Solvent effect on the DPPH radical scavenging assay for evaluating natural antioxidants as food additives
2016
Yamauchi, R. (Fukuoka Women's University, Fukuoka (Japan). Department of International Liberal Arts) | Ishii, S. | Kusaba, Y. | Kobayashi, H. | Shimamura, T. | Ukeda, H. | Akiyama, H. | Ishikawa, H.
The 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay has proven to be valuable in the quality assessment of natural antioxidants. The effect of different solvent systems on the DPPH radical scavenging assay was examined using 16 polyphenols. The DPPH values of catechol and pyrogallol compounds determined with a Tris-HCl buffer/EtOH system were higher than those determined with a MeCN system. These results suggest that the DPPH values determined in the Tris-HCl buffer/EtOH system result from the reactivation of the catechol and pyrogallol moieties of the antioxidants. We also found that the DPPH values determined in the Tris-HCl buffer/EtOH system exhibit a higher correlation with Ferric Reducing Antioxidant Power (FRAP) values than those determined in the MeCN system. As the DPPH assay for the Tris-HCl buffer/EtOH system reflects the ferric-reducing capacity of the antioxidants as polyphenols, this system appears to be an appropriate buffer system for the DPPH assay. The effect of the volume ratio of the Tris-HCl buffer and EtOH in the system on the DPPH values was examined. The DPPH values for the catechol and pyrogallol derivatives increased with the volume ratio, suggesting that the buffer ratio is a key factor to determine the values in this assay. We thus conclude that the buffer system selection in the DPPH radical scavenging assay is a critical factor for the quality assessment of natural antioxidants used as food additives.
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