Endogenous Polyphenols Research Articles

Study on the effects of endogenous polyphenols on the structure, physicochemical properties and in vitro digestive characteristics of Euryales Semen starch based on multi-spectroscopies, enzyme kinetics, molecular docking and molecular dynamics simulation

Euryales Semen (ES) is a highly nutritious food with low digestibility, which is closely associated with its endogenous phenolic compounds. In this study, five phenolic compounds (naringenin, isoquercitrin, gallic acid, epicatechin and quercetin) with high concentrations in ES were selected to prepare starch-polyphenol complexes. Subsequently, the effects of endogenous polyphenols on the structure, physicochemical properties and digestion characteristics of ES starch were studied using multiple techniques. The addition of phenolic compounds markedly reduced the in vitro digestibility, swelling power, gelatinization enthalpy, while increased the solubility of ES starch. Fourier-transform infrared spectroscopy and X-ray diffraction analysis showed that phenolic compounds interacted with the starch through non-covalent bonds. Five phenolic compounds inhibited α-amylase activity through a mixed competitive inhibition mechanism, with the inhibition potency ranked as follows: quercetin > epicatechin > gallic acid > isoquercitrin > naringenin. The spectroscopic analysis and molecular dynamics simulations confirmed that five phenolic compounds interacted with the amino acid residues of α-amylase through hydrogen bonding and hydrophobic interactions, caused α-amylase static fluorescence quenching, and altered its conformation and microenvironment. This study provides a better understanding of the interaction mechanisms between ES starch and polyphenols, and supports the development of ES as a food that lowers sugar levels.

Enhancing in vitro starch digestion of tartary buckwheat: Unveiling the vital role of endogenous polyphenols in starch fine structure

In this study, the effect of buckwheat polyphenols (rutin and quercetin) on in vitro digestion of cooked starch was analyzed from view of the grain source, fine structure of starch and enzymatic inhibition. The results showed no significant difference in the inhibition of rutin on tartary buckwheat starch digestion as compared with common buckwheat and wheat starches. However, their inhibitory effects were negatively correlated with the content of long amylose chains (2000 < DP < 20000) but positively correlated with that of short amylose chains (100 < DP < 500) and amylopectin (13 < DP < 24) chains (p < 0.05). There was a significant difference in the digestive inhibition of rutin on starches obtained from different tartary buckwheat varieties, and the optimal ratio of rutin (2%) addition for TS1 (tartary buckwheat starch, Heifeng No.1). Quercetin showed stronger inhibition on the digestion of tartary buckwheat starch, which was attributed to the following fact: quercetin can significantly change the structure of enzymatic molecular, thereby inhibiting enzyme activity. Overall, the inhibition of rutin on starch digestion was mainly determined by starch fine structure, and 2% of rutin could show optimal inhibition on the digestion of tartary buckwheat starch.

A new insight into synergistic effects between endogenous phenolic compounds additive and α-tocopherol for the stability of olive oil.

Investigation of edible oil stability involves interactions between additive polyphenols and the inherent tocopherols. The work aimed to identify endogenous polyphenols to produce the synergistic effect with α-tocopherol in olive oil and to find the right action ratio. Caffeic acid and quercetin were selected from the 15 main endogenous phenolic compounds in olive oil. Quercetin had the strongest synergistic effect with α-tocopherol at 2:1 in the olive oil model. The rate of 2:1 also was the turning point of the change of synergism. Furthermore, the addition of quercetin and α-tocopherol at 2:1 to olive oil resulted in lower POV, K232, K270, and secondary oxidation products such as (E, E)-2,4-decadienal and 2-pentylfuran than the olive oil model with a single antioxidant in three months of accelerated oxidation. The dynamic changes of antioxidants during oxidation in olive oil indicated that their synergistic effect was the repair and regeneration of α-tocopherol by quercetin.

