GB708484A - Improvements in or relating to method for isolation and purification of active plantprinciples - Google Patents

Abstract

Active plant principles are isolated by extracting Ammi visnaga seeds with water, mixing the resultant aqueous solution with a water-immiscible solvent in which the active principles are preferentially soluble, separating the aqueous and solvent phases, and recovering the active principles from the solvents. Solvents specified are benzene, carbon tetrachloride, trichlorethylene and chloroform. Complete evaporation yields a high-melting, waxlike residue consisting of khellin, visnagin, and a small proportion of unidentified highly-coloured contaminants, which may be defatted by the use of petroleum ether. Partial evaporation, which produces a crystalline product practically free from contaminants, is preferably effected. The aqueous phase after extraction of the p desired principles is preferably returned to the process. Concentrations of khellin far in excess of its solubility in pure water are thus obtained, due possibly to the presence of an unidentified water-soluble solubilizing agent present in the Ammi visnaga seeds. Pure khellin may be isolated from khellin/visnagin mixtures by recrystallization from solution in an aliphatic alcohol containing from 4 to 8 carbons atoms, for example n-butycarbinol and less preferably amyl alcohol. Using n-butylcarbinol as solvent, pure visnagin may be obtained from the mother liquor resulting from the recrystallization of the khellin by agitating with water and allowing the mixture to stand, preferably cooling with ice.