• 한국균학회지
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• 제21권4호
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• pp.285-292
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• 1993

에너지 요구 반응 인 5'-XMP 의 5'-GMP 보의 효소적 전환을 위해 Escherichia coli CH 41(guaB mutant)로부터 추출 정제한 XMP aminase에 Saccharomyces cerevisiae의 glycolysis를 통한 ATP 재생계를 도입하였다. 전환 반응의 ATP원으로는 동결 건조 효모가 가장 효율적이었으며, 전환 반응의 최적 온도 및 pH는 각각 $40{\circ]C$, pH 7.4였다. 또한 100 mM glucose, 100 mM inorganic phosphate 및 6mM AMP 에서 가상 높은 전환율을 보였다. 상기의 조건에서 36 unit/ml의 XMP aminase 가 이용될 경우 효모 농도는 60 mg/ml로 충분하였으며, 최적 조건에서 6시간 반응시 1.8 mM(65.6 mg/100 ml) 5'- XMP 의 약 71%가 5'-GMP로 전환되었다.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 1993년도 학술대회지
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• pp.94-101
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• 1993

Lipophilic fraction(LF) from Panax ginseng C.A. Meyer inhibited the aggregation of human platelets induced by th rombin(0.1u/$m{\ell}$). LF and Molsidomine(vasodilator) induced the stimulation of cGMP - elevation and 50KD - Phosphorylation. and then the inhibition of 20KD - Phosphorylation in human platelets activated by thrombin. LF also inhibited the $Ca^{2-}-influx$ into platelets. When rat(SD : male) was fed with LF, the level of cGMP was increased in rat platelets stimulated by collagen and thrombin. On the other hand. verapamil, $Ca^{2-}-antagonist$ increased cAMP level ;n platelet stimulated by thrombin. but LF does not affected. However LF potently inhibited the thromboxane $A_2(TXA_2)$ production. The results suggest that the inhibitory effects of LF are mediated by regulation the phosphorylatior. of 50KD via cGMP-elevation and depend upon the decrease of $TXA_2$ level.

• Archives of Pharmacal Research
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• 제25권6호
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• pp.873-878
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• 2002

OA-8159, a new Phosphodiesterase (PDE) 5 inhibitor, has exhibited potent erectogenic potential in a penile erection test in rats and anesthetized dogs. In this study, we investigated the mechanism of its erectogenic activity by measuring the activity of OA-8159 against a various PDE isozymes and assessing cGMP and cAMP formation in a rabbit corpus cavernosum in vitro. DA-8159 inhibited the PDE 5 activity in rabbit and human platelets, which the $IC_{50}$ was 5.84$\pm$1.70 nM and 8.25$\pm$2.90 nM, respectively. The $IC_{50}$ of DA-8159 on PDE 1, PDE2, PDE 3 and PDE 6 were 870$\pm$57.4 nM, $101\pm$5 $\mu$M, 52.0$\pm$3.53 $\mu$M and 53.3$\pm$2.47 nM, respectively. This suggests that DA-8159 is a potent, highly selective, competitive inhibitor of PDE 5-catalyzed cGMP hydrolysis. The rates of cGMP hydrolysis catalyzed by human platelets-derived PDE 5 as a function of the cGMP concentration (5~100 nM) and two-fixed DA-8159 concentration (11.3 and 18.8 nM) were investigated in order to characterize the mode of PDE 5 inhibition by DA-8159. DA-8159 increased the apparent 4K_{m}$ value for cGMP hydrolysis but had no effect on the apparent $V_{max}$, indicating a competitive mode of inhibition. DA-8159 increased the cGMP concentrations in the rabbit corpus cavernosum dose dependently. In the presence of sodium nitroprusside (SNP), DA-8159 significantly sti\mulated the accu\mulation of cGMP when compared to the control level. This indicated that the enhancement of a penile erection by DA-8159 involved the relaxation of the cavernosal smooth \muscle by NO-sti\mulated cGMP accu\mulation. In conclusion, DA-8159 is a selective inhibitor of PDE 5-catalyzed cGMP hydrolysis and the enhancement of a penile erection by DA-8159 is mediated by the relaxation of the cavernosal smooth \muscle by the NO-sti\mulated cGMP accu\mulation.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2002년도 제9회 학술 발표회 프로그램과 논문초록
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• pp.15-15
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• 2002

