• Title, Summary, Keyword: Phospholipase $A_2$

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Antioxidantive, Phospholipase $A_2$ Inhibiting, and Anticancer Effect of Polyphenol Rich Fractions from Panax ginseng C. A. Meyer (한국산 인삼의 Polyphenol 분획물의 항산화, Phospholipase $A_2$ 및 암세포증식 억제효과)

  • Choi, Hee-Jin;Han, Ho-Suk;Park, Jung-Hye;Son, Jun-Ho;Bae, Jong-Ho;Seung, Tae-Su;Choi, Cheong
    • Applied Biological Chemistry
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    • v.46 no.3
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    • pp.251-256
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    • 2003
  • The polyphenol fractions of Korean ginseng were purified using Sephadex LH-20, MCI gel, Bondapak $C_{18}$ TLC, and HPLC from the 60% acetone soluble fraction. Fraction I showed 48.16%, 79.71% and 43.55% inhibition at 150 ppm against lipid oxidation in the presence of copper ion, superoxide and hydrogen peroxidation. Electron donating abilities of fraction II showed 35.17% inhibition at 200 ppm. Fraction III showed 48.49% and 25% inhibition at 150 ppm against lipid oxidation in the presence of ferrous ion and hydroxy radical ion. The phospholipase $A_2$ inhibitory effect of fraction III was 48.9% at the concentration of $60\;{\mu}g/ml$. The cytotoxic effects of fraction II was the highest (73.29% at 0.25 mg/ml) among the tested polyphenol fractions.

The Effects of Bee Venom on PLA2 and Calcium Concentration in Raw 264.7 Cells (봉약침액(蜂藥針液)이 RAW 264.7 세포의 PLA2 및 Calcium Concentration에 미치는 영향(影響))

  • Yun, Jong-Il;Jo, Hyun-Chul;Sim, Sung-Yong;Kim, Kee-Hyun
    • Journal of Pharmacopuncture
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    • v.6 no.2
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    • pp.149-158
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    • 2003
  • Objective : The purpose of this study was to investigate the effect of Bee Venom on the lipopolysaccharide, sodium nitroprusside and hydrogen peroxide induced expression phospholipase $A_2$ and calcium concentration in RAW 264.7 cells, a murine macrophage cell line. Method : The expression of phospholipase $A_2$ was determined by western blotting with corresponding antibodies, and the generation of intracellular calcium concentration was investigated by delta scan system in RAW 264.7 cells. Results : 1. Compared with control, expressions of lipopolysaccharide-induced phospholipase $A_2$ were decreased significantly by $1\;{\mu}g/{\mu}l$ of bee venom and decreased by 0.5, $5\;{\mu}g/{\mu}l$ of bee venom. 2. Compared with control, expressions of sodium nitroprusside-induced phospholipase $A_2$ were decreased significantly by $5\;{\mu}g/{\mu}l$ of bee venom but increased by 0.5, $5\;{\mu}g/{\mu}l$ of bee venom. 3. Compared with control, expressions of hydrogen peroxide-induced phospholipase $A_2$ were decreased significaltly by $1{\mu}g/{\mu}l$ of bee venom and decreased by $0.5\;{\mu}g/{\mu}l$ of bee venom but increased by $5\;{\mu}g/{\mu}l$ of bee venom. 4. Compared with control, lipopolysaccharide, sodium nitroprusside and hydrogen peroxide- induced intracellular calcium concentrations were decreased by 0.5, 1, $5\;{\mu}g/{\mu}l$ of bee venom and by indomethacin

Effect of concentration, pressure, and cut-off size on removing phospholipase A2 in bee venom by ultrafiltration (Ultrafilteration을 이용한 봉독의 phospholipase A2 제거에서 농도, 압력, 분자크기의 영향)

  • Lee, Ji-Yeon;Kim, Il Kwang;Lee, Jong Soo;Kim, Eui Kyung;Kim, Choul-Goo
    • Analytical Science and Technology
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    • v.27 no.6
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    • pp.277-283
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    • 2014
  • The effects of concentration, pressure, and molecular sige on removing allergenic substance (phospholipase $A_2$) in bee venom by ultrafiltration were investigated. The membrane pore sizes were selected based on the molecular weight of the main compounds. The conditions of concentration and pressure were selected randomly. As results, we obtained the optimum condition (1 mg/mL, 20 psi, 10,000 dalton) for removing $PLA_2$ at constant concentration of melittin and apamin and confirmed the separation results by HPLC and SDS-PAGE.

