• Translational and Clinical Pharmacology
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• v.26 no.4
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• pp.160-165
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• 2018

Indobufen ($Ibustrin^{(R)}$), a reversible inhibitor of platelet aggregation, exists in two enantiomeric forms in 1:1 ratio. Here, we characterized the anti-platelet effect of S- and R-indobufen using response surface modeling using $NONMEM^{(R)}$ and predicted the therapeutic doses exerting the maximal efficacy of each enantioselective S- and R-indobufen formulation. S- and R-indobufen were added individually or together to 24 plasma samples from drug-naïve healthy subjects, generating 892 samples containing randomly selected concentrations of the drugs of 0-128 mg/L. Collagen-induced platelet aggregation in platelet-rich plasma was determined using a Chrono-log Lumi-Aggregometer. Inhibitory sigmoid $I_{max}$ model adequately described the anti-platelet effect. The S-form was more potent, whereas the R-form showed less inter-individual variation. No significant interaction was observed between the two enantiomers. The anti-platelet effect of multiple treatments with 200 mg indobufen twice daily doses was predicted in the simulation study, and the effect of S- or R-indobufen alone at various doses was predicted to define optimal dosing regimen for each enantiomer. Simulation study predicted that 200 mg twice daily administration of S-indobufen alone will produce more treatment effect than S-and R-mixture formulation. S-indobufen produced treatment effect at lower concentration than R-indobufen. However, inter-individual variation of the pharmacodynamic response was smaller in R-indobufen. The present study suggests the optimal doses of R-and S-enantioselective indobufen formulations in terms of treatment efficacy for patients with thromboembolic problems. The proposed methodology in this study can be applied to the develop novel enantio-selective drugs more efficiently.

• Journal of Ginseng Research
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• v.32 no.1
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• pp.73-78
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• 2008

Red ginseng acidic polysaccharide (RGAP), isolated from Korean red ginseng (Panax ginseng C.A. Meyer), has been shown to have a variety of biological functions such as immunostimulating and anti-tumor activities. In the present study, we investigated whether RGAP inhibited ligand-induced platelet aggregation. The washed platelet-rich plasma was prepared from male SD rats with successive centrifugation. The platelets $(10^8/ml)$ were preincubated with 1 mM of $CaCl_2$ for 2 min either in the presence or in the absence of RGAP $(10{\sim}50\;{\mu}g/ml)$ and were stimulated with collagen (2.5 ${\mu}g/ml$) and thrombin (0.1 U/ml). RGAP dose-dependently inhibited thrombin-induced platelet aggregation with $IC_{50}$ value of $26.2{\pm}2.0$ ${\mu}g/ml$. In collagen-induced platelet aggregation, RGAP inhibited the reaction with an $IC_{50}$ value of $31.5{\pm}3.0\;{\mu}g/ml$. RGAP potently suppressed the intracellular calcium ion, which was stimulated by thrombin (0.1 U/ ml). Among mitogen-activated protein kinase (MAPK) subtypes, the extracellular signal-regulated kinase (ERK) 1/2 and p38 MAPK were analyzed in the present study. RGAP inhibited the phosphorylation of ERK2 and p38 MAPK, which was activated by collagen (2.5 ${\mu}g/ml$). Finally, these results suggested that besides saponin fraction, RGAP take an important role in the preventive effect of Korean red ginseng against cardiovascular disease such as thrombosis and atherosclerosis.

• The Korea Journal of Herbology
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• v.28 no.3
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• pp.39-44
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• 2013

