• Toxicological Research
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• v.6 no.1
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• pp.109-119
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• 1990

Ro09-0198, a cyclic peptide isolated from culture filtrates of Streptoverticillium griseoverticillatum, induced lysis of erythrocytes. Ro-09-0198-induced hemolysis was temperature-dependent and the sensitivity of hemolysis differed greatly among animal species. Preincubation of the peptide with phosphatidylethanolamine reduced the hemolytic activity, whereas other phospholipids present in erythrocytes in nature had no effect. A study of the structural requirements on phosphatidylethanolamine necessary for interaction with the peptide indicates that Ro09-0198 recognizes strictly a particular chemical structure of phosphatidylethanolamine: dialkylphosphoethanolamine as well as 1-acylglycerophosphoethanolamine showed the same inhibitory effct on hemolysis induced by Ro09-0198 as diacylphosphatidyl-ethanolamine, whereas phosphoethanolamine gave no inhibitory effect. Neither phosphatidyl-N-monomethylethanolamine nor alkylphosphopropanolamine had an inhibitory effect. Proton resonances of the peptide were observed in dimethyl sulfoxide solution in the presence of 1-dodecanoyl-sn-glycerophosphoethanolamine. This peptide caused permeability increase and aggregation of liposomes containing phosphatidylethanolamine. A glycerol backbone and a primary amino group of phosphatidylethanolamine are necessary for interaction with Ro09-0198 to cause membrane damage. Ro09-0198 induced a selective permeability change on liposomes. Glucose and umbelliferyl phosphate were effluxed significantly, but sucrose was only slightly permeable and inulin could not be released. Platelet aggregation and serotonin release simultaneously induced by Ro09-0198. Addition of peptide to rat platelet, loaded with the fluorescent $Ca^{++}$ chelator quin-2, caused immediate rise in cytosolic free $Ca^{++}$ to liposomal membrane containing phosphatidylethanolamine was observed dose dependently.

• YAKHAK HOEJI
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• v.38 no.3
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• pp.238-249
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• 1994

The purpose of this research was to investigate effects of baicalin on the differentiation of preadipocytes, 3T3-L1, and to characterize the action of baicalin that affect the responses of 3T3-L1 cells during differentiation. In various culture conditions, effects of baicalin and adrenoreceptor agonists such as phenylephrine(PE) and isoproterenol(IPR) on cell differentiation were examined. Also, effects of the drugs on differentiation, triglyceride(TG) contents, expression of insulin receptor, cAMP contents, the cytosolic $Ca^{2+}$ levels, and amount of calmodulin(CaM) were examined. The results suggest that baicalin has adrenergic receptor blocking activity during the process of differentiation of 3T3-L1 cells and that in the early stage of the adipose conversion, the effect of baicalin on the adipocyte differentiation is mediated by the regulation of insulin receptor expression, but by alterations of the cAMP and the calcium metabolism in the late stage. These results also suggest that the action of baicalin may be significant in the lipid metabolism, lipogenic and lipolytic pathways, of adipose cells.

• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1134-1138
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• 2007

Cordycepin (3'-deoxyadenosine) is an adenosine analog, isolated from Cordyceps militaris, and it has been used as an anticancer and anti-inflammation ingredient in traditional Chinese medicine. We investigated the effects of cordycepin (3'-deoxyadenosine) on human platelet aggregation, which was induced by thapsigargin, a tumor promoter, and determined the cytosolic free $Ca^{2+}$ levels ($[Ca^{2+}]_i$) (an aggregation-stimulating molecule) and cyclic-guanosine monophosphate (cGMP) (an aggregation-inhibiting molecule). Cordycepin inhibited thapsigargin-induced platelet aggregation in a dose-dependent manner, and it clearly reduced the levels of $[Ca^{2+}]_i$, which was increased by thapsigargin ($1\;{\mu}M$) or U46619 ($3\;{\mu}M$). Cordycepin also increased the thapsigargin-reduced cGMP levels. Accordingly, our data demonstrated that cordycepin may have a beneficial effect on platelet aggregation-mediated thrombotic diseases through the $[Ca^{2+}]_i$-regulating system such as cGMP.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.3
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• pp.163-167
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• 2010