Involvement of Cytosolic Phospholipase $A_2$ in Nerve Growth Factor-Mediated Neurite Outgrowth of PC12 Cells

  • Choi, Soon-Wook;Yu, Eun-Ah;Lee, Young-Seek;Yoo, Young-Sook
    • BMB Reports
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    • v.33 no.6
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    • pp.525-530
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    • 2000
  • The nerve growth factor (NGF) induces neuronal differentiation and neurite outgrowth of PC12 cells, whereas epidermal growth factors (EGF) stimulate growth and proliferation of the cells. In spite of this difference, NGF-or EGF-treated PC12 cells share various properties in cellular-signaling pathways. These include the activation of the phosphoinositide (PI)-3 kinase, 70 kDa S6 kinase, and in the mitogen-activated protein (MAP) kinase pathway, following the binding of these growth factors to intrinsic receptor tyrosine kinases (RTKs). Therefore, many studies have been attempted to access the critical signaling events in determining the differentiation and proliferation of PC12 cells. In this study, we investigated the cytosolic phospholipase $A_2$ ($cPLA_2$) in neurite behavior in order to identify the differences of signaling pathways between the NGF-induced differentiation and the EGF-induced proliferation of PC12 cells. We have showed here that the $cPLA_2$ was translocated from cytosol to membrane only in NGF-treated cells. We also demonstrated that this translocation is associated with NGF-induced activation of phospholipase $C-{\gamma}(PLC-{\gamma})$, which elevates intracellular $Ca^{2+}$ concentration. These results reveal that the translocation of $cPLA_2$ may be a requisite event in the neuronal differentiation of PC12 cells. Various phospholipase inhibitors were used to confirm the importance of these enzymes in the differentiation of PC12 cells. Neomycin B, a PLC inhibitor, dramatically inhibited the neurite outgrowth, and two distinct $PLA_2$ inhibitors, 4-bromophenacyl bromide (BPB) and arachidonyltrifluoro-methyl ketone ($AACOCF_3$) also suppressed the neurite outgrowth of the cells, as well Taken together, these data indicated that $cPLA_2$ is involved in NGF-induced neuronal differentiation and neurite outgrowth of PC12 cells.

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Inactivation of human pleural fluid phospholipase $A_2$ by dioscin

  • Beak, Suk-Hwan;Kim, Sung-Hwan;Son, Kun-Ho;Chung, Kyu-Charn;Chang, Hyeun-Wook
    • Archives of Pharmacal Research
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    • v.17 no.4
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    • pp.218-222
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    • 1994
  • The natural product, spirostanol glycoside dioscin, was shown to directly inactivate human pleural fluid phospholipase $A_2{\;}(PLA_2)$ Inactivation was dose, and time dependent. The $IC_{50}$ was estimated at 18 .mu.M and virtually complete inactivation of the enzyme occurred at 50 .mu.M. Using Michaelis-Menten kinetics, dioscin inactivated the enzyme by a competitive inhibitory manner, the apparent Ki value was $6.9{\times}10_{-4}$. Reversibility was studied directly by dialysis method, the inhibition was reversible. Additioin of excess $Ca^{2+}$ concentration up to 8 mM did not antagonize the inhibitory activity of dioscin. Inactivation of several kinds of $PLA_2$ by dioscin is due to interaction with the active site of $PLA_2$ and may be a useful adjunt in the theraphy of inflammatory diseases.

