Folin-Ciocalteu assay

The Folin-Ciocalteu assay is the most widely used method to determine the total content of food phenolics (Fleck and others 2008). Folin-Ciocalteu reagent is not specific and detects all phenolic groups found in extracts, including those found in extractable proteins. A disadvantage of this assay is the interference of reducing substances, such as ascorbic acid (Singleton and others 1999). The content of phenolics is expressed as gallic acid or catechin equivalents. 

Table 5.6 shows the total phenolic content (determined using the Folin-Ciocalteu assay) and antioxidant activity (ABTS radical scavenging capacity) of extracts from morama bean seed coat and cotyledon prepared with acidified mefhanol. If is clear fhaf morama bean seed coat and cotyledon have appreciable levels of fofal phenolics and antioxidant activity. These phenolics are concentrated in the seed coat. It has been reported that the morama bean cotyledon contains high levels of the amino acid tyrosine (Maruatona et ah, 2010) which is phenolic in nature and can therefore confribufe fo fhe fofal phenolic content of the cotyledon as determined with the Folin-Ciocalteu assay. 

Folin-Ciocalteu (Lowry) Assay. The quantitative Folin-Ciocalteu assay (also often called the Lowry assay ) can be applied to dried material as well as to solutions. In addition, the method is sensitive samples containing as little as 5 /Ug of protein can be analyzed readily. The color formed by the Folin-Ciocalteu reagent is thought to be caused by the reaction of protein with the alkaline copper in the reagent (as in the biuret test) and the reduction... 

Colorimetric Indirect Method based on the typical reaction of polyphenols with formaldehyde, Singleton " proposed an assay for the quantification of phenolic material condensable with formaldehyde. He described a colorimetric procedure, instead of the gravimetric method, combining the Folin-Ciocalteu assay wifii the method of Stiasny (Fig 2). First, the total phenol content of the extract was measured before the precipitation reaction by the Folin-Ciocalteu method following the... 

Leamsomrong, K., M. Suttajit, and P. Chantiratikul. 2009. Flow injection analysis system for the determination of total phenolic compounds by using Folin-Ciocalteu assay. Asian J. Appl. Sci. 2(2) 184-190. 

Phenolic Content of Different Fractions of 70% Methanolic Extract Estimated Using HPLC (330 nm) and Folin-Ciocalteu Assay (750 nm)... 

Fig. 2 SEC elution profile of apple procyanidins using a Toyopearl HW-40 F column. Experimental conditions the column size was 950 x 25 mm inner diameter mobile phase solvent was acetone-8 M urea (pH 2) (6 4) flow rate was 1.0 mL/min the eluent was fractionated into 3 ml fractions each the total phenolics content (i.e., the value corresponding to the absorbance at 760 nm) in each fraction was estimated by modified Folin-Ciocalteu assay filled circle= chromatogram of apple procyanidins (10 mg/0.5 ml of mobile phase) open c// c/e=chromatogram of a mixture of standard oligomers from monomer to trimer (each 2 mg/0.5 ml of mobile phase) (reproduced from ref. [24] with permission from Elsevier)...

Total Phenols Assay (Folin-Ciocalteu Reagent)... 

Methods used for the detection of PAs in cmde or partially purified extracts can also be adapted for post-column analysis after fractionation (see below). Direct quantitative analysis of PAs in crude grape phenolic extracts is often impossible due to the complex sample matrix. Thus, fractionation or purification is often necessary before analysis. The Folin-Ciocalteu and Pmssian Blue assays are widely used for the quantification of total polyphenols in plants [27,28]. These methods are not specific for PAs due to the reaction of other phenolic compounds with these reagents. 

In vitro tests, used in evaluation of antioxidant properties make use of the ability of antioxidants to quench free radicals. Based on this mechanism, the methods are divided into two groups SET - single electron transfer, and HAT - hydrogen atom transfer. Reactions with antioxidants in assays with the DPPH radical, ABTS and the Folin-Ciocalteu reagent both operate according to the SET and HAT mechanism. Due to the kinetics of the reaction, they are included in the... 

Performing the assay is reduced to putting an alcoholic solution of the analysed sample, Folin-Ciocalteu reagent and solution of sodium carbonate into a reaction tube, which brings the pH of the reaction environment to approx. 10. According to various literature reports, the reaction runs in the darkness for 10 to 120 minutes. After that time, the blue colour of the solution is observed colorimetrically at 725 nm - 760 nm [34, 35, 36, 37, 38]. The results are expressed based on calibration curves prepared for catechol and gallic acid. 

In the Biuret reaction, a purple colour develops when the protein is treated with alkaline copper sulphate. This reaction is dependent on peptide bonds and not on the side chains of individual amino-acids present. In the Folin-Ciocalteu reaction, the protein is treated with tungstate and molybdate under alkaline conditions and the formation of a complex such phenylalanine and tyrosine gives rise to a blue colour. Lowry developed one of the most widely used protein assays in which a combination of the above reactions is involved07, l8). 

There are few spectrophotometric methods published to determine ezetimibe in pharmaceutical dosage forms. The first one was established by Mishra et al. [17] by applying colorimetric assay of phenol group. This method was developed based on the reaction between Folin-Ciocalteu s (FC) phenol reagent and phenol group of ezetimibe, which results in a blue chromogen that was then observed at 760 nm. 

A. Lowry assay (Lowry et al., 1951) Folin-Ciocalteu phenol reagent (Merck). 

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