and thrombin. The inhibition of $TXA_2$ production by WIB-801CE was due to the inhibition of cyclooxygenase-1, $TXA_2$ synthase, and cytosolic phospholipase $A_2$ activity. Therefore, these data suggest that WIB-801CE may be a beneficial component against protection from platelet aggregation-mediated thrombotic disease.

• 대한의생명과학회지
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• 제23권4호
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• pp.310-320
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• 2017

Ginseng has been widely used for traditional medicine in eastern Asia and is known to have inhibitory effects on cardiovascular disease (CVD) such as thrombosis, atherosclerosis, and myocardial infarction. Because, platelet is a crucial mediator of CVD, many studies are focusing on inhibitory mechanism of platelet functions. Among platelet activating molecules, thromboxane $A_2$ ($TXA_2$) and P-selectin play a central role in CVD. $TXA_2$ leads to intracellular signaling cascades and P-selectin plays an important role in platelet-neutrophil and platelet-monocyte interactions leading to the inflammatory response. In this study, we investigated the inhibitory mechanisms of total saponin fraction from Korean red ginseng (KRG-TS) on $TXA_2$ production and P-selectin expression. Thrombin-elevated $TXA_2$ production and arachidonic acid release were decreased by KRG-TS dose (25 to $150{\mu}g/mL$)-dependently via down regulation of microsomal cyclooxygenase-1 (COX-1), $TXA_2$ synthase (TXAS) activity and dephosphorylation of cytosolic phospholipase $A_2$ ($cPLA_2$). In addition, KRG-TS suppressed thrombin-activated P-selectin expression, an indicator of granule release via dephosphorylation of mitogen-activated protein kinases (MAPK). Taken together, we revealed that KRG-TS is a beneficial novel compound inhibiting $TXA_2$ production and P-selectin expression, which may prevent platelet aggregation-mediated thrombotic disease.

• The Korean Journal of Physiology and Pharmacology
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• 제16권1호
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• pp.59-64
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• 2012

Hypoxic pulmonary vasoconstriction (HPV) is physiologically important response for preventing mismatching between ventilation and perfusion in lungs. The HPV of isolated pulmonary arteries (HPV-PA) usually require a partial pretone by thromboxane agonist (U46619). Because the HPV of ventilated/perfused lungs (HPV-lung) can be triggered without pretone conditioning, we suspected that a putative tissue factor might be responsible for the pretone of HPV. Here we investigated whether HPV can be also observed in precision-cut lung slices (PCLS) from rats. The HPV in PCLS also required partial contraction by U46619. In addition, $K^+$ channel blockers (4AP and TEA) required U46619-pretone to induce significant contraction of PA in PCLS. In contrast, the airways in PCLS showed reversible contraction in response to the $K^+$ channel blockers without pretone conditioning. Also, the airways showed no hypoxic constriction but a relaxation under the partial pretone by U46619. The airways in PCLS showed reliable, concentration-dependent contraction by metacholine ($EC_{50}$, ~210 nM). In summary, the HPV in PCLS is more similar to isolated PA than V/P lungs. The metacholineinduced constriction of bronchioles suggested that the PLCS might be also useful for studying airway physiology in situ.

• Biomolecules & Therapeutics
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• 제3권2호
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• pp.143-148
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• 1995

Recently, we reported that GS 389 has vasodilating action without cardiac inotropic action (Chang et al., Can. J. Physiol. Pharmacol. 72, 327-334, 1994). However the mechanism of action of GS 389 has not been thoroughly evaluated. In the present study, we performed functional study of GS 389 in rat trachealis, thoracic aorta, pig coronary artery by isometric tension and in human platelets by aggregation experiments. We also tested if GS 389 influences on $Ca^{2+}$movement and inositol phosphate metabolism. In rat trachealis, GS 389 concentration-dependently relaxed carbachol (0.1 $\mu$M)- and high $K^{+}$(65.4 mM)-induced contraction with p$IC_{50}$/ of 4.43$\pm$ 0.19 and 4.11$\pm$0.12, respectively. In $Ca^{2+}$-free media, GS 389 inhibited carbachol-induced phasic contraction. In rat thoracic aorta, GS 389 inhibited $^{45}$ Ca uptake due to norepinephrine and high $K^{+}$, indicating that GS 389 has direct inhibitory action of $Ca^{2+}$movement. Furthermore, GS 389 competitively inhibited U46619-induced contraction in rat thoracic aorta and pig coronary artery with K, values of 5.23$\pm$0.12 and 5.56$\pm$0.14, respectively, and inhibited U 46619-induced phosphatidylinositide (PI) turnover in rat aorta. GS 389 also concentration-dependently inhibited the human platelet aggregation against U 46619 with p$IC_{50}$/ 5.66$\pm$0.02. These results indicate that GS 389 has thromboxane $A_2$ antagonistic action in vascular and platelets as well as direct action on $Ca^{2+}$ movement, which may account, at least in part, for relaxing action of rat trachealis. trachealis.

