The Effect And Mechanism Study Of Crude Flavonoids From Rice Bran Inhibits Hydroxyl Radical And A?-induced Apoptosis In SH-SY5Y

Alzheimer's disease(AD)is one of the neurodegenerative diseases.The clinical pathological feature of AD patients are including brain atrophy,extracellular amyloid plaques,intracellular neuronal fibrosis,large loss of neurons and excessive accumulation of metal ions and so on.Recent studies have shown that the metal-induced oxidative stress and the aggregation of the Amyloid beta peptide(A?)have been implicated in the pathogenesis of AD.Free radicals which induced by Cu2+ related redox reaction can destroy the normal physiological function of mitochondria,oxidize cell membrane,tissue and enzyme,eventually leading to neurodegenerative diseases;the aggregats of A?(oligomers,fibers,etc.)can destroy the cell membrane,causing inflammation,and ultimately lead to neuronal apoptosis.To investigate the inhibitory effect and mechanism of crude flavonoids from rice bran on the inhibition of hydroxyl radical and A?-induced apoptosis of SH-SY5Y neurons,fluorescence,AFM and other biochemical methods were employed.Our results demonstrated that:1.The extraction process of crude flavonoids from rice bran was optimized by enzymolysis assisted extraction.The yield of rice bran was 3.26%,which including 4.47%naringenin.2.Hydroxyl radicals produced by Cu2+ catalyzed redox reaction can be reduced by the crude flavonoids from rice bran.With the addition of Crude flavonoids,the amount of the hydroxyl radicals which produced by the Cu2+ catalyzed redox reaction could be reduced by 61.82%?57.46%,and the viability of SH-SY5Y cells was increased from(25.97±2.06)%to(76.96±4.39)%.Thus our results demonstrated that the crude flavonoids from rice bran could inhibit the hydroxyl radicals induced cell apoptosis with the scavenging activity to Cu2+ catalyzed redox reaction.3.Crude flavonoids from rice bran can inhibit the toxic aggregates formation of A?(1-42).Our AFM results demonstrated that the toxic aggregates formation(oligomers,protofibrils and fibrils)was inhibited by the crude flavonoids from rice bran,and the inhibition effect was concentration depended.4.Crude flavonoids from rice bran can inhibit the apoptosis of SH-SY5Y cells which induced by A?(1-42)toxic aggregates.With incubation of 80 ?M A?(1-42),the cell viability of Ap(1-42)was reduced to(52.25±1.34)%.In the presence of crude flavonoids from rice bran,the viability of SH-SY5Y cells increased from 52.25%to(91.47±1.45)%Thus our results demonstrated that.crude flavonoids from rice bran can significantly inhibit the apoptosis of SH-SY5Y cells which induced by A?(1-42).5.Crude flavonoids from rice bran can reduce the endogenous ROS and down-regulate caspase-3 to inhibit A?(1-42)induced apoptosis of SH-SYSY cells.Compare with the A?(1-42)incubated cells,in the presence of crude flavonoids from rice bran,the endogenous ROS was reduced from 1.72±0.02 to 1.12±0.04 by using the DCFH-DA.Western blot results showed that crude flavonoids from rice bran can reduce the relative expression of caspase-3 protein from 1.73±0.07 to 1.07±0.02.Thus our results demonstrated that the mechanism of the protected effect of crude flavonoids from rice bran to A?(1-42)induced apoptosis of SH-SYSY cells could be reducing the amount of endogenous ROS and down-regulating caspase-3.In this work,the extraction process of crude flavonoids from rice bran was optimized and its components were determined by HPLC;then,the inhibitory effects and the protected mechanism of crude flavonoids from rice bran on hydroxyl radicals and A?-induced apoptosis were studied.Therefore,it provides a new idea for the treatment of AD,which provides a theoretical basis for the development of new therapeutic drugs and provides a new research direction for the comprehensive utilization of rice bran,This is of great practical significance.