97 



precipitation, and requires a succession of similar operations in order to recover 

 it. Althougli we have used about ]2 kilos, of the plant, we were not able to 

 jirepare more than about 2 grams of the pure active constituent. In all pro- 

 bability the plant does not contain as much as 0"1 per cent, of this substance, 

 but exerts so powerful a physiological action that from the effect produced 

 by chewing the leaves or root one is led to expect a far larger proportion. 



Properties and Composition of the Active Constituent, Piperovatine. 



When pure, the active constituent forms colourless, light needless which 

 often crystallise in rosettes. In appearance, these somewhat resemble the 

 alkaloid caffeine, and melt at 12.3° (ccrr.), decomposing slightly. The substance 

 is nearly insoluble in water, very sparingly soluble in light petroleum, and not 

 much more so in dry ether. It dissolves readily in alcohol, chloroform, and 

 acetone. The solution of the highly purified substance in strong alcohol has 

 the curious property of apparently gelatinising when water is added to it in 

 just sufficient quantity to cause precipitation ; the dissolved substance being 

 thrown out in a bulky mass of microscopic crystals resembling a jelly. On this 

 account it is difficult to obtain it in well-defined crystals, but this may be 

 managed by adding dry ether to the solution in absolute alcohol, and allowing 

 the liquid to evaporate spontaneously. The substance appears to be optically 

 inactive ; an alcoholic solution containing. 1 '5 per cent, did not rotate the 

 polarised ray. The compound contains carbon, hydrogen, nitrogen, and oxygen. 

 Several combustions have been made with different specimens of the material, 

 with the following results. 



I. 0-1054 gave 0.2813 CO, and 0-0858 H^O. C = 72-78 ; H = 9-04. 



XL 0-2023 ,, 0-5335 ,, ,,0-1484 ,, C = 71-92 ; H = 8.15. 



III. 0-1847 „ 0-4982 „ ,,0.1391 ,, C = 73-56 ; H = 8-37. 



IV. 0-1775 „ 0-4810 ,, ,,0-1356 ,, C = 73-90 ; H = 8-49. 



Of these four combustions, III and IV were made with the purest specimens, 

 and give as a mean composition C = 73-73, H — 8*43 per cent., the percentage 

 of nitrogen (determined by tlie absolute method) was 5-96. These data agree 

 well with those calculated from the formula CjgH2.^N02, which requires C = 

 74-13 ; H = 8-10 ; N = 5-40 per cent. The active constituent exhibits, therefore, 

 the composition of a vegetable alkaloid, and shows some resemblance to piperine 

 (C^ryHigNOg), the alkaloid of pepper, a plant belonging to the same natural 

 order. 



Piperine has very feebly basic properties, and forms salts which are very 

 unstable. The substance from Piper ovatum, to which we propose to assign the 

 name pij)erovafine, is devoid of basic properties, being nearly insoluble in dilute 

 acids, and therefore, from this point of view, does not come within tlie usual 

 definition of an alkaloid. Nevertheless, further investigation will probably show 

 that its constitution is precisely similar to that of such alkaloids as piperine, 

 atropine, and aconitine, that is to say, it would seem from our observations to be 

 composed of a basic pyridine nucleus (e.g., piperidine), associated with an acid 

 radicle, the acidity of the radicle exactly neutralising the basic power of the 

 other residue, so that the resulting derivative is neither basic nor acidic. 



Piperovatine dissolves in glacial acetic acid, but may be precipitated 

 unchanged by the addition of water. It is insoluble in dilute hydrochloric acid 

 and in dilute sulphuric acid ; on boiling it with these acids, hydrolysis appears 

 to take place, and the solution now gives the reactions of an alkaloid, but we 

 have not obtained sufficient of the product for identification. It appears, 

 however, to be a pyridine derivative, and to present some analogies to pii^eridine ; 

 there would seem to be also an acid product of hydrolysis, but this we have never 

 obtained except in traces. 



Piperovatine is also devoid of acid properties. It does not dissolve in weak 

 alkalis. Strong alkalis such as potasli, especially when warm, appear to hydrolyse 

 it, quickly forming the acid and the jiyridine base referred to above. 



Its decomposition products require a fuller examination than we have been 

 able to subject them to with the small quantity of material at our disposal. 



Physiological Action of Piperovatine. 



The physiological action of piperovatine has been investigated for us by 

 Professor Cash, F.R.S., of Aberdeen. He finds it to act as a temporary depressant 

 of both motor and sensory nerve fibres, and also of sensory nerve lerniinations. 



