Process for recovering glycofrangulins from crude plant material, esp. the dried bark of the alder buckthorn (Rhamnus frangula L.) comprises extracting the material with a solvent mixt. of (i) a 1-3C alcohol and (ii) a 3-6C aliphatic or cyclic oxo and/or oxido cpd.; removing impurities from the extract by adsorption onto an activated polyamide; treating the purified soln. with a non-aqueous, esp. methanolic, soln. of an alkali hydroxide to produce a salt which is then treated with an acid or ion-exchanger, and solvent removed from the final product in the usual manner. Extract is a mild laxative. Process gives a purer product (90-95% consisting of molecules having at least 2 sugar residues bound to emodin) than prior art processes. Extraction solvent has excellent selectivity; most of the impurities (which are foul smelling and cause undesirable side effects) are irreversibly bound to the polyamide, and the process is suitable for large scale operation.
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