Isolation of the pressor principles of putrid meat / by George Barger and G.S. Walpole.

  • Barger, George, 1878-1939
Date:
[1909?]
Catalogue details

Licence: Public Domain Mark

Credit: Isolation of the pressor principles of putrid meat / by George Barger and G.S. Walpole. Source: Wellcome Collection.

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    steam, when it was found that the whole of the pressor substance had passed into the receiver. Identification of the second pressor principle. When the crude acid solution of the bases, after washing with chloroform, was made alkaline and distilled with steam until no more pressor principle passed over, the solution was still strongly active physiologically. The whole of the pressor base in the distillate could readily be extracted by chloroform, but the non-volatile portion could not be extracted at all by this solvent, nor by ether or ethyl acetate. In concentrated aqueous solution it was precipitated by phospho-tungstic acid, but scarcely at all by lead acetate or mercuric chloride. Its isola¬ tion became possible by the observation that it was readily removed by amyl alcohol from a solution containing a slight excess of sodium N carbonate, but not from a solution containing — sodium hydroxide, nor from an acid solution ; the substance was thus immediately characterised as a phenolic base. By washing the solution in sodium hydroxide with amyl alcohol, all other bases and the neutral substances were removed; the solution was then neutralised and again made alkaline with a slight excess of sodium carbonate. On extraction with amyl alcohol the pressor principle was now removed in a relatively pure condition. The amyl alcohol was removed by distillation in vacuo and steam distillation. As tyrosine is the only phenolic fission-product of protein, we suspected a relationship of the base to tyrosine, similar to that which we had already observed between the first pressor principle and leucine. In that case the second pressor principle would be 2>hydroxyphenylethyl- amine, formed from tyrosine by elimination of carbon dioxide. This hypothesis received support from the fact that the purified aqueous solu¬ tion of the base gave a strong Millon reaction. We therefore benzoylated the base according to Schotten- Baumann; after the benzoyl-derivative had been dried on a porous plate, it readily crystallised from alcohol in needles melting at 169°, which were found to be identical with dibenzoyl-^-hydroxyphenylethyl- amine, first prepared by Emerson1. On recrystallisation from alcohol the melting point was 170° (uncorr.) and was found to be identical with 1 lieitr. z. chem. Physiol, u. Pathol, i. p. 501. 1902. 23—3