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THE TOXICOLOGICAL IMPORTANCE OF PTOMAÏNES AND OTHER PUTREFACTIVE PRODUCTS.

BY

VICTOR C. VAUGHAN, M.D., PH.D.

PUTREFACTION consists of the splitting up of complex molecules into simpler ones by the agency of micro-organisms. Among those molecules which result from the action of bacteria, certain ones are basic in character. These are known as ptomaïnes. A ptomaïne may, therefore, be defined as a basic product of putrefaction, or a putrefactive alkaloid. Ptomaïnes have been called animal alkaloids, but this is a misnomer, because they may result from the putrefaction of vegetable as well as of animal substances. Besides, the term "animal alkaloid" is more strictly applicable to those basic substances which result from the chemical activity of the cells of the animal body wholly independent of bacterial agency. Like the vegetable alkaloids, ptomaïnes may be volatile or nonvolatile. All contain nitrogen; some contain oxygen, while others do not. The latter correspond to the volatile vegetable alkaloids, nicotine and coniine, and the former correspond to the fixed alkaloids.

Since all putrefaction is due to the action of bacteria, it follows that all ptomanïes result from the growth of these micro-organisms. The kind of ptomaïne formed will depend upon the individual bacterium engaged in its production, the nature of the material being acted upon, and the conditions under which the putrefaction proceeds, such as the temperature, amount of oxygen present, and the duration of the process. Generally speaking, in all toxicological research the tissue under examination has undergone putrefactive changes in the absence of air. Therefore those products which are formed by anaerobic bacteria are the ones which concern us especially. This fact seems to have been overlooked by the majority of toxicologists. Its importance is great, and it renders worthless the great number of experiments which have been made upon tissues allowed to decompose in the presence of an unlimited air-supply. Bacteria are always present in certain portions of the alimentary canal and in certain other cavities of the body. The death of the host does not mean the death of these bacteria. On the contrary, it enables them to extend their growth to adjacent tissues, until the whole of the cadaver may be involved.

Ptomaïnes are present probably to a greater or less extent in every organ which is submitted to the toxicologist for examination. If he be ignorant of the nature of these substances, he may mistake them for

vegetable alkaloids, and making this mistake, he may report a given poison present when it is not present, and thus lead to the conviction of an innocent person. This whole subject needs thorough study. It is a new line of work, which has not been followed to any great extent, and the amount of information which we have concerning these substances is very small and inadequate.

It must not be understood that basic substances are the only putrefactive products which may interfere with the tests for vegetable alkaloids. Other products of putrefaction besides those which are basic in character must also be taken into consideration; for instance, certain proteids, notably albumoses and peptones, are marked reducing agents, and give certain color reactions, such as the reduction of ferric salts, which may lead us into error. Then there are organic acids, some of which have been identified, while the nature of others remains undetermined, which may lead us into the same error. It is the purpose of this paper to point out the few facts which we do know concerning those putrefactive substances, which may seriously modify the tests which have heretofore been considered as positive.

THE PURITY OF REAGENTS.

One of the first things to be ascertained by the chemist who undertakes to do toxicological work is the purity of his reagents. Especially is this true in the employment of alkaloidal solvents. The writer has found a number of samples of German ether, which was imported on account of its supposed purity, to yield on spontaneous evaporation a residue which gave several of the alkaloidal reactions, and a few drops of which, injected under the skin of a frog, caused paralysis and death within a few hours. In the use of ether I would advise that 500 c.c. of this reagent be allowed to evaporate spontaneously, and the residue, if there be one, be examined both chemically and physiologically. The basic substance which is found in some samples of sulphuric ether is pyridine. Commercial alcohol almost invariably contains small quantities of an alkaloidal substance the odor of which is similar to that of nicotine and pyridine. Solutions of this substance are precipitated by gold chloride, phospho-wolframic acid, phospho-molybdic acid, potassium iodide, and Meyer's reagent, but not by platinum chloride or tannic acid. It does not reduce, or reduces feebly, ferric chloride. From one sample of alcohol Guareschi and Mosso obtained a base which, in addition to the above reactions, did give a precipitate with platinum chloride. Alcohol may be freed from these substances by distillation over tartaric acid. Chloroform sometimes leaves a marked residue on evaporation. When this is the case, the chloroform should be washed first with distilled water, then with distilled water rendered alkaline with potassium carbonate, then dried over calcium chloride, and distilled. Petroleum ether and benzole sometimes contain a base which has an odor similar to that of trimethylamine or pyridine, and which gives a precipitate with platinum chloride, crystallizing in octahedra. Of all the solvents used in the extraction of vegetable alkaloids, amylic alcohol is the one most likely to lead the chemist into serious error. This fact is due to two causes: in the first place, the amylic alcohol itself is very likely to contain impuri

ties-in one sample Haitinger found as much as .5 percent. of pyridine; the second source of danger in amylic alcohol lies in the fact that it is a ready solvent for many of the putrefactive alkaloids. For this reason the amylic alcohol residue is probably less suitable than any other for the application of color tests in the final identification of poisons. Amylic alcohol, when found to be impure, may be rectified in the same manner as recommended above for ethylic alcohol.

I will now give a brief account of those substances which have been found to resemble in their reactions the vegetable alkaloids.