Objectives : The purpose of this study was to identify active fraction and components from antiplatelet Ulmi cortex extract. Methods : The 70% ethanol extract of Ulmi cortex was subjected to column chromatography over D101 resin and eluted with an 20% (W1), 30% (W2), 40% (W3), 50%(W4), 70% (W5), and 100% ethanol (W6) to yield 6 fractions. W6 was further fractioned and its active components were purified using semi-preparative HPLC. The isolated compounds were identified by MS and NMR, and their contents were simultaneously analyzed using HPLC/UV. Antiplatelet aggregation activities of the fractions and the compounds were evaluated using rat platelet-rich plasma in presence of collagen ($5{\mu}g/ml$), arachidonic acid (0.05 U/ml), or thrombin ($100{\mu}M$). Results : Among six fractions, W3 prominently inhibited platelet aggregation. At the concentration of $200{\mu}g/ml$, W3 strongly inhibited arachidonic acid- and collagen-induced platelet aggregations by 78.2% and 65.9%, respectivley, and weakly inhibited thrombin-inducded platelet aggregation by 32.6%. Catechin, epicatehin, and catechin-7-O-${\beta}$-D-glucopyranoside were isolated from W3 and their contents were revealed to be 15.1%, 0.87%, and 0.32%. Catechin and epicatechin at the concentrations of $100{\mu}M$ strongly inhibited collagen-induced platelet aggregation by 79.9% and 86.6%, respectively, but weakly inhibited arachidonic acid- and thrombin-induced platelet aggregations. Conclusions : A main active principle of anitplatelet Ulmi Cortex extract is W3 fraction, of which main active component is catechin considering its antiplatelet activity and content.

• Nutritional Sciences
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• v.5 no.4
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• pp.197-202
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• 2002

We compared the radical scavenging activity of flavonoids and their antioxidant effects on erythrocyte Na leak, platelet aggregation and TBARS (thiobarbituric acid reactive substance) production, using Sprague Dawley rats. The concentrations of flavonoids needed for scavenging radicals by 50% ($SC_{50}$) in 0.1mM DPPH (2,2 Diphenyl 1-picryl hydrazyl) were: Quercetin, 7.4/$\mu$M; Catechin, 10.6$\mu$M; Morin, 22$\mu$M; Hesperidin, 400uM; and Naringin, 3.95mM. Morin completed its antioxidant activity in 2 minutes, while catechin, hesperidin and naringin had slow but long lasting antioxidant activity. Whole blood platelet aggregation, when incubated with quercetin or catechin, was significantly decreased (P<0.05) compared with the control. Sodium leak in intact erythrocytes was significantly lower when incubated with quercetin, compared with other flavonoids (P<0.05). Morin, hesperidin and naringin somewhat increased Na leak in intact erythrocytes. Sodium leak in erythrocytes treated with phenazine methosulfate (PMS) was increased overall, but was not affected by flavonoids. Intracelluar Na and K were not affected by treatment with PMS. TBARS production in platelet rich plasma (PRP) was significantly lower (P<0.05) than the control when incubated with quercetin or hesperidin. PMS treatment caused an increase in TBARS production regardless of flavonoids. In the present study antioxidant effects of flavonoids were not well correlated with their radical scavenging activities, although quercetin, which showed the strongest radical scavenging activity, had the greatest antioxidant effect.

• Journal of Ginseng Research
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• v.47 no.6
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• pp.706-713
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• 2023

Background and objective: The ability to inhibit aggregation has been demonstrated with synthetically derived ginsenoside compounds G-Rp (1, 3, and 4) and ginsenosides naturally found in Panax ginseng 20(S)-Rg3, Rg6, F4, and Ro. Among these compounds, Rk3 (G-Rk3) from Panax ginseng needs to be further explored in order to reveal the mechanisms of action during inhibition. Methodology: Our study focused to investigate the action of G-Rk3 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, dense granule secretion, and thromboxane B₂ secretion. In addition, we checked the regulation of phosphorylation on PI3K/MAPK pathway, and thrombin-induced clot retraction was also observed in platelets rich plasma. Key Results: G-Rk3 significantly increased amounts of cyclic adenosine monophosphate (cAMP) and led to significant phosphorylation of cAMP-dependent kinase substrates vasodilator-stimulated phosphoprotein (VASP) and inositol 1,4,5-trisphosphate receptor (IP₃R). In the presence of G-Rk3, dense tubular system Ca²⁺ was inhibited, and platelet activity was lowered by inactivating the integrin αIIb/β₃ and reducing the binding of fibrinogen. Furthermore, the effect of G-Rk3 extended to the inhibition of MAPK and PI3K/Akt phosphorylation resulting in the reduced secretion of intracellular granules and reduced production of TXA₂. Lastly, G-Rk3 inhibited platelet aggregation and thrombus formation via fibrin clot. Conclusions and implications: These results suggest that when dealing with cardiovascular diseases brought upon by faulty aggregation among platelets or through the formation of a thrombus, the G-Rk3 compound can play a role as an effective prophylactic or therapeutic agent.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.2
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• pp.158-164
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• 2008

