Determination Of Total Polyphenol Content Research Articles

Precise evaluation of batch adsorption kinetics of plant total polyphenols based on a flow-injection online spectrophotometric method.

Efficient evaluation of adsorption kinetics of plant total polyphenols is essential for the design of adsorption separation of bioactive compounds. The conventional method uses manual sampling with poor reproducibility. Here, we developed a new method for on-line determination of total polyphenol content (TPC) in plant extracts by applying the Folin-Ciocalteu method in flow-injection analysis (FIA). The FIA parameters were optimized and a standard curve with excellent linearity was established. Precise determination of TPC with a satisfactory sample throughput of 20 h-1 was achieved for the adsorption kinetic study. The pseudo-second-order kinetic model was found to better describe the kinetic parameters of the batch adsorption/desorption process. The developed method proved to be accurate compared with the conventional method. The FIA method holds significant promise for studying and monitoring adsorption processes, due to its automatic on-line nature, low consumption of reagents and samples, and the ability to generate large quantities of highly accurate adsorption data.

Comparative Study on the Total Phenolics, Total Flavonoids, and Biological Activities of Papaver rhoeas L. Extracts from Different Geographical Regions of Morocco

In this research, a comparative analysis was carried out to characterize the content of phenolics and biological activities of the whole plant of Papaver rhoeas L. (P. rhoeas) from different geographical regions of Morocco, as well as to determine the synergistic antimicrobial and antioxidant effects of all parts of P. rhoeas. The determination of total polyphenol content (TPC), total flavonoid content (TFC), and total anthocyanin content (TA) in extracts of whole plants of P. rhoeas from three different geographical regions: Taounate (P1E), Fez (P2E), and Sefrou (P3E) were estimated by the Folin–Ciocalteu reaction, the aluminum trichloride method and the differential pH absorption technique, respectively. Two tests were used to evaluate the antioxidant power of our samples: the DPPH test and the TAC test. Using two methods, disk diffusion and microdilution, antimicrobial activity was studied against four pathogenic bacteria and one yeast. The results of TPC, TFC, and TA show that the P3E sample is the richest in polyphenols, flavonoids, and anthocyanins, with values 37.33 ± 1.307 mg GAE/g, 4.72 ± 0.346 QE/g, and 1.77 ± 0.026 CGE/g, respectively. In addition, P3E showed the best antioxidant activity with an IC50 = 0.27 ± 0.001 mg/mL and TAC = 9.99 ± 0.768 mg AAE/g, respectively. The results of antimicrobial activity showed significant activity on almost all the tested strains. The lowest MIC was recorded for P3E against E. coli ATCC 25922 and E. coli CIP 53126 strains at 0.78 and 0.78 mg/mL, respectively. These results show that the geographical region can influence the plant’s phytochemistry and then these biological activities.

Total Polyphenol Content of Bromelia Leaves (Neoregelia marmorata) Etanol Extract

This study aims to determine total polyphenol content of Bromelia (Neoregelia marmorata) leaves extract with ethanol and water solvent ratio. There are three kinds of comparisons, ethanol 96%, ethanol 50 % and aquadest. The third variation of the extract is then determined the total polyphenol content. Determination of total polyphenol content was performed using visible light spectrophotometry at wavelength 758 nm with Folin-ciocalteu reagent and standard used was gallic acid. The highest average polyphenol content was obtained ethanol extract 96% then ethanol 50%, aquadest that is 0,4710 mgGAE / g; 0.3677 mgGAE / g; 0.1847 mgGAE / g. The more part of ethanol 96%, the total polyphenol content is higher. Furthermore, one way anova test is used to know the difference in the three extracts and followed by Post Hoc test. The results of the analysis showed significant differences between the three variants extract with probability value (p≤0,05).

