In vitro and in vivo aldose reductase inhibitory activity of standardized extracts and the major constituent of Andrographis paniculata.

Aldose reductase is the first enzyme in the polyol pathway and catalyzes the reduction of glucose to sorbitol by coupling with the oxidation of NADPH to NADP(+) . This sorbitol accumulation leads to various diabetic complications, including neuropathy, nephropathy, cataracts, and retinopathy. In the present study, aldose reductase inhibitory (ARI) activity of the methanolic as well as standardized extracts of Andrographis paniculata (Burm. f.) Wall. ex Nees (Acanthaceae) and its chief constituent, andrographolide, were studied using in vitro and in vivo methods. In the in vitro method, rat lens as well as kidney homogenates were used for the preparation of enzyme, whereas the effect of these test samples on the galactitol level in the eye lens was studied in a galactosemic rat model in vivo. The results of the study revealed that both extracts of the plant and its major compound, andrographolide, possess ARI activity in vitro. They were also found to significantly decrease galactitol accumulation in vivo.