Walnut Extract Inhibits the Fibrillization of Amyloid Beta-Protein, and also Defibrillizes its Preformed Fibrils

摘要

Fibrillar amyloid beta-protein (Ab) is the principal component of amyloid plaques in the brains of patients withnAlzheimer’s disease. We have studied the effect of walnut extract on Aß fibrillization by Thioflavin T fluorescencenspectroscopy and electron microscopy. The walnut extract not only inhibited Aß fibril formation in a concentration andntime- dependent manner but it was also able to defibrillize Ab preformed fibrils. Over 90% inhibition of Ab fibrillizationnwas observed with 5 ml of methanolic extract of walnut (MEOW) both after 2 and 3 days of incubation. The maximumndefibrillization (91.6%) was observed when preformed Ab fibrils were incubated with 10 ml of MEOW for 2 days. Thesenresults suggest that walnuts may reduce the risk or delay the onset of Alzheimer's disease by maintaining Aß in the solublenform. Further studies showed that anti-amyloidogenic compound in walnut is an organic compound of molecular weightnless than 10 kDa, which is neither a lipid nor a protein. Chloroform extract of walnut had no effect on Ab fibrillizationnwhile MEOW and its 10 kDa filtrate inhibited Ab fibrillization equally. It is proposed that polyphenolic compounds (suchnas flavonoids) present in walnuts may be responsible for its anti-amyloidogenic activity