• Natural Product Sciences
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• v.8 no.4
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• pp.152-154
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• 2002

The methanol extract of Viscum album var. coloratum, Korean mistletoe, showed potent prolongation effects on the bleeding time in rats in vivo, and whole blood clotting time and plasma recalcification time in rats ex vivo. The prolongation effect on the bleeding time of Korean mistletoe is comparable to that of Viscum album L., European mistletoe, 185.6% and 176.5%, respectively. However, the water extracts of the both plants did not show any prolongation effects. Platelet activating factor (PAF) receptor binding assay was carried out to elucidate the action mechanisms of the extracts, and both of the methanol extracts did not show any inhibitory activity. The $LD_{50}$ of the methanol extracts of both mistletoes are more than 2 g/kg. These results suggest that the mehtanol extract of Korean mistletoe might be a potential candidate to develop new drug to improve microcirculation.

• Food Science and Biotechnology
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• v.16 no.2
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• pp.218-222
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• 2007

The anticoagulant properties of Cinnamomum cassia bark-derived materials were evaluated against platelet aggregation induced by arachidonic acid (AA), collagen, platelet activating factor (PAF), or thrombin, and these effects were then compared to those of three commercially available compounds (cinnamic acid, cinnamyl alcohol, and aspirin). The active constituent obtained from C. cassia barks was isolated by silica gel column chromatography and high pressure liquid chromatography (HPLC), and was characterized as trans-cinnamaldehyde by MS, $^1H-NMR$, $^{13}C-NMR$, and IR spectroscopy. With regard to 50% inhibitory concentration ($IC_{50}$) values, cinnamaldehyde was found to effectively inhibit platelet aggregation induced by AA ($IC_{50},\;43.2\;{\mu}M$) and collagen ($IC_{50},\;3.1\;{\mu}M$). By way of comparison, cinnamaldehyde proved to be a significantly more potent platelet inhibitor against platelet aggregation induced by collagen than aspirin. The effect exerted by cinnamaldehyde against platelet aggregation induced by AA was 1.2 times less than that of aspirin. These results indicate that cinnamaldehyde may prove useful as a lead compound for the inhibition of platelet aggregation induced by AA and collagen.

• Journal of Chest Surgery
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• v.35 no.5
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• pp.343-349
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• 2002

background: In an attempt to investigate the role of oxidants in the activation of phospholipase $A_2$(PLA$_2$) and endogenous oxidative stress in the lung. acute inflammatory lung injury was induced by the instillation of hydrogen peroxide into the trachea of Sprague-Dawley rats. Material and Method: To prove the hypothesis thats released oxidants from neutrophils activate the PLA$_2$ retrogradely, activities of PLA$_2$ and lysoplatelet activating factor acetyltransferase(lysoPAF AT) were assayed i hours after instillation of hydrogen peroxide. In addition, to confirm the impairing effects of the activation of PLA$_2$ associated with endogenous oxidative stress, lung weight/body weight ratio(L$\times$10$^{-3}$ B), protein contents(mg/two lungs) in bronchoalveolar lavage(BAL) were measured. As neutrophilic respiratory burst has been known to play a pivotal role in the genesis of endogenous oxidative stress associated with acute inflammatory lung injury, BAL neutrophils counts and level of lung myelperoxidase(MPO) were measured after hydorgen peroxide insult. Morphological and histochemical studies were also performed to identify the effect of the endogenous oxidative stress. Result: Five hours after hydrogen peroxide instillation, lungs showed marked infiltration of neutrophils and increased weight. Protein contents in BAL increased significantly compared to those of normal rats. PLA$_2$ activity was enhanced in the hydrogen peroxide instilled group. Interestingly, the accelerated production of platelet activating factor(PAF) was confirmed by the increased activity of lysoPAF AT in the $H_2O$$_2$ employed lung. Morphologically, light microscopic findings of lungs after instillation of hydrogen peroxide showed atelectasis and infiltration of inflammatory cells, which was thought to be caused by lipid mediators produced by PLA$_2$ activation. In cerium chloride cytochemical electron microscopy, dense deposits of cerrous perhydroxide were identified. In contrast, no deposit of cerrous perhydroxide was found in the normal lung.

