Antioxidant activities of phenols in different solvents using DPPH assay

Autor:	K.I. Priyadarsini, Atanu Barik, Parimal Gaikwad, B. S. M. Rao
Rok vydání:	2010
Předmět:	Solvent chemistry.chemical_compound Reaction rate constant chemistry DPPH Substituent Polar effect Phenol Organic chemistry General Chemistry Phenols Solvent effects Nuclear chemistry
Zdroj:	Research on Chemical Intermediates. 36:1065-1072
ISSN:	1568-5675 0922-6168
DOI:	10.1007/s11164-010-0220-8
Popis:	Studies on the antioxidant activity of two model phenols containing either an electron withdrawing (p-nitrophenol) or electron donating (p-aminophenol) group and p-hydroxyacetophenone in different solvents are reported using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical assay by spectrophotometry and stopped-flow techniques. The second-order rate constants measured with p-nitrophenol were found to be (1.2–5.5) × 10−2 dm3 mol−1 s−1 but the DPPH radical reacts much faster with p-aminophenol (k = 0.5–1.1 × 104 dm3 mol−1 s−1). The normal kinetic solvent effect in H atom transfer was seen in the case of p-nitrophenol with the solvent independent rate constant k o = 0.1 dm3 mol−1 s−1. The IC50 values in p-nitrophenol are similar to those measured in p-hydroxyacetophenone. On the other hand, much lower IC50 values of more than four orders of magnitude with p-aminophenol were observed. This work demonstrates that the phenol with the electron donating –NH2 substituent is a better antioxidant.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::d5fb143557c03ffebccb91d1355fdee8 https://doi.org/10.1007/s11164-010-0220-8 Zobrazit plný text záznamu Plný text ve formátu PDF