Insight into the dynamic molecular mechanism underlying the endogenous polyphenols inhibiting the in vitro starch digestion of highland barley noodles

Highland barley is a type of grain with slow-digesting characteristics. It is worth exploring the impact of non-starch components on starch digestion. In this study, four varieties of highland barley were used to investigate the impacts of endogenous polyphenols (EP) on the relationship between starch structure, physicochemical properties, and the time course digestibility of highland barley noodles. The results showed that EP removal decreased the proportion of long-chain amylopectin and disrupted the crystalline structure, while increasing the short-range ordered structure in the residue. Significant correlations indicated that these structural changes make starch more susceptible to thermal degradation and digestion, causing a 12.60%-52.00% increase in rapidly digestible starch (RDS) and a 12.70%-25.22% decrease in resistant starch (RS). These results revealed the internal factors that affect the slow digestion characteristics of highland barley noodles from the perspective of EP and provide important reference values for a slow digestion diet.

THE INFLUENCE OF ENDOGENOUS POLYPHENOLS, PHOTOPERIOD AND MINERAL COMPOSITION OF THE NUTRIENT MEDIUM ON THE FORMATION OF CALLUS TISSUE OF RELIC GYMNOSPERMS SEQUOIA SEMPERVIRENS (D.DON) ENDL.

Relrvance. Sequoia sempervirens (D.Don) Endl. are the tallest relict long–lived plants characterized by a limited range of growth. Valuable sequoia wood is able to accumulate unique secondary metabolites that do not have synthetic analogues. Sequoia plants grow in specialized microecological niches that limit their natural distribution area. It is known that biotic stress is one of the main environmental factors limiting the introduction of valua-ble plant species – possible sources of production of unique metabolites. Limiting environmental factors have a direct impact on the growth, develop-ment and productivity of secondary plant metabolism. Stress-resistant and highly productive plants can be created using cell biotechnology methods, in particular, in vitro cell selection, which is carried out on a callus culture. Therefore, at the first stage, it is necessary to develop in vitro technology for the rapid production of well-proliferating callus tissue. Purpose of the study. To study the effect of the mineral composition of the nutrient medium, photoperiod and endogenous polyphenols on the for-mation of the callus tissue of sequoia (Sequoia sempervirens (D.Don) Endl.) in vitro. Material and methods. The object of the study was Sequoia sempervirens (D.Don) Endl. plants. Callus tissue was obtained from segments of leaf blades and stem internodes, which were isolated from intact plants. Explants were cultured on MS and WPM nutrient medium containing BAP 2.5 mg/l and 2.5 mg/L 2,4-D. The localization of phenolic compounds was studied in the leaves, stems, apical buds of sequoia plants, as well as in callus tis-sue obtained on a nutrient medium with different mineral composition and under different lighting conditions. To do this, histochemical methods were used: for the sum of phenolic compounds, the material was stained with 0.08% Fast Blue reagent raster, a reaction with vanillin reagent in hydrochloric acid vapor was used to study the localization of flavans (catechins and proanthocyanidins). Results. It was found that the applied lighting mode had a significant effect on the intensity of callus tissue formation, its consistency and color. A well-proliferating callus tissue of light yellow color was obtained on two types of nutrient media with no light source. At a 16–hour photoperiod, a dark brown callus tissue was formed, which died during cultivation. As a rule, callus tissue was formed in those places where the localization of phenolic compounds was insignificant. It was found that in the initiated callus cultures grown on the studied nutrient media with no illumination, the content of cells with phenolic compounds was less than that of callus obtained on the same nutrient media, but with the presence of illumination. Conclusion. Sequoia plants have the ability to synthesize polyphenols, including the flavan series, which is preserved under in vitro conditions. The mineral composition of the studied nutrient media does not significantly affect the biosynthetic ability to form polyphenols in vitro cultures and their growth characteristics.

Effects of Endogenous Polyphenols in Acorn (Quercus wutaishanica Blume) Kernels on the Physicochemical Properties of Starch

AbstractThe effects of endogenous polyphenols in acorn kernels on granule morphology, crystal properties, and in vitro digestibility of starch are investigated. The granule surface smoothness, relative crystallinity, short‐range molecular order, and starch hydrolysis rate increase after the removal of polyphenols from acorn flour. With the addition of polyphenol extracts, the hydrolysis rates of acorn, corn, potato, and chestnut starches are all reduced, and the free‐polyphenol extract shows higher inhibitory activity than the bound‐polyphenol extract. These results are expected to be helpful for understanding the low digestibility of starch in acorn kernels, which is attributed to the inhibitory effects of polyphenols on the activities of α‐amylase and α‐glucosidase, but not the increase of long and short‐range molecular orders of starch.

