Isolation of ajmalicine from Catharanthus roseus roots - by extn. with methanol, adding aq. citric acid, removing tetra:hydro:alstonine with a hydrocarbon and extn. with a chlorinated hydrocarbon

摘要

Isolation of ajmalicine (I) and its acid addn salts from Catharanthus roseus plant roots comprises (a) with a 1-5C alkanol pref methanol; (b) opt. concn the extract (c) addn of an aq soln of a weak acid (pref citric acid) (d) extrn of this mixt with a hydrocarbon (pref benzene, toluene or xylene); e) extraction with a chlorinated hydrocarbon (e.g. chloroform or dichloromethane) or with an ester (f) opt. isolation from the hydrocarbon soln of tetrahydro-abstonine (II) (g) opt. purificn by phase changes and/or adsorption (pref on alimenum oxide) of the extract obtd in (e) with the chlorinated hydrocarbon or ester and (h) isolation of (I) from this extract in known manner and opt conversion to the acid addn salts. (I) (also known as -yohimbine or raubasene) is a hypotensive, sedative and tranquiliser which may be isolated from Corynanthe johimbe, Rauwolfin serpentina or Catharanthus roseus. The present process allows isolation of pure (I) without difficult chromatographic purificn stages.