Synthesis of inositol glycan cyclic phosphates.

An efficient synthesis of tri-, tetra-, and pentasaccharide cyclic phosphates 1-5, structurally related to natural inositol phosphate glycans, is reported. The title compounds were assembled by PhSeOTf-promoted glycosylation of the known glucosamine precursor, t-butyldimethylsilyl 2-azido-3,6-di-O-benzyl-2-deoxy-beta-D-glucopyranoside (8) with protected 1-methylthio mono-, di-, and trimannosides 7a-c, and, after conversion into glycosyl fluorides, Cp2ZrCl2- AgOTf-promoted glycosylation of differentially protected optically pure 1D-myo-inositol 11. The syntheses were completed by installing the cyclic phosphate moieties with methylpyridinium dichlorophosphate and finally, removal of all protecting groups by dissolving-metal reduction.

Synthesis of a jojoba bean disaccharide.

A synthesis of the disaccharide recently isolated from jojoba beans, 2-O-alpha-D-galactopyranosyl-D-chiro-inositol, has been achieved. The suitably protected chiro-inositol unit was prepared by an enantiospecific synthesis from L-xylose utilizing SmI2-mediated pinacol coupling as a key step.

Synthesis of inositol 2-phosphate-quercetin conjugates.

The antiproliferative flavonoid, quercetin, is limited in its pharmacological utility by its low water solubility. In this paper, we describe the synthesis of two quercetin analogues prepared by linking the hydroxyl group at the 3- or 5-position of the flavonoid to the 1-hydroxyl group of myo-inositol-2-phosphate via a succinate diester linkage. The resulting conjugates were found to have dramatically enhanced water solubility relative to quercetin; the 5-linked quercetin analogue 2 had a water solubility of > 300 mg/mL at 20 degrees C. Comparison of the in vitro cytotoxicity and antiproliferative activity of conjugate 2 with those of quercetin toward cultured human colon adenocarcinoma (SW480) and human glioblastoma (U87MG) cells indicated that this modification of quercetin does not significantly diminish its activity in these assays.

Formation and cell-medium partitioning of autoinhibitory free fatty acids and cyclodextrin's effect in the cultivation of Bordetella pertussis.

Palmitic, palmitoleic and stearic acids were found in the extracted cellular lipids of virulent Bordetella pertussis as unesterified acids in confirmation of earlier taxonomic analyses. The same free fatty acids (FFAs) were found in the spent culture supernatant in concentrations higher than in the uninoculated medium, indicating that they are released into the extracellular medium. These long-chain fatty acids are known to inhibit the growth of B. pertussis at concentrations as low as 1 ppm. Measurement of palmitate cell-medium partitioning demonstrated a strong tendency of FFAs for cellular adsorption. Inhibition kinetics indicated that the cell-bound FFA was responsible for inhibition and that the specific cellular FFA concentrations actually found during growth were similar to those determined to be inhibitory. Autoinhibition by these endogenous FFAs provides an explanation of the low maximum cell concentrations currently attainable in liquid media. Addition of soluble dimethyl-beta-cyclodextrin (MebetaCD) to FFA-inhibited cultures resulted in a rapid reversal of the inhibition. A corresponding shift in the distribution of FFAs from the cells to the extracellular medium demonstrated that MebetaCD sequesters FFAs. Although MebetaCD did not increase final cell concentrations and even had an adverse effect on growth at concentrations above 1 g l-1, it did (at 1 g l-1 extend the initial period of high growth rate leading to shorter cultivation times.

Relaxing effects of 15-lipoxygenase products of arachidonic acid on rat aorta.

