Biochemical Analysis and Human Aldose Reductase Inhibition Activity of Selected Medicinal Plants of Nepal

Aldose reductase has received extensive research as a key enzyme in the development of long-term problems linked to diabetes mellitus. Overexpression of this enzyme or with exceeded glucose concentration in the blood increases sorbitol on the retina leading to retinopathy, which is the adverse effect of type II diabetes. Approximately 100 million people are suffering from diabetic retinopathy globally. This research is focused on studying the total phenolic content (TPC), total flavonoid content (TFC), antioxidant potential, and aldose reductase inhibiting properties of selected medicinal plants such as Anacyclus pyrethrum, Bergenia ciliata, Rhododendron arboreum, and Swertia chirayita. In addition, ADMET analysis and molecular docking of seven previously identified compounds from the chosen medicinal plants were carried out against human aldose reductase (PDB ID: 4JIR). The ethanol extract of S. chirayita exhibited the highest TPC (4.63 & PLUSMN; 0.16 mg GAE/g) and TFC (0.90 & PLUSMN; 0.06 mg QE/g). Analysis of 2,2-diphenyl-1-picrylhydrazyl (DPPH)-based antioxidant assay showed that IC50 of the ethanolic extract of B. cilata and R. arboreum showed a significant antioxidant activity with IC50 value of 0.05 mg/mL. The percentage inhibition of AR by extract of B. ciliata (94.74 & PLUSMN; 0.01%) was higher than other plant extracts. A molecular docking study showed that morin isolated from B. ciliata showed a good binding interaction with AR. This study showed that the extracts of A. pyrethrum, B. ciliata, and R. arboreum could be potential sources of inhibitors against AR to treat retinopathy.

Automated summary

Aldose reductase is a key enzyme in the development of diabetic retinopathy. This study investigated the potential of medicinal plants in inhibiting aldose reductase and treating retinopathy. The ethanol extract of Swertia chirayita exhibited the highest total phenolic content (TPC) and total flavonoid content (TFC), while Bergenia ciliata and Rhododendron arboreum showed significant antioxidant activity. The extract of Bergenia ciliata also showed the highest inhibition of aldose reductase.