• Archives of Pharmacal Research
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• v.20 no.6
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• pp.633-636
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• 1997

In the course of searching for PAF receptor antagonists, pregomisin (1) and chamigrenal (2) were isolated from the fruits of Schizandra chinensis Baill by the bioactivity-guided isolation. Both compounds showed PAF antagonistic activity and the $IC_{50}$ values were $4.8{\times}10^{-5} M and 1.2{\times}10^{-4}M,$ respectively. In addition, the $^{13}C$ NMR assignments of 1 and 2 using DEPT, HMQC, COLOC and HMBC were reported for the first time.

• Tuberculosis and Respiratory Diseases
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• v.53 no.6
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• pp.595-611
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• 2002

Akt/PKB protein kinase B, ALI acute lung injury, ARDS acute respiratory distress syndrome, CREB C-AMP response element binding protein, ERK extracelluar signal-related kinase, fMLP fMet-Leu-Phe, G-CSF granulocyte colony-stimulating factor, IL interleukin, ILK integrin-linked kinase, JNK Jun N-terminal kinase, LPS lipopolysaccharide, MAP mitogen-activated protein, MEK MAP/ERK kinase, MIP-2 macrophage inflammatory protein-2, MMP matrix metalloproteinase, MPO myeloperoxidase, NADPH nicotinamide adenine dinucleotide phosphate, NE neutrophil elastase, NF-kB nuclear factor-kappa B, NOS nitric oxide synthase, p38 MAPK p38 mitogen activated protein kinase, PAF platelet activating factor, PAKs P21-activated kinases, PMN polymorphonuclear leukocytes, PI3-K phosphatidylinositol 3-kinase, PyK proline-rich tyrosine kinase, ROS reactive oxygen species, TNF-${\alpha}$ tumor necrosis factor-a.

• Journal of Food Hygiene and Safety
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• v.8 no.4
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• pp.181-188
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• 1993

It is well known that bacterial lipopolysaccharide (LPS) stimulates the prostaglandin (PG) synthesis in various experimental system, but the mechanism and the detailed nature of its action are yet to be understood. Thus, this study was designed to characterize LPS induced PG synthesis in rat alveolar macrophage. Although results were not so much prominent, LPS stimulated PGE2 synthesis in macrophage with short term exposure, and this was thought to be mainly due to the activation of phopholipase A2+ But there was a burst in the PG synthesis 6 hours after the LPS treatment and this was accompanied with the increase of cyclooxygenase activity. This effect was not mediated by tumor necrosis factor (TNF) or platelet activating factor (PAF), and the existence of serum was prerequisite for its action. Growth factors such as epidermal growth factor (EGF) and platelet derived growth factor (PDGF) themselves did not stimulate PG synthesis and the showed stimulatory activities to some extent. Normal rat serum was more effective for the elicitation of the LPS action than growth factors. Thus, considering the amounts of growth fafctors contained in normal serum, it was suggested that another factors like LPS binding protein (LBP) might be involved in the serum effect on LPS action. Conclusively. it was thought that LPS could stimulate PG synthesis through interaction with serum factors such as EGF, PDGF and/or LBP.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.4
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• pp.405-414
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• 1999

The role of platelet-activating factor (PAF) was investigated in intestinal ischemia/reperfusion (I/R) induced acute lung injury associated with oxidative stress. To induce acute lung injury following intestinal I/R, superior mesenteric arteries were clamped with bulldog clamp for 60 min prior to the 120 min reperfusion in Sprague-Dawley rats. Acute lung injury by intestinal I/R was confirmed by the measurement of lung leak index and protein content in bronchoalveolar lavage (BAL) fluid. Lung leak and protein content in BAL fluid were increased after intestinal I/R, but decreased by WEB 2086, the PAF receptor antagonist. Furthermore, the pulmonary accumulation of neutrophils was evaluated by the measurement of lung myeloperoxidase (MPO) activity and the number of neutrophils in the BAL fluid. Lung MPO activity and the number of neutrophils were increased (p＜0.001) by intestinal I/R and decreased by WEB 2086 significantly. To confirm the oxidative stress induced by neutrophilic respiratory burst, gamma glutamyl transferase (GGT) activity was measured. Lung GGT activity was significantly elevated after intestinal I/R (p<0.001) but decreased to the control level by WEB 2086. On the basis of these experimental results, phospholipase $A_2\;(PLA_2),$ lysoPAF acetyltransferase activity and PAF contents were measured to verify whether PAF is the causative humoral factor to cause neutrophilic chemotaxis and oxidative stress in the lung following intestinal I/R. Intestinal I/R greatly elevated $PLA_2$ activity in the lung as well as intestine (p<0.001), whereas WEB 2086 decreased $PLA_2$ activity significantly (p<0.001) in both organs. LysoPAF acetyltransferase activity, the PAF remodelling enzyme, in the lung and intestine was increased significantly (p<0.05) also by intestinal I/R. Accordingly, the productions of PAF in the lung and intestine were increased (p<0.001) after intestinal I/R compared with sham rats. The level of PAF in plasma was also increased (p<0.05) following intestinal I/R. In cytochemical electron microscopy, the generation of hydrogen peroxide was increased after intestinal I/R in the lung and intestine, but decreased by treatment of WEB 2086 in the lung as well as intestine. Collectively, these experimental results indicate that PAF is the humoral mediator to cause acute inflammatory lung injury induced by intestinal I/R.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.3
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• pp.219-226
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• 2000

