Effects of furanocoumarins fromAngelica dahurica on aldose reductase and galactosemic cataract formation in rats

Abstract

The ether extract from the roots ofAngelica dahurica was found to inhibit bovine lens aldose reductase (BLAR) activityin vitro by 100% at 100 μg/ml. Systematic fractionation of the ether soluble fraction and subsequent active fractions monitored by bioassay led to isolation of four furanocoumarins, isoimperatorin (I), imperatorin (II), ter-O-methyl byakangelicin (III) and byakangelicin (IV), among which compound III and IV were identified as potential AR inhibitors, their IC50 values being 2.8 μM and 6.2 μM, respectively. Galactosemic cataract formation in rats treated with 40 g/kg/day of galactose was blocked almost completely throughout the experimental periods up to 44 days by i.p. administrations of byakangelicin (IV) at 50 mg/kg/day. In coincidence with the inhibitory action on cataract formation, the galactitol accumulation in rats treated with byakangelicin (IV) was found to be markedly prevented by approximately 80.5% compared to those of the control. These results indicate that byakangelicin (IV), as a main principle of this plant, possesses high potential for a clinically useful drug of the future which prevents and/or improves sugar cataract as well as diabetic complications.