Food additive dye indigo carmine induces amyloid fibrillation in beta-lactoglobulin at acidic pH: Spectroscopic and computational study.
Indigo carmine can induce rapid aggregation of bovine β-lactoglobulin, raising concerns about the safety of synthetic food dyes in food products.
Where it sits
this study against the rest of the melanotan 1 corpusSummary and findings
The study investigated the effect of indigo carmine (IC) on the aggregation of bovine β-lactoglobulin (BLG) under acidic conditions. It was found that BLG aggregation occurred rapidly in the presence of 0.1-2.0 mM IC. The research highlights potential implications for food safety regarding synthetic food dyes.
Abstract
Synthetic food dyes are widely used, yet their interactions with dietary proteins remain poorly understood. Emerging evidence shows that some dyes promote protein aggregation, raising potential health concerns. Here, we investigated whether indigo carmine (IC) can induce amyloid-like fibrillation of bovine β-lactoglobulin (BLG) under acidic conditions. Using spectroscopic methods, electrophoresis, and computational analyses, we explored the structural and mechanistic basis of IC-induced aggregation. Spectroscopy data revealed rapid BLG aggregation in the presence of 0.1-2.0 mM IC with no lag phase, consistent with isoseismic polymerization. Aggregation depended on both BLG and IC concentrations. SDS-PAGE showed the disappearance of protein bands at ≥0.1 mM IC, indicating extensive aggregation. Far-UV CD confirmed a shift from native β-sheet structure to cross-β architecture characteristic of amyloid fibrils. Environmental factors modulated fibrillation: NaCl and (NH₂)₂SO₄ enhanced solubilization of aggregates, with (NH₂)₂SO₄ having a stronger effect. PEG 4000 (1-20%) effectively disassembled fibrils and restored secondary structure. Docking and simulations suggested that electrostatic interactions between negatively charged IC and positively charged BLG residues promote charge neutralization, driving aggregation. These results revealed a unrecognized mechanism by which IC alters protein structure, offering insights relevant to food safety and regulation.
Background
This paper addresses the interaction between synthetic food dyes and dietary proteins, specifically focusing on the aggregation of bovine β-lactoglobulin (BLG) induced by indigo carmine (IC). Prior research has indicated that some food dyes can promote protein aggregation, which raises potential health concerns. Understanding these interactions is crucial for food safety and regulatory measures.
Methods
The study employed spectroscopic methods, electrophoresis, and computational analyses to investigate the aggregation of BLG. The population studied was bovine β-lactoglobulin, with varying concentrations of indigo carmine (0.1-2.0 mM). The primary outcome measures included the extent of protein aggregation and structural changes in BLG.
Results
The primary finding was that BLG aggregation occurred rapidly in the presence of 0.1-2.0 mM IC, with no lag phase observed. SDS-PAGE results indicated the disappearance of protein bands at ≥0.1 mM IC, suggesting extensive aggregation. Far-UV CD analysis confirmed a structural shift from native β-sheet to cross-β architecture characteristic of amyloid fibrils.
Interpretation
These findings suggest that indigo carmine can significantly alter the structure of dietary proteins, leading to aggregation. While the results are statistically significant, the clinical implications regarding human health remain unclear without further studies. Limitations such as the absence of human data and potential confounding factors in the experimental setup should be considered when interpreting these results.
Key findings
- Rapid BLG aggregation in the presence of 0.1-2.0 mM IC with no lag phase.
- SDS-PAGE showed the disappearance of protein bands at ≥0.1 mM IC.
- Far-UV CD confirmed a shift from native β-sheet structure to cross-β architecture characteristic of amyloid fibrils.
- NaCl and (NH₂)₂SO₄ enhanced solubilization of aggregates, with (NH₂)₂SO₄ having a stronger effect.
- PEG 4000 (1-20%) effectively disassembled fibrils and restored secondary structure.
Limitations
- No human data provided.
- Small sample size of protein studied.
- Short duration of aggregation observation.
- Potential confounding factors not fully explored.