Isolation of Histamine from the Pyloric Mucosa.

Abstract

Although histamine has been isolated from the intestinal mucosa, and from the combined gastric and intestinal mucosa, its isolation from the gastric mucosa alone has not been reported. This report deals with the isolation of the substance in crystalline form, from the pyloric mucosa of the hog, under conditions which preclude the possibility that it is present as a result of putrefaction. The material was obtained at the slaughter house within 30 minutes after the animal was killed. The mucosa was washed with water and immediately subjected to extraction by 1% sulfuric acid in 80% alcohol. Activated charcoal was added to the extract in sufficient quantity to remove all pigment, the extract filtered from the charcoal, and the histamine adsorbed on Lloyd's Reagent (hydrous aluminum silicate). The Lloyd's Reagent was then extracted with dilute aqueous ammonia, which liberated the histamine. The ammoniacal solution was evaporated to a small volume and mixed with 1 1/2 times its weight of anhydrous sodium carbonate. On standing overnight in a dessicator, this formed a dry cake. This was powdered and extracted with chloroform in a continuous extraction device, until fresh chloroform extracts no longer gave a Pauly reaction. The combined chloroform extracts were filtered from some gummy substance and extracted with a small amount of water. The aqueous extract was boiled to remove chloroform and volatile bases, and then submitted to fractional precipitation with silver nitrate and barium hydroxide, according to the method of Kutscher. The histamine was found in the fraction precipitated by silver in alkaline solution. The silver precipitate was decomposed with dilute hydrochloric acid and the solution evaporated to a small volume. On standing, a crystalline material separated. This was removed by filtration and the filtrate concentrated to a thin syrup.