Quercetin glycosides and chlorogenic acid in highbush blueberry leaf decoction prevent cataractogenesis in vivo and in vitro: Investigation of the effect on calpains, antioxidant and metal chelating properties.

The present study investigates whether highbush blueberry leaf polyphenols prevent cataractogenesis and the underlying mechanisms. Chlorogenic acid, quercetin, rutin, isoquercetin and hyperoside were quantified in Vaccinium corymbosum leaf decoction (BBL) using HPLC-DAD. Wistar rats were injected subcutaneously with 20 μmol selenite (Na2SeO3)/kg body weight on postnatal (PN) day 10 (Se, n = 8-10/group) only or also intraperitoneally with 100 mg dry BBL/kg body weight on PN days 11 and 12 (SeBBL group, n = 10). Control group received only normal saline (C). Cataract evaluation revealed that BBL significantly prevented lens opacification. It, also, protected lens from selenite oxidative attack and prevented calpain activation, as well as protein loss and aggregation. In vitro studies showed that quercetin attenuated porcine lens turbidity caused by [Formula: see text] or Ca(2+) and interacted efficiently with those ions according to UV-Vis titration experiments. Finally, rutin, isoquercetin and hyperoside moderately inhibited pure human μ-calpain. Conclusively, blueberry leaf extract, a rich source of bioactive polyphenols, prevents cataractogenesis by their strong antioxidant, chelating properties and through direct/indirect inhibition of lens calpains.