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

Accumulation of ordered protein aggregates (or amyloids) is responsible for several neurodegenerative diseases. The behaviour of amyloidal fibril formation of beta -lactoglobulin ( beta -lg) during heat treatment depends on the environmental conditions. In this study the Al(iii) and Zn(ii) induced amyloid fibrillations of beta -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 beta -lg. Our experimental findings demonstrate that the metal-curcumin mixture can inhibit the transition from less structured oligomers to beta -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 beta -lg.