Isolation of choline esters from aqueous solutions by extraction with sodium tetraphenylboron in organic solvents

Abstract

1. The method is based on the observation that choline esters and sodium tetraphenylboron (Kalignost) form complexes that are insoluble in water but soluble in organic solvents such as nitriles, higher ketones and benzyl alcohol. 2. The extraction procedure is an example of liquid cation exchange where tetraphenylboron is the cation-exchange group. 3. The proportion of choline esters extracted depends on the type and total amount of cation in the aqueous phase and the amount of sodium tetraphenylboron in the organic solvent. 4. The proportion of choline esters extracted is independent of the choline ester concentration, the pH (between 8 and 3) and the relative volumes of the two phases. 5. The affinity of sodium tetraphenylboron for choline esters increases with an increase in the size of the acyl group. 6. The choline ester extracted can be released into an aqueous solution by treatment with strong acids, silver salts and anion-exchange resins.

Characterisation and properties of a small cell lung cancer cell line and xenograft WX322 with marked sensitivity to alpha-interferon

“…The lysate was mixed with pyridoxal-5-phosphate (final concentration of 400 pM). Enzyme activity was measured as the rate of conversion of 3H L-3,4-dihydroxyphenylalanine to 3H L-dopamine and the 3H L-dopamine is separated from 3H L-3,4-dihydroxyphenylalanine by liquid cation exchange (Fonnum, 1969 The isoenzyme profile was determined electrophoretically using a kit (Cardiotrak-CK, Corning Diagnostics Ltd, Hal-stead, Essex). The relative amounts of the three isoenzymes was determined with a scanning fluorimeter (Helena Densitometer, Beaumont, Texas, USA).…”

Effects of Tri-, Di and Monobutyltin on Synaptic Parameters of the Cholinergic System in the Cerebral Cortex of Mice

“…A crude extract containing choline acetyltransferase (ChAT) was prepared by the method of Fonnum (14). The cerebral cortex was homogenized in 0.01 M potassium phosphate buffer (pH 6.3) that contained 1 mM ethylenediaminetetraacetic acid with a Biotron for 10 sec.…”

“…The supernatant was used as the preparation of ChAT. The activity of ChAT was determined by the method of Fonnum (14). The reaction mixture contained 0.01 ml buffer substrate (final concentrations of components: 20 mM sodium phosphate buffer, 0.1 mM choline chloride, 0.1 mM neostigmine bromide and 0.1 mM [14C]acetyl coenzyme A), 5 p1 of a solution of tributyltin, dibutyltin or monobutyltin and 5 pl of the preparation of ChAT.…”

Effects of triethyl lead on various cholinergic parameters in the rat brain in vitro.

“…Assay of choline acetyltransferase (ChAT) activity A preparation of ChAT was obtained by the method of Fonnum (17). The cerebral cortex of the rat was homogenized twice in 0.01 M potassium-phosphate buffer (pH 6.3, containing 1 mM EDTA) with a Biotron (Biotrona Switzerland, setting 10) for 10 sec.…”