THE OXIDATIVE MECHANISM OF CATARACT INDUCED BY UV IRRADATION AND ITS INHIBITION BY NATURAL PRODUCTS

摘要

Cataract accounts for more than 40 million cases of visual impairment and is the main causeof human blindness in China. UV- irradiation is one of the important factors that can induce cataract in human eyes. After lens proteins were exposed to UV-irradiation ranging from 200 to 400 nm wavelength, fluorescence absorbance of tryptophan, the low molecular weight (LMW) proteins decreased, while that of the light-sensitive material, N-formyl-kynurenine (NFK) increased. During the same irradiation process, the lens proteins kept on cross-linking and polymerizing, and the ratio of high molecular weight (HMW) proteins increased. Since UV irradiation also could produce free radicals, which could cause damages to the lens, as a result, the lens became cloudy and cataract was formed. The production of free radical from lens protein after UV-irradiation indicates that UV-irradiation damage to lens induced by the free radical oxidative mechanism. Some natural products such as Se-containing polysaccharide (Se-GPS) isolated from Se-rich garlic and Flavornoids extracted from Ginkgo biloba L.(F-EGb) possess protective effects on lens protein against oxidative damage induced by UV-irradiation. Therefore, the study could potentially shed some light on the discovery of medications to treat UV-irradiation-induced cataract.