Method For Determination Of Polyphenols Research Articles

Development of an analytical method for determination of polyphenols and total tannins from leaves of Syzygium cumini L. Skeels.

Syzygium cumini L. Skeels belongs to Myrtaceae family. This species has been recognized by its antidiabetic, anti-inflammatory, and antimicrobial activities. Despite ever-increasing scientific interest for this species there is no pharmacopeia method for characterization and standardization of S. cumini yet. So, toward this aim, the objective of this work was to develop an efficient analytical methodology able to determine polyphenols and tannins content from leaves hydroethanolic extract of S. cumini using Folin-Ciocalteu method by ultraviolet absorption spectrophotometry (UV-Vis). The analytical methodology was developed for the first time in the literature for leaves of this specie shown to be fast and low-cost with results expressed through tannic acid equivalent (TAE). Moreover, the methodology presented selectivity with maximum absorption at 706 nm wavelength, linearity with R2>0.99; limit of detection 0.275 µg TAE mL-1 and 0.102 µg TAE mL-1; limit of quantification 1.046 µg TAE mL-1 and 0.912 µg TAE mL-1 for total polyphenols and total tannins, respectively. Furthermore, the methodology was accurate with recover value greater than 98%, as well as exact, reproductive, and robust with coefficient of variation values less than 15% for both compounds. All the results are found within the fixed limits according to RDC 166/2017.

Development and validation of ultrasound assisted extraction (UAE) and HPLC-DAD method for determination of polyphenols in dry beans (Phaseolus vulgaris)

An analytical method for extraction and quantitative determination of the main phenolic compounds (hydroxycinnamic acids and derivatives, anthocyanins and flavonols) in dry beans (Phaseolus vulgaris) is described. The best extraction conditions were: 100% sonication amplitude, 10.3 min extraction, 46% ethanol, 1.5 g dry bean flour and 30 mL of solvent. The developed method was validated in terms of accuracy and precision. Good linearity was obtained, with correlation coefficients exceeding 0.999 and the quantification limits ranged from 0.25 μg/g (p-coumaric acid) to 1.38 μg/g (kaempferol). The accuracy ranged between 88 and 92% and the reproducibility of the method was always < 5.8% (RSD). The method was applied to a set of 17 accessions with different phenotypes. Results showed a greater presence, in all cases, of ferulic acid derivatives, compared to the sinapic acid and p-coumaric acid derivatives. Except for the white variety Xana, flavonoids were detected in all samples. Higher levels of anthocyanins were detected in Black Turtle Soup, a black bean, characterized by a higher content of delphinidin 3-O-glucoside, petunidin 3-O-glucoside and malvidin 3-O-glucoside. The flavonols showed a remarkable diversity, the 3-glucoside derivatives being the most abundant in all samples.

Determination of polyphenols in oats by near-infrared spectroscopy (NIRS) and two-dimensional correlation spectroscopy

Two-dimensional correlation spectroscopy (2DCOS) and near-infrared spectroscopy (NIRS) were used to determine the polyphenol content in oat grain. A partial least squares (PLS) algorithm was used to perform the calibration. A total of 116 representative oat samples from four locations in China were prepared and the corresponding near-infrared spectra were measured. Two-dimensional correlation spectroscopy was employed to select wavelength bands for the PLS regression model for the polyphenol determination. The number of PLS components and intervals was optimized according to the coefficients of determination (R2) and root mean square error of cross validation (RMSECV) in the calibration set. The performance of the final model was evaluated using the correlation coefficient (R) and the root mean square error of validation (RMSEV) in the prediction set. The results showed the band corresponding to the optimal calibration model was between 1350 and 1848 nm and the optimal spectral preprocessing combination was second derivative with second smoothing. The optimal regression model was obtained with an R2 of 0.8954 and an RMSECV of 0.06651 in the calibration set and R of 0.9614 and RMSEV of 0.04573 in the prediction set. These measurements reveal the calibration model had qualified predictive accuracy. The results demonstrated that the 2DCOS with PLS was a simple and rapid method for the quantitative determination of polyphenols in oats.

Evaluation of the Chemiluminometric Method for Determination of Polyphenols in Wine

The Pholasin chemiluminometric method for determination of polyphenols in wine was evaluated by comparison with liquid chromatography with mass-spectrometric detection. The results were also compared with the conventional Singleton-Rossi spectrophotometric method for determination of total polyphenols. A total of 141 wine samples were examined using all three methods and the results indicated a good agreement between the chemiluminometric and the Singleton-Rossi methods; however, the chromatographic data correlated reasonably well with the chemiluminometric data only for gallic acid, but less well or not at all with other determined phenolic antioxidants: trans-resveratrol, (+)-catechin, (−)-epicatechin, quercetin, vanillic-, caffeic-, caftaric-, p-coumaric-, 3,4-dihydroxybenzoic-, ellagic-, sinapic-, ferullic-, and ellagic acid.