• Biomolecules & Therapeutics
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• 제21권1호
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• pp.54-59
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• 2013

In this study, we investigated the effect of (-)-epigallocatechin-3-gallate (EGCG), a major component of green tea catechins from green tea leaves, on activities of cyclooxygenase (COX)-1 and thromboxane synthase (TXAS), thromboxane $A_2$ ($TXA_2$) production associated microsomal enzymes. EGCG inhibited COX-1 activity to 96.9%, and TXAS activity to 20% in platelet microsomal fraction having cytochrome c reductase (an endoplasmic reticulum marker enzyme) activity and expressing COX-1 (70 kDa) and TXAS (58 kDa) proteins. The inhibitory ratio of COX-1 to TXAS by EGCG was 4.8. These results mean that EGCG has a stronger selectivity in COX-1 inhibition than TXAS inhibition. In special, a nonsteroid anti-inflammatory drug aspirin, a COX-1 inhibitor, inhibited COX-1 activity by 11.3% at the same concentration ($50{\mu}M$) as EGCG that inhibited COX-1 activity to 96.9% as compared with that of control. This suggests that EGCG has a stronger effect than that of aspirin on inhibition of COX-1 activity. Accordingly, we demonstrate that EGCG might be used as a crucial tool for a strong negative regulator of COX-1/$TXA_2$ signaling pathway to inhibit thrombotic disease-associated platelet aggregation.

• 한국식품영양과학회지
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• 제27권1호
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• pp.175-181
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• 1998

The relation between lipid peroxidation and thrombotic reaction were investigated in streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley male rats weighing 100$\pm$10gm were randomly assigned to normal and STZ-induced diabetic group(DM). Diabetes was experimentally induced by intravenous injection of 55mg/kg of body weight of STZ in citrate buffer(pH 4.3) after 4 weeks feeding of basal diet. Animals were sacrificed at the 6th day of diabetic states. Body weight gains were lower in diabetic group after STZ injection. Serum levels of thiobarbituric acid reacting substances(TBARS) that were markedly increased in DM group compared with of normal group. TBARS levels of HDL and LDL were similar patterns to total TBARA of serum. Activities of platelet phospholipase A2(PLA2) were higher in diabetic group than those of normal group. Activities of platelet cyclooxygenase were 106% in DM group than normal group. Platelet thromboxane A2(TXA2) formation was increased in DM group than normal group. Production of aortic prostacyclin(PGI2) was lower in diabetic group than that of normal group. PGI2/TXA2 ratios were decreased by 55% in DM groups than those of normal group. The present results indicate that STZ-induced diabetic rats are more sensitive to oxidative stess which leads to acceleration of lipid peroxidation and platelet aggregability. In conclusion, accelerating effect of lipid peroxidation and thrombogenesis in diabetic state is regareded to be resulted from enhancement of PLA2 activity and arachidonic acid metabolism, inhibition of antiaggrgating agent and aortic PGI2 formation.

• Journal of Ginseng Research
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• 제36권1호
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• pp.40-46
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• 2012

Ginseng, the root of Panax ginseng Meyer, has been used frequently in traditional oriental medicine and is popular globally. Ginsenosides, which are the saponins in ginseng, are the major components having pharmacological and biological activities, including anti-diabetic and anti-tumor activities. In this study, we investigated the effects of total saponin from Korean red ginseng(TSKRG) on thrombin-produced thromboxane $A_2$ ($TXA_2$), an aggregating thrombogenic molecule, and its associated microsomal enzymes cyclooxygenase (COX)-1 and $TXA_2$ synthase (TXAS). Thrombin (0.5 U/mL) increased $TXA_2$ production up to 169 ng/$10^8$ platelets as compared with control (0.2 ng/$10^8$ platelets). However, TSKRG inhibited potently $TXA_2$ production to the control level in a dose-dependent manner, which was associated with the strong inhibition of COX-1 and TXAS activities in platelet microsomes having cytochrome c reductase activity. The results demonstrate TSKRG is a beneficial traditional oriental medicine in platelet-mediated thrombotic diseases via suppression of COX-1 and TXAS to inhibit production of $TXA_2$.

