Measuring Brain Uptake and Incorporation into Brain Phosphatidylinositol of Plasma myo-[2H6]Inositol in Unanesthetized Rats: An Approach to Estimate In vivo Brain Phosphatidylinositol Turnover

The in vivo rate of turnover of phosphatidylinositol (PtdIns) in brain is not known. In brain, certain receptor-mediated signal transduction involves metabolism of PtdIns and a method to measure its turnover in awake animals is useful in studying the effect of lithium and other therapeutic agents. In a method described here, rats were infused subcutaneously with myo-[²H₆]inositol (Ins*) using an osmotic pump and, at 1 and 8 weeks, concentrations of free myo-inositol (Ins) and Ins* in plasma and brain were measured by GC-MS (chemical ionization). Also, PtdIns and PtdIns* together in brain were isolated, and Ins and Ins* from their headgroups were released enzymatically and specific activity of incorporated inositol was measured. The specific activity of inositol reached a steady state in plasma within 1 week of infusion, but not in brain even at 8 weeks. However, in brain, the specific activity of phosphatidylinositol was same as that of inositol at both time-points, suggestive of fast turnover of PtdIns. The animal experiment and the analytical methodology described here should be useful for measuring the rate of turnover of brain PtdIns in pathological and drug treatment conditions.     

Incorporation of label from d-β-hydroxy-[14C]butyrate and [3-14C]acetoacetate into amino acids in rat brain in vivo

The metabolism of ketone bodies by rat brain was studied in vivo. Rats starved for 48h were given either d-beta-hydroxy[3-(14)C]butyrate or [3-(14)C]acetoacetate by intravenous injection and killed after 3 or 10min. Total radioactivity in the acid-soluble material of the brain and the specific radioactivities of the brain amino acids glutamate, glutamine, aspartate and gamma-aminobutyrate were determined. A group of fed animals were also given d-beta-hydroxy[3-(14)C]butyrate. In the brains of all animals (14)C was present in the acid-soluble material and the specific radioactivity of glutamate was greater than that of glutamine.     

Incorporation of dl-[2-14C]mevalonic acid lactone into β-carotene and the phytol side chain of chlorophyll in cotyledons of four species of pine seedlings

1. The incorporation of dl-[2-(14)C]mevalonic acid lactone into beta-carotene and the phytol side chain of chlorophyll has been investigated in cotyledons of four species of pine seedlings (Pinus silvestris, P. contorta, P. radiata and P. jeffrei) grown in darkness and in light. 2. The relative incorporation of label into beta-carotene and the phytol side chain of chlorophyll is similar to that observed in experiments on monocotyledons and dicotyledons. 3. The relative incorporation of (14)CO(2) into beta-carotene and phytol is much higher than the incorporation of [2-(14)C]mevalonic acid.     

Synthesis,biological evaluation and molecular docking study of N-arylbenzo[d]oxazol-2-amines as potential α-glucosidase inhibitors

A novel series of N-arylbenzo[d]oxazol-2-amines (4a–4m) were synthesized and evaluated for their α-glucosidase inhibitory activity. Compounds 4f–4i, 4k and 4m displayed potent inhibitory activity against α-glucosidase with IC₅₀ values in the range of 32.49 ± 0.17–120.24 ± 0.51 μM as compared to the standard drug acarbose. Among all tested compounds, compound 4g having 4-phenoxy substitution at the phenyl ring was found to be the most active inhibitor of α-glucosidase with an IC₅₀ value of 32.49 ± 0.17 μM. Analysis of the kinetics of enzyme inhibition indicated that compound 4g is a noncompetitive inhibitor of α-glucosidase with a K_i value of 31.33 μM. Binding interaction of compound 4g with α-glucosidase was explored by molecular docking simulation.     

Acute effects of sodium valproate and γ-vinyl gaba on regional amino acid metabolism in the rat brain: Incorporation of 2-[14C]glucose into amino acids