A paper-based analytical device with in-situ Carrez pretreatment for the determination of total polyphenolic content and antioxidant capacity

A µPAD to determine the total polyphenol content (TPC) by Folin-Ciocalteau (FC) method, and antioxidant capacity by ABTS method, coupling an in-situ pretreatment zone with Carrez reagents is proposed. Conditions of FC, K2S2O8, ABTS reagents concentrations, pH, and incubation were established using 2k factorial designs. The proposed µPAD showed linearities upper than 0.99 in ranges 0.150–2.000 mg L−1 and 0.100–1.000 mg L−1 for FC and ABTS methods, respectively, detection limits were lower than 0.135 mg L−1, precision lower than 13.47 %, and recoveries between 82.27 % and 114.60 %. Ten different food samples were analyzed to demonstrate the applicability of the µPAD, and the results were compared with those obtained by the batch methods, showing no significant differences (p > 0.05). The µPAD in-situ sample treatment allowed removing interferences before the TPC and ABTS detection avoiding overestimation of the results.

Characterization of antioxidant activity and analysis of phenolic acids and flavonoids in linden honey

Ten linden honey samples from China and Russia were analyzed in this study. Based on the determination of total polyphenol content (TPC) and total flavonoid content (TFC), the antioxidant activities of ten linden honey samples were analyzed. The results showed that the TPC and TFC in linden honey were ranged from 17.57 to 31.95 mg GAE 100 g-1 and 0.81 to 1.77 mg RE 100 g-1. The TPC and TFC of linden honey were strongly correlated with the antioxidant capacity, and the pearson’s correlation values (p≤0.01) were 0.828 and 0.770 respectively. In this work, the phenolic acids and flavonoids of linden honey were analyzed by high performance liquid chromatography (HPLC). It was found that there were a lot of lindenin and abscisic acid in linden honey. Principal component analysis (PCA) and differential characteristic analysis were used to analyze the composition differences among linden honey samples. The results obtained for TPC, TFC and antioxidant capacities of linden honeys indicate linden honey had good quality as a healthy food.

Chemical Composition of White Wines Produced from Different Grape Varieties and Wine Regions in Slovakia

In this work, chemical parameters such as sugar (glucose and fructose) content, organic acid (total acids, malic and tartaric acids), total phenolic content and the antioxidant activity of 12 white wines (chardonnay, pinot blanc and pinot gris) from various wine regions in Slovakia were studied in order to identify differences among the varieties and wine-growing regions. The wine samples were examined by Fourier-transform infrared spectroscopy (FTIR) and UV-VIS spectrophotometry (for determination of total polyphenolic content (TPC) and total antioxidant activity (TAA)) methods. Content of alcohol ranged between 11.50% and 13.80% with the mean value 12.52%. Mean content of total acids varied between 4.63 ± 0.09 and 6.63 ± 0.05 g.L−1, tartaric acid varied between 1.62 ± 0.09 and 2.93 ± 0.03 g L−1, malic acid was found in the concentrations ranged from 0.07 ± 0.05 and 2.50 ± 0.08 g L−1 and lactic acid was present between 1.53 and 0.01 g L−1. The content of fructose was, in general, higher in the samples from the Južnoslovenská and Nitrianska wine regions and glucose was higher in the Malokarpatská wine region. Chardonnay wines showed the highest content of total polyphenols and the antioxidant activity in the samples ranged from 51.06 ± 027 to 72.53 ± 0.35% inhibition of DPPH. The PCA analysis based on chemical descriptors distinguished the Nitrianska and Stredoslovenská wine regions. According to similarities among the wine samples, four main classes were formed by cluster analysis.

Innovative Combination of Dispersive Solid Phase Extraction Followed by NIR-Detection and Multivariate Data Analysis for Prediction of Total Polyphenolic Content.

