The constitution of ergothioneine : a betaine related to histidine / by George Barger and Arthur James Ewins.

  • Barger, George, 1878-1939.
Date:
[between 1910 and 1919?]
Catalogue details

Licence: In copyright

Credit: The constitution of ergothioneine : a betaine related to histidine / by George Barger and Arthur James Ewins. Source: Wellcome Collection.

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    CCLVII.—The Constitution of Ergothioneine: a Betaine Related to Histidine. By George Barger and Arthur James Ewins. Two years ago Tanret (J. Pharm. Chim., 1909, [vi], 30, 145) isolated from ergot a new crystalline base containing sulphur, and having the formula 09H1502N3S. The description of the base given by Tanret suggested to us a possible relationship to the amino-acid histidine; thus ergothioneine, as the new base was called by Tanret, is precipitated by mercuric chloride, and forms a compound with silver. These properties, together with the large nitrogen content, were strongly suggestive of the presence of a glyoxaline ring. Since one of us in conjunction with H. H. Dale (Trans., 1910, 97, 2592) had already isolated another histidine derivative from ergot, namely, 4(or 5)-/3-aminoethylglyoxaline, a substance of great physiological activity and interest, we prepared a small quantity of ergothioneine according to Tanret’s method, and found that, like histidine and many other glyoxaline derivatives, it gives an intense red coloration with sodium ^-diazobenzenesulphonate, thus still further supporting our surmise with regard to the constitution of this base. Ergothioneine contains (in addition to the sulphur atom) three carbon atoms and six hydrogen atoms more than histidine. These might well result from the substitution of three hydrogen atoms of histidine by methyl groups in such a manner that ergothioneine would be a new member of the class of methylated amino-acids or betaines, of which a number of examples are now known to occur in plants. This hypothesis proved to be correct; the substance is indeed a betaine, and almost certainly /3-2-thiolglyoxaline-4(or 5)- propiobetaine (I). Like other betaines it has no marked physio¬ logical action. On boiling with a concentrated (50 per cent.) aqueous solution of potassium hydroxide, the base is decomposed quantitatively into