The effect of the hormonal composition of the nutrient medium and endogenous polyphenols on the formation of callus tissue Ipomoea batatas (L.)

The effect of the hormonal composition of the nutrient medium and endogenous polyphenols on the formation of callus tissue Ipomoea batatas (L.)

An interspecies hybrid between Pyrus ussuriensis and P. bretschneideri exhibits resistance to Venturia nashicola induced by salicylic acid

ABSTRACT Pear is the third most widely grown fruit species in China, a region accounts for over 60% of the world’s pear cultivation area and production. Pear scab (Venturia nashicola and Venturia pirina) is one of the most serious diseases of pear. Here, we report a new interspecies hybrid (03-04-034) between Pyrus ussuriensis and Pyrus bretschneideri that exhibits consistently high resistance to Venturia nashicola. We compare its response to leaf infection by hyphae with that of its highly susceptible sister line 03-19-136, measure differences in their production of pathogenesis-related substances in response to infection, the results indicated hyphae could penetrate the cuticle of 03-04-034 in the early stages of infection and grew between cells and died finally in later infection stages, which suggested the resistance of 03-04-034 to scab was initiated by pathogen infection and occurred in later infection stages, typical of systemic acquired resistance. Experiments with the pathogen itself and with exogenous salicylic acid demonstrated 500 µg/ml salicylic acid treatment caused a resistance response similar to that induced by the pathogen, including dramatic increases in endogenous salicylic acid, polyphenols and lignification. In conclusion, 03-04-034 exhibits resistance to Venturia nashicola induced by salicylic acid at an appropriate concentration.

Pulp obtained after isolation of starch from red and purple potatoes (Solanum tuberosum L.) as an innovative ingredient in the production of gluten-free bread.

Starch based gluten-free bread (formulations containing mixture of corn and potato starch with hydrocolloids) are deficient in nutrients and do not contain health promoting compounds. Therefore they could be supplemented with raw materials rich in such components, especially antioxidants. Among them pseudo-cereals, seeds, fruits and vegetables are often applied to this purpose. Potato pulp produced by processing red fleshed (Magenta Love) and purple fleshed (Violetta) varieties could become a new innovative substrate for gluten-free bread enrichment, because of high levels of endogenous polyphenols, namely flavonoids, flavonols, phenolic acids and especially anthocyanins with high antioxidant potential, as well as dietary fiber. Study material consisted of gluten-free bread enriched in the pulp. Dietary fiber, acrylamide content and antioxidant and antiradical potential of the bread were determined. Sensory evaluation included crumb elasticity, porosity and other characteristics, taste and smell. Among all analyzed gluten-free breads, the sample containing 7.5% share of freeze-dried red potato pulp Magenta Love was characterized by high content of phenolic compounds and dietary fiber, pronounced antioxidant activity, low levels of potentially dangerous acrylamide and good physical and sensory characteristics. Therefore such an addition (7.5% Magenta Love) could be recommended for industrial production of gluten-free bread.

Infusion of trans-resveratrol in micron-scale grape skin powder for enhanced stability and bioaccessibility

A novel delivery system using micron-scale grape skin powder (GSP) was developed that enhanced loading, stability and bioaccessibility of trans-resveratrol (trans-Res). Vacuum assisted infusion of GSP results in a high yield (~1 mg/g) of trans-Res and improved photostability of infused trans-Res in GSP exposed to UV-A light. The release of trans-Res from GSP was ~ 45% during gastric digestion and the total release in the intestinal phase during sequential digestion processes using low and high bile salts was ~ 70% and ~ 90%, respectively. Moreover, the release of endogenous polyphenols in GSP during simulated gastrointestinal digestion was similar to the release profile of infused resveratrol, suggesting strong interactions of infused resveratrol with the GSP matrix. In summary, this research illustrates a novel approach to utilize food by-products to enhance stability and bioaccessibility of bioactive compounds.

Extensive Profiling of Polyphenols from two Trollius Species Using a Combination of Untargeted and Targeted Approaches.

