Art. XXXII.—On the Extraction of the poisonous principle of the Tutu Plant (Coriaria ruscifolia.)
[Read before the Willington Philosophical Society, August 14, 1869.]
A Great many experiments have, from time to time, been made upon the Tutu plant, with the object of extracting the formidable poison known by sad experience to exist therein; but, as is well known, these attempts have been always unsuccessful, and have, besides, completely failed to discover anything at all definite as to the chemical or physical character of the poison.
Among these experiments is a series I made while connected with the Geological Survey Department of Otago, a notice of which appeared in the “Juror's Report for the New Zealand Exhibition of 1865,” the only result, however, being to prepare the way for future enquiry, which was promised at the time.
The Tutu plant does not grow in the neighbourhood of Wellington in any quantity, hence I have been greatly delayed in fulfilling my promise, much against my will; but recently a large quantity of the seed of this plant has been kindly presented to the Survey, for this particular purpose by Mr. H. H. Travers, and upon this I at once commenced operations.
The plan I adopted, was to separate, as well as I could, all the more immediate proximate constituents of the seed (in which the poison is known to exist), and to test each likely one by itself, in its effects upon the animal economy.
First, I extracted a portion of the finely-ground seed with cold water, and another portion with weakly acidified water, and treated them separately by a new process, now much in vogue, for the separation of alkaloids (Rogers and Girwood), all the evaporations being conducted at a temperature not exceeding 90°Fah.
The residuum from these processes was very small, and gave no indications of the presence of alkaloids to the proper tests; it consisted almost wholly of gummy matters.
The result seemed to dispose of all that was soluble in water or weak acids, and, to a certain extent, impugned the correctness of the general idea that this poison is of the nature of an alkaloid.
The part of the seed insoluble in these re-agents was next examined.
Alcohol was passed through this, repeatedly, and the extract evaporated, when a large quantity of a greenish-red coloured substance discovered itself; this treated with Ether separated into two parts, one a green-coloured oil, soluble therein; the other a resinous substance quite insoluble in this menstruum.
The resinoid substance was reserved for after-examination, and the oil at once tested in regard to its effects on the animal economy.
For this purpose, I administered about five minims of it to a full-grown cat, after a twelve-hours' fast; the oil acted as an emetic in a short time, and the greater portion of it was vomited. In half-an-hour, however, the animal showed signs of uneasiness and convulsive twitches of the ears and eyes, together with a forward jerking of the head, took place; also much frothing of the mouth, culminating in a convulsive fit, in about one hour after the dose was administered. After a little while this fit passed off, only the twitches and forward jerkings continuing; but a second very severe fit, of short duration, occurred in about one hour afterwards, after which the cat gradually rallied. These symptoms agreed generally with those exhibited by cattle and sheep, when poisoned by this plant.
Although I have made but one experiment, I think it will be allowed
that the result of this has fairly proved that the poison of the seed, and so, by a very proper inference, the poison of the plant generally, since I find an oily substance throughout it, exists in this oil, if it is not the oil itself. It therefore now only remains to be ascertained whether this oil is a single proximate substance, or a mixture or compound of such, and if the latter, which is, or which are, the active ones concerned in the production of these phenomena I have described. Unfortunately I had not sufficient of the oil to allow me to test this properly, but I am in hopes of having it by next autumn, as I have been promised a large quantity of these seeds from Taranaki.
The following are the characteristics of this oil, as ascertained up to the present time.
Somewhat viscid at common temperature, but flowing freely at a little above this; colour, pale-green; reaction, acid; taste, bland; burns away readily with much flame; scarcely volatile without decomposition; soluble in ether, alcohol, chloroform, and strong acetic acid; insoluble in hydrochloric or nitric acid; also insoluble in water; does not dry when long exposed to the air.
When boiled with solutions of the caustic alkalies there is much frothing, but only a portion of the oil dissolves, even when the boiling is continued for many hours; the portion dissolved was found to be saponified. The whole of the oil is, however, soluble in a cold alcoholic solution of potash, without yielding a precipitate when admixed with water; hence it is probable that all the acid portion of the oil is really saponifiable, that which was unsaponifiable, in the first instance, being a product of the metamorphosis of a portion of the normal oil by the process employed.
When the oil is heated to the decomposing point, a substance is given off having the pungent odour of acrolein, a substance characteristic of the the presence of glycerine, or oxide of lipyle the base of common fatty bodies.
Heated with caustic alkalies, either in the wet or the dry way, there are no alkaline vapours evolved, but in the latter case an odorous oil forms, probably, œnanthylic acid.
From the reaction of this oil, here described, it evidently belongs to the series of non-drying fixed oils; in its solubility in alcohol or acetic acid, it bears a remarkable resemblance to castor oil, the only other fixed oil, which I find to be wholly soluble in acetic acid. Now castor oil, it will be remembered, is a very peculiar oil: it does not contain any of the acids of the common oils or fats, but in place of them, two very singular acids, quite peculiar, I believe, to this variety of oil; hence I conceive that the acid part of this oil of Tutu to be also quite distinct from the ordinary fatty acids; to be in all probability, peculiar to it; and to one or more of these acids I should ascribe the poisonous effects of the oil.
If further experiments should confirm the correctness of the views here stated, this case will, I conceive, become invested with an interest beyond that immediately under our notice; since it will offer another instance in which a non-nitrogenous oily principle, is proved to affect the system like a neurotic poison; this class of poisons being almost always alkaloids, or at least nitrogenous substances.
Not it will be remembered there are several poisonous plants in Europe, which have, hitherto, refused to yield any pure poisonous principle to chemical processes, but then these processes have been, as a general rule, I believe, especially for the detection of alkaloids. With this case to point, therefore, it does seem in the highest degree probable, that in some of these cases, at least, the poisonous effects may be due to a non-nitrogenous oil, not yet isolated or examined. In view of this I have recommended the subject for examination
to a friend of mine residing in England, so that I expect in a few months to hear something more of this, or else to have selections of seeds, etc., from the plants I have named in my letter, so that I can enquire into this subject myself. *
With regard to antidotes for administration of animals, etc., poisoned with the Tutu plant, I should be inclined to think that in addition to emetics and purgatives, very dilute acids would be beneficial, since by preventing saponification of the oil, they would tend to keep it insoluble, and therefore inert.
As being somewhat related to the subject, I may state that the seed of the Karaka tree (Corynocarpus loevigata), which is also of a poisonous nature, has refused, in a similar manner, to yield any alkaloid to my processes, but it gives up an oil to alcohol, which resembles the above in some of its reactions. It seems to exercise a specific effect upon the animal economy, when administered in small doses, inducing at first, great uneasiness, and afterwards, restless, unwilling sleep, with sudden starting; unfortunately I had not sufficient of it to get any decisive results.
This oil is also soluble in alcohol acetic acid, ether, and in hydrochloric acid.
It is very bitter, and feebly soluble in water.
In one important respect it differs from the oil of Tutu; it evolves ammonia when boiled with potash, thus, in regard to its composition, allying itself to the alkaloids, though in its reactions apparently distinct.
[Footnote] * Since this paper was read, I learn from the “London Chemical News” for August 6, 1869, that M. Van Ankum has discovered the poisonous principle of the Cicuta virosa to be an essential oil, of formula, C10. H8. but “could not find any alkaloid in this plant at all.” This was one of the plants especially selected for examination in the communication alluded to.