Cyclic nucleotide phosphodiesterases (PDEs) regulate physiological processes by degrading ubiquitous intracellular second messengers, cAMP or cGMP. The first crystal structure of PDE4D catalytic domain and a bound inhibitor, zardaverine, was determined. Zardaverine binds to a highly conserved pocket that includes the catalytic metal binding site.(omitted)

• 대한의생명과학회지
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• 제16권4호
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• pp.377-380
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• 2010

In this study, we investigated the effect of egg yolk lipids (EYL) on collagen ($10\;{\mu}g/ml$)-stimulated platelet aggregation in vivo. Dietary EYL significantly inhibited collagen-induced platelet aggregation, in addition, increased the formation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), intracellular $Ca^{2+}$-antagonist as aggregation-inhibiting molecules, in collagen-stimulated platelets. These results suggest that EYL inhibits the collagen-induced platelet aggregation by up-regulating the cAMP and cGMP production. On the other hands, prothrombin time (PT) on extrinsic pathway of blood coagulation was potently prolonged by dietary EYL in vivo. These findings suggest that EYL prolongs the internal time between the conversion of fibrinogen to fibrin. Accordingly, our data demonstrate that EYL may be a crucial tool for a negative regulator during platelet activation and blood coagulation on thrombotic diseases.

• 대한의생명과학회지
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• 제20권2호
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• pp.70-76
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• 2014

In this study, we investigated the effect of DMSO, a highly dipolar organic liquid, in collagen ($5{\mu}g/ml$)-stimulated platelet aggregation. DMSO inhibited platelet aggregation at 0.5% by inhibiting production of thromboxane $A_2$ ($TXA_2$) which was associated with blocking cyclooxygenase (COX)-1 activity and $TXA_2$ synthase. In addition, DMSO significantly increased the formation of cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP) and cyclic guanosine monophosphate (cGMP) from guanosine triphosphate (GTP). On the other hand, DMSO (0.1~0.5% concentration) did not affect the LDH release which indicates the cytotoxicity. Based on these results, DMSO has anti-platelet effect by regulation of several platelet signaling pathways, therefore we suggest that DMSO could be a novel strategy on many thrombotic disorders.

• Journal of Applied Biological Chemistry
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• 제63권3호
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• pp.235-241
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• 2020

An essential component of the hemostatic process during vascular damage is platelet activation. However, many cardiovascular diseases, such as atherosclerosis, thrombosis, and myocardial infarction, can develop due to excessive platelet activation. Isoscopoletin, found primarily in plant roots of the genus Artemisia or Scopolia, has been studied to demonstrate potential pharmacological effects on Alzheimer's disease and anticancer, but its mechanisms and role in relation to thrombus formation and platelet aggregation have not yet been discovered. This research investigated the effect of isoscopoletin on collagen-induced human platelet activation. As a result, isoscopoletin strongly increased cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) levels in a concentration-dependent manner. In addition, isoscopoletin greatly phosphorylated inositol 1,4,5-triphosphate receptor (IP₃R) and vasodilator-stimulated phosphoprotein (VASP), known substrates of cAMP-dependent kinase and cGMP dependent kinase. Phosphorylation of IP₃R by isoscopoletin induced Ca²⁺ inhibition from the dense tubular system Ca²⁺ channels, and VASP phosphorylation was involved in fibrinogen binding inhibition by inactivating αIIb/β₃ in the platelet membrane. Isoscopoletin finally reduced thrombin-induced fibrin clot production and finally reduced thrombus formation. Therefore, this research suggests that isoscopoletin has strong antiplatelet effects and is likely to be helpful for thrombotic diseases involving platelets by acting as a prophylactic and therapeutic agent.

