Preliminary chemical characterization of pharmacologically active compounds in aqueous plant extracts

A test system is described which, based on the use of ion exchangers, gel filtration on Sephadex, and extraction with organic solvents, gives information about the stability, molecular size, charge, and polarity of pharmacologically active compounds in aqueous plant extracts. Knowledge of these properties permits development of a suitable isolation method for the compounds. The method is illustrated by the identification of quaternary ammonium salts as responsible for the contracting activity on the isolated guinea pig ileum of an aqueous extract of roots of Maeura subcordata.