566 



NA TURE 



\_April 14, 1887 



Some authentic leaves were procured by Mr. Lawson 

 from Guindy Park, Madras, who placed them at my dis- 

 posal for chemicai examination. They had a bitterish 

 astringent and slightly acid taste. After chewing one or 

 two leaves it was proved undoubtedly that sugar had no 

 taste immediately afterwards; the saltish taste experienced 

 by others was due to an insufficiency of the leaf being 

 used. Sugar in combination with other compounds in 

 dietetic articles is plainly destroyed as to its taste after 

 using these leaves. In ginger-bread, for instance, the 

 pungency of the ginger is alone detected, the rest is taste- 

 less meal ; in a sweet orange the taste of the sugar is so 

 suppressed and that of the citric acid consequently de- 

 veloped that in eating it resembles a lime in sourness. 

 Among the several kinds of foods, drugs, and beverages 

 which affect the palate Gymnema does not pretend to 

 render them all tasteless ; it does not affect pungent and 

 saline things, astringents, and acids. It is limited to 

 apparently two diverse substances, sweets and bitters. 

 It has been noted that sugar taken after the leaf tastes 

 like sand, so I have found that sulphate of quinine taken 

 after a good dose of the leaf tastes like so much chalk. 

 I am not going to propose its use in the administration 

 of nauseous drugs, until the medical properties of the 

 Gymnema have been more studied, otherwise the cpian- 

 tity of the vehicle taken may prove to counteract the 

 effect of the medicines. The experience of several friends 

 as well as my own is that the effect does not last for 

 twenty-four hours as stated, but for only one or two hours ; 

 after that time the tongue resumes its appreciation of all 

 that is sweet or bitter. 



The powdered leaves were submitted to the action of 

 various solvents, and by this means it was ascertained 

 that the peculiar property of Gymnema leaves was dis- 

 solved out by alcohol, and, as it occurred in the aqueous 

 extract of the residue, it was therefore soluble in water. 

 As benzene and ether took from the leaves certain prin- 

 ciples of the same appearance and weight, it was con- 

 ceived that nothing would be gained by using both 

 solvents ; the preliminary extraction was therefore made 

 with ether rectified from water and spirit. The ether 

 extract consisted of chlorophyll and two resins separated 

 by their solubility in alcohol. The resin insoluble in 

 spirit formed the larger portion ; it was soluble in chloro- 

 form, bisulphide of carbon, and benzene. It was elastic 

 and tenacious, decomposed by warming with nitiic acid, 

 the product being precipitated with water ; only partially 

 saponified with caustic potash. Sulphuric acid dissolved 

 it m the cold, giving a green solution. It seemed to con- 

 sist principally of a neutral resin. The resin soluble in 

 spirit was readily saponified with soda, and gave a per- 

 manent bluish-green colour with sulphuric acid ; like the 

 former resin, it was of an acrid nature, and left a tingling 

 sensation in the throat. 



The alcoholic solution of the leaves was almost entirely 

 soluble in water; in fact, by treating the leaves separately 

 by alcohol and water, 36'37 per cent, organic matter was 

 extracted ; by treating the drug with water alone 36 per 

 cent, w-as removed. By direct experiment it was found 

 that in the former extract 0-47 per cent, was an acrid 

 resin similar to those found in the ether extract; The 

 aqueous solution of the substances soluble in alcohol had 

 a decidedly acid reaction ; it gave no coloration with 

 ferric chloride, showing absence of tannin. It was deep- 

 ened in colour with alkalies, but gave a bulky precipitate 

 with sulphuric, nitric, hydrochloric, and acetic acid. It 

 reduced Fehling's solution on boiling, and gave a cloudi- 

 ness with Nessler, a precipitate with lead acetate, but 

 none with tannin or picric acid. The precipitate caused 

 by sulphuric acid was collected on a filter and washed 

 till it ceased to give a cloudiness with barium chloride. 