Amino acid concentrations have been determined in rat brain regions (cortex, striatum, cerebellum, and hippocampus) by HPLC after administration of acute anticonvulsant doses of sodium valproate (400 mg/kg, i.p.) and -vinyl-GABA (1g/kg, i.p.). After valproate administration the GABA level increases only in the cortex; aspartic acid concentration decreases in the cortex and hippocampus, and glutamic acid decreases in the hippocampus and striatum and increases in the cortex and cerebellum. There are no changes in the concentrations of glutamine, taurine, glycine, serine, and alanine following valproate administration. Only the GABA level increases in all the regions after -vinyl-GABA administration. Cortical analyses 2, 4 and 10 minutes after pulse labeling with 2-[¹⁴C]glucose, i.v., shown no change in the rate of cortical glucose utilization in the valproate treated group. The rate of labeling of glutamic acid is also unchanged, but the rate of labeling of GABA is reduced following valproate administration. After -vinyl-GABA administration there is no change in the rate of labeling of GABA. These biochemical findings can be interpreted in terms of a primary anticonvulsant action of valproate on membrane receptors with secondary effects on the metabolism of amino acid neurotransmitters. This contrasts with the primary action of -vinyl-GABA on GABA-transaminase activity.This paper is dedicated to Dr. Derek Richter on his sevety-fifth birthday     

Dietary α-Linolenic Acid Increases the Biosynthesis of the Choline Glycerophospholipids from [14C]CDPcholine in Rat Liver and Kidney But Not in Brain

The effect of feeding rats for 30 days with diets containing high levels of linoleic acid (sunflower oil, SO) or -linolenic acid (perilla oil, PO) was studied in the liver, kidney and brain. The PO group showed a higher labeling of choline glycerophospholipids (CGP) in liver and kidney but no difference with the SO group in ethanolamine glycerophospholipids (EGP) labeling. The brain displayed the lowest incorporation of both precursors and no difference between the two diets. Analyses of brain CGP and EGP fatty acid compositions showed that in the PO group the ratio n-6/n-3 was lower than in the SO group, mainly as a consequence of lower levels of n-6 fatty acids. The mole % of docosahexaenoate (DHA) in these lipids was the same for both groups and only triacylglycerols (TAG) displayed a higher DHA. Therefore, at least in the brain, the magnitude of fatty acid changes observed in CGP and EGP for the PO group does not affect the uptake/incorporation of the precursors into phospholipids.     

Incorporation of [2-14C,(5R)-5-3H1]mevalonic acid into cholesterol by a rat liver homogenate and into β-sitosterol and 28-isofucosterol by Larix decidua leaves

1. Incubation of a rat liver homogenate with 3R-[2-(14)C,(5R)-5-(3)H(1)]mevalonic acid gave cholesterol with (3)H/(14)C atomic ratio 6:5. 2. Conversion of the labelled cholesterol into 3beta-acetoxy-6-nitrocholest-5-ene or cholest-4-ene-3,6-dione resulted in the loss of one tritium atom from C-6. 3. These results show that during cholesterol biosynthesis the 6alpha-hydrogen atom of a precursor sterol is eliminated during formation of the C-5-C-6 double bond. 4. Incorporation of 3R-[2-(14)C,(5R)-5-(3)H(1)]mevalonic acid into the sterols of larch (Larix decidua) leaves gave labelled cycloartenol and beta-sitosterol with (3)H/(14)C atomic ratios 6:6 and 6:5 respectively. 5. One tritium atom was lost from C-6 on conversion of the labelled beta-sitosterol into either 3beta-acetoxy-6-nitrostigmast-5-ene or stigmast-4-ene-3,6-dione, demonstrating that formation of the C-5-C-6 double bond of phytosterols also involves the elimination of the 6alpha-hydrogen atom of a precursor sterol. 6. The 3R-[2-(14)C,(5R)-5-(3)H(1)]mevalonic acid was also incorporated by larch (L. decidua) leaves into a sterol that co-chromatographed with 28-isofucosterol. Confirmation that the radioactivity was associated with 28-isofucosterol was obtained by co-crystallization with carrier 28-isofucosterol and ozonolysis of the acetate to give radioactively labelled 24-oxocholesteryl acetate. 7. The significance of these results to phytosterol biosynthesis is discussed.     

Synthesis, cytotoxic activities and cell cycle arrest profiles of naphtho[2,1-α]pyrrolo[3,4-c]carbazole-5,7(6H,12H)-dione glycosides

Naphtho[2,1-α]pyrrolo[3,4-c]carbazole-5,7(6H,12H)-dione (NPCD) is known to be a very potent and selective cyclin D1-CDK4 inhibitors and could induce strong G1 phase arrest in breast tumor cell lines. In this work, the synthesis of five NPCD glycosides and their cytotoxic activities against eight tumor cell lines are presented, as well as the investigation of their cell cycle arrest profiles. The results showed that the introduction of a sugar moiety onto NPCD did not affect much of their cytotoxic activities, while the subtle structure of the sugar moiety affected the underlying mechanism strongly. In addition, NPCD showed distinct cell-cycle arrest profiles in BxPC3 prostate cells and MCF-7 breast cells, while NPCD glycosides shared similar cell cycle arrest profiles in MCF-7 and BxPC3 cells, which also indicated that not only the indolocarbazole framework as well known before but the sugar moiety can have a profound impact on the mechanism of action for these types of compounds.     

