• YAKHAK HOEJI
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• v.56 no.2
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• pp.80-85
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• 2012

Previously, we have reported that arachidonic acid (AA) appears to be involved in the induction of apoptosis in HepG2 human hepatoblastoma cells. In this study we investigated the possible role of the NADPH oxidase, a membranebound enzyme generating reactive oxygen species (ROS), in the mechanism of AA-induced apoptosis in HepG2 cells. Apoptotic cell death induced by AA was significantly suppressed by various inhibitors of the NADPH oxidase, diphenylene iodonium (DPI), apocynin (Apo) and neopterine (NP). In addition, these inhibitors of the NADPH oxidase completely blunted the AA-induced ROS elevation. Next, we investigated the implication of metabolic pathway of AA in these AA actions. Both apoptosis and ROS production induced by AA were not significantly altered by treatment with indomethacin (Indo) or nordihydroguaiaretic acid (NDGA), selective inhibitors of cyclooxygenase (COX) and lipoxygenase (LOX), respectively, suggesting that AA metabolites produced by COX or LOX may not have an essential role in the AA-induced apoptosis and ROS generation. Collectively, these results suggest that the NADPH oxidase may be a key player in the mechanism of AA-induced apoptosis in HepG2 cells. These results further suggest that NADPH oxidase may be a good target for the management of human hepatomas.

• Biomolecules & Therapeutics
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• v.17 no.4
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• pp.379-387
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• 2009

We have previously reported that N-ethylmaleimide (NEM) induces apoptosis through activation of $K^+$, $Cl^-$-cotransport (KCC) in HepG2 human hepatoblastoma cells. In this study we investigated the possible role of phospholipase $A_2$ ($PLA_2$)-arachidonic acid (AA) signals in the mechanism of the NEM-induced apoptosis. In these experiments we used arachidonyl trifluoromethylketone ($AACOCF_3$), bromoenol lactone (BEL) and p-bromophenacyl bromide (BPB) as inhibitors of the calcium-dependent cytosolic $PLA_2$ ($cPLA_2$), the calcium-independent $PLA_2$ ($iPLA_2$) and the secretory $PLA_2$ ($sPLA_2$), respectively. BEL significantly inhibited the NEM-induced apoptosis, whereas $AACOCF_3$ and BPB did not. NEM increased AA liberation in a dose-dependent manner, which was markedly prevented only by BEL. In addition AA by itself induced $K^+$ efflux, a hallmark of KCC activation, which was comparable to that of NEM. The NEM-induced apoptosis was not significantly altered by treatment with indomethacin (Indo) and nordihydroguaiaretic acid (NDGA), selective inhibitors of cyclooxygenase (COX) and lipoxygenase (LOX), respectively. Treatment with AA or 5,8,11,14-eicosatetraynoic acid (ETYA), a non-metabolizable analogue of AA, significantly induced apoptosis. Collectively, these results suggest that AA liberated through activation of $iPLA_2$ may mediate the NEMinduced apoptosis in HepG2 cells.

• KSBB Journal
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• v.20 no.1 s.90
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• pp.60-65
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• 2005

The objective of this work was to evaluate a solid-state fermentation process for the practical production of arachidonic acid(AA) by Mortierella alpina ATCC 32222. In the present investigation, batch culture kinetics for both submerged- and solid-state fermentations was carried out at $25^{\circ}C$ to identify the relationship between growth and arachidonic acid (AA) production. Glucose and yeast extract were used in submerged fermentations by using flasks, while rice bran was used as a sole raw material in the other type of fermentations by using a series of Petri dishes. It was evident that a mixed-growth associated pattern existed between the two variables, irrespective of modes of fermentations. The effect of carbon to nitrogen (CfN) ratio on AA production in solid-state fermentation was studied in the range of 6.5 - 20. As a result, an optimum condition was found to be 6.5. Supplementary carbon source was not necessary to meet the optimum C/N ratio. Unlike the Previous results obtained by other researchers, a supplement of sodium glutamate up to $4\%$ (w/w) to the rice bran medium did not have a positive effect on the AA productivity. However, an increase in AA productivity was obtained with the rice bran medium supplemented with sesame oil.