This study investigated the effects of the methanol extracts of Morinda citrifolia containing numerous anthraquinone and iridoid on phospholipase $A_2$ ($PLA_2$) isozyme. $PLA_2$ activity was measured using various $PLA_2$ substrates, including 10-pyrene phosphatidylcholine, 1-palmitoyl-2-[$^{14}C$]arachidonyl phosphatidylcholine ([$^{14}C$]AA-PC), and [$^3H$]arachidonic acid (AA). The methanol extracts suppressed melittin-induced [$_3H$]AA release in a concentration-dependent manner in RAW 264.7 cells, and inhibited $cPLA_2/sPLA_2$-induced hydrolysis of [$^{14}C$]AA-PC in a concentration- and time-dependent manner. A Dixon plot showed that the inhibition by methanol extracts on $cPLA_2$ and $sPLA_2$ appeared to be competitive with inhibition constants ($K_i$) of $3.7{\mu}g/ml$ and $12.6{\mu}g/ml$, respectively. These data suggest that methanol extracts of Morinda citrifolia inhibits both $Ca^{2+}$-dependent $PLA_2$ such as, $cPLA_2$ and $sPLA_2$. Therefore, Morinda citrifolia may possess anti-inflammatory activity secondary to $Ca^{2+}$-dependent $PLA_2$ inhibition.

• Journal of Ginseng Research
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• v.17 no.2
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• pp.131-134
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• 1993

Panaxadiol (PD) from Korean red ginseng C.A. Meyer did not control the concentration of cytosolic free $Ca^{2+}$ influxes by thrombin (5 $\mu$/ml). However, PD strongly inhibited the synthesis of thromboxane. $A_2$ (TX$A_2$) in the aggregation of human platelets induced by thrombin (5 $\mu$/ml). These rexults suggest that PD blocks the any Pathway transforming to TX$A_2$ from arachidonic acid (AA) which release out of plasma membrane phospholipids by $Ca^{2+}$-dependent phospholipase C or phospholipase $A_2$. It may be also concluded that PD has the antiplatelet function by inhibiting the synthesis of TX$A_2$, which known to be the potent stimulator of the aggregation of human platelet.

• The Korean Journal of Pharmacology
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• v.32 no.1
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• pp.103-112
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• 1996

Roles of protein kinase C and protein tyrosine kinase in the activation of neutrophil respiratory burst, degranulation and elevation of cytosolic $Ca^{2+}$ in platelet-activating factor (PAF)-stimulated neutrophils were investigated. Superoxide and $H_2O_2$ production and myeloperoxidase and acid phosphatase release in PAF-stimulated neutrophils were inhibited by protein kinase C inhibitors, staurosporine and H-7 and protein tyrosine kinase inhibitors, genistein and tyrphostin. The PAF-induced elevation of $[Ca^{2+}]_i$ in neutrophils was inhibited by staurosporine, genistein and methyl-2,5-dihydroxycinnamate. Staurosporine inhibited both intracellular $Ca^{2+}$ release and $Mn^{2+}$ influx in PAF-stimulated neutrophils. Genistein and methyl-2,5-dihydroxycinnamate inhibited $Mn^{2+}$ influx induced by PAF, whereas their effects on intracellular $Ca^{2+}$ release were not detected. In neutrophils preactivated by PMA, the stimulatory effect of PAF on the elevation of $[Ca^{2+}]_i$ was reduced. Protein kinase C and protein tyrosine kinase may be involved in respiratory burst, lysosomal enzyme release and $Ca^{2+}$ mobilization in PAF-stimulated neutrophils. The elevation of $[Ca^{2+}]_i$ appears to be accomplished by intracullular $Ca^{2+}$ release and $Ca^{2+}$ influx which are differently regulated by protein kinases. Preactivation of protein kinase C appears to attenuate the stimulatory action of PAF on intracellular $Ca^{2+}$ mobilization.

• Journal of Plant Biology
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• v.39 no.2
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• pp.113-121
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• 1996

The role of Ca2+ on benzyladenine (BA)-induced senescence retardation in mature wheat (Triticum aestivum L.) primary leaves was investigated. When an extracellular calcium chelator, ethylene glycol-bis-($\beta$-aminoethylether)-N, N'-tetraacetic acid (EGTA) together with BA, was applied to senescing leaves for 4 days of dark incubation, the content of chlorophyll and soluble protein decreased rapidly. And, the content of malondialdehyde (MDA), known to be a degradation product of membrane lipids, increased compared with the BA alone control. The BA-EGTA combination also caused the stimulation of protease and RNase activity and a rapid loss of catalase activity owing to the decling of BA effects. In the case of treatment with only intracellular calcium antagonist 3, 4, 5-trimethoxybenzoic acid 8-(diethylamino) octyl ester (TMB-8) without the BA addition, the chlorophyll content at day 4 after dark incubation decreased in paralled with the increasing concentration of the antagonist. In addition, the chlorophyll content at 10-5 M calcium ionophore A23187 treatment in the absence of BA was similar to that of the BA alone treatment. These results suggest that calcium may mediate the retardation effect of BA on leaf senescence by acting as a second messenger and that the calcium input from cell organelles, as well as the calcium inflow from intercellular spaces and cell walls, may be involved in modulating cytosolic calcium levels related to BA action.

