First Meeting: Tuesday, 11th May, 1909.
Professor James Park, President, in the chair.
The following new members have been elected since the last meeting: Messrs. Charles E. Clarke, Henry Guthrie, J. C. Marshall, J. A. Fitzgerald, J. G. Paterson, M.A., M.Sc.
Two new members, duly proposed and seconded, were now elected—Messrs. Edward F. Roberts and David Miller.
An original paper, by Bernard Cracroft Aston, F.C.S., communicated by G. M. Thomson, F.L.S.—“The Alkaloids of the Pukatea”*—was laid on the table for publication in the Transactions.
The pukatea (Laurelia novæ-zealandiæ) is one of the most characteristic trees of the northern part of New Zealand, and belongs to the Monimiaceæ, a small family best represented in the tropics. The genus is confined to South America and New Zealand.
Attention was first drawn by the author (New Zealand Department of Agriculture Report, 1901, p. 284) to the occurrence of alkaloids in the tree; and the peculiar property possessed by the bark of causing, when chewed, a tingling sensation on the tongue was traced to an alkaloid of definite melting-point. More recently the investigation of the bark has been continued. It has been found that the alkaloid, melting at 200o C., for which the name “pukateme” is proposed, has the composition and molecular weight corresponding to the formula C17H17NO3. At least one other alkaloid is present in mother liquors obtained in the extraction of pukateine. Pukateine hydrochloride is only mildly toxic.
Fresh bark weighing 75 kilos (166 lb.) from trees in the Marlborough Sounds, collected in July, was reduced to a fine pulp and steeped in alcohol containing 0.5 per cent. of acetic acid. By three similar treatments 21.75 gallons of alcoholic extract were obtained. From the cooled and filtered hot aqueous extract of the alcoholic residue the pukateine was obtained by shaking the acid extract with chloroform. The chloroformic residue yielded the alkaloid in white prisms on the addition of a little alcohol.
A sample of the crushed bark was found to contain 0.7 per cent. of approximately pure pukateine—a yield not realised on a large scale, as only 64 grams of the alkaloid were obtained from the 166 lb. of bark. The content of alkaloid in the bark appeared to vary at different times of the year. If the bark is allowed to stand in a dry room some months before extraction the yield is very small.
Pukateine is a white crystalline alkaloid, melting at 200o C. (uncorr.), insoluble in water, sparingly soluble in light petroleum, more soluble in ether, and absolute in alcohol. The freshly precipitated base is very soluble in ether and chloroform. Pukateine is precipitated from its solution in slight excess of acetic acid by iodine in potassic iodide,
[Footnote] * The full details of the research may be found in the annual reports of the Department of Agriculture for 1907 (p. 31) and 1908 (p. 224), and in the forthcoming volume of the Australasian Association for the Advancement of Science (Brisbane meeting)
picric acid, auric chloride, platinic chloride, bromine water, ammonia, sodic bicarbonate, Mayer's reagent, disodic hydric phosphate, and phospho-molybdic acid. It is soluble in caustic alkali solutions, and is precipitated on passing a current of CO2 gas through the solution.
Analyses of five preparations of pukateine were made, which agreed within the limits of experimental error with the formula C17H17NO3, requiring—
Molecular weight determinations by the melting-point method in phenol gave numbers between 277 and 303, which accords well with the theoretical number 283. Titration values and chlorine estimation of the hydrochloride showed that the formula of the crystalline hydrochloride, after drying at 50o under diminshed pressure, was C17H17NO3HCl. Analyses of the crystalline platinum salt agreed with the formula (C17H17NO3)2PtCl6.
Action of Concentrated Sulphuric Acid.
Pukateine dissolves slowly when macerated with concentrated sulphuric acid in the cold, and on diluting the syrupy solution with water an intensely insoluble amorphous white compound is formed, which up to the present has baffled all attempts to dissolve or crystallize it. It contains nitrogen. With gentle heating, sulphuric acid will produce a dull violet colour with pukateine.
Action of Hydrochloric Acid in a Sealed Tube.
A gram of the base was heated in a sealed tube for three hours at 110o with 5 c.c. of concentrated hydrochloric acid. On opening the tube there was no pressure. The product had a glassy appearance, and its product was pure white. It was insoluble in alcohol, ether, glacial acetic acid, aniline, pyridine, acetone, or ammonia. On washing with hydrochloric acid no pukateine could be recovered. The substance does not melt below 240o C. It is probably the same as is formed by sulphuric acid, and contains nitrogen.
A gram of the base heated with 10 c.c. of water in a sealed tube for two hours at 140o remained unchanged.
Colour Reactions of Pukateine.
If a solution of bichromate of potash in concentrated sulphuric acid, prepared as for the strychnine reaction, be brought into contact in not too great an excess with a few crystals of pukateine, a persistent purple coloration is produced. If excess of the reagent be applied, a greenish colour merely results. The colour which the reagent gives with strychnine cannot be confused with that given with pukateine. The former is a bright violet, quickly changing to purple, and finally to a bright red. At one stage the purple colour of the strychnine reaction closely resembles that of pukateine, but the ephemeral nature of the one precludes confusion with the other. Concentrated nitric acid dissolves pukateine, with the formation of a dark-red colour closely resembling that given by morphine.
