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A series of six new synthetic dinitroglycerol esters of fatty acids on the human platelet aggregation was studied in vitro. Inclusion of the dinitroglycerol moiety into the molecule of arachidonic acid deprived this acid from pro-aggregant activity. All six compounds produced moderate (dose-dependent) inhibition of the platelet aggregation process induced by arachidonic acid (1 x 10(-3) M). Platelet aggregation was most significantly affected by dinitroglycerol esters of arachidonic and docosahexaenoic acids. This is probably explained by the influence of these esters on the oxidative metabolism of arachidonic acid to eicosanoids playing the role of proaggregants. In the presence of vessel wall (rat aorta fragments), dinitroglycerol esters of arachidonic and docosahexaenoic acids incubated with platelets (5 min, 37 degrees C) significantly reduced their aggregation induced by arachidonic acid (1 x 10(-3) M) or docosahexaenoic acid (1 x 10(-5) M) under the conditions of endothelial cyclooxygenase suppressed by acetylsalicylic acid (10 mg/ml). The pronounced antiaggregant effect of the synthetic dinitroglycerol esters studied is probably related to their ability to act as NO donors suppressing the activity of thrombocytes (provided that the NO production activity is present in the system).

(+/-)-15-Fluoro-11,15-dideoxyprostaglandin E1 and its methyl and ethyl esters were synthesized. Dehydroxyfluorination reaction (+/-)-11-deoxyprostaglandin E1 esters with various reagents based on SF4 was studied. Along with the target 15-fluorides (mixtures of alpha- and beta-epimers), products of allylic shift and dehydration in a ratio dependent on the fluorination agent were shown to be formed. With a morpholinotrifluorosulfuran-tris(morpholine)sulfonium trimethyldifluorosilicate mixture, the maximal excess (70%) of one of the 15-fluoro epimers was achieved. Possible mechanisms of dehydroxyfluorination of (+/-)-11-deoxyprostaglandin E1 esters with dialkylaminoflluorosulfurans were proposed. Methyl esters of 15-alpha-fluoro- and 15-beta-fluoro-11,15-dideoxyprostaglandin E1 exhibited moderate antiaggregation activity in rabbit platelet tests.

In a search for stable thromboxanomimetics the action of 11-fluoro-11-deoxyprostaglandin F2 alpha (11-fluoro-PGF2 alpha) on the aggregatory properties of platelets and the tone of the vascular, respiratory and gastrointestinal smooth muscles was studied. It was found that 11-fluoro-PGF2 alpha, in contrast to PGF2 alpha, induces platelet aggregation and exhibits a high activity with respect to smooth muscles sensitive to thromboxane A2 alpha (TXA2) and a low activity for smooth muscles sensitive to PGF2 alpha 9-11-epoxyimino-PGH2 (a specific antagonist of TXA2 receptors) competitively blocked the action of 11-fluoro-PGF2 alpha on vascular smooth muscles. Thus, 11-fluoro-PGF2 exhibits properties of a thromboxanomimetic that makes it possible to propose it for modelling TXA2-induced biological effects.

The effect of exchange of 15-hydroxyl for fluor on biological activity of PGF2 alpha and PGE2 on isolated smooth muscles of different organs has been studied. The exchange leads to significant increase in contractile (100-fold) and relaxation (1000-fold) activity of PGF2 alpha on smooth respiratory muscles. At the same time, the effect of 15-fluor-15-deoxyprostaglandin F2 alpha on smooth muscles of intestinal and vascular tracts did not differ from that of PGF2 alpha. Similar modification of PGE2 led to the decrease (10-fold) both in contractile and relaxation activity on all studied types of smooth muscles. The data obtained have been discussed within the boundaries of prostanoid receptor classification (Kennedy, 1982). Fluor derivative of PGF2 alpha may be used for pharmacological differentiation of EP-receptors.