Various species of globeflowers, belonging to the genus Trollius, have been extensively used in traditional Chinese medicine due to their anti-inflammatory, antimicrobial, and antiviral properties, which are mainly attributed to their high polyphenol content. Differences in polyphenol composition, and abundances, will lead to varying treatment efficacies of globeflowers. Herein, we employ a combination of targeted and untargeted mass spectrometry (MS) approaches to characterize and quantify a comprehensive array of polyphenols, mainly including flavonoids and phenolic acids in two globeflower species commonly used in Chinese medicine, Trollius chinensis Bunge and Trollius ledebouri Reichb. In addition, free radical scavenging activity was investigated to evaluate the association between polyphenol composition and antioxidation capacity. Liquid chromatography (LC)-based separation and multiple-reaction-monitoring (MRM) transitions were optimized using a library of 78 polyphenol reference compounds to achieve absolute quantification on triple quadrupoles MS (QqQ). The analytical method was further expanded via high-resolution MS to provide relative quantitation of an additional 104 endogenous polyphenols in globeflowers not included in our reference library. Our results revealed stark differences in polyphenol content between T. chinensis and T. ledebouri, emphasizing the need for systematic characterization of polyphenol composition to ensure treatment efficacy and consistency in standardizing the use of globeflowers in Chinese medicine.

Interaction effects on a gold nanoparticle-based colorimetric assay for antioxidant capacity evaluation of polyphenols.

A gold nanoparticle (AuNP)-based colorimetric assays have been applied to evaluate the total antioxidant capacities (TAC) of various food samples, while the potential endogenous polyphenol interaction effects on the AuNP assays are less explored. In this work, 12 representative polyphenols were strategically selected, and their corresponding AuNPs were synthesized and characterized by UV-Vis spectroscopy and transmission electron microscopy, which conformed the formation of AuNPs. Then, the TAC of the polyphenols, alone and in their equimolar binary or ternary combinations, were estimated and their synergistic effects were evaluated. In addition, the matrix effects of endogenous components from 6 kinds of foods on the recovery of the TAC estimation of gallic acid and rutin were evaluated. Markedly stronger interaction effects and matrix effects were observed in the AuNP assay than in conventionally well-established methods, indicating that the validation and application of the AuNP assay for TAC evaluation should be fully studied and explored.

Evidences for Chlorogenic Acid--A Major Endogenous Polyphenol Involved in Regulation of Ripening and Senescence of Apple Fruit.

To learn how the endogenous polyphenols may play a role in fruit ripening and senescence, apple pulp discs were used as a model to study the influences of chlorogenic acid (CHA, a major polyphenol in apple pulp) on fruit ripening and senescence. Apple (‘Golden Delicious’) pulp discs prepared from pre-climacteric fruit were treated with 50 mg L-1 CHA and incubated in flasks with 10 mM MES buffer (pH 6.0, 11% sorbitol). Compared to the control samples, treatment with CHA significantly reduced ethylene production and respiration rate, and enhanced levels of firmness and soluble solids content of the pulp discs during incubation at 25°C. These results suggested that CHA could retard senescence of the apple pulp discs. Proteomics analysis with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry (MALDI-TOF/TOF) revealed that the expressions of several key proteins correlated to fruit ripening and senescence were affected by the treatment with CHA. Further study showed that treating the pulp discs with CHA remarkably reduced levels of lipoxygenase, β-galactosidase, NADP-malic enzyme, and enzymatic activities of lipoxygenase and UDP-glucose pyrophosphorylase, all of which are known as promoters of fruit ripening and senescence. These results could provide new insights into the functions of endogenous phenolic compounds in fruit ripening and senescence.

Antioxidant capacity index based on gold nanoparticles formation. Application to extra virgin olive oil samples

A simple gold nanoparticles (AuNPs) based colorimetric assay for the antioxidant activity determination has been developed. The AuNP formation is mediated by extra virgin olive oil (EVOO’s) endogenous polyphenols; the reaction is described by a sigmoidal curve. The ratio KAuNPs/Xc50 (slope of the linear part of the sigmoid/concentration at half value of the absorbance) was found to be the optimal parameter to report the antioxidant capacity with respect to the single KAuNPs or Xc50 values. The obtained data demonstrated that the compounds with ortho-diphenols functionality are most active in reducing gold (III) to gold (0). Thus, intermediate activity was found for gallic acid, while tyrosol (mono-phenols) had a significant lower activity than the others antioxidant compounds (at least one order of magnitude). In the analysis of olive oil samples, a significant correlation among classical methods used to determine antioxidant activity and the proposed parameter was found with R values in the 0.96–0.97 range.

