Drevogenin D prevents selenite-induced oxidative stress andcalpain activation in cultured rat lens

[摘要] Purpose: Selenite-induced cataractogenesis is mediated by oxidativestress, accumulation of calcium and activation of lenticular calpains.Calpains are a super family of Ca2+ dependent proteases, which areinvolved in lens protein proteolysis and insolubilization. Manyinhibitors could prevent calpain-induced proteolysis of α- andβ-crystallins in rodent cataracts. Evaluating natural sources withantioxidant property and subsequent prevention of calpain activation maylead to the development of safer and more effective agents againstcataractogenesis. There are no reports on the protective role ofbioactive components against calpain-mediated proteolysis and subsequentcataractogenesis. The purpose of the study was to evaluate the role ofDrevogenin D, a triterpenoid aglycone, isolated from Dregeavolubilis in preventing selenite-induced, calcium-activated,calpain-mediated proteolysis in cultured rat lenses.Methods: Lenses were extracted from Sprague-Dawley strain rats atthe age of one month and were organ cultured in M-199 medium with HEPESbuffer. The lenses were divided into three groups with eight lenses ineach group as follows: lenses cultured in a normal medium (GI), lensescultured in a sodium selenite supplemented medium (GII), and lensescultured in a medium supplemented with sodium selenite and DrevogeninD-treated (GIII). Changes to transparency and opacity formation oflenses were monitored under microscopic observation. At the end of theexperiment, biochemical parameters such as activity of lens superoxidedismutase (SOD), lens Ca2+ ATPase, concentration of Ca2+,levels of sulfhydryl content, and thiobarbituric acid reactingsubstances (TBARS) were determined. Changes to casein zymography forcalpains, immunoblot for Lp82, and SDS-PAGE of lens water solubleprotein fraction (WSF) were also done.Results: Microscopic evaluation of lens morphology showed thatDrevogenin D prevented the opacification in G-III. Drevogenin Dinhibited the accumulation of calcium, the activation of calpain system,and lipid peroxidation. Activity of Ca2+ATPase, SOD, and SDS-PAGEprofile of water soluble proteins was normalized following treatmentwith Drevogenin D.Conclusions: Selenite-induced cataractogenesis is mediated byoxidative stress leading to a decrease in the activity of Ca2+ATPase, resulting in the accumulation of calcium and the subsequentactivation of lenticular calpains. The results obtained indicated thatDrevogenin D treatment was effective in protecting the lens proteins bycontrolling stress-induced protein oxidation, maintenance of Ca2+ATPase activity, calcium accumulation, lipid peroxidation, andprevention of calpain activation. Hence, Drevogenin D can be used as apotential therapeutic agent against oxidative stress-induced cataract.

[学科分类] 生物化学/生物物理