How does the FRAP assay work?
FRAP assay stands for Ferric Reducing Antioxidant Power Assay. The assay measures the antioxidant potential in samples through the reduction of ferric iron (Fe3+) to ferrous iron (Fe2+) by antioxidants present in the samples.
What is TPTZ in FRAP?
FRAP assay is based on the rapid reduction in ferric-tripyridyltriazine (FeIII-TPTZ) by antioxidants present in the samples forming ferrous-tripyridyltriazine (FeII-TPTZ), a blue-colored product (Benzie and Strain 1996).
What is the FRAP method?
The ferric reducing antioxidant power (FRAP) assay is a typical ET-based method that measures the reduction of ferric ion (Fe3+)-ligand complex to the intensely blue-colored ferrous (Fe2+) complex by antioxidants in an acidic medium.
What is the chemistry of FRAP antioxidant assay?
Ferric Reducing Antioxidant Power assay (FRAP) [17] is based on reduction of a colorless Fe3+-TPTZ complex into intense blue Fe2+-TPTZ once it interacts with a potential antioxidant. At low cost, this method showed to be useful for screening of antioxidant capacities and comparing efficiencies of different compounds.
Why is FRAP assay done?
The FRAP assay is used to measure the antioxidant power based on the reduction at low pH of ferric-tripyridyltriazine (Fe3 +-TPTZ) to an intense blue color ferrous-tripyridyltriazine complex (Fe2 +-TPTZ) with an absorption maximum at 593 nm.
What is FRAP reagent?
Ferric reducing ability of plasma (FRAP, also Ferric ion reducing antioxidant power) is an antioxidant capacity assay that uses Trolox as a standard. This assay is often used to measure the antioxidant capacity of foods, beverages and nutritional supplements containing polyphenols.
What is TPTZ?
2,4,6-Tripyridyl-S-triazine (TPTZ) is the most widely used analytical regent for the spectrophotometric determination of phenols, phonetic drugs which easily undergoes exudation under experimental conditions. It is widely used for the determination of Iron.
What is ABTS assay?
The ABTS assay measures the relative ability of antioxidants to scavenge the ABTS generated in aqueous phase, as compared with a Trolox (water soluble vitamin E analogue) standard. The ABTS is generated by reacting with a strong oxidizing agent (eg, potassium permanganate or potassium persulfate) with the ABTS salt.
What is trolox used for?
Trolox is a water-soluble antioxidant, which was synthesized as a vitamin E derivative in 1974. Trolox has been used as a standard antioxidant for these antioxidant capacity assays.
How do you make TPTZ solution?
TPTZ Stock Solution To make a 10 mM 2,4,6-tri(2-pyridyl)-1,3,5-triazine (TPTZ) solution, add 0.31 g to 100 mL HCl (40 mM). This solution is stable for at least 1 month at 4°C.
What is TPTZ reagent?
2,4,6-Tripyridyl-S-triazine (TPTZ), with the molecule formula of C18H12N6 [1] is the most widely used analytical reagent for the spectrophotometric determination of phenols, phonetic drugs which easily undergoes exudation under experimental conditions. It is widely used for the determination of Iron [2].
How do you use a FRAP assay?
The FRAP assay is based on the ability of PH to reduce Fe3+ to Fe2+. The FRAP reaction is conducted at acidic pH 3.6 to maintain iron solubility, so the reaction at low pH decreases the ionization potential that drives hydrogen atom transfer and increases the redox potential, which is the dominant reaction mechanism.
Can the FRAP assay measure antioxidant power?
DOI: 10.1006/abio.1996.0292 Abstract A simple, automated test measuring the ferric reducing ability of plasma, the FRAP assay, is presented as a novel method for assessing “antioxidant power.” Ferric to ferrous ion reduction at low pH causes a colored ferrous-tripyridyltriazine complex to form.
How are FRAP values obtained?
FRAP values are obtained by comparing the … A simple, automated test measuring the ferric reducing ability of plasma, the FRAP assay, is presented as a novel method for assessing “antioxidant power.” Ferric to ferrous ion reduction at low pH causes a colored ferrous-tripyridyltriazine complex to form.
What are the alternative ligands used in the FRAP assay?
Although the original FRAP assay uses tripyridyltriazine (TPTZ) as the iron-binding ligand, alternative ligands have also been employed for ferric binding, such as ferrozine for ascorbic acid–reducing power evaluation ( Molina-Diaz, Ortega-Carmona, & Pascual-Reguera, 1998 ).
What is the modified FRAP method?
In this modified FRAP method, an antioxidant reacts with coulometric titrants (electrogenerated ferricyanide ions), and the quantity of electricity consumed for the titration till the end point (when initial current is resumed) serves as the indicator for reducing power of the antioxidant ( Ziyatdinova et al., 2014 ).