CONIINE.

At present it is very difficult, probably impossible, for the chemist to state with absolute certainty that he has detected true coniine in the dead body. Before he can do this even with a reasonable degree of certainty, the symptoms and the post-mortem appearances must conform with those induced by the vegetable alkaloid, the analysis must be made before decomposition sets in, and the amount of the base found must be sufficient for physiological experiments to be made with it.

Brouardell and Boutmy found in the body of a woman who had died. after suffering from choleraic symptoms caused by eating of a stuffed goose, a base which gave the odor of coniine and the same reactions with gold chloride, iodine in potassium iodide, etc., as coniine. The same base was found in the remainder of the goose. This substance did not give the red coloration with the vapor of hydrochloric acid, and it did not form butyric acid on oxidation, and although it was poisonous it did not induce in frogs the symptoms of coniine poisoning. Selmi repeatedly found coniine-like substances in decomposing animal tissue. By distilling an alcoholic extract from a cadaver, acidifying the distillate with hydrochloric acid, evaporating, treating the residue with barium hydrate and ether, and allowing the ether to evaporate spontaneously, he obtained a residue of volatile bases, the greater part of which consisted of trimethylamine. After removing this base, the residue had the odor of the urine of the mouse. Later, Selmi obtained an unmistakable coniine odor from a chloroform extract of the viscera of a person who had been buried six months, and in another case ten months after burial. The chloroform residue was alkaline in reaction, and when dissolved in a few drops of water and allowed to evaporate on a glass plate it gave off such a penetrating odor that the chemist was compelled to withdraw from close proximity to the substance. The odor imparted to the hands. in testing the substance with the general alkaloidal reagents remained for half an hour. This volatile base seemed to be formed by the spontaneous decomposition of other ptomaïnes. An aqueous solution of a ptomaïne obtained by Selmi by extraction with ether according to the Stas-Otto method from the undecomposed parts of a cadaver had no marked odor, but after having been kept for a long time in a sealed tube, it not only gave off a marked coniine odor, but the vapor turned red litmus-paper blue. Selmi also obtained a ptomaïne from putrid egg albumen. After converting this base into a sulphate, and allowing it to stand, it formed in two layers, one of which was a golden yellow liquid; and this, on being treated with barium hydrate, gave off ammonia, and later the odor

of coniine. Finding that butyric and acetic acids were formed by the oxidation of this base, Selmi concluded that he had real coniine or methylconiine, and that it was formed by the oxidation of certain fixed ptomaïnes, or by the action of amido bases on volatile fatty acids. For these reasons Selmi believed in the bacterial origin of coniine or closely allied bases, also in the existence of a "cadaveric coniine."

In a criminal trial in east Prussia, Sonnenschein found a substance which he believed to be the alkaloid of the water-hemlock, but Otto, Husemann, and others believed it to be a cadaveric coniine. Otto says that the symptoms reported in the case were not those of either coniine or cicuta. This base was obtained six weeks after the exhuming of the body, which had been buried for three months. It had the odor of coniine, the taste of tobacco, and gave with potassium bichromate and sulphuric acid the odor of butyric acid, and behaved with reagents like coniine.

The most celebrated trial in which a putrefactive coniine has figured was the Brandes-Krebs investigation, which took place in Braunschweig in 1874. Two chemists obtained from the undecomposed parts of the body, in addition to arsenic, an alkaloid which they pronounced coniine. This substance was referred to Otto for further examination. He reported that it was neither coniine nor nicotine, nor any vegetable alkaloid with which he was acquainted. He converted the substance into an oxalate, dissolved it in alcohol, evaporated the alcohol, dissolved the residue in water, rendered the solution alkaline with potash, and extracted the base with petroleum ether. On evaporation of the petroleum ether the alkaloid appeared as a bright yellow oil, which had a strong, unpleas ant odor, quite different, however, from that of coniine. It was strongly alkaline, and had an intensely bitter taste. At ordinary temperature it was volatile. From its aqueous solutions it was precipitated by the chlorides of platinum, mercury, and gold. In these reactions it resembled nicotine, from which, however, it differed in the double refracting and crystalline character of its hydrochloride. With an ethereal solution of iodine this substance did not give the Roussin test for nicotine, but instead of the long, ruby-red crystals there appeared small darkgreen needle-shaped crystals. The substance was found to be highly poisonous. Seven centigrams injected subcutaneously into a large frog produced instantaneous death, and forty-four milligrams given to a pigeon caused a similar result. On account of its poisonous properties the jury of medical experts decided that the substance was a vegetable alkaloid. The reason for this decision certainly must now be regarded as wholly inadequate. We know that some of the most highly poisonous substances are found among putrefactive products.

In examining the stomach and intestines in a case of suspected poisoning, Liebermann found in the ether extract from alkaline solution a brownish, resinous mass, which dissolved in water to a turbid solution, the cloudiness increasing on heating. The aqueous, strongly alkaline solution of this substance gave the following reactions:

First, with tannic acid, a white precipitate.

Second, with potassium iodide, a yellow brown, turning to dark-brown precipitate.

Third, with chlorine water, a marked white cloudiness.

Fourth, with phospho-molybdic acid, a yellow precipitate.

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