KN(n\i.i;i)(-i 



I EHRl!AKY, 1912. 



/ 



3.- 



-Aconiti' Kool. 

 -Calabar Hcans. 

 -Cinchona Hark. 



iiiiiliT siiitalilc iiiMtiiU'iil. iKitiirai products, siirli as 

 loaves, routs ami l)arks may Ik- made to yield delinitc 

 ciicmifal compomuls. amonf^st 

 wliirli arc tiic alkaloids and 

 jL^hicosidcs : tlicsc lia\c in many 

 cases Ill-en \ery fully investi- 

 fjated both from tlic |K)int of 

 view of tlieir chemical structure 

 and their action on living 

 orjjianisms. l-'if^iu'e 59 shows 

 six natural jjfoducts from 

 which powerful alkaloids are 

 extracted : Aconite root and 

 Calabar beans (obtained from 

 West Coast of Africa) re- 

 spectively contain aconitine 

 and ph\sostigmine. (luininc 

 exists in Cinchona bark, 

 cocaine in Coca leaves, 

 ergotiniiic in Mrgot, and Nux- 

 \'omica gives rise to the well- 

 known substance stryrhninc. 

 The vast strides in organic 

 chemistry have also enabled 

 the chemist to synthesise large 

 numbers of compounds possess- 

 ing a known structure and a 

 known action — which action 

 can frequentl}' be modified by 

 a modihcation of structure : 

 these synthetic compounds 

 have, after investigation, been 



classified according to their action as antipyrctirs 

 antiseptics, diuretics. h\-pnotics, and so on 



At the i)resent time, there- 

 fore, instead of administering mi.. 

 to his patient large quantities 

 of indefinite and uncertain 

 preparations containing numer- 

 ous ingredients which may lie 

 chemically or physiologically 

 antagonistic to each otlur. 

 the jihysician is enabled to 

 select some definite compound 

 regarding which he knows both 

 the chemical constitution and 

 the physiological action : by 

 sub.sequent observation of tin- 

 patient he can ascertain 

 whether the drug is acting in a 

 satisfactory manner, and. if not. 

 administer one of a different 

 chemical constitution: but under 

 the old conditions of "polyphar- 

 mac\' " it was a \irtual impossi- 

 bility to attribute the harmful or ., ^^^ „. 

 beneficial action of a preijar- 

 ation to any special ingredient. 



As an illustration of the possibility of modifying 

 the action of a chemical compound, the case of 

 aniline and certain of its derivatives ma\- be taken. 



Aniline, which has verv marked plusiological 



•^f* 



4. — Coca Leaves. 



.i.— Krgot. 



6. — Nnx Vomica Seeds. 



a< lions, owes its ac tivity largcl\- to the |>resence of 

 the benzene nucleus, and the view ma\ be held that 

 the "amino" group - N H,j, 

 ' rves as an "anchoring group," 

 I lid thus brings the molecule 

 into contact with the proto- 

 plasm. It is far too to.xic for 

 satisfactory application as a 

 <lrug, but In- rejjlacing one of 

 the hydrogen atoms of the 

 • iinino grou|) by the "acetyl" 

 radicle — COCH;,, we obtain a 

 substance known as Acetanilide, 

 iir .\ntifebrin. This is ver\- 

 -jowlv hydrolysed within the 

 iiiganism, with gradual elimin- 

 ation of small quantities of 

 aniline, which becomes oxidized 

 in the body to i)ara-amino- 

 pheiiol. to which the phvsio- 

 logiral action is i)artly due. 

 and ina\ thus be used with a 

 reasonable amount of safety as 

 an antii)yretic : the formulae 

 in Figure 60 show ver\- 

 clearlv how the molecule of 

 aniline ma\' be modified in this 

 and other directions to give 

 rise to medicinal products of 

 varxing structure and activity. 

 It is obvious that without a 

 definite knowledge of the fate 

 of a comiioiiiui within the organism it would be 

 (|uitc impossililc to modify the action of aniline as 

 above described by ad- 

 ministering it in the 

 form of various deriva- 

 tives. In a somewhat 

 similar way. other synthetic 

 preparations have been intro- 

 duced, which are decomposed 

 into definite i)r(Klucts within 

 the body. 



Salol. for cxamiile. is the 



phcinl ester of Salicylic .\cid. 



and in presence of the 



alkaline juices of the 



'"^ " ■ duodenum gives rise to 



salicylic acid and phenol 



or their salts, which act as 



intestinal disinfectants: a less 



toxic product. /3 Xaphthol. 



may be similarly liberated in 



a "nascent" condition in the 



\ duodenum by em|)lo_ving 



\. ,j^ the /i Naphthyl Ester of 



Salicvlic .Acid, which is 



^■■^"^'^ ^'°- known as Betol. 



Another drug of tlu same type largely and 

 successfully employed, under different names, is 

 .\cetyl-Salicylic-.\cid, which gives rise internally to 

 Acetic and Salicvlic .\cids ; such examples as this 



-NH. COCH:, 



/ 



\ 



