The alkaloids of ergot. Pt. 2 / by George Barger and and Arthur James Ewins.

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

Licence: Public Domain Mark

Credit: The alkaloids of ergot. Pt. 2 / by George Barger and and Arthur James Ewins. Source: Wellcome Collection.

    4/14 (page 285)
    is an ethyl ester was shown by analysis, and especially by a deter¬ mination of the ethoxy-group by Zeisel’s method. It thus follows that ergotoxine contains a carboxyl group, and that ergotinine is its lactone (or lactam). In accordance with this view, ergotoxine is soluble in sodium hydroxide, but ergotinine is not, nor is the ester-base above referred to. Esterification probably takes place to some extent when ergotoxine is boiled with alcohol (in the absence of phosphoric acid). We have noticed repeatedly in converting ergotoxine into ergotinine by boiling with methyl alcohol (Kraft’s method) that the yield is far from quantitative; some of the ergotoxine is probably converted by this process into the very soluble ethyl ester, instead of the crystalline anhydride. It is, moreover, quite likely that ergotinine itself when boiled with alcohol forms ergotoxine ester to some extent; this behaviour would explain the loss of ergotoxine on recrystallisation which we our¬ selves and others (Tanret, Meulenhoff) have noticed. The fall in optical rotation shown by alcoholic ergotinine solutions, especially on boiling, is also probably due to the formation of an ergotoxine ester. Besides proving the presence of a carboxyl group in ergotoxine, we have been able to establish the presence of a somewhat larger and more characteristic fragment of the complicated molecule of the ergot alkaloids. On destructive distillation, both ergotoxine and ergotinine yield a small quantity of a crystalline substance, and this we have been able to identify as «'sobutyrylformamide, CHMe2*CO,CO*NH2. The yield of this substance is only 5 per cent, of the (very costly) alkaloid employed; as we had only a few decigrams of the substance at our disposal, its identification was somewhat troublesome, but was finally rendered certain by direct comparison with a specimen of isobutyrylformamide syn¬ thesised for the purpose. A ketonic amide of this type does not appear to have been previously obtained from a natural substance, and we are unable to suggest the mechanism of its formation from the ergot alkaloids. We do not think, however, that either of the oxygen atoms of the amide belongs to the carboxyl group which we have shown to be present in ergotoxine. If this be admitted, we have accounted for four out of the six oxygen atoms of that alkaloid (or three out of the five present in ergotinine). The two remaining oxygen atoms are not present as phenolic hydroxy- or methoxy-groups, because ergotinine is insoluble in sodium hydroxide, and when examined by Zeisel’s method yields a negative result. One of the nitrogen atoms probably has a methyl group attached to it, because some-