Recently polyphenols attracted great interest in the field of food and nutrition as well as in the pharmaceutical and cosmetics industries due to their health benefits through antioxidative behavior in the human body. However, because of the high number of compounds characterized as phenols and their structural diversity, quantification of polyphenols turns out to be a highly complex task. Although, a wide variety of analytical methods are used for the determination of total polyphenolic content, they are all found to be lacking in a variety of different tasks, such as their limits of detection and quantification, repeatability, accuracy and specificity. For this reason, a novel approach combining the advantages of solid phase purification, near infrared analysis and multivariate data analysis was investigated for the prediction of total polyphenolic content, suitable for a wide range of sample matrices. Dispersive solid phase extraction was performed and optimized using polyvinylpyrrolidone as sorbent, known to selectively bind polyphenols. Near-infrared detection of adsorbed polyphenols was carried out subsequently. Furthermore, the method was in-house validated, examining selectivity, repeatability and accuracy, working range, as well as multivariate limit of detection and limit of quantification, comparing it with two routinely used methods—namely, Folin–Ciocalteu photometric assay and Löwenthal titration. The novel established method was applied for the prediction of total polyphenolic content in tea and wine samples.

Identification and Quantification of Valuable Compounds in Red Grape Seeds

Grape seeds are a by-product of the wine industry. They represent 38–52% of grape pomace and about 5% of the weight of grapes. The main objective of this study is to establish some important characteristics of grape seeds from red varieties cultivated in Romania. The analyzed grape varieties were Cabernet Sauvignon, Merlot, Pinot noir, Burgund Mare, Cadarcă, Syrah, Novac. The grape seeds were dried and ground and the following determinations were made: determination of total polyphenol content, antioxidant capacity, antiradical capacity and determination of phenolic compounds. The analyses were performed on the first day after obtaining the grape extract, on the 14th day and the 30th day. The obtained results demonstrate that all the analyzed samples have a high content of polyphenols and show antioxidant and antiradical capacity. The highest values were obtained on the first day after separation, drying, grinding and extraction of the grape seeds and began to decrease almost constantly in time, so that for 30 days from storage the values obtained could ensure good operating yields. The seeds from the Novac grape variety obtained the best results throughout the analysis period. In the case of the total polyphenol content, the average value of the three samples Novac was 394.57 mgGAE/g dry extract and the average value of antioxidant capacity was 284.35 mgAAE/g dry extract. The greatest antiradical capacity was presented by the seeds of the Syrah and Novac varieties. The average value of the three samples from the Syrah variety was 62.1%, and in the case of the Novac variety was 61.33%. The paper demonstrates the opportunity of superior capitalization of seeds from the seven grape varieties cultivated on the territory of Romania due to the characteristics it possesses. At present, there is a major interest of consumers in the most natural products, with a major contribution to increasing the body’s immunity. The use of natural compounds in the food and pharmaceutical industry can be an important alternative.

Assessment of Genetic Diversity of Edible Honeysuckle Monitored through RAPD in Relative to Bioactive Substances

This study aimed to analyze the genetic diversity of selected cultivars and clones of Lonicera sp. (edible honeysuckle) from two countries with different climatic and soil conditions. Accordingly, the determination of total polyphenols content (TPC) and total antioxidant activity (TAA) in fruits of Lonicera sp. in 2018–2019 was performed. Applied statistical methods evaluating TPC and TAA were: correlation and regression, ANOVA, and agglomerative hierarchical clustering. The neighbor-joining method and gel images analysis (PyElph software, Pavel and Vasile, Bucharest, Romania) were used for genetic analysis. The average TPC of all cultivars and clones was 5.32 mg L−1 in the year 2018 and 3.78 mg L−1 in 2019. The average TAA values of all samples in 2018 were 8.24 mg L−1, and 9.27 mg L−1 in 2019. Statistically significant correlations between years and cultivars and clones were found. Based on the lengths and number of fragments by random amplified polymorphic DNA (RAPD)-PCR’s, it was found that ‘clone 5’ and ‘clone 7’ were genetically close to the grown cultivars from the Czech Republic. Therefore, edible honeysuckle fruits are a valuable source of important nutrients for the human body and its health.

