162 
Root  of  Polygonum  Cuspidatum. 
/Am.  Jour.  Pnarm.- 
I      Marcli,  1896. 
to  cool,  the  product  collected,  washed  with  water,  and  dried  at  120°. 
It  formed  orange-red  needles,  readily  soluble  in  alcohol.  They 
melted  at  253-2540,  and  sublimed  at  higher  temperatures  with  par- 
tial carbonization.  A  study  of  the  decomposition  products  and 
derivatives  of  the  substance  showed  it  to  be  emodin,  which  exists  in 
rhubarb  root  and  also  in  the  bark  of  Rhamnus  frangula,  as  a  gluco- 
side  (Trans.,  1892,  61,  1,  Thorpe  and  Miller). 
A  determination  of  the  amount  of  emodin  produced  by  the  hydro- 
lysis of  the  glucoside  gave  6r82  per  cent,  as  the  result.  This  is  in 
accordance  with  the  following  equation,  which  requires  62  50  per 
cent. 
C2iH20O10  +  H20  =  C15H10O5  +  C6HI206. 
The  filtrate  from  the  emodin,  after  neutralization  with  silver 
carbonate,  and  evaporation,  yielded  an  almost  colorless  syrup,  which 
reacted  with  phenylhydrazine  acetate  on  gently  warming,  lemon- 
yellow  aggregates  of  an  osazone  being  deposited  on  cooling. 
Frangulin,  the  only  glucoside  of  emodin  hitherto  known,  and 
found  in  Rhamnus  frangula,  is  not  identical  with  the  above,  When 
hydrolyzed,  for  instance,  it  yields  emodin  and  rhamnose  (Thorpe  and 
Miller,  loc.  at), 
Q1H20O9  +  H20  —  C15H10O5  4-  C6H10O5, 
a  reaction  which  requires  64  9  per  cent,  of  emodin  ;  and  its  difference 
in  composition  (C21H20O9  requires  C,  60  57 ;  H,  4-80),  crystalline  ap- 
pearance, solubility  and  other  properties  from  the  glucoside  found 
in  Polygonum  cuspidatum,  show  clearly  that  they  are  distinct  sub- 
stances. Polygonin  is  the  name  proposed  for  this  new  glucoside  of 
emodin. 
The  gelatinous  residue  obtained  during  the  purification  of  the 
polygonin  had  the  properties  of  a  glucoside,  and,  upon  hydrolysis  by 
digestion  with  dilute  hydrochloric  acid,  yielded  emodin,  and  a  second 
substance  which  differed  from  emodin  by  melting  at  1990,  and  by 
being  sparingly  soluble  in  alcohol  and  insoluble  in  dilute  ammonium 
hydrate.  This  substance  was  identified  as  emodin  monomethyl  ether, 
which  has  been  found  to  exist  in  the  root  bark  of  Ventilago  madras- 
potana  in  the  free  state  (Perkin  and  Hummel,  Trans.,  1894,  65,  932). 
It  is  interesting  to  note  that  Schwabe  {Arch.  Pharm.,  1888,  26, 
569),  and  subsequently  Thorpe  and  Miller  (Trans.,  1892,  61,  6),  iso- 
lated from  the  bark  of  Rhamnus  frangula,  not  only  frangulin,  but  a. 