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Effects of Brazilin on the Phospholipase $A_2$ Activity and Changes on Intracellular Free Calcium Concentration in Rat Platelets

  • Hwang, Gwi-Seo;Kim, Ji-Young;Chang, Tong-Shin;Jeon, Sun-Duck;So, Dhong-Su;Moon, Chang-Kiu
    • Archives of Pharmacal Research
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    • v.21 no.6
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    • pp.774-778
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    • 1998
  • Brazilin [7,11b-dihydrobenz[b]indeno[1,2-d]pyran-3,6a,9,10(6H)-tetrol] inhibited thrombin-, collagen- and ADP-induced aggregation of washed rat platelets. T hrombin- and collagen-induced ATP release were also inhibited by brazilin in a concentration-dependent manner. Brazilin inhibited the formation of platelet thromboxane $A_2$ caused by thrombin, whereas it had no effect on the prostaglandin $D_2$ formation. Brazilin inhibited $^3H$-arachidonic acid liberation from membrane phospholipids of thrombin-stimulated platelets. Brazilin inhibited the rise of intracellular free calcium caused by thrombin. These results indicate that the inhibition of phospholipase ($PLA_2$) activity and [$[Ca^{2+}]_1$ elevation might be at least a part of antiplatelet mechanism of brazilin.

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Effect of Substrate Micellization on the Hydrolysis Rate of Phospholipid by Phospholipase $A_2$ (Phospholipase $A_2$에 의한 인지질의 가수분해반응에서 기질의 미셀화가 반응속도에 미치는 영향)

  • 김형주;신우진;최태부
    • Microbiology and Biotechnology Letters
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    • v.21 no.2
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    • pp.163-170
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    • 1993
  • The effect of substrate micellization on the hydrolysis rate in the production of lysopho-sphatidylcholine (LPC) from phosphatidylcholine (PC) using hog pancreas phospholipase A2(PLA2) was studied. The optimal temperature and pH for the reactions in aqueous phase was found 42C and 7.2, respectively. For a given PC concentration, initial reaction rate was progressively increased with the addition of sodium deoxycholate (DOC), which could transform the bilayer of phospholipids into micellar structure.

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Inhibitory Effects of Verapamil and TMB-8 on Tonic Contraction Are Accompanied by Inhibition of Phospholipase C Activity in Intact Gastric Smooth Muscle Cells

  • Sim, Sang-Soo;Yoon, Shin-Hee;Hahn, Sang-June;Rhie, Duck-Joo;Jo, Yang-Hyeok;Kim, Myung-Suk
    • The Korean journal of physiology & pharmacology
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    • v.29 no.1
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    • pp.29-37
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    • 1995
  • Gastric smooth muscle of guinea pigs was used to investigate whether the inhibitory effect of calcium antagonists on tonic contraction was accompanied by inhibition of phospholipase C activity. Tonic contraction and $[^{3}H]$ inositol phosphate (IP) formation in response to acetylcholine were measured after pretreatment with verapamil, nifedipine, 8-(N,N-diethylamino)octyl 3,4,5-trimethoxy-benzoate (TMB-8) or EGTA. Verapamil $(10\;{\mu}M)$, TMB-8 $(10\;{\mu}M)$ or EGTA (2 mM) significantly inhibited acetylcholine $(1\;{\mu}M)$-stimulated tonic contraction but nifedipine (100 nM) did not. Acetylcholine dose-dependently increased the formation of $[^{3}H]IP$. This effect was not observed in the presence of 2 mM EGTA. Both verapamil and TMB-8 significantly inhibited $[^{3}H]IP$ formation induced by $10\;{\mu}M$ acetylcholine, whereas nifedipine did not. In a subsequent study, we measured phospholipase C activity in gastric muscle cell homogenate and in permeabilized cells to determine whether calcium antagonists could inhibit the activity directly. The calcium antagonists did not change the phospholipase C activity of the cell homogenate or the permeabilized cells. But EGTA decreased phospholipase C activity by 50%. These results suggest that the inhibitory effects of verapamil and TMB-8 on acetylcholine-stimulated tonic contraction may be accompanied by inhibition of phospholipase C activity.