Effect of time–temperature conditions and clarification on the total phenolics and antioxidant constituents of muscadine grape juice

Juices have lower quantities of total phenolics content (TPC), anthocyanins, and antioxidant compared to the whole fruit. Furthermore, only low levels of these compounds are extracted from fruit skins during the initial juice processing steps with the majority staying in the skins and seeds. Once the initial juicing starts, degradative reactions begin to convert endogenous polyphenols into new compounds. Even though temperature is the key factor which determines this degradation rate, there is limited information about the temperature at which it begins, and the effects of centrifuging particles before or after thermal processing. The objectives were, first to determine the effects of different time–temperature conditions on the TPC, and antioxidant activity; second, to assess both parameters when the juice was clarified before or after thermal processing. Processing conditions were: 50–80 °C, and 1–30 min as residence time. At temperatures greater than 60 °C, both parameters began to decrease. The optimum processing condition for greatest retention of both parameters was 60 °C and 30 min. TPC and antioxidant activity retention were significantly higher on the juice clarified after thermal processing, compared to the one clarified before. This information can help juice processors and equipment manufacturers to optimize their process and design.

Gold-nanosphere formation using food sample endogenous polyphenols for in-vitro assessment of antioxidant capacity

In this work it was demonstrated that sample endogenous polyphenols are selectively driving the gold-nanoparticle (AuNPs)-formation process when representative food samples were used as natural sources of reducing compounds. The process of AuNPs formation was characterized by UV-visible spectroscopy and was described by a sigmoidal curve (R (2) ≥ 0.990) which gave information about the polyphenol concentration at which the localized surface plasmon resonance (LSPR) absorption reached its half-value, X (c) (50) , and about AuNPs production per polyphenol concentration unit, K (AuNPs). The behavior of phenolic acids was different, with lower X (c) (50) and higher K (AuNPs) values than flavonoids. For the food samples tea, apple, pear, wine, and honey X (c) (50) values were 0.22, 7.3, 11.5, 20.4, 30.3, and 53.5 (mg mL(-1)) and K (AuNPs) values were 28.7, 0.70, 0.60, 0.20, 0.14, and 0.10 (mg(-1) mL), respectively. Excellent correlation between K (AuNPs) and total phenolics (TP) was obtained (r = 0.98, p-value < 0.05), implying K (AuNPs) is a novel marker for evaluation of food sample antioxidant capacity in vitro. The K (AuNPs) values of samples indicated their antioxidant capacity was in the order: tea > apple > pear > wine > honey. The reproducibility of the AuNPs formation approach was excellent, not only for polyphenol standards (RSD < 6% for X (c) (50) and RSD < 11% for K (AuNPs)) but also for food samples (RSD < 9% for X (c) (50) and RSD < 15% for K (AuNPs)). Transmission electronic microscopy (TEM) enabled confirmation of the formation of stabilized Au-nanospheres from endogenous polyphenols with very well-defined sizes under 20nm diameter for all the food samples investigated.

Correlation of Malt Quality Parameters and Beer Flavor Stability: Multivariate Analysis

Malt is known to have an impact on beer flavor stability mainly due to the presence of antioxidants. In this study, five barley varieties were malted at industrial and micro scale, and quality parameters of the resulting malts were measured (diastatic power, friability, beta-glucan content, antiradical power, reducing power, lipoxygenase activity, and nonenal potential) and correlated with the sensory data obtained for the corresponding fresh and forced aged beers. A statistical strategy using multiple linear regressions was applied to explore relationships between the malt chemical parameters and beer sensory data, showing antiradical power as the major contribution of malt to beer flavor stability. Additionally, the measured antiradical power, which is well correlated with the polyphenolic content, was found to be very similar for malt and barley, emphasizing the key role of barley endogenous polyphenols.

Modified Immunoliposome Sandwich Assay for the Detection of Escherichia coli O157:H7 in Apple Cider

Detection of Escherichia coli O157:H7 in fruit juices such as apple cider is necessary for diagnosis of infection and epidemiological investigations. However, inhibitors in the apple cider