Purpose : Recently, various materials were developed for enhancing bone formation capacity. Platelet rich plasma(PRP) is an autologous source with several growth factors and obtained by sequestering and concentrating platelets by gradient density centrifugation. This study was to evaluate the effect of PRP on healing of grafted bone. Materials and methods : Two blood samples were obtained and analysed for measuring platelet counts of normal blood and PRP. In experimental group, two defects of mandibular bone, 10mm in diameter and 4.0mm deep, were created in the mandible and immediately grafted with autogenous bone chips mixed with PRP. In control group, same bone defects were prepared and grafted with autogenous bone chips. Gelform was used for carrier of PRP. 2 weeks, 4 weeks, 8 weeks later, each group was evaluated with histologi-cal and histomorphometric analyses. Results : According to histological observation, experimental group was showed more anastomosing newly-formed woven bone having osteoblastic activation than control group. According to histomorphometric analysis, there were 9.11% more newly-formed bone volume in experimental group than control group at 2 weeks, 7.91% more at 4 weeks, 20.08% more at 8 weeks. Conclusion: Our results demonstrated PRP in autogenous bone graft could enhance the bone formation.

• Archives of Pharmacal Research
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• v.18 no.4
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• pp.256-261
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• 1995

The elevation of intracellular $Ca^{2+}$ in various tissue through oxidative stress induced by menadione has been well documented. Increase of $Ca^{2+}$ level inplatelets results in aggreaction of patelets. To test the hypothesis that menadione-induced $Ca^{2+}$ elevations can play a role in platelet aggregation, we have studied the effect of menadione on aggragation of platelets isolated from female rats. Treatment with menadione to platelet rich plasma (PRP), which proved to be 60% as determined by aggregometry. however, exposure of PRP to menadione leads to a loss of cell viability, as measured by lactae dehydrogenase (LDH) leakage, suggesting that menadione might induce cell lysis rather than aggregation of platelets. Turbidty changes induced by menadione were unaffected by addition ofl dicoumarol, which is a quinone reducellular factions of patelets. These data, which indicate an absence of the QR detoxifying pathway, suggest that platelets may be more susceptible to menadione-induced cytotoxicity than certain other cell, as hepatocytes.

• Restorative Dentistry and Endodontics
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• v.40 no.4
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• pp.314-321
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• 2015

Tooth related factors such as palatoradicular groove can be one of the causes for localized periodontal destruction. Such pathological process may result in apicomarginal defect along with inflammation of pulp. This creates challenging situation which clinician must be capable of performing advanced periodontal regenerative procedures for the successful management. This case report discusses clinical management of apicomarginal defect associated with extensive periradicular destruction in a maxillary lateral incisor, along with histopathologic aspect of the lesion.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2004.05a
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• pp.93-93
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• 2004

• Toxicological Research
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• v.12 no.2
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• pp.289-293
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• 1996

Our previous studies demonstrated that quinone (menadione) is cytotoxic to rat platelets. In an attempt to assess the relative contributions of redox cycling and/or arylation in quinone-induced cytotoxicity, we have studied three quinones with different mechanisms: 2, 3-dimethoxy-1, 4-naphthoquinone (DMNQ; pure redox cycler), menadione (both redox cycler and arylator), and 1, 4-benzoquinone (pure arylator). The order of redox cycling capacity in platelet rich plasma (PRP) isolated from rats was menadione>DMNQ>1, 4-benzoquonone, which was consistent with the previous studies using isolated hepatocytes. 1, 4-Benzoquinone was more toxic to rat platelets than menadione, while DMNQ did not cause cell death at all. Lactate dehydrogenase inhibition studies revealed that 1, 4-benzoquinone inhibited significantly in a time-dependent manner, while menadione and DMNQ did not at all. These results suggested that arylation by quinone compounds might play a critical role in quinone-induced cytotoxicity in rat platelets.