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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
Structural features, kinetics and SAR study of radical scavenging and antioxidant activities of phenolic and anilinic compounds
Chemistry Central Journal, Volume 7, No. 1, Article 53, Year 2013
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Description
Background: Phenolic compounds are widely distributed in plant kingdom and constitute one of the most important classes of natural and synthetic antioxidants. In the present study fifty one natural and synthetic structurally variant phenolic, enolic and anilinic compounds were examined as antioxidants and radical scavengers against DPPH, hydroxyl and peroxyl radicals. The structural diversity of the used phenolic compounds includes monophenols with substituents frequently present in natural phenols e.g. alkyl, alkoxy, ester and carboxyl groups, besides many other electron donating and withdrawing groups, in addition to polyphenols with 1-3 hydroxyl groups and aminophenols. Some common groups e.g. alkyl, carboxyl, amino and second OH groups were incorporated in ortho, meta and para positions. Results: SAR study indicates that the most important structural feature of phenolic compounds required to possess good antiradical and antioxidant activities is the presence of a second hydroxyl or an amino group in o- or p-position because of their strong electron donating effect in these positions and the formation of a stable quinone-like products upon two hydrogen-atom transfer process; otherwise, the presence of a number of alkoxy (in o or p-position) and/or alkyl groups (in o, m or p-position) should be present to stabilize the resulted phenoxyl radical and reach good activity. Anilines showed also similar structural feature requirements as phenols to achieve good activities, except o-diamines which gave low activity because of the high energy of the resulted 1,2-dimine product upon the 2H-transfer process. Enols with ene-1,2-diol structure undergo the same process and give good activity. Good correlations were obtained between DPPH inhibition and inhibition of both OH and peroxyl radicals. In addition, good correlations were obtained between DPPH inhibition and antioxidant activities in sunflower oil and liver homogenate systems. Conclusions: In conclusion, the structures of good anti radical and antioxidant phenols and anilines are defined. The obtained good correlations imply that measuring anti DPPH activity can be used as a simple predictive test for the anti hydroxyl and peroxyl radical, and antioxidant activities. Kinetic measurements showed that strong antioxidants with high activity have also high reaction rates indicating that factors stabilizing the phenoxyl radicals lower also the activation energy of the hydrogen transfer process. © 2013 Ali et al.; licensee Chemistry Central Ltd.
Authors & Co-Authors
Ali, Hussein M.
Egypt, Cairo
College of Agriculture
Saudi Arabia, Dammam
Imam Abdulrahman Bin Faisal University
Abo-Shady, Ahmed
Egypt, Cairo
College of Agriculture
Sharaf Eldeen, Hany A.
Egypt, Cairo
College of Agriculture
Sror, H. A.M.
Egypt, Cairo
College of Agriculture
Shousha, Wafaa Gh
Egypt, Helwan
Faculty of Science
Abdel-Barry, Osama A.
Egypt, Cairo
College of Agriculture
Saleh, Ahmed
Egypt, Helwan
Faculty of Science
Statistics
Citations: 86
Authors: 7
Affiliations: 3
Identifiers
Doi:
10.1186/1752-153X-7-53
e-ISSN:
1752153X