Experimental researches on specific therapeutics. Lecture III, Chemo-therapeutic studies on trypanosomes / by Paul Ehrlich.

  • Paul Ehrlich
Date:
1907
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Licence: Public Domain Mark

Credit: Experimental researches on specific therapeutics. Lecture III, Chemo-therapeutic studies on trypanosomes / by Paul Ehrlich. Source: Wellcome Collection.

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    that this innocent substance might well be employed in the Tropics for the prophylaxis of human sleeping-sickness. As regards the second type of substances, belonging to the benzi- dine group, trypan-red is a cotton dye which shows the remarkable property of staining mice an intense red, which remains fast for months. I have also prepared a number of similar dyes belonging to the benzidine series, some of which possess an even more power- ful action than trypan-red. In several cases a blue dye belonging to the same group, which was prepared by Nicolle and Mesnil, has proved still more efficient. The value of arsenic acid which has for a long time been employed in the treatment of trypanosome diseases was first - recognised by Laveran. Later on it was discovered, at the Liver- pool School of Tropical Medicine, that atoxyl was a far more powerful substance. It is prepared by treating aniline with arsenic acid. The makers believe it to be an anilide of arsenic acid, 2.e., a compound in which the arsenic acid radical is supposed to be attached to the amido group in a similar manner as the acetic acid is present in acetanilide. Now, as you all know, the ammonia radical, which in aniline is very ready to react, has completely lost this property in acetanilide. ‘This latter body is in fact almost an indifferent compound. Similarly, by the view that atoxyl was the anilide of arsenic acid, any further development of this compound was rendered impossible. I was, however, able to prove, together with Dr. Bertheim, that this compound is to be regarded as some- thing entirely different, namely, that the amido group is quite free and that the arsenic acid radical is attached to the benzol ring in the para position. Atoxyl must, therefore, be regarded as the sodium salt of paramido-phenyl-arsenic acid. We have obtained a great number of substances derived from it, and have tested them therapeutically. Thus we found that, e.g., by the introduction of the acetyl radical into the amido group the acetyl-amido-phenyl-arsenic acid 1s produced, which is far less toxic for mice than atoxyl. By means of this substance it is even possible to solve one of the most difficult therapeutic problems imaginable. For mice that have been infected with our most viru- lent strains, and which, without treatment, would die within three days, can in two-thirds of the cases be saved by this substance if it is given twelve to fourteen hours before death. Such curative results have never yet been published; for in previous communica- 22500888830
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