• The Korean Journal of Physiology and Pharmacology
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• 제12권1호
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• pp.25-30
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• 2008

Although many studies show that thromboxane $A_2\;(TXA_2)$ has the action of gastrointestinal (GI) motility using GI muscle cells and tissue, there are no reports on the effects of $TXA_2$ on interstitial cells of Cajal (ICC) that function as pacemaker cells in GI tract. So, we studied the modulation of pacemaker activities by $TXA_2$ in ICC with whole cell patch-clamp technique. Externally applied $TXA_2\;(5{\mu}M)$ produced membrane depolarization in current-clamp mode and increased tonic inward pacemaker currents in voltage-clamp mode. The tonic inward currents by $TXA_2$ were inhibited by intracellular application of GDP-${\beta}$-S. The pretreatment of ICC with $Ca^{2+}$ free solution and thapsigargin, a $Ca^{2+}$-ATPase inhibitor in endoplasmic reticulum, abolished the generation of pacemaker currents and suppressed the $TXA_2$-induced tonic inward currents. However, chelerythrine or calphostin C, protein kinase C inhibitors, did not block the $TXA_2$-induced effects on pacemaker currents. These results suggest that $TXA_2$ can regulate intestinal motility through the modulation of ICC pacemaker activities. This modulation of pacemaker activities by $TXA_2$ may occur by the activation of G protein and PKC independent pathway via extra and intracellular $Ca^{2+}$ modulation.

• Biomolecules & Therapeutics
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• 제7권3호
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• pp.227-233
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• 1999

The effects of 2-bromo-3-(3,5-tert-butyl-4-hydroxylphenyl)-1,4-naphthalenedione(TPN2), a synthetic vitamin K derivative, on platelet aggregation and its action mechanisms were investigated in rat platelet. TPN2 inhibited the platelet aggregation induced by collagen($10\mu\textrm{g}$/ml), thrombin(0.1 U/ml), A23187($10\mu\textrm{M}$) and arachidonic acid($100\mu\textrm{M}$) in concentration-dependent manner with $IC_{50}$ values of 6.5$\pm$1.3, 59.3$\pm$4.5, 13.0$\pm$2.37 and 2.9$\pm$$1.0\mu\textrm{M}$, respectively. Collagen-induced serotonin release was significantly reduced by TPN2. The elevation of intracellular free $Ca^{2+}$ concentration ([$Ca^{2+}$]i) by collagen stimulation was greatly decreased by the pretreatment of TPN2, which was due to the inhibition of calcium release from intracellular store and influx from outside of the cell. TPN2 also significantly reduced the thromboxane $A_2$($TXA_2$) formation in a concentration-dependent manner. The collagen-induced arachidonic acid (AA) release in [$^3H$]-AA incorporated platelet, an indicative of the phospholipase $A_2$ activity, was decreased by TPN2 pretreatment. TPN2 significantly inhibited the activity of thromboxane synthase, but did not affect the cyclooxygenase activity. From these results. it is suggested that TPN2 exert its antiplatelet activity through the inhibition of the intra-cellular $Ca^{2+}$ mobilization and the decrease of the $TXA_2$ synthesis.

• Journal of Ginseng Research
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• 제43권2호
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• pp.236-241
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• 2019

Background: Thromboxane A2 ($TXA_2$) induces platelet aggregation and promotes thrombus formation. Although ginsenoside Ro (G-Ro) from Panax ginseng is known to exhibit a $Ca^{2+}-antagonistic$ antiplatelet effect, whether it inhibits $Ca^{2+}-dependent$ cytosolic phospholipase $A_2$ ($cPLA_{2{\alpha}}$) activity to prevent the release of arachidonic acid (AA), a $TXA_2$ precursor, is unknown. In this study, we attempted to identify the mechanism underlying G-Ro-mediated $TXA_2$ inhibition. Methods: We investigated whether G-Ro attenuates $TXA_2$ production and its associated molecules, such as cyclooxygenase-1 (COX-1), $TXA_2$ synthase (TXAS), $cPLA_{2{\alpha}}$, mitogen-activated protein kinases, and AA. To assay COX-1 and TXAS, we used microsomal fraction of platelets. Results: G-Ro reduced $TXA_2$ production by inhibiting AA release. It acted by decreasing the phosphorylation of $cPLA_{2{\alpha}}$, p38-mitogen-activated protein kinase, and c-Jun N-terminal kinase1, rather than by inhibiting COX-1 and TXAS in thrombin-activated human platelets. Conclusion: G-Ro inhibits AA release to attenuate $TXA_2$ production, which may counteract $TXA_2-associated$ thrombosis.