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Role of Phospholipase $A_2$ on lipid peroxidation (과산화지질 형성에 있어서 Phospholipase $A_2$의 역할)

  • 황화신;정규찬;장현옥
    • Proceedings of the Korean Society of Applied Pharmacology
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    • pp.341-341
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    • 1994
  • 생체막의 주요 구성성분인 인지질의 2번 위치에 결합한 불포화지방산은 각종 전이금속이나 각종 활성산소들의 공격을 쉽게 받아 지질과산화반응이 일어나서 생체에 유독한 화합물을 생성하게 된다. 생체는 이러한 기구의 해독을 위하여 크게 2가지 방어기전을 갖고 있다. 즉 Vitamin- C, $\alpha$-tocopherol, flavonoid, SOD, catalase 등과 같이 생성된 활성산소를 제거시키는 기구와. 활성산소에 의해 생성된 과산화물을 제거시키는 기구로 glutathione peroxidase (GPX)가 알려졌으며 GPX에 의해 독성이 낮은 수산화물까지 환원시키는 기구가 보고되었다. 그러나 인지질의 과산화물 그대로는 GPX의 기질이 쥘수 없으므로, 산화된 지방산을 절단하는 효소에 대한 기구의 해석이 요구되고 있다. 최근 여러질병에 관련되어 있는 인지질 2번위치의 지방산을 분해하는 phospholipase $A_2$ (PLA$_2$)가 과산화지질의 분해에 관여한다는 주장이 제기되었다. 따라서 본 연구에서는 rat liver microsome에 $CCl_4$투여로 일어나는 과산화반응에 있어서 PLA$_2$의 역할을 규명하기 위하여 본 실험을 행하였다.

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The Role of Oxygen Free Radicals and Phospholipase $A_2$ in Ischemia-reperfusion Injury to the Liver

  • Park, Mee-Jung;Cho, Tai-Soon;Lee, Sun-Mee
    • Archives of Pharmacal Research
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    • v.18 no.3
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    • pp.189-194
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    • 1995
  • The focus of this study was to investigate the influences of enzymatic scavengers of active oxygen metabolites and phospholipase $A_2$ inhibitor on hepatic secretory and microsomal function during hepatic ischemia/reperfusion. Rats were pretreated with free radical scavengers such as superoxide dismutase (SOD), catalase, deferoxamine and phospholipase $A_2$ inhibitor such as quinacrine and then subjected to 60 min. no-flow hepatic ischemia in vivo. After 1, 5 hr of reperfusion, bile was collected, blood was obtained from the abdominal aorta, and liver microsomes were isolated. Serum aminotransferase (ALT) level was increased at 1 hr and peaked at 5 hr. The increase in ALT was significantly attenuated by SOD plus catalase, deferoxamine and quinacrine especially at 5 hr of reperfusion. The wet weight-to-dry weight ratio of the liver was significantly increased by ischemia/reperfusion. SOD and catalase treatment minimized the increase in this ratio. Hepatic lipid peroxidiltion was elevated by ischemia/reperfusion, and this elevation was inhibited by free radical scavengers and quina crine. Bile flow and cholate output, but not bilirubin output, were markedly decreased by ischemia/reperfusion and quinacrine restored the secretion. Cytochrome $P_{450}$ content was decreased by ischemia/reperfusion and restored by free radical scavengers and quinacrine to the level of that of the sham operated group. Aminopyrine N-demethylase activity was decreased and aniline p-hydroxylase was increased by ischemia/reperfusion. The changes in the activities of the two enzymes were prevented by free radical scavengers and quinacrine. Our findings suggest that ischemia/reperfusion diminishes hepatic secretory functions as well as microsomal drug metabolizing systems by increasing lipid peroxidation, and in addition to free radicals, other factors such as phospholipase $A_2$ are involved in pathogenes of hepatic dysfunction after ischemia/reperfusion.

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