| 摘要 |
A method for purifying gibberellins comprises treating an impure aqueous solution of alkali metal salts of gibberellins with activated carbon, the said solution being obtained by suspending in water raw crystals containing 70-85% of gibberellins and adding thereto the necessary amount of caustic alkali solution to raise the pH of the solution to around 5, extracting the gibberellins from the treated solution with an organic solvent, preferably ethyl acetate, and recovering crystalline gibberellins from the extract. The aqueous solution preferably contains 15 to 20 grams per litre of alkali metal salts of gibberellins and 5-10% by weight of carbon based on the gibberellins is preferably used. The treated solution is preferably acidified to pH 3 before extraction. Two methods of obtaining the raw gibberellin crystals are described:-(1) by extraction and crystallisation of gibberellins from the first fractions desorbing at pH 5-8 obtained by percolating aqueous ammonia over a column of weak p anion-exchange resin which has been used to absorb gibberellins from a culture medium. (2) From impure extraction fractions, production residues, crystallisation mother liquors, solvents used for washing crystals or other impure extracts, e.g. acetone extracts from charcoal absorption by: (a) diluting with water, e.g. 10 times, (b) adjusting to pH 4,5 with acid or a weak cationexchange resin in the H-form, (c) absorbing on a weak anion-exchange resin, e.g. in the formate form, and (d) continuing as in (1). Specification 936,548 is referred to. |
