Duncan R. Rae

The glycine neurotransmitter transporter GLYT1 is an organic osmolyte transporter regulating cell volume in cleavage-stage embryos

Cells subjected to sustained high osmolarity almost universally respond by accumulating compatible organic osmolytes that, in contrast to inorganic ions, are not deleterious even at high intracellular concentrations. Their accumulation from the external environment by known organic osmolyte transporters, such as the four identified in mammals, occurs only slowly in response to sustained high osmolarity, by synthesis of new transporter proteins. Most cells, however, are not subject to high or varying osmolarity, and it is not clear whether organic osmolytes are generally required at normal osmolarities or how they are regulated. The fertilized egg of the mouse is protected in the oviduct from perturbations in osmolarity. However, deleterious effects of osmotic stress were evident in vitro even at normal oviductal osmolarity. Glycine was found to protect development, indicating that early mouse embryos may use glycine as an organic osmolyte at physiological osmolarity. We have now found that GLYT1, a glycine transporter of the neurotransmitter transporter gene family, functions as the organic osmolyte transporter that mediates the osmotically regulated accumulation of glycine and regulates cell volume in early embryos. Furthermore, osmotic stimulation of GLYT1 transport was immediate, without a requirement for protein synthesis, implying regulation different from known organic osmolyte transporters. Thus, GLYT1 appears to have a previously unidentified role as an organic osmolyte transporter that functions in acute organic osmolyte and volume homeostasis near normal osmolarity.

Discovery and SAR of org 24598-a selective glycine uptake inhibitor.

The discovery of Org 24598, one of the first potent and selective inhibitors of the glycine transporter is discussed. In vitro structure-activity relationships (SARs) data for interaction of a ligand with this system is discussed.

Synthesis and muscarinic activities of 3-(pyrazolyl)-1,2,5,6-tetrahydropyridine derivatives

A series of 3-(pyrazolyl)-1,2,5,6-tetrahydropyridine derivatives (B) was synthesized and tested for muscarinic activity in receptor binding assays using [3H]-oxotremorine-M (3H-OXO-M) and [3H]-pirenzepine (3H-PZ) as ligands. Potential muscarinic agonistic or antagonistic properties of the compounds were determined using binding studies measuring their potencies to inhibit the binding of 3H-OXO-M and 3H-PZ. Preferential inhibition of 3H-OXO-M binding was used as an indicator for potential muscarinic agonistic properties; this potential was confirmed in functional studies on isolated organs. All compounds with agonistic properties showed 3H-PZ/3H-OXO-M potency ratios in excess of 20. In contrast, for antagonists this ratio was found to be close to unity. Mono-halogenation resulted in compounds (4b and 4d) with M3 agonistic properties as shown by their atropine sensitive stimulant properties in the guinea pig ileum, but with very little or no M1 activity. Some minor in vivo effects were observed for both these compounds, with the iodinated compound 4d inducing salivation. Compound 4d also showed some positive mnemonic properties in rats where spatial short-term memory had been compromised by temporary cholinergic depletion. These data indicate that some M3 agonism may be desired in therapeutic agents aimed at the treatment of the cognitive deficits of Alzheimers disease patients.

Preparation and decomposition of some steroidal 4′β,5′-dihydro-[17α,16-c]pyrazoles

Reaction of a series of aliphatic diazo-compounds with Δ16-20-oxo-steroids has given the corresponding 4′,5′-dihydro-[17α,16α-c]pyrazoles ([17α,16α-c]pyrazolines). Pyrolysis of the pyrazolines gave in the cases where the substituent on the heterocyclic ring is unsaturated, the 1′β,3′-dihydrocyclopropa[16,17α]-compounds (8) and (9). Pyrolysis of the pyrazolines with a saturated substituent on the heterocyclic ring gave a mixture of the Δ16-16-alkyl- and the 1′β,3′-dihydrocyclopropa[16,17α]-compounds. Photolytic decomposition of the pyrazolines gave only the cyclopropa[16α,17α]-compounds.

11-(Tetrahydro-3 and 4-pyridinyl)dibenzo[b,e][1,4]diazepines undergo novel rearrangements on treatment with concentrated HBr

Abstract 11-(1,2,5,6-Tetrahydro-1-methyl-3-pyridinyl)-5-methyl-5 H -dibenzo[ b , e ][1,4]diazepine on heating in conc. HBr afforded trans -5-(2-aminophenyl)-1,3,4,4a,5,10a-hexahydro-2-methylbenzo[ b ][1,6]naphthyridin-10(2 H )-one in one step. The isomer 11-(1,2,5,6-tetrahydro-1-methyl-4-pyridinyl)-5-methyl-5 H -dibenzo[ b , e ][1,4]diazepine underwent a novel rearrangement resulting in the pentacycle, 4-amino-5,13-diaza-13-methyl-bicyclo[3.3.1]nonan[6,7,8- k , l ]acridine.

Reactions of steroidal ketones with diazocyclopropane

Diazocyclopropane reacts with pregn-4-ene-3,20-dione (7) to give a ring expansion product, spiro[cyclopropane-1,4′-A-homopregn-4a′-ene]-3′,20′-dione, and further reaction of this compound occurs with an excess of diazocyclopropane to give several cyclobutanone derivatives. Diazocyclopropane reacts with cholestan-3-one to give mainly cyclobutane derivatives, and with two pregnan-20-ones to give only cyclobutanone products. 20-Oxo-groups with electronegative substituents at C-17 react with diazocyclopropane to give only 20-spirocyclopropane derivatives.

Synthesis of 1-amino-1,2,3,14b-tetrahydro-4H-pyrido[1,2-d]-dibenzo[b,f][1,4]oxazepine and related compounds

The synthesis is described of the epimeric 1-amino-1,2,3,14b-tetrahydro-4H-pyrido [1,2-d]dibenzo [b,f][1,4]oxazepines 2 and their N-substituted analogues. The cis-amines 33, 36 and 38 were prepared from the ketone 31 by reduction of the corresponding oxime whereas the trans isomers 12, 50 and 51 were prepared from the 1-ethoxycarbonyl derivative 44 by Curtius degradation. Attempts to convert the trans alcohol 7 into the epimeric azido compound by an SN2 replacement reaction with sodium azide resulted in rearrangement to give the novel ring system, 14-azido-11-methoxy-1,2,14,14a-tetrahydro-4H-pyrrolo [1,2-d] dibenzo [b,g][1,4] oxazocine 24 instead of the titled compounds.

5,9-Methanobenzoannulenamines. Part 1. Improved synthesis of 11-amino-5,9-methanobenzo[8]annulenes

Reaction of 1-(3,4-dihydronapthalen-2-yl)pyrrolidine with acrylaldehyde gave an epimeric mixture of 8-hydroxy-5,6,7,8,9,10-hexahydro-5,9-methanobenzo[8]annulen-11-ones which was used for the synthesis of several 11 -amino derivatives.

Reaction of diazocyclopropane with steroidal 16-bromo-17-ketones

The reaction of diazocyclopropane with both 16α- and 16β-bromo-3β-acetoxy-5β-androstane-11,17-dione has been found to give a mixture of the four possible 16-bromo-17-spiro-oxirans (4a), (4b), (5a), and (5b), of which (17R)-3β-acetoxy-16α-bromodispiro[5β-androstane-17,2′-oxiran-3′,1″-cyclopropane]-11-one (5a) was found to be the major isomer. Rearrangements of these spiro-oxirans by boron trifluoride to give 17-spirocyclobutanones are described. Mechanisms of both reactions are discussed.