Investigation of the inhibition effect of some plant extracts on aldose reductase activity

Aldose reductase (AR) (Alditol: NADP+ 1-oxidoreductase, E.C. 1.1.1.21), one of the polyol pathway enzymes that has an important role in the development and prevention of diabetic complications, was partially purified from sheep kidney. Viscum Album L. (The effects of extracts prepared from fruit, leaf and stem parts of mistletoe) on enzyme activity were investigated. Partial purification of AR enzyme was performed by preparation of homogenate, ammonium sulfate precipitation and dialysis steps. The AR enzyme, which has a protein specific activity of 0.486 EU/mg, was purified approximately 1.09-fold, with a yield of 44.43%. In vitro and in silico inhibition effects of Viscum Album L. plant extracts on aldose reductase (AR) enzyme were investigated. After the in vitro inhibition effects were determined by spectrophotometric method, the binding energy and binding modes were determined by molecular docking method. It was determined that the extract prepared by using the methanol solvent of the stem part of the Viscum Album L plant has the strongest inhibitory effect against the AR enzyme with an IC50 value of 0.156 µM. The IC50 values of the extracts prepared using ethanol, methanol and water solvents of the fruit parts of the Viscum Album L plant are 1.174 μM, 0.860 μM, 1.560 μM, respectively, and the IC50 values of the extracts prepared using the ethanol, methanol and water solvents of the leaf parts of the plant are 1.090 μM, 0.190 μM, 9.260 μM, respectively. and the IC50 values of the extracts prepared using ethanol, methanol and water solvents of the stem parts of the plant were determined as 0.700 μM, 0.153 μM, and 0.906 μM, respectively. The results of this study showed that Viscum Album L plant extracts can be effective AR inhibitors. The results of molecular docking of the extracts showing an in vitro inhibition effect against the AR enzyme also support the data obtained.