• Journal of Acupuncture Research
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• v.24 no.2
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• pp.31-38
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• 2007

목적 : 백자인에서 추출된 Carvacrol이 혈소판 활성화와 혈액 응고에 미치는 영향에 대해 알아보고자 하였다. 방법 : Carvacrol의 항혈소판 효과의 기제를 밝히기 위해 토끼 혈소판으로 Arachidonic Acid 유리，TXB2, PGD2, 12-HETE의생성을 방사선 크로마토그래피 분석을 사용하여 측정하였다. 결과 : 1. U46619를 제외하고 Collagen과 AA에 의해 유발된 응고는 Carvacrol 농도에 따라 억제되었다. 2. Collagen으로 인하여 자극된 AA 유리에 대한 Carvacrol의 유의한 억제 효과는 나타나지 않았다. 3. AA로 유발된 TXB2, PGD2와 12-HETE의 생성억제에 대한 실험에서 Carvacrol은 유의한 억제가 있는 것으로 나타났으며，농도의존적으로 억제되었다. 결론 : Carvacrol은 항혈소판 작용이 있는 것으로 볼 수 있다. 이는 한의학에서 활혈거어 작용으로 해석될수 있으며，타박상，윌경곤란증，탈모증 등 어혈질환의 예방 및 치료와 관련된 약침개발에 기초가 될수 있을 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.350-355
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• 2009

Arachidonic acid (AA) is a polyunsaturated fatty acid that is a normal constituent of membrane lipids in animal cells. In addition to its role as a precursor of prostaglandins, AA itself may play an important role in the regulation of cell function. The effect of AA on functions of granulosa cells was investigated in pre-hierarchical small yellow follicles of laying hens. Immuno-cytochemical staining showed that AA ($10^{-7}-10^{-5}$ M) increased the expression of the extracellular matrix glycoprotein laminin, gap junction connexin 43 and protein kinase C (PKC). Therefore, mediated by the PKC signal pathway, AA may regulate the intercellular communication of granulosa cells and follicular development by increasing the expression of laminin and connexin.

• BMB Reports
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• v.32 no.1
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• pp.33-38
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• 1999

The effects of eicosapentaenoic (EPA, 20:5n-3) and docosahexaenoic acids (DHA, 22:6n-3) on the phospholipase $A_2$ ($PLA_2$)-mediated release of arachidonic acid (AA, 20:4n-6) were studied in kidney microsomes from rats fed diets containing sunflower oil (SO) or fish oil (FO) concentrate for 11 months. The amounts of AA released by the endogenous $PLA_2$ enzyme were significantly lower by 38% in the FO, compared to the SO-fed rats (23.2 nmol versus 60.7 nmol AA released/mg protein/h in the FO- and SO-treated groups, respectively). The FO-derived microsomes released less linoleic acid (LA, 18:2n-6) and adrenic acid (22:4n-6), but larger amounts of the n-3 fatty acids, including EPA, DHA, docosapentaenoic acid (DPA, 22:5n-3), and 20:4n-3 than the SO-derived microsomes. A similar replacement of the AA and adrenic acid with the n-3 fatty acids including EPA and DHA was also observed in the microsomal phospholipid fraction from the FO-fed rats relative to the SO-treated group. The results suggest that the $PLA_2$-mediated release of AA is reduced and that of EPA is increased in compensation for AA decline in kidney microsomes from FO-fed rats (0.7 nmol EPA/mg protein/h versus 22.7 nmol EPA/mg protein/h for the SO and FO-treated groups). Replacement of the n-6 with n-3 fatty acids may explain the reduced synthesis of the AA-derived prostaglandins and the concomitant rise in the EPA-derived prostaglandins observed in kidneys of FO-treated rats.

• Fisheries and Aquatic Sciences
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• v.15 no.2
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• pp.163-168
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• 2012

The non-utilized biomass of the aquacultured seaweed Undaria pinnatifida, particularly the rhizoid, is an alternative source of arachidonic acid (AA). Of the five aquacultured kelps that were tested, U. pinnatifida yielded the highest amount of AA, which was isolated from the rhizoids. Its identity (C20:4 n-6) was confirmed from gas chromatography-mass spectrometry spectral data. The optimal conditions for post-harvest storage or pretreatment of the rhizoids in Provasoli's enriched seawater for AA extraction were determined to be pH 7.8, 2% $CO_2$-enriched air, 20 ${\mu}mol\;m^{-2}\;s^{-1}$ light, and $10^{\circ}C$. Under these conditions, the AA content after 1 day of storage was enhanced by up to 127%. In the absence of light under ambient aeration, the AA content after 1 day of storage diminished to 90%. Rhizoids collected late in the season (April and May) contained the highest amounts of AA (approximately 2.5 mg/g tissue).