 It yielded a greenish powder, insoluble in water, but 

 soluble in alcohol, ether, benzene, and chloroform. With 



potash, soda, and ammonia it afforded fine red solutions 

 with orange-coloured froth, but they were both precipi- 

 tated on the addition of the mineral acids. It dissolved 

 in concentrated sulphuric and nitric acids with intense 

 red colour, but in both mixtures it was destroyed and 

 precipitated by water. It fused at about 60° C. into a 

 blackish brittle mass. Heated in a test-tube it gave off 

 fumes of creosote, but no crystals were obtained in a sub- 

 liming apparatus. Gently ignited it burned with a bright 

 flame, leaving no ash. It was thrown down as a bulky 

 gray mass by acetate of lead ; the lead salt decomposed 

 by sulphuretted hydrogen in water left the substance in 

 the reddish evaporated filtrate from the lead sulphide. 

 The body just described has the characteristics of an 

 organic acid related in some particulars to chrysophanic 

 acid, but having some distinctly peculiar reactions, and 

 possessing the anti-saccharine property ascribed to the 

 lea\'es. 1 propose to call it Gymneinic acid. 



Gymnemic acid forms more than 6 per cent, of the 

 constituents of Gymnema leaves, in combination with a 

 base which has not been isolated. Another organic acid 

 was present in the lead acetate precipitate, which was 

 identified as tartaric acid. The filtrate from the insoluble 

 lead compounds w.\s treated with sulphuretted hydrogen 

 gas, and the clear liquor after evaporation was examined 

 for sugar. Glucose was detected in some quantity by its 

 immediate and abundant reduction of Fehling's solution ; 

 the sugar examined in a polariscope had a left-handed 

 rotation. 



Chloroform agitated with an alkaline solution of the 

 leaf left a crystalline residue of a brownish colour ; it had 

 a bitter taste, and acted as a sialagogue. With the ordin- 

 ary alkaloidal reagents it afforded coloured precipitates, 

 but was a neutral principle. Its further examination 

 together with that of gymnemic acid are reserved for 

 further investigation. 



The leaves after being exhausted with ether and then 

 alcohol were treated with water. The gum was detected 

 and estimated in the usual manner. A carbohydrate, 

 optically inactive, and, after boiling with acid, reducing 

 Fehling's solution, was found in this extract. 



Diluted soda removed a brownish liquid which con- 

 sisted of albuminous matters only partially soluble in 

 alcoholic and acetic acid. These were not weighed but 

 calculated by difference. 



A solution of i per cent, hydrochloric acid was em- 

 ployed to remove the oxalate of calcium. A micro- 

 scopical examination of the powdered leaves showed a 

 fair sprinkling of the conglomerate crystals or raphides 

 so well known to exist in rhubarb. The dilution of the 

 acid menstruum rendered this process very tedious, so a 

 stronger acid was used and the marc washed with it until 

 ammonia produced no cloudiness. The collected liquors 

 were allow to deposit, the sediment was then collected on 

 a filter, dried and weighed ; then incinerated and weighed 

 again. The calcium carbonate was calculated into oxalate, 

 and the difference between this and the first weighing was 

 reckoned as pararabin. No oxalic acid was found in a 

 free state. 



The ash of Gymnema sylvcstrc is very high, a fact in 

 accordance with the amount of lime salts it contains. 

 Gentle ignition of the air-dried leaves left as much as i r65 

 per cent., and about one-half of this was calcium carbon- 

 ate. One hundred parts contained — 



i5'4i soluble in water. 

 7871 soluble in acid. 

 5'88 sand and siliceous residue. 



The cellulose was estimated by steeping the leaves in 

 sulphuric acid of specific gravity 1-50 for 30 hours, wash- 

 ing, drying, burning, and deducting the ash ; this result 

 did not difi'er materially from the weight of the totally 

 exhausted powder treated with chlorine water. 



