Effect of the tannoid enriched fraction of Emblica officinalis on -crystallin chaperone activity under hyperglycemic conditions in lens organ culture

Abstract

Chaperone-like activity (CLA) of α-crystallin is known to be compromised in diabetic conditions and associated with cataract formation. Protecting α-crystallin CLA may help in delaying and/or preventing cataracts. In this study, we employed a lens organ culture model to study the effect of hyperglycemia on the CLA of α-crystallin and investigated the protective effect the tannoids of Emblica officinalis had on the CLA of α-crystallin. Goat lenses were treated with 30 mM glucose with or without an aqueous extract of E. officinalis tannoids (25 or 50 μg/ml) for 12 days. Cataract development due to hyperglycemia was monitored and a lens soluble protein profile was analyzed using HPLC. α-crystallin fractions from cultured lenses were isolated by gel filtration; CLA, hydrophobicity and structural confirmation of α-crystallin were assessed using light scattering methods. Culturing the lenses with 30 mM glucose resulted in the development of cortical cataracts and the formation of high molecular weight aggregates. α-crystallin isolated from lens incubated in hyperglycemic conditions displayed a significant decrease in CLA. Co-culturing lenses with glucose and tannoids normalized the altered crystallin profile, preserved α-crystallin CLA and prevented cataract formation. This suggests that tannoids may mitigate hyperglycemia mediated manifestations to α-crystallin thereby preventing cataract formation. Tannoids of E. officinalis prevented the loss of α-crystallin CLA and cataract formation in lens organ culture. Thus, lens organ culture can be employed to investigate the pharmacological potential of compounds that modulate α-crystallin CLA and consequently delay or prevent cataractogenesis. Key words: α-Crystallin, chaperone-like activity, hyperglycemia, lens organ culture, tannoids.