If one drop of a very dilute solution of potassium nitrite be added to a solution of pukateine in slight excess of sulphuric acid, a dark red-brown or greenish solution is developed. The base remains unchanged in dilute sulphuric-acid solutions.
Pukateine is soluble in caustic-soda solutions, and on concentrating the solution by boiling the pure base crystallized out in characteristic prisms, melting at 200o C. If a solution of pukateine in soda be allowed to stand in an open test-tube for a few hours the solution becomes greenish, and upon acidifying with hydrochloric acid the colouring matter may be extracted by ether, forming a purple solution. The experiment was repeated on the purest pukateine recrystallised from soda solution. The amount of colouring-matter formed is too small to examine.
100 grams boiling alcohol dissolve 4.17 grams pukateine.
100 grams alcohol at 175o dissolve 1.10 grams pukateine.
100 grams boiling ether dissolve 0.84 grams pukateine.
100 grams ether at 17o dissolve 0.62 grams pukateine.
Dry Distillation of the Base.
On heating pukateine to redness with soda lime, ammonia and unrecognisable fumes are given off. On heating with zinc-dust no smell of quinoline or pyridine could be detected.
Pukateine, examined by Zeisel's method for meth-oxy groups, gives negative results.
Pukateine dissolved in pyridine, when treated with benzoyl chloride, gives a compound which is under investigation.
Pukateine in solution in glacial acetic acid is easily nitrated by the cautious addition of a few drops of concentrated nitric acid. The nitro-derivative has strongly acidic functions, and dissolves in alkalis to an orange-red solution.
Chloroform extracts from the neutralised alcoholic extracts a rubbery mass, which, on treatment with dilute sulphuric acid, yielded a crystalline salt of another alkaloid, of which but a small quantity has been prepared. The sulphate dissolves to a darkbrown or yellow solution in hot water, recrystallizing on cooling, melts between –110o C., turns pink on exposure to light, and gives the characteristic reactions with alkaloid reagents. Concentrated sulphuric acid dissolves this alkaloid with the production of a beautiful nickel-green colour, which turns to a rose colour on standing. The name “laureline” is proposed for this alkaloid.
Professor John Malcolm, of Dunedin, is investigating the pharmacology of the alkaloids of the pukatea, and furnishes the following preliminary note:—
Pukateine itself is apparently inactive, due probably to its insolubility. The hydrochloride is very soluble, and shows some of the typical actions of the alkaloids in general.
Like strychnine, though in relatively much larger doses (0.25 grams per kilo.), it has a convulsant action on the nerve-cells of the spinal cord. In the rabbit the convulsions resemble closely those of strychnine poisoning, but in the frog the effect of the drug on the peripheral neuro-muscular apparatus modifies the result, for, though the spasms are easily set up and begin by an intense general contraction of all the muscles of the body, relaxation follows almost immediately. An isolated nerve-muscle preparation from such a frog cannot be tetanised by a succession of stimuli—the contraction begins well, but ceases very soon, although the stimulation continues.
This is probably allied to the general action of alkaloids in paralysing the motor nerve-endings in muscle, or it may be regarded as a fatigue phenomenon.
Apart from such alkaloidal effects, pukateine salts have not been found to possess any marked pharmacological actions. On intravenous injection the blood-pressure falls slightly, the heart beats slowly and forcibly, and death results from respiratory failure, sometimes with great suddenness.
When the alkaloid is rubbed on to the tongue some localised numbness is felt, and in frogs under the influence of the drug there may be no reflex response from some areas of the skin, while other areas give reflexes, but this effect appears late, and is probably due to an action on the nerve-cells of the spinal cord.
Mr. Thomson, Editor of the “Transactions of the New Zealand Institute,” announced that it had been decided to enlarge the size of the volume, commencing with the forthcoming volume (xli), which would be about the same size as the original seventeen volumes; also, that the Proceedings will in future be published separately, at intervals, containing the minutes of the annual meeting of the Governors of the New Zealand Institute, the proceedings of the affiliated societies, with abstracts of papers read, and any notes of interest to naturalists in the Dominion.
The presidential address was then delivered by Professor Park; it was entitled “The Origin and History of the Wakatipu District,” and was
founded on his survey of this region, already published as a bulletin of the Geological Survey.
The address was illustrated by many photo-slides, showing the action of ice in its various aspects. The President deduced from the numerous facts observed that at one time, probably in the Pleistocene period, the southern portion of the South Island had been covered with an ice-sheet, some 7,500 ft. thick—in other words, that there had been an Ice Age in New Zealand similar to that in the Northern Hemisphere.
(A full account of the address was published in the Otago Daily Times of the 12th May; and a rejoinder, by Professor Marshall, in the same paper on the 13th May.)