Inhibition of Indoleamine 2, 3-Dioxygenase (Ido) Activity of Hemidesmus Indicus Root Extract and Its Attenuate Effect on Streptozotocin Induced Diabetic Cataract in Rats

Background: Increased Indoleamine 2, 3-dioxygenase (IDO) activity has been performed in the development of cataract and IDO Inhibition with natural medicine is a therapeutic strategy for the management of diabetic cataract. Our present study assessed the inhibitory effect IDO and anti- cataract properties of Hemidesmus indicus R. Br. root extracts in Streptozotocin (STZ) induced diabetic rats. Material and Methods: In vitro enzyme kinetics were carried out using hIDO (purified from cloned E. coli cells) with Hemidesmus indicus root extracts. To explore in-vivo anti-cataract properties of Ethyl acetate extract (EAHI), diabetes was in SD rats by single intraperitoneal injection of STZ at dose 35 mg/kg body weight. Experimental rats were divided into four groups (Control & diabetic) orally treated with 0, 250, 350 mg/kg bw of the EAHI up to 6 weeks. The evaluation of enzymatic parameters of kynurenine pathway (KP) metabolites, i.e Kynurenine, 3-hydroxy kynurenine, kynurenic acid, tryptophan and IDO expression level were examined in experimental rat lens and histopathological change were evaluated in retina by using Hematoxylin & eosin staining. . Results: Among all, EAHI exhibited strong inhibition of hIDO activity with IC 50 value of 34.74±0.82 ug/ml in a non-competitive manner. Extract doses treated with EAHI (250 & 350 mg/kg bw) have been showed a significant alternative changes in retinal morphology, expression of IDO and were significant (p<0.05) suppresses kynurenine pathway (KP) metabolites, i.e Kynurenine, 3-hydroxy kynurenine, kynurenic acid and tryptophan in experimental rat lens. Beside this, rat fed with EAHI have shown significant decreased level (p<0.05) of IDO in lenticular tissues. Conclusion: Overall results obtained in the study concluded that EAHI possess pharmacologically active constituents attributing its IDO inhibitory potential and delaying the cataract in lenses. Thus the study clearly suggested the traditional medicinal claim of the plant Hemidesmus indicus possessing the anti-cataract drug.