Arachidonic acid comparative

In showing that the release of arachidonic acid was selective. Bills el al7 had studied the incorporation of several radiolabelled fatty acids into the complex lipids of human platelets and the subsequent fate of the radiolabel after stimulation of the platelets with thrombin. They found a dramatically greater loss from phosphatidylcholine of radioactive arachidonic acid compared with the other radiolabelled fatty acids. By contrast, Mahadevappa and Holub observed decreases in all the molecular species of phosphatidylcholine after thrombin treatment of platelets prelabelled with radioactive glycerol. They concluded that arachidonate is not selectively released from this phospholipid because the results obtained with radioactive fatty acids were due to unique patterns of incorporation, while those obtained with radioactive glycerol represented the endogenous phospholipid pool. 

The prostaglandins (qv) constitute another class of fatty acids with aUcycHc structures. These are of great biological importance and are formed by i vivo oxidation of 20-carbon polyunsaturated fatty acids, particularly arachidonic acid [27400-91-5]. Several prostaglandins, eg, PGE [745-65-3] have different degrees of unsaturation and oxidation when compared to the parent compound, prostanoic acid [25151 -18-9]. 

Aspirin is maximally effective as an antithrombotic agent at the comparatively low dose of 81 to 325 mg per day. (The antipyretic dose of aspirin in adults is 325 to 650 mg every 4 h.) Higher doses of aspirin are actually contraindicated in patients prone to thromboembolism. At higher doses, aspirin also reduces synthesis of prostacyclin, another arachidonic acid metabolite. Prostacyclin normally inhibits platelet aggregation. The prophylactic administration of low-dose aspirin has been shown to increase survival following myocardial infarction, decrease incidence of stroke, and assist in maintenance of patency of coronary bypass grafts. 

Table I. Relative Yields of Diastereomeric Adducts From Anti-diol Epoxide Plus Polyguanylic Acid Compared to Adducts Generated During Metabolism of BP-7,8-dihydrodiol by Ram Seminal Vesicles in the Presence of Arachidonic Acid...

The major omega-3 fatty acid in hsh oil is eicosapentae-noic acid, which contains hve double bonds compared with only four present in the omega-6 fatty acid, arachidonic acid. When eicosapentaenoic acid is substrate for eico-sanoid production, it gives rise to prostacyclins and thromboxanes of the three series (Figure 22.9(a)) whereas when arachidonic acid is substrate, it gives rise to the two series, thromboxane A2 and prostacyclin I2. Thromboxane A3 has... 

The 6- or 7-phenyl-substituted l-ethyl-pyrazino[2,3-r-][l,2,6]thiadiazine 2,2-dioxides 187 were found to show significant platelet aggregation inhibition comparable to other antithrombotic agents. Strong evidence was found that this activity was due to interference with the platelet arachidonic acid pathway <1999JME1698>. 

No increase in % kinetochore-positive micronuclei compared with controls Supplemented with arachidonic acid increase in both kinetochore-positive and -negative micronucleated cells compared with controls (CREST-... 

The key elements in such an area analysis are palmitoleic and arachidonic acids (peaks 5 and 6, Fig. 2). Complete resolution of these two acids precludes the use of a starting solvent system with acetonitrile composition of over 67%. If only one of these two acids is present, however, a rapid analysis is feasible. A separation of this type is illustrated in Fig. 3. The time required for this analysis is 70 min, compared to 4 h for the separation shown in Fig. 2. 

It was discovered that 3-nitro-2-piperidino-, 3-nitro-7-piperidino-, and 7-iV-diethanolamino-3-nilro-l, H-naphthyridin-2(1 H)-ones and 2-diethanol-amino-7-piperidino-3-nitro-l,8-naphthyridine showed remarkable activity to inhibit human platelet aggregation in vitro induced by arachidonic acid, collagen, and ADP. This activity was comparable to papaverine, dipyridamole, and ibuprofen (94EJMC735). 

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