Electrochemical Sensing of Caffeic Acid Using Gold Nanoparticles Embedded in Poly(3,4-ethylenedioxythiophene) Layer by Sinusoidal Voltage Procedure

The increasing demand for sensitive electrochemical sensors in various medical and industrial applications promotes the fabrication of novel sensing materials with improved electrocatalytic and analytical performances. This work deals with the development of a composite material based on gold nanoparticles (AuNPs) embedded in poly(3,4-ethylenedioxythiophene) (PEDOT) layer for electrochemical determination of caffeic acid (CA). CA is a phenolic compound with excellent antioxidant properties that is present in vegetables, fruits, and alcoholic and non-alcoholic beverages. Its analytical quantification is of great interest in food production monitoring and healthcare applications. Therefore, the development of sensitive analytical devices for CA monitoring is required. The AuNPs have been prepared in situ onto PEDOT coated glassy carbon electrode (GC) by means of an innovative procedure consisting on the use of a sinusoidal voltage (SV) superimposed on a constant potential. The physico-chemical properties of the PEDOT-AuNPs composite material were investigated by a range of techniques including cyclic voltammetry, electrochemical quartz crystal microbalance, and scanning electron microscopy. The glassy carbon electrode/poly(3,4-ethylenedioxythiophene)-gold nanoparticles-sinusoidal voltage (GC/PEDOT-AuNPs-SV) sensor exhibited good analytical performance toward the CA quantification with a linear response over a wide concentration range from 10 µM to 1 mM. In addition, the proposed GC/PEDOT-AuNPs-SV sensor was successfully applied in the determination of total polyphenols content expressed as equivalents of CA in juice samples.

Сrude Plant Extracts Mediated Polyphenol Oxidation Reactions in the Presence of 3-Methyl-2-Benzothiazolinone Hydrazone for the Determination of Total Polyphenol Content in Beverages

Background: The consumption of antioxidants, including phenolic compounds, is considered important for preventing the oxidative damage diseases and ageing. The total polyphenol content (TPC) is the parameter used to estimate the quality of plant-derived products. Methods: Phenol oxidase activity of green bean (Phaseolus vulgaris) crude extract (in the presence of hydrogen peroxide) and banana (Musa sp.) pulp crude extract has been studied spectrophotometrically using catechol, gallic acid, caffeic acid, ferulic acid, and quercetin as substrates. All studied compounds have been oxidized in the presence of green bean crude extract and hydrogen peroxide; all studied compounds except ferulic acid have been oxidized in the presence of banana pulp crude extract. Michaelis constants (Km) and maximum reaction rates (Vmax) have been determined for oxidation in the presence of green bean crude extract and hydrogen peroxide (Km are 3.8×10-4 M, 1.6×10-3 M, 2.2×10-4 M, 2.3×10-4 M, 1.4×10-4 M and Vmax are 0.046 min-1, 0.102 min-1, 0.185 min-1, 0.053 min-1, 0.041 min-1 for catechol, gallic acid, caffeic acid, ferulic acid, and quercetin, respectively) and for oxidation in the presence of banana pulp crude extract (Km are 1.6×10-3 M, 3.8×10-3 M, 2.2×10-3 M, 4.2×10-4 M and Vmax are 0.058 min-1, 0.025 min-1, 0.027 min-1, 0.015 min-1 for catechol, gallic acid, caffeic acid, and quercetin, respectively). The influence of 3-methyl-2-benzothiazolinone hydrazone (MBTH) on the oxidation reactions kinetics has been studied: Michaelis constants values decrease and maximum reaction rates increase, which contributes to the increase in sensitivity of the determination. Results: Kinetic procedures of Total Polyphenol Content (TPC) determination using crude plants extracts in the presence of MBTH have been proposed (time of analysis is 1 min). For gallic acid (used as a standard for TPC determination) detection limit is 5.3×10-5 M, quantitation limit is 1.8×10-4 M, and linear range is 1.8×10-4 - 1.3×10-3 M for green bean crude extract; detection limit is 2.9×10-5 M, quantitation limit is 9.5×10-5 M, and linear range is 9.5×10-5 - 2.4×10-3 M for banana pulp crude extract. Proposed procedures are characterized by higher interference thresholds for sulfites, ascorbic acid, and citric acid compared to pure enzymes (horseradish peroxidase and mushroom tyrosinase) in the same conditions. Compared with standard Folin-Ciocalteu (FC) method the procedures described in this work are also characterized by less interference and more rapid determination. Conclusion: The procedures have been applied to TPC determination in tea, coffee, and wine samples. The results agree with the FC method for tea and coffee samples and are lower for wine samples, probably, due to sulfites interference.

