Curcumin inhibits the Al(iii) and Zn(ii) induced amyloid fibrillation of β-lactoglobulin in vitro

Abstract

Accumulation of ordered protein aggregates (or amyloids) is responsible for several neurodegenerative diseases. The behaviour of amyloidal fibril formation of β-lactoglobulin (β-lg) during heat treatment depends on the environmental conditions. In this study the Al(III) and Zn(II) induced amyloid fibrillations of β-lg, in the absence and presence of curcumin, were evaluated using fluorescence, Thioflavin T, Congo red, Rayleigh scattering, dynamic light scattering analysis, FT-IR, CD spectroscopy and transmission electron microscopy. Curcumin, a natural phenolic antioxidant, is capable of binding with Al³⁺, Zn²⁺ and β-lg. Our experimental findings demonstrate that the metal–curcumin mixture can inhibit the transition from less structured oligomers to β-sheet rich protofibrils which act as seeding factors for further fibrillization. The Al(III)–curcumin mixture has greater inhibition capability than the Zn(II)–curcumin mixture of heat treated metal induced aggregation of β-lg.