METHODS OF PREPARATIVE ISOLATION OF ISOALANTHOLACTONE AND ALANTHOLACTONE FROM ELE-CAMPANE ROOT

Abstract

Alantolactone and isoalantolactone accumulate in large quantities in elecampane (Inula helenium L.) roots, however, their isolation in individual states is difficult due to the same chromatographic mobility. This work presents various working methods for producing alantolactone and isoalantolactone as individual substances from elecampane root in multigram quantities. Although alantolactone and isoalantolactone can be isolated simultaneously when separated on silica gel with impregnated silver nitrate, it is more practical to obtain alantolactone or isoalantolactone from the extract of elecampane roots separately. Pure isoalantolactone can be isolated by repeated crystallization from 75% aqueous methanol. Another, faster, method of producing isoalantolactone is to react a mixture of elecampane lactones with dimethylamine or morpholine. Isoalantolactone in the form of an adduct with an amine is readily separated by crystallization and then regenerated through the preparation of a quaternary ammonium salt. Alantolactone is conveniently produced in large quantities through the oxidation of isoalantolactone in a mixture of selenium dioxide to more polar lactones, which are separated chromatographically. Hydrogen peroxide, t-butyl hydroperoxide or potassium periodate can be used as co-oxidizing agents.