464 RESINS 



Constituents. Purified araroba varies considerably both in the 

 constituents present and the proportion in which they occur. The 

 following table may suffice to indicate its approximate composition 

 (Tutin and Clewer, 1913) : 



Chrysophanol (chrysophanic acid) . . 4-7 to 6'7 per cent. 



Emodin monomethyl ether . . . about T6 to 2-2 



Chrysophanolanthranol (' chrysarobin ') about 26*0 to 62*0 

 Anthranol of emodin monomethyl ether . Small amount 



Monomethyl ether of dehydroemodin- 



anthranol . . . . . . 13-4 to 41*1 per cent. 



Ararobinol . ..... about 4 



Emodin . . . . . . . trace 



Inseparable mixture of substances and 



amorphous matter .... about 12*0 to 30 '0 per cent. 



Chrysophanolanthranol, often called chrysarobin, C 15 H 12 O 3 , crystallises in 

 yellow leaflets melting at 199. It is insoluble in aqueous ammonia, but is 

 converted by oxidation into chrysophanol which is soluble. 



Chrysophanol (chrysophanic acid), C 15 H 10 4 , crystallises in deep orange- 

 coloured leaflets melting at 191. 



Monomethyl ether of dehydroemodinanthranol, C 16 H 12 O 4 , crystallises in pale 

 yellow needles melting at 265. 



Ararobinol, C 23 H 16 O 5 , crystallises in yellow crystals without definite melting 

 point. 



There is no definite knowledge as to which constituent or constituents its 

 medicinal value is to be attributed. 



Uses. Purified araroba has been used successfully in ringworm, 

 psoriasis, and other skin diseases ; it acts apparently by destroying 

 low vegetable organisms. 



BENZOIN 



(Benzoinum) 



Benzoin occurs in several well-defined commercial varieties, one only 

 of which, viz., Sumatra benzoin, is official. 



The trees from which benzoin is obtained do not contain any special 

 secreting cells or ducts, nor is normally any benzoin produced ; the 

 drug is a purely pathological product, the formation of which may be 

 induced by injury to the tree. 



SUMATRA BENZOIN 



Description. This, the official variety, is obtained from Styrax 

 Benzoin, Dryander (N.O. Styracece), a tree indigenous to Sumatra and 

 Java. The drug is obtained by hacking the bark of the tree with an 

 axe. After the infliction of such injury the cambium rapidly produces 







