Evaluation of aldose reductase inhibition and docking studies of 6'-nitro and 6',6''-dinitrorosmarinic acids.

Aldose reductase (ALR2) of the polyol metabolic pathway is a target enzyme for the treatment of diabetic complications. A variety of synthetic and natural compounds have been observed to inhibit aldose reductase. Among them, rosmarinic acid has been shown to be in vitro an aldose reductase inhibitor in a micromolar range. In this study, two nitro derivatives of rosmarinic acid synthesized previously, 6'-nitro and 6',6''-dinitrorosmarinic acids, are proposed as aldose reductase inhibitors. Docking studies of the nitro derivatives have been carried out in the active site of aldose reductase. The theoretical results have shown a higher estimated binding energy of both compounds in comparison to that of rosmarinic acid suggesting a higher ALR2 inhibitory activity. The in vitro biological assays confirmed that these compounds were more potent than the parent rosmarinic acid.