Some new physiologically active derivatives of choline / by A.J. Ewins.

  • Ewins, Arthur James.
Date:
[1914?]
Catalogue details

Licence: In copyright

Credit: Some new physiologically active derivatives of choline / by A.J. Ewins. Source: Wellcome Collection.

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    XLII. SOME NEW PHYSIOLOGICALLY ACTIVE DERIVATIVES OF CHOLINE. By ARTHUR JAMES EWINS. [From the Wellcome Physiological Research Laboratories, Herne Hill, S.E.) (.Received July 10th, 1911/,.) A short time ago I described [Ewins, 1914, 1] the isolation from extract of ergot, of a new active principle which was identified as acetyl-choline. The action of this base was shown by Dale [1914] to be closely related to that of muscarine, the active principle of the fungus Amanita muscaria, to which Harnack [1875] assigned the formula C5H1503N, and suggested that it was an oxidation product of choline. “ Synthetic ” muscarine (pseudo-muscarine), originally obtained by Schmiedeberg and Harnack [1877], and considered by them to be identical with muscarine, but shown bv later observers to differ from natural muscarine in physiological action, I have recently shown to be the choline ester of nitrous acid [Ewins, 1914, 2]. The constitution of the natural muscarine, however, still remained (and remains) unsolved, but from the fact that acetyl-choline and pseudo-muscarine, both of which are choline esters, very closely resemble the natural base in physiological action, we were led to suppose that muscarine might also be an ester of choline. Some support was given to this idea when we found that the nitric acid ester of choline, originally prepared by Schmidt and Wagner [1904], still more closely resembled muscarine in its action. It was found, however, that the action of extracts of Amanita muscaria was not appreciably lessened by boiling with dilute acid or alkali, so that it seems highly improbable that the natural base is a choline ester. Since the amount of Amanita muscaria1 at our disposal was too small to admit of isolation of the natural base in a state of purity, or in any quantity, 1 For an extract of Amanita muscaria we are indebted to Dr 0. Rosenheim, and for a quantity of dried material to Prof. W. Wiechowski, to both of whom we wish to render our best thanks.