The Combined Effects of Curcumin and Cyanidin-3-Glucoside on Lipopolysaccharide-induced Denaturation in Bovine Serum Albumin

Neurodegenerative diseases (NDs) are projected to increase from 50 million to 152 million cases globally by 2060. Cognitive and motor decline associated with these disorders are caused by the accumulation of denatured proteins, disrupting cellular function (Armstrong, 2020). This study evaluated whether the polyphenols curcumin and cyanidin-3-glucoside (C3G), can prevent protein denaturation to provide a potential therapeutic treatment against NDs. It was hypothesized that combined curcumin and C3G treatment would protect bovine serum albumin (BSA) from lipopolysaccharide (LPS)-induced denaturation by stabilizing hydrophobic regions. Different concentrations of curcumin and C3G were added to LPS-BSA solutions while absorbance was measured via UV-Vis spectroscopy. For the bis-ANS fluorescence assay, various concentrations of the polyphenols were added to solutions containing LPS, BSA, and bis-ANS dye and measured for relative fluorescence units (RFU). A one-way ANOVAs of max wavelengths (λmax) and RFU revealed a significant difference for all concentrations of treatments for UV-vis, F(4, 25)= 444.7; p > .001, while only 62.5 nM was significant for bis-ANS treatment, F(4, 170)= 3.991; p = .0040. Post hoc analysis indicated that 25 µM curcumin and C3G treatment had a significant impact in preventing the hypsochromic shift caused by LPS. In the bis-ANS fluorescence assay at 62.5 nM, combined treatment significantly decreased RFU, indicating reduced hydrophobic exposure. Curcumin and C3G treatment provide enhanced protection of BSA's hydrophobic regions. The combined treatment may prevent or slow the progression of ND's by stopping denatured proteins and limiting the accumulation of aggregates.