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.

In vitro and in vivo inhibitory activities of four Indian medicinal plant extracts and their major components on rat aldose reductase and generation of advanced glycation endproducts.

The polyol enzyme aldose reductase (AR) and advanced glycation endproducts (AGEs) play an important role in diabetic complications such as cataracts. The purpose of this study was to investigate four standardized plant extracts used for the treatment of diabetes and related diseases, and their principal components for AR inhibitory activity and to find out their influence in diabetic complications. Thus, Boswellia serrata Triana & Planch. (Burseraceae), Lagerstroemia speciosa (L.) Pers. (Lythraceae), Ocimum gratissimum (L.) (Lamiaceae) and Syzygium cumin (L.) Skeels. (Myrthaceae) and their respective major constituents, boswellic acid, corosolic acid, ursolic acid and ellagic acid, were studied for their inhibitory activity against rat lens AR, rat kidney AR, human recombinant AR and generation of AGEs. In addition, in vivo inhibition of lens galactitol accumulation by the major constituents of the plants in galactose-fed rat has been studied. The results revealed that all the tested extracts and their active ingredients possess significant AR inhibitory actions in both in vitro and in vivo assays with urosolic acid showing the most potent effect. Furthermore, the study indicates the potential of the studied plants and their major constituents as possible protective agents against long-term diabetic complications.