PURPOSE: To obtain a Maillard reaction inhibitor, containing a flavonoid contained in Scutellariae Radix as a pharmacologically active ingredient and capable of inhibiting the formation itself of an Amadori transition reaction product which is a direct causative substance for forming intermolecular crosslinkages. between protein molecules in the Maillard reaction.

CONSTITUTION: Scutellariae Radix is dipped in a mixture solution of water and a lower alcohol, preferably a mixture solution of 80-70wt.% methanol or ethanol based on 20-30wt.% water and warmed (preferably at 40-60°C) to provide an extract solution. To the resultant extract solution, is added water in an amount of ≥2 times based thereon. Alternatively, the alcohol is volatilized to reduce the concentration thereof to ≤25wt./vol.% and afford an extract composed of a sparingly water-soluble deposited substance. The obtained extract is then contained as a pharmacologically active ingredient in the objective inhibitor. The aforementioned inhibitor is used for treating or preventing various diabetic complications or diseases of the same kind (e.g. atherosclerosis, cerebal angiopathy or senile cataract) caused by aging.