METHOD OF DIHYDROQUERCETIN PREPARING Russian patent published in 2002 - IPC

FIELD: technology of natural compounds, medicine. SUBSTANCE: method involves milling larch wood, its heat treatment and extraction and the following evaporation and purification of extract obtained. Heat treatment is carried out by steam at 110-120 C. Extraction is carried out in solvent followed by separation of solvent by filtration. Solvent is evaporated up to preparing an aqueous extract solution from filtrate. Then an aqueous solution is evaporated up to 10% content of dihydroquercetin in extract and obtained extract residue is acidified with acid to pH 5-6. Then residue is decanted at 90-98 C from precipitated resins to obtain an aqueous solution of dihydroquercetin which is acidified with acid again to pH 3-3.5, cooled to the room temperature, formed crystals of dihydroquercetin are filtered off and dried at 105-110 C for 2-3 h. An aqueous-acetone solution or ethyl or methyl alcohol solutions are used as a solvent. Hydrochloric, sulfuric or ortho-phosphoric acid is used as an acid. Extraction in solvent is carried out three-fold being each time with fresh solvent. EFFECT: decreased loss of product. 5 cl, 4 tbl