PURPOSE: To obtain an inhibitor of an aldose reductase, having high inhibiting activities against the aldose reductase and useful as a preventing and a therapeutic agents for diabetic complications having high safety without any toxicity.
CONSTITUTION: This inhibitor of an aldose reductase contains a compound expressed by formula I (R1 is pentadecenyl; R2 is H; R3 is a 1-4 alkoxy or R1 is H; R2, together with R3, is a dihydroxy condensed benzene ring) or its pharmaceutically permissible salt, e.g. 2-hydroxy-5-methoxy-3-(10- pentadecenyl)-1,4-benzoquinone expressed by formula II or 2,5,7-trihydroxy-1,4- naphthoquinone expressed by formula III. Although the compound can be prepared according to a well-known chemical synthetic method, the compound expressed by formula II can be extracted from Maesa lanceolata of the family Myrsinaceae (especially a fruit thereof) which is a plant produced in East Africa.
KOYAMA KEIZO
HARAGUCHI HIROYUKI
NAKAYAMA MITSURU
SOGA OSAMU
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