Sang Gyeong Lee

20-Hydroxyeicosatetraenoic acid is an endothelium-dependent vasoconstrictor in rabbit arteries

Recently we have demonstrated that 20-hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE) constricts rat aortic rings and that this effect is cyclooxygenase- and endothelium-dependent. Incubation of 20-HETE with ram seminal vesicles, a rich source of cyclooxygenase, led to the identification of vasoconstrictor metabolites, the 20-hydroxy-endoperoxides. In the present study, we demonstrated differences in the potency of 20-HETE to constrict several arteries. In all blood vessels tested, the 20-HETE contractile effect was cyclooxygenase- and endothelium-dependent. Differences in contractile potency of 20-HETE varied according to the blood vessels; potency being higher in more muscular arteries than elastic ones. Furthermore, 20-HETE was more potent in eliciting vasoconstriction than its precursor, arachidonic acid. We also provide evidence for the generation of 20-hydroxy-endoperoxides from 20-HETE by the endothelial cyclooxygenase. 20-HETE is a major arachidonate metabolite formed by the cytochrome P450 monooxygenases in rat, human and rabbit kidneys. In addition, blood cells such as leukocytes have the ability to produce 20-HETE, suggesting its presence in the circulation. Furthermore, 20-HETE has been shown to inhibit platelet aggregation. Thus, the ability of 20-HETE to modulate vascular tone and platelet function implicates a role for this compound in the regulation of hemostasis.

Efficient cleavage of terminal acetonide group: Chirospecific synthesis of 2,5-dideoxy-2,5-imino-D-mannitol

Abstract Dowex 50W-X8 was efficient catalyst for selective cleavage of terminal actonide including acid-sensitive multifunctional groups. A facile and economically synthesis of DMDP (2,5-dideoxy-2,5-imino-D-mannitol) is described via selective hydrolysis and intramolecular nucleophilic amination.

Enantiospecific synthesis of 17- and 18-hydroxyeicosatetraenoic acids, cytochrome P450 arachidonate metabolites

Abstract The title bioactive eicosanoids were prepared from dimethyl L -malate by a convergent strategy exploiting the differential reactivity of ethereal dialkylcuprates towards tosylates versus bromides.

Simple synthesis of (–)-deoxymannojirimycin and (2S,3R,4R,5R)-3,4,5-trihydroxypipecolic acid via regioselective hydrolysis

A short and efficient synthesis of (–)-deoxymannojirimycin and (2S,3R,4R,5R)-3,4,5-trihydroxypipecolic acid is described with D-glucono-δ-lactone as chiral educt. Key transformations included selective cleavage of a terminal isopropylidene group with Dowex 50W-X8 (H+) and intramolecular nucleophilic amination.

SYNTHESIS OF ALCOHOLS VIA MILD OXIDATION OF PERFLUOROETHYLSTANNANES

Abstract Alkaline H 2 O 2 oxidizes perfluoroethyl-substituted stannanes to the corresponding alcohols with retention of configuration.

Vic-Diol chirons : enantiospecific synthesis of 11,12- and 14,15-dihydroxyeicosatrienoic acids

Abstract A differentiated, six-carbon vicinal -diol chiron was prepared from D -glucurono-6,3-lactone and exploited in the asymmetric synthesis of the erythro/threo -isomers of the title eicosanoids.