PURPOSE: To obtain an aldose reductase inhibitor comprising an active substance separated from an extract of dried core material of Sappan lignum of crude drug with methanol as an active ingredient.
CONSTITUTION: An aldose reductase inhibitor comprising compounds shown by formula I to formula VII obtained from separated from an extract of dried core material of Sappan lignum of crude drug with methanol as an active ingredient. A dose of the compound is 50mg-5g per adult daily in the case of oral drug and preferably 0.1mg-1g in the case of parenteral drug. Methanol essence is obtained by distilling away a solvent under reduced pressure from an extracted solution of Sappan lignum with methanol, then dissolved in water, extracted with ethyl acetate three times, prepared ethyl acetate essence is chromatographed by silica gel column, extracted with chloroform, then a mixed solvent of chloroform and methanol (methanol content: 5, 10, 15, 20%), elution part of 5 % methanol-chloroform is chromatographed by Sephadex LH-20 column and fractionated to give compounds shown by formula I to formula VII.
TAKEDA HIROKO
SASAKI HIROSHI
SATO SHUNJI