Fast Analysis of Total Polyphenol Content and Antioxidant Activity in Wines and Oenological Tannins Using a Flow Injection System with Tandem Diode Array and Electrochemical Detections

An analytical method for simultaneous determination of total polyphenol content (TPC) and antioxidant activity (AA) of wines (white and red wines) and oenological tannins, using a flow injection system with sequential diode array and electrochemical amperometry detectors (DAD-ECD), was proposed. The signal at 280 nm provided aggregate data for TPC. The anodic peak related to wine phenolic oxidation was scanned using pulsed integrated amperometry over the potential of 800 mV vs. Ag/AgCl, to obtain AA. Serial dilutions avoided the poisoning at the glassy carbon (GC) electrode and the linear response obtained with both detectors was compared with spectrophotometric assays commonly used in oenology laboratory. Intraday and interday analytical repetitions showed a good repeatability and reproducibility (relative standard deviation RSD < 6% for both detectors), and the satisfactory relationship between the proposed coupled flow injection/DAD-ECD and the classic UV methods (R2TPC = 0.9967; R2DPPH = 0.9621) confirmed the efficacy of flow injection analysis with a coupled detection system, for the reliable quality control of wine and wine-related products.

Rapid test for the determination of total phenolic content in brewed-filtered coffee using colorimetric paper

This work was aimed to develop a chemical sensor for the determination of total polyphenol content (TPC) of coffee samples. The polyphenol sensor was based on co-immobilization of NaIO4 and MBTH in paper as a test strip. The sensor showed sensitive response to chlorogenic acid by forming pink color adduct which can be scanned and quantified by Imagej program. The sensor had response time of 14min and a linear range between 0.07 and 0.71mM of chlorogenic acid with a detection limit at 0.002mM toward chlorogenic acid. The reproducibility of the sensor was good (RSD=0.44%) with a life time within 27days when stored at 4°C. TPC of coffee samples were determined by the sensor, and the results were in agreement with the Folin-Ciocalteu method suggesting its practical use as a tool for TPC determination in coffee samples.

Determination of total polyphenols in tea by a flow injection-fiber optic spectrophotometric system

ABSTRACTA flow injection-fiber optic spectrophotometric system was established for the online determination of total polyphenol content in tea samples. The method was based on the chromogenic reaction between the phenolic compounds (gallic acid) and ferrous tartrate which was used as the colorimetric reagent and the absorption was determined at the maximum absorption wavelength of 540 nm at 20°C and pH 7.5. The calibration curve from standard solutions of gallic acid was linear in the range from 0.010 to 0.100 mg/mL with a correlation coefficient of 0.9970. The relative standard deviation of polyphenol measurements for eight tea samples was between 0.55 and 3.18%. It can be concluded that the proposed method has allowed simple, fast, and accurate determination of total polyphenol content in tea products.