Synthesis of 1,3,4,6-tetra-O-acetyl-2-[3-alkyl-(aryl)-thioreido]-2-deoxy-α-d-glucopyranoses and their transformation into 2-alkyl(aryl)amino-(1,2-dideoxy-α-d-glucopyrano)[2,1-d]-2-thiazolines

1,3,4,6-Tetra-O-acetyl-2-deoxy-2-isothiocyanato-α-d-glucopyranose, produced from 1,3,4,6-tetra-O-acetyl-2-amino-2-deoxy-α-d-glucopyranose hydrochloride, thiophosgene, and calcium carbonate, was condensed with alkyl- and aryl-amines in ether to afford the crystalline 1,3,4,6-tetra-O-acetyl-2-[3-alkyl(aryl)-thioureido]-2-deoxy-α-d-glucopyranoses (2). Compounds 2 and the β anomers 3 were converted in high yield into 2-alkyl(aryl)amino-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-d-glucopyrano)[2,1-d]-2-thiazoline hydrobromides (4) by hydrogen bromide-promoted cyclisation. The O-deacetylated thiazoline hydrobromide 5 was also isolated and converted into 2-[N-(4-methoxyphenyl)acetamido]-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-d-glucopyrano)[2,1-d]-2-thiazoline (8). Conformational studies of 4 and 8 were made by ¹H-n.m.r. spectroscopy.     

A Synthesis of the Potent A2 Selective Adenosine Agonist N6-[2-(3,5-Dimethoxyphenyl)-2-(2-Methylphenyl)Ethyl]Adenosine,and Its 5′-N-Ethyl Ribofuranuronamide Derivative

Abstract

A detailed experimental procedure for the synthesis and resolution of 2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)ethylamine, and its conversion into the titled adenosine reference agonists is given.     

Relation among the 2:2-, 1:1- and 1:2-type complexes of hafnium(IV)/zirconium(IV) with mono-lacunary α2-Dawson polyoxometalate ligands: Synthesis and structure of the 2:2-type complexes [{α2-P2W17O61M(μ-OH)(H2O)}2] (M = Hf, Zr)

The synthesis and characterization of di-nuclear Hf^IV and Zr^IV complexes (the Dawson 2:2-type complexes) sandwiched between 2 mono-lacunary α₂-Dawson polyoxometalate (POM) ligands, i.e., (Me₂NH₂)₁₄[{α₂-P₂W₁₇O₆₁Hf(μ-OH)(H₂O)}₂]·17H₂O (Me₂NH₂-1) and (Me₂NH₂)₁₄[{α₂-P₂W₁₇O₆₁Zr(μ-OH)(H₂O)}₂]·16H₂O (Me₂NH₂-2) are described. [Note: the moieties of their polyoxoanions are abbreviated simply as 1 and 2, respectively.] A pair of Hf^IV- and Zr^IV-containing POMs belonging to the same family were herein isolated as dimethylammonium salts and were unambiguously characterized by complete elemental analysis, in addition to potassium analysis, TG/DTA, FTIR, single-crystal X-ray structure analysis, and solid-state (³¹P CPMAS) and solution (³¹P and ¹⁸³W) NMR spectroscopy. Polyoxoanions 1 and 2 were isostructural with each other. The central [M₂(μ-OH)₂(H₂O)₂]⁶⁺ (M = Hf, Zr) cation unit was composed of 2 polyhedral M units, which were linked through 2 μ-OH groups and contained 1 water molecule coordinated to each metal center. Since the mono-lacunary Dawson POM acts as an oxygen-donor quadridentate ligand, the Hf and Zr centers are 7-coordinate. The Dawson 2:2-type complexes were converted to the Dawson 1:2-type complexes [M(α₂-P₂W₁₇O₆₁)₂]¹⁶⁻ (M = Hf, Zr), or vice versa, in solution under appropriate conditions. Also, the Dawson 2:2-type complex can be reversibly converted to the 1:1-type complex under the pH-dependent conditions. The Dawson 2:2-type POMs 1 and 2 can be compared with the recently reported, Keggin 2:2-type POMs, i.e., [M₂(μ-OH)₂(H₂O)₂]⁶⁺ (M = Hf, Zr) complexes sandwiched between 2 mono-lacunary α-Keggin POM ligands.