Curcumin's pre-incubation temperature affects its inhibitory potency toward amyloid fibrillation and fibril-induced cytotoxicity of lysozyme

• Published in: Biochimica et biophysica acta Vol. 1820; no. 11; pp. 1774 - 1786
• Main Authors: Liu, Kuan-Nan, Lai, Chia-Min, Lee, Yi-Ting, Wang, Sung-Ning, Chen, Rita P.-Y., Jan, Jeng-Shiung, Liu, Hwai-Shen, Wang, Steven S.-S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.11.2012
• Subjects: Amyloid; Amyloid - antagonists & inhibitors; Amyloidosis - drug therapy; Animals; Cell Survival - drug effects; cell viability; correlation; Curcumin; Curcumin - chemistry; Curcumin - pharmacology; Cytotoxicity; denaturation; Flow Cytometry; fluorescence emission spectroscopy; hens; humans; Inhibitors; lysozyme; Muramidase - chemistry; Muramidase - pharmacology; PC12 Cells; Pre-treatment; Protein Folding; Rats; Spectrophotometry, Ultraviolet; Temperature; therapeutics; thermal stability; Thermodynamics; Thermostability; transmission electron microscopy; Thermostability; Cytotoxicity; Amyloid; Curcumin; Inhibitors; Pre-treatment
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2012.07.012

More than twenty-seven human proteins can fold abnormally to form amyloid deposits associated with a number of degenerative diseases. The research reported here is aimed at exploring the connection between curcumin's thermostability and its inhibitory activity toward the amyloid fibrillation of hen egg-white lysozyme (HEWL). ThT fluorescence spectroscopy, equilibrium thermal denaturation analysis, and transmission electron microscopy were employed for structural characterization. MTT reduction and flow cytometric analyses were used to examine cell viability. The addition of thermally pre-treated curcumin was found to attenuate the formation of HEWL fibrils and the observed fibrillation inhibition was dependent upon the pre-incubation temperature of curcumin. Our results also demonstrated that the cytotoxic effects of fibrillar HEWL species on PC 12 and SH-SY5Y cells were decreased and negatively correlated with curcumin's thermostability. Next, an enhanced stability of HEWL was perceived upon the addition of curcumin pre-incubated at lower temperature. Furthermore, we found that the alteration of curcumin's thermostability was associated with its inhibitory potency against HEWL fibrillation. We believe that the results from this research may contribute to the development of effective therapeutics for amyloidoses. ► Fibrillogenesis of hen lysozyme is attenuated by thermally pre-treated curcumin. ► Thermally pre-treated curcumin enhances lysozyme’s structural stability. ► Thermally pre-treated curcumin protects cells against fibril-induced cell death. ► Curcumin’s protection toward fibril cytotoxicity relates to its thermostability.