• The Korean Journal of Pharmacology
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• v.28 no.1
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• pp.91-102
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• 1992

In $Ca^{++}$ containing media, arachidonic acid markedly stimulated superoxide and $H_2O_2$ generation and activated NADPH oxidase. In $Ca^{++}$ free media, stimulatory action of arachidonic acid on NADPH oxidase was not detected. Arachidonic acid-stimulated respiratory burst was inhibited by EGTA, TMB-8, verapamil, diltiazem, nifedipine, dibucaine, lidocaine, CCCP, 2,4-dinitrophenol, sodium arsenate, chlorpromazine, theophylline, $HgCl_2$, PCMB and PCMBSA but not affected by tetrodotoxin, tetraethylammonium chloride and procaine. EGTA almost completely inhibited release of ${\beta}-glucuronidase$ by arachidonic acid and verapamil, CCCP and theophylline slightly inhibited it, whereas dibucaine did not show any significant effect. Arachidonic acid induced $Ca^{++}$ release from intact neutrophils and it was decreased by TMB-8. Arachidonic acid-induced elevation of intracellular free $Ca^{++}$ level was inhibited by EGTA and CCCP and slightly inhibited by TMB-8. Amount of intracellular free $Ca^{++}$ increased by either arachidonic acid plus verapamil or arachidonic acid plus dibucaine was greater than that by arachidonic acid alone. These results suggest that various changes of biochemical events may be implicated in the functional expression in neutrophils activated by arachidonic acid. Arachidonic acid appears to elevate cytosolic free $Ca^{++}$ level by stimulating $Ca^{++}$ release from intracellular $Ca^{++}$ storage sites. During activation of neutrophils, $Ca^{++}$ influx and efflux may be accomplished, simultaneously.

• Korean Journal of Medicinal Crop Science
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• v.14 no.2
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• pp.70-76
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• 2006

Paeoniae radix has been widely used for its anti-allergic, anti-inflammatory and analgesic effects, and demonstrated to have anticonvulsant, memory enhancing and anxiolytic activities. The present study was performed to examine the protective effect of methanol extract of Paeoniae radix (PR) from Paeoniae Japonica Miyabe et Takeda (Paeoniaceae) on hydrogen peroxide $(H_2O_2)-induced$ neurotoxicity using cultured rat cerebral cortical neuron. $H_2O_2$ produced a concentration-dependent reduction of neuronal viability, PR, over a concentration range of 10 to $100\;{\mu}g/ml$ showed concentration-dependent decrease of the $H_2O_2$$(100\;{\mu}M)-induced$ neuronal cell death, as assessed by a 3-[4,5-dimethylthiazol-2-yl]-2,5-di-phenyl-tetrazolium bromide assay and the number of apoptotic nuclei, evidenced by Hoechst 33342 staining. PR $(100\;{\mu}g/ml$ inhibited $100\;{\mu}M$ $H_2O_2-induced$ elevation of the cytosolic $Ca^{2+}$ concentration $([Ca^{2+}]_c)$, which was measured by a fluorescent dye, flue-4 AM. PR $(50\;{\mu}g/ml$ inhibited glutamate release into medium induced by $100\;{\mu}M$ $H_2O_2$, which was measured by HPLC, and generation of reactive oxygen species (ROS). These results suggest that PR may mitigate the $H_2O_2-induced$ neurotoxiciy by interfering with the increase of $[Ca^{2+}]_c$, and then inhibiting glutamate release and generation of ROS in cultured neurons.

• Korean Journal of Medicinal Crop Science
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• v.15 no.2
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• pp.105-111
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• 2007

The protective effect of ethanol extract of Korean mistletoe (KM; Viscum album coloratum) on hydrogen peroxide $(H_{2}O_{2})-induced$ neurotoxicity was examined in primary cultured rat cortical neurons. $H_{2}O_{2}$ reduced viability of cortical neurons in a concentration-dependent manner. The addition of KM, over a concentration range of 10 to 100 ${\mu}g/ml$, concentration-dependently prevented the $H_{2}O_{2}(100\;{\mu}M)-induced$ neuronal cell death, as assessed by a 3-[4,5-dimethylthiazol-2-yl]-2,5-di-phenyl-tetrazolium bromide (MTT) assay and Hoechst 33342 staining. KM significantly inhibited $H_{2}O_{2}-induced$ elevation of the cytosolic $Ca^{2+}$ concentration $([Ca^{2+}]_{c})$, which was measured by a fluorescent dye, fluo-4 AM. KM inhibited glutamate release into medium and generation of reactive oxygen species (ROS) induced by $H_{2}O_{2}$. These results suggest that KM may mitigate the $H_{2}O_{2}-induced$ neurotoxiciy by interfering with the increase of $[Ca^{2+}]_{c}$, and inhibiting glutamate release and generation of ROS in cultured neurons.