In order to elucidate the role of platelet activating factor (PAF) in the acute lung injury induced by endotoxin (ETX), activities of phospholipase A2, lyso PAF acetyltransferase and oxidative stress by neutrophilic respiratory burst were probed in the present study. To induce acute lung injury, $100\;{\mu}g$ of E.coli ETX (type 0127; B8) was instilled directly into the tracheae of Sprague-Dawley rats. Five hours after the ETX instillation, induction of acute lung injury was confirmed by lung leak index and protein contents in the bronchoalveolar lavage (BAL) fluid. At the same time, lung phospholipase A2 (PLA2) activity and expression of group I and II secretory type PLA2 were examined. In these acutely injured rats, ketotifen fumarate, known as lyso PAF acetyltransferase inhibitor and mepacrine were administered to examine the role of PAF in the pathogenesis of the acute lung injury. To know the effect of the ETX in the synthesis of the PAF in the lungs, lyso PAF acetyltransferase activity and PAF content in the lungs were measured after treatments of ETX, ketotifen fumarate and mepacrine. In addition, the role of neutrophils causing the oxidative stress after ETX was examined by measuring lung myeloperoxidase (MPO) and enumerating neutrophils in the BAL fluid. To confirm the oxidative stress in the lungs, pulmonary contents of malondialdehyde (MDA) were measured. After instillation of the ETX in the lungs, lung leak index increased dramatically (p＜0.001), whereas mepacrine and ketotifen decreased the lung leak index significantly (p＜0.001). Lung PLA2 activity also increased (p＜0.001) after ETX treatment compared with control, which was reversed by mepacrine and ketotifen (p＜0.001). In the examination of expression of group I and II secretory PLA2, mRNA synthesis of the group II PLA2 was enhanced by ETX treatment, whereas ketotifen and WEB 2086, the PAF receptor antagonist, decreased the expression. The activity of the lysoPAF acetyltransferase increased (p＜0.001) after treatment of ETX, which implies the increased synthesis of PAF by the remodelling of lysoPAF in the lungs. Consequently, the contents of the PAF in the lungs were increased by ETX compared with control (p＜0.001), while mepacrine (p＜0.001) and ketotifen (p＜0.01) decreased the synthesis of the PAF in the lungs of ETX treated rats. The infiltration of the neutrophils was confirmed by measuring and enumerating lung MPO and the neutrophils in the BAL fluid respectively. Compared with control, ETX increased lung MPO and number of neutrophils in BAL significantly (p＜0.001) whereas mepacrine and ketotifen decrerased number of neutrophils (p＜0.001) and MPO (p＜0.05, p＜0.001, respectively). The lung MDA contents were also increased (p＜0.001) by ETX treatment, but treatment with mepacrine (p＜0.001) and ketotifen (p＜0.01) decreased the lung MDA contents. Collectively, we conclude that ETX increases PLA2 activity, and that the subsequently increased production of PAF was ensued by the remodelling of the lyso PAF resulting in tissue injury by means of oxidative stress in the lungs.