• Preventive Nutrition and Food Science
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• v.4 no.3
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• pp.203-208
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• 1999

The effect of the polyunsaterated fatty acids, linoleic acid(LA), arachidonic acid(AA) and conjugated dienoic linoleic acid(CLA) on IEC-6 cells (rat intestinal cell)proliferation and cell transduction have been determined in vitro. IEC-6 cells proliferation was assessed by cell growth and [3H]-thymidine incroporation analysis. At 10 μM concentration , the proliferationof cells supplemented with AA or LA was significantly higher than that of CLA. [3H]-thymidine uptake showed the same results. LA and AA increased [3H]-thymidine uptake more than CLA. The stimulatory effect of LA or AA was even more pronounced in the presence of IGF. Both cell number analysis and [3H]-thymidine incorporation revealed that IEC-6 cell proliferation was influenced differently by exogenous free fatty acids, in which AA or LA stimulated IEC-6 cell proliferation and CLA inhibited it. Tyorosine phosphorylation provides a key switch to regulate celluar acitivity in response to extracellular stimuli. At 20 μM and 10μM, AA with IGF-1 stimulated protein tyrosine phophorylation in IEC-6 cells, but LA's impact was less than that of AA. CLA and CLA with IGF-1 inhibited protein tyrosine phosphorylation in IEC-6 cells. These results suggest there is a possible correlation between cell proliferation and IGF receptor tyrosine knase activity driven by AA.

• Biomolecules & Therapeutics
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• v.3 no.2
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• pp.104-110
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• 1995

Arachidonic acid (AA, C20 : 4, $\omega$-6) and eicosapentanoic acid (EPA,C20 : 5, $\omega$-3), which are polyunsaturated fatty acids forming eicosanoids, were tested for their effects on blood pressure in Wistar rats and SHR. AA is the most important precursor for the biosynthesis of eicosanoids which include the prostaglandins, prostacyclin (PGI$_2$), thromboxane $A_2$ (TXA$_2$) and the leukotriens. TXA$_2$is a potent vasoconstrictor and a powerful inducer of platelet aggregation causing myocardial infarction and hypertention. In contrast, PGI$_2$ induces vasodilation and inhibits platelet aggregation. In this study, AA markedly increased blood pressure, but its effect was antagonized by both EPA, a structural analog of AA, and dazmegrel, a TX synthetase inhibitor. Also, AA enhanced the antihypertensive effects of hydralazine and captopril, and EPA reduced TXA$_2$ production. These results indicate that the hypotensive effects of EPA might be closely related to the decrease in TXA$_2$ biosynthesis due to competitive inhibition by structural similarity of the EPA to the AA, the precursor of TXA$_2$.

• Archives of Pharmacal Research
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• v.24 no.6
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• pp.552-556
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• 2001

Histamine and arachidonic acid (AA) release was measured using the P2-purinoceptor antaongists, phospholipase $A_2{\;}(PLA_2)$ and cyclooxygenase (COX)/lipoxygenase (LOX) inhibitors to determine whether or not ATP-induced histamine release is associated with arachidonic acid (AA) release in rat peritoneal mast cells. ATP increased histamine release in a dose dependent manner, whereas adenosine did not. PPADS (a selective P2X-purinoceptor antagonist) and suramin (a nonselective P2X,2Y-purinoceptor antagonist) inhibited ATP-induced histamine release in a dose dependent manner. However, RB-2 (a P2Y-purinoceptor antagonist) did not block ATP-induced histamine release. Manoalide and oleyloxyethyl phosphorylcholine (OPC), secretory PLA$_2$ inhibitors, also inhibited ATP-induced histamine release dose-dependently. Both COX inhibitors (ibuprofen and indomethacin) and LOX inhibitors (baicalein and caffeic acid) inhibited ATP-induced histamine in a dose dependent manner. ATP significantly increased [$^3H$]AA release by 54%. PPADS and suramin significantly inhibited ATP-induced [3H]Ph release by 81% and 39%, respectively. ATP-induced histamine release was significantly inhibited by a variety of protein kinase inhibitors, such as bisindolmaleimide, genistein, methyl 2,5-dihydroxycinnamate, W-7 and trifluoperazine. Overall, the results suggest that ATP-induced histamine release is in part related to the PLA2-mediated AA metabolism and P2X-purinoceptors.