Dear Ahmad,

The following describes all radical scavenging assay methods:

Review: Methods Used to Evaluate the Free Radical Scavenging Activity in Foods and Biological Systems

C. Sánchez-Moreno

Abstract

Free radical generation is directly related with oxidation in foods and biological systems. Therefore, the search for methods to determine free radical scavenging is important. In this work are described the methods used for this purpose in both substrates as well as in specific cases of their application. The main methods comprise superoxide radicals scavenging (O2 ·-); hydrogen peroxide scavenging (H2O2); hypochlorous acid scavenging (HOCl); hydroxyl radical scavenging (HO.); peroxyl radical scavenging (ROO.), among them are the methods that use azo-compounds to generate peroxyl radicals, such as the ``TRAP'' method (Total Radical-Trapping Antioxidant Parameter) and the ``ORAC'' method (Oxygen-Radical Absorbance Capacity); the scavenging of radical cation 2,2-azinobis-(3-ethylbenzothiazoline-6-sulphonate) or the ABTS or the ``TEAC'' method (Trolox Equivalent Antioxidant Capacity); the scavenging of stable radical 2,2-diphenyl-1-picrylhydrazyl or DPPH . method and the scavenging of radical cation N,N-dimethyl-p-phenylenediamine or DMPD method. At present, in spite of the diversity of methods, there is a great need to standardize measurements of antioxidant activity. The search for more specific assays, giving us chemical information that could be related directly to oxidative deterioration of foods and biological systems could be the objective of future research.

http://fst.sagepub.com/content/8/3/121.short?rss=1&ssource=mfc

The most used method is based on reducing DPPH.

https://www.google.co.il/?gfe_rd=cr&ei=eRGUVrCBFsWH8QeA4oHIBA&gws_rd=ssl#

https://www.google.co.il/?gfe_rd=cr&ei=eRGUVrCBFsWH8QeA4oHIBA&gws_rd=ssl#

https://www.google.co.il/?gfe_rd=cr&ei=eRGUVrCBFsWH8QeA4oHIBA&gws_rd=ssl#

Hoping this will be helpful,

Rafik

Depends really on your extracts/ compounds/ samples! However, by personal experience, still:

1. Best time? DPPH- Really quick and gives positive results anyways!

2. Sensitivity ? FRAP  and Metal Chelating assay.

3. Cumbersome/ Difficult interpretations ? TBRS, ABTS, HRSA and Reducing Assay Power.

Attached is also one of our publications where we used 9 such assays in a comparative manner. Hope it helps.  Thanks, Biswa

Dear Ahmad,

The following describes all radical scavenging assay methods:

Review: Methods Used to Evaluate the Free Radical Scavenging Activity in Foods and Biological Systems

C. Sánchez-Moreno

Abstract

Free radical generation is directly related with oxidation in foods and biological systems. Therefore, the search for methods to determine free radical scavenging is important. In this work are described the methods used for this purpose in both substrates as well as in specific cases of their application. The main methods comprise superoxide radicals scavenging (O2 ·-); hydrogen peroxide scavenging (H2O2); hypochlorous acid scavenging (HOCl); hydroxyl radical scavenging (HO.); peroxyl radical scavenging (ROO.), among them are the methods that use azo-compounds to generate peroxyl radicals, such as the ``TRAP'' method (Total Radical-Trapping Antioxidant Parameter) and the ``ORAC'' method (Oxygen-Radical Absorbance Capacity); the scavenging of radical cation 2,2-azinobis-(3-ethylbenzothiazoline-6-sulphonate) or the ABTS or the ``TEAC'' method (Trolox Equivalent Antioxidant Capacity); the scavenging of stable radical 2,2-diphenyl-1-picrylhydrazyl or DPPH . method and the scavenging of radical cation N,N-dimethyl-p-phenylenediamine or DMPD method. At present, in spite of the diversity of methods, there is a great need to standardize measurements of antioxidant activity. The search for more specific assays, giving us chemical information that could be related directly to oxidative deterioration of foods and biological systems could be the objective of future research.

http://fst.sagepub.com/content/8/3/121.short?rss=1&ssource=mfc

The most used method is based on reducing DPPH.

https://www.google.co.il/?gfe_rd=cr&ei=eRGUVrCBFsWH8QeA4oHIBA&gws_rd=ssl#

https://www.google.co.il/?gfe_rd=cr&ei=eRGUVrCBFsWH8QeA4oHIBA&gws_rd=ssl#

https://www.google.co.il/?gfe_rd=cr&ei=eRGUVrCBFsWH8QeA4oHIBA&gws_rd=ssl#

Hoping this will be helpful,

Rafik

Hi Ahmad 

I am sharing some papers on antioxidant and radical scavenging activity. I am sure they will help you to understand the relevance of different assays. Regards

Thank you for the link Dr. Alok Nahata

HPPH is a reliable method.

If needed, combine with FRAP

DPPH, ABTS, metal cheating activities will gives quick results. But if u want explore it more follow all the pdf given by Alok Nahata.....

DPPH and ABTS are quick and reliable for free radical scavenging activity.

good luck