Determination of Antioxidant Activity and Polyphenols Content in Chips by Raman and IR Spectroscopy

The application of vibrational spectroscopy for the determination of total polyphenols content, antioxidant activity, colour parameters, and fat level in chips originated from yellow-, red- and purple-fleshed potato varieties is reported. Raman, infrared (IR) and near-infrared (NIR) spectra of the laboratory-prepared chips were collected. Combining spectral data with the results of reference analyses, partial least squares regression models were built. To characterise and compare the elaborated models, the relative standard errors of prediction were calculated for calibration and validation sets. In the case of total phenolics quantification by Raman/IR/NIR techniques, these errors (%) amounted to 4.0/7.0/7.1 and 6.4/8.5/8.4 for calibration and validation samples, respectively, whereas they were 4.9/7.7/4.8 and 6.6/8.3/6.8 for antioxidant activity. The obtained results demonstrate that both infrared and Raman spectroscopy can effectively replace commonly used extraction methods. It follows that Raman spectroscopy has the highest potential to be adopted for the online potato-derived product analysis.

Optimization and validation of Folin–Ciocalteu method for the determination of total polyphenol content of Pu-erh tea

Pu-erh tea is a post-fermented tea that has recently gained popularity worldwide, due to potential health benefits related to the antioxidant activity resulting from its high polyphenolic content. The Folin–Ciocalteu method is a simple, rapid, and inexpensive assay widely applied for the determination of total polyphenol content. Over the past years, it has been subjected to many modifications, often without any systematic optimization or validation. In our study, we sought to optimize the Folin–Ciocalteu method, evaluate quality parameters including linearity, precision and stability, and then apply the optimized model to determine the total polyphenol content of 57 Chinese teas, including green tea, aged and ripened Pu-erh tea. Our optimized Folin–Ciocalteu method reduced analysis time, allowed for the analysis of a large number of samples, to discriminate among the different teas, and to assess the effect of the post-fermentation process on polyphenol content.

Electrochemical and Spectrophotometric Determination of Total Polyphenol Content in Croatian Apple Varieties

Electrochemical and Spectrophotometric Determination of Total Polyphenol Content in Croatian Apple Varieties

Amperometric biosensor based on Laccase immobilized onto a screen-printed electrode by Matrix Assisted Pulsed Laser Evaporation

A Laccase-based biosensor for the determination of phenolic compounds was developed by using Matrix Assisted Pulsed Laser Evaporation as an innovative enzyme immobilization technique. and the deriving biosensor was characterized and applied for the first time. Laccase was immobilized onto different substrates including screen printed carbon electrodes and spectroscopic, morphologic and electrochemical characterizations were carried out. A linear range from 1 to 60μM was achieved working at 5.5pH and −0.2V detection potential vs Ag pseudoreference. The limits of detection and quantification were found to be 1 and 5μM, respectively. A good fabrication reproducibility, stability of response and selectivity toward interferents were also found The potential of the developed biosensor was tested in the determination of total polyphenol content in real matrices (tea infusion, ethanolic extract from Muscari comosum bulbs and aqueous solution of a food supplement from black radish root and artichoke leaves) and the results were compared with those obtained by using the Folin–Ciocalteu method.

Covalent functionalization of single-walled carbon nanotubes with polytyrosine: Characterization and analytical applications for the sensitive quantification of polyphenols

This work reports the synthesis and characterization of single-walled carbon nanotubes (SWCNT) covalently functionalized with polytyrosine (Polytyr); the critical analysis of the experimental conditions to obtain the efficient dispersion of the modified carbon nanotubes; and the analytical performance of glassy carbon electrodes (GCE) modified with the dispersion (GCE/SWCNT-Polytyr) for the highly sensitive quantification of polyphenols. Under the optimal conditions, the calibration plot for the amperometric response of gallic acid (GA) shows a linear range between 5.0 × 10−7 and 1.7 × 10−4 M, with a sensitivity of (518 ± 5) m AM−1 cm−2, and a detection limit of 8.8 nM. The proposed sensor was successfully used for the determination of total polyphenolic content in tea extracts.

The rapid determination of total polyphenols content and antioxidant activity in Dendrobium officinale using near-infrared spectroscopy

NIR spectroscopy coupled with chemometric methods for rapid quantification of total polyphenols content and antioxidant activity inDendrobium officinale.