• Tuberculosis and Respiratory Diseases
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• v.48 no.6
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• pp.887-897
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• 2000

Background : Since the exact pathogenesis of sepsis-induced ARDS has not been elucidated, the mechanisms of enhanced neutrophilic respiratory burst were probed in endotoxin primed neutrophils associated with the roles of phospholipase A2(PLA2), platelet activating factor(PAF) and apoptosis. Methods : In isolated fresh human neutrophils, effects of the inhibition of PLA2 and PAF on the apoptosis were examined by the method of Annexin-FITC/dual PIflow cytometry. The roles of PLA2 and PAF on the neutrophilic respiratory burst were also examined by measuring oxidant generation in cytochrome-c reduction assay. Activities of the PLA2 and lysoPAF acetyltransferase (lysoPAF AT) of the neutrophils were determined to understand the effect of endotoxin on these enzymatic activities which may be related to the neutrophilic respiratory burst and apoptosis. In addition, the role roles of PLA2 and PAF in neutrophilic adhesion to bovine endothelial cells were examined in vitro by neutrophil adhesion assay. To investigate the effect of oxidants on pulmonary surfactant, cytochemical ultrastructural microscopy was performed. To inhibit PLA2 and PAF, non-specific PLA2 inhibitor mepacrine (100 nM) and WEB 2086 (100 nM) or ketotifen fumarate (10 ${\mu}g$/ml) were used respectively in all in vitro experimental sets. WEB 2086 is PAF receptor antagonist, and ketotifen fumarate is a lyso PAF AT inhibitor. Results: The mapacrine treatment, provided and the endotoxin (ETX) treatment, resulted in increased apoptosis of neutrophils (p<0.001) while treatments of WEB 2086 and ketotifen did not. The inhibition of PLA2 and PAF decreased (p<0.001) production of oxidants from PMA-stimulated neutrophils. While endotoxin increased the PLA2 activity of neutrophils (p<0.01), mepacrine supressed (p<0.001) the activity, provided after treatment of ETX. The lyso PAF actyltransferase activity (lyso PAF AT) increased (p<0.01) after treatment of ETX. In contrast, mepacrine, WEB 2086 and ketotifen showed a tendency of decreasing the activity after treatment of ETX. The treatment of ETX incresed (p<0.001) neutrophil adhesion to endothelial cells, which was reversed by inhibition of PLA2 and PAF (p<0.01). The binding of oxidants to pu1monary surfactant was identified histologically. Conclusions : The enhanced neutrophilic respiratory burst by ETX plays a pivotal role in the pathogenesis of ARDS in terms of oxidayive oxidative stress. Increased production of oxidants from neutrophils is mediated by the activations of PLA2 and lyso PAF AT.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.187-187
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• 1996

세포질에 존재하는 100 kDa Phospholipase $A_2$(cPLA$_2$)는 인지질의 sn-2 위치의 에스테르결합을 가수분해함으로서 Prostaglandin과 Leukotriene등 Eicosanoids 생합성의 전구체인 아라키돈산과 Platelet activating factor(PAF)를 생합성하는 전구체를 동시에 생성시키는 효소로 염증과 세포손상등에 중요한 역할이 기대된다. 본 효소의 활성화 기전을 규명하고자 하는 최근의 활발한 연구에도 불구하고 불명확한 점이 많은 것이 현실이다. 특히 세포를 자극하였을 때 유리되는 아라키돈산의 증가율과 세포를 파괴한 후 조제한 가용성분획에서 측정한 활성의 증가율과는 많은 차이를 나타냈다. 이러한 결과부터 cPLA$_2$ 효소 자체를 활성화시키는 어떤 인자를 가정하였다. 최근, PLA$_2$의 또다른 형태인 14 kDa의 분비성 PLA$_2$의 in vitro 활성을 증가시키는 인자가 동정되어 그 생화학적 특성이 규명되고 있으나 이 인자는 cPLA$_2$의 활성에는 아무런 증가효과를 나타내지 않았다. 본 연구자들은 소의 뇌조직에서 cPLA$_2$의 활성을 증가시키는 인자를 발견하고 그의 생화학적인 특성을 규명하였다. 돼지 비장에서 정제한 cPLA$_2$를 사용하였으며 소의 뇌 조직의 가용성 분획으로부터 본 활성화 인자를 동정하였으며 그 활성분획을 양이온 크로마토그라피로서 Mono S EPLC와 Superose 12 Sepharose gel filtration 크로마토그라피를 이용하여 더욱 분리한 결과 약 70 kDa과 25 kDa에서 각각 용출되었다. 이렇게 부분정제한 활성은 췌장에서 분리한 group I과 흰주의 group I과 흰주의 혈소판에서 분리한 group II PLA$_2$에 대해서는 아무런 증가효과를 나타내지 않는 반면, cPLA$_2$의 활성만을 약 5배 증가시켰다. 본 활성은 cPLA$_2$ 효소량의 증가에 따라 활성의 증가효과가 정차 감소하므로 화학량적인 반응(Stoichiometric reaction)일 것으로 예상되었다.