• 생약학회지
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• 제52권1호
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• pp.26-33
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• 2021

During blood vessel damage, an essential step in the hemostatic process is platelet activation. However, it is important to properly control platelet activation, as various cardiovascular diseases, such as stroke, atherosclerosis, and myocardial infarction, are also caused by excessive platelet activation. Found primarily in the roots of plants of the genus Artemisia or Scopolia, isoscopoletin has been studied to demonstrate its potential pharmacological effects against Alzheimer's disease and anticancer, but the mechanisms and roles involved in thrombus formation and platelet aggregation are insufficient. This study investigated the effect of isoscopoletin on U46619-induced human platelet activation. As a result, isoscopoletin significantly increased the levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) dose-dependently. In addition, isoscopoletin significantly phosphorylated inositol 1, 4, 5-triphosphate receptor (IP3R) and vasodilator-stimulated phosphprotein (VASP), which are known substrates for cAMP-dependent kinases and cGMP-dependent kinases. Phosphorylated IP3R by isoscopoletin inhibited Ca2+ mobilization from the dense tubular system Ca2+ channels to cytosol, and phosphorylated VASP was involved in the inhibition of fibrinogen binding through αIIb/β3 inactivation in the platelet membrane. Isoscopoletin finally reduced thrombin-induced fibrin clotting production. Therefore, this study suggests that isoscopoletin has a potent antiplatelet effect and may be helpful for platelet-related thrombotic diseases.

• 대한의생명과학회지
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• 제27권4호
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• pp.270-276
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• 2021

Physiological agents trigger a signaling process called "inside-out signaling" and activated platelets promote adhesion, granule release, and conformational changes of glycoprotein IIb/IIIa (αIIb/β₃). Activated αIIb/β₃ interacts with fibrinogen and initiates a second signaling step called "external signaling". These two signaling pathways can cause hemostasis or thrombosis, and thrombosis is a possible medical problem in arterial and venous vessels, and platelet-mediated thrombosis is a major cause of cardiovascular disease (CVD). Therefore, modulating platelet activity is important for platelet-mediated thrombosis and cardiovascular disease. Esculetin is a coumarin-based physiologically active 6,7-dihydroxy derivative known to have pharmacological activity against obesity, diabetes, renal failure and CVD. Although some studies have confirmed the effects of esculetin in human platelet activation and experimental mouse models, it is not clear how esculetin has antiplatelet and antithrombotic effects. We confirmed the effect and mechanism of action of escultein on human platelets induced by collagen. As a result, esculetin decreased Ca²⁺ recruitment through upregulation of inositol 1, 4, 5-triphosphate receptor. In addition, esculetin upregulates cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP)-dependent pathways and inhibits fibrinogen binding and thrombus contraction. Our results demonstrate the antiplatelet effect and antithrombotic effect of esculetin in human platelets. Therefore, we suggest that esculetin could be a potential phytochemical for the prevention of thrombus-mediated CVD.

• 대한의생명과학회지
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• 제29권1호
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• pp.41-47
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• 2023

Discovery of new substance that can regulate platelet aggregation or suppress aggregation will aid in the prevention and treatment of cardiovascular diseases. Artesunate is a compound from plant roots of Artemisia or Scopolia, and its effects have shown to be promising in areas of anticancer and Alzheimer's disease. However, the role and mechanisms by which artesunate affects the aggregation of platelets, and the formation of a thrombus are currently not understood. This study examined the ways artesunate affects platelets activation and thrombus formation induced by collagen. As a result, cAMP and cGMP production were increased significantly by artesunate relative to the doses, as well as phosphorylated VASP and IP₃R, substrates to cAMP-dependent kinase and cGMP-dependent kinase, in a significant manner. The Ca²⁺ normally mobilized from the dense tubular system was inhibited due to IP₃R, phosphorylation from artesunate, and phosphorylated VASP aided in inhibiting platelet activity via αIIb/β₃ platelet membrane inactivation and inhibiting fibrinogen binding. Finally, artesunate inhibited thrombin-induced thrombus formation. Therefore, we suggest that artesunate has importance with cardiovascular diseases stemming from the abnormal platelets activation and thrombus formation by acting as an effective prophylactic and therapeutic agent.