The alkaloids of ergot. [Pt. I] / by George Barger and Francis Howard Carr.

  • George Barger
Date:
1907
Catalogue details

Licence: In copyright

Credit: The alkaloids of ergot. [Pt. I] / by George Barger and Francis Howard Carr. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    In the course of a prolonged investigation of ergot we obtained the second amorphous alkaloid for the first time in a state of purity by crystallising its salts, and were thus able to distinguish it from ergotinine, which is itself crystalline but only yields amorphous salts. Moreover, the amorphous alkaloid is very soluble in alcohol, the crystalline only slightly so. As the second alkaloid is now also recognisable as a chemical individual, and as it has proved to be a substance of great physiological potency, we suggested for it the name ergotoxine in a preliminary communication to the British Association at York (Chem. News, 1906, 94, 89. See also Report of Brit. Med. Assoc. Meeting, Aug. 1906, in Brit. Med. J., Dec. 22nd, 1906, p. 1792). We found in ergotinine considerably more nitrogen than Tanret, and hence were unable to confirm his formula, Cs5H40O6N4. As we could not prepare any crystalline ergotinine salts we relied on determinations of the molecular weight of the free alkaloid by physical methods, which made us suggest the provisional formula, C28H3204lSr4. Our analysis of crystalline ergotoxine salts indicated a close relationship between the two alkaloids, and later we proved this relationship by converting ergotoxine into ergotinine by boiling with acetic anhydride ; we also obtained a crystalline phosphate closely resembling ergotoxine phosphate by boiling ergotinine with dilute alcoholic phosphoric acid. Soon after our preliminary note was published, there appeared an important paper by Kraft (Arch. Pharm., 1906, 244, 336), who was, in the first place, concerned with the examination of an ethereal extract of ergot. He lays stress on the following circumstances, which make the separation of the extract into its various constituents very troublesome : the presence of ergosterol and of fat, the feebly acidic nature of the acids, and the feebly basic nature of the alkaloids, the presence of phenolic hydroxyls in the latter giving them also acid properties. Although chemically rather inert, these colloidal bodies “ unite among themselves and with fat to form quite stable adsorption compounds.” It is, therefore, well nigh impossible to effect a quantitative separation of the alkaloidal from the acid constituents, for instance, by extraction with dilute acetic acid and with ammonia. Kraft concludes that the mere use of solvents and of fractional precipitation is worthless, and that for this reason the numerous ergot substances of Jacob j are but mixtures. At these conclusions we had ourselves arrived. Acid substances, such as sphacelotoxin, owe their physiological activity to contamina- tion with a powerfully active alkaloid, and we agree with Kraft in emphasising the physiological importance of the alkaloidal as opposed to the acidic constituents of ergot. Without knowledge of our work, Kraft prepared the amorphous alkaloid by fractional precipitation of the sulphate and observed its conversion into ergotinine, his method
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