Aldose Reductase Inhibitory Alkaloids from Corydalis ternata

A methanolic extract of Corydalis ternata having aldose reductase inhibitory activity was examined as a possible aldose reductase (ALR2) inhibitor, a key enzyme involved in diabetic complications. Seven alkaloids, tetrahydrocoptisine (1), corydaline (2), tetrahydropalmatine (3), isocorybulbine (4), corybulbine (5), dehydrocorydaline (6), and N-methyltetrahydroberbinium (7) were isolated from CHCl₃ fraction of C. ternata methanol extract. Among them, compounds 1, 5, and 7 exhibited 5.04 ± 1.97%, 5.00 ± 1.26%, and 1.80 ± 2.33% inhibitions, respectively at 40 µM. The activities of the single compounds were not comparable to that of the whole extract, suggesting that the whole combination of each single compound was responsible for the activity of the extract as shown in many cases of natural medicines. Even though this is the second report on aldose reductase inhibition activity of C. ternata, recombinant human aldose reductase was employed in this study unlike in the previous report. Furthermore, the aldose reductase inhibitory activities of isocorybulbine, corybulbine, and N-methyltetrahydroberbinium, to the best of our knowledge, were evaluated for the first time in this study. These results suggest a use of the extract of C. ternata for ameliorating diabetic complications.

Antioxidative and aldose reductase-inhibitory effects of a fermentation filtrate of Rubus coreanus / 한국실험동물학회지

Antioxidative and aldose reductase (AR)-inhibitory effects of a fermentation filtrate of Rubus coreanus (FRC) were investigated using corneal/retinal homogenate and lens cytosol, respectively. Rat corneal/retinal homogenate was treated with 50 microM FeCl3 in the presence of FRC (3.2-100 microg/mL) for 30 min at 37degrees C, and thiobarbituric acid-reactive substances (TBARS) was quantified as a lipid peroxidation parameter. FRC markedly suppressed the TBARS production in a concentration-dependent manner, leading to 50% (IC50) and 100% (IC100) inhibitory concentrations of 20 and 95 microg/mL, respectively, which was similar to the effect of butylated hydroxyanisole. Activity of AR from rat lens was assayed in the presence of FRC (1-31.6 microg/mL) at 25degrees C using glyceraldehyde as a substrate. FRC inhibited lens AR by 50% (IC50) and 90% (IC90) at approximately 2 and 31.6 microg/mL, respectively, comparable to the effect of quercetin. The results indicate that ERC could be a promising candidate for the improvement of eye injury and visual dysfunction of dry eye and diabetic patients.