Optimized DPPH assay in a detergent-based buffer system for measuring antioxidant activity of proteins

Area of Science:

• Biochemistry
• Analytical Chemistry
• Food Science

Background:

• The 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) assay is a standard method for determining antioxidant activity.
• Traditional DPPH assays use alcoholic solvents, which limit the solubility of proteinaceous antioxidants.
• Existing protocols struggle to maintain the solubility of protein antioxidants across various pH levels.

Purpose of the Study:

• To modify the standard DPPH assay for improved analysis of protein antioxidants.
• To enhance the solubility of both the DPPH radical and protein antioxidants.
• To ensure assay reliability and accuracy across different pH conditions.

Main Methods:

• Incorporation of non-ionic detergents to solubilize the DPPH radical and protect protein structure.
• Limitation of DPPH concentration to 100 μM to optimize detector sensitivity and assay dynamic range.
• Introduction of a 0.1 M citrate phosphate buffer to maintain consistent buffering capacity.

Main Results:

• The modified assay successfully maintained the solubility of proteinaceous antioxidants.
• Non-ionic detergents provided a mild, non-denaturing environment suitable for protein analysis.
• The adjusted buffer system prevented experimental artifacts related to pH variations.

Conclusions:

• The modified DPPH assay protocol enhances the utility of this method for evaluating protein antioxidant activity.
• This adaptation allows for accurate assessment of antioxidant properties in complex biological samples.
• The protocol improvements facilitate broader application of the DPPH assay in biochemical and food analyses.