In the presence of indomethacin, arachidonic acid relaxes precontracted rings of rat aorta only when the endothelium is intact. Arachidonate-induced, endothelium-dependent relaxation is potentiated by superoxide dismutase. In contrast, linoleic acid (LA) contracts endothelium-intact and -denuded rings. Arachidonate is metabolized in endothelial cells by both cyclo-oxygenase and 15-lipoxygenase. Therefore, we determined the vasodilatory effect of 15-lipoxygenase products. The products generated by soybean lipoxygenase (SLO) from arachidonate in the bioassay bath relax precontracted, de-endothelialized ring segments of rat aorta. This relaxation is potentiated by superoxide dismutase and is more prominent when high concentrations of SLO are used. The main metabolites recovered from the bioassay bath were 5,15-dihydroperoxyeicosatetraenoic acid and 8,15-dihydroperoxyeicosatetraenoic acid. At lower concentrations of SLO the degree of relaxation is less and the major product is 15-hydroperoxyeicosatetraenoic acid. LA is metabolized by SLO to 13-hydroperoxyoctadecadienoic acid. The relaxation induced by the incubation of LA with SLO in endothelium-denuded rings is less than that obtained with arachidonic acid. In endothelium-denuded rings that were precontracted with phenylephrine authentic 15-hydroperoxyeicosatetraenoic acid did not induce clear effect (at 40 microM 15-hydroperoxide caused relaxation, whereas at 15 microM induced small contraction) and 13-hydroperoxyoctadecadienoic acid of LA induced contraction. Neither 5,15-dihydroperoxyeicosatetraenoic acid nor 8,15-dihydroperoxyoctadecadienoic acid (1-15 microM) induced a well defined relaxation. This study indicates that arachidonic acid is metabolized by SLO to a vasodilatory compound(s) that is possibly derived from 15-hydroperoxyeicosatetraenoic acid.

The vasodilatation induced by hydroperoxy metabolites of arachidonic acid in the rat mesenteric and pulmonary circulation.

The effects of 15-hydroperoxy metabolites of arachidonic acid on vascular tone were evaluated in the perfused mesenteric preparation, the isolated perfused lung and segments of pulmonary arteries of the rat. In the mesenteric preparation, precontracted with phenylephrine, both 15-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE, ED50 1.6 nmol) and 8,15-dihydroperoxy-5,9,11,13-eicosatetraenoic acid (8,15-diHPETE, ED50 0.3 nmol) induced dose-dependent vasodilatation, whereas 5,15-diHPETE (0.2-100 nmol) had no effect. Prostacyclin (ED50 0.01 nmol) was, however, more potent than the hydroperoxides. In the rat isolated lung, precontracted with the stable thromboxane agonist U-46619, dose-dependent decrease in the perfusion pressure occurred with 15-HPETE(ED50 40 nmol), 5,15-diHPETE (ED50 30 nmol) and 8, 15-diHPETE (ED50 7 nmol) while 13-hydroperoxide of linoleic acid had no effect. Prostacyclin was 10 times more potent than 8, 15-diHPETE. The vasodilator effects were not affected by indomethacin. In both endothelium intact and denuded rat pulmonary arteries the hydroperoxides 15-HPETE, 8,15-diHPETE, and 5,15-diPETE induced dose-dependent relaxation. The hydroperoxide, 8,15-diHPETE was at least 3 times more potent than 15-HPETE or 5,15--diHPETE. The hydroperoxides had no effect on the basal tone of vessel segments and the relaxation induced by 15-HPETE was not attenuated by methylene blue (5 microM). These data indicate that 8,15-diHPETE may be a significant endothelium-independent vasodilator product of arachidonate lipoxygenation.

Characterization of DNA adenine methylation mutants of Escherichia coli K12.

The phenotypic traits of 7 independently isolated dam mutants of Escherichia coli have been examined. The mutant strains differ from the wildtype in the following respects: (1) decreased DNA adenine methylase activity in vivo and in vitro; (2) a 14--85-fold increase in spontaneous mutability; (3) decreased survival after ultraviolet irradiation; (4) a 10--21-fold increase in spontaneous induction of lambda phage from lysogens; (5) a 3--17-fold increase in the level of recombination; and (6) inviability of double mutants containing dam- and recB- or recC-. Unmethylated fd phage chromosomes are able to replicate normally in dam- mutants. A mutant strain in which the dcm gene is deleted is viable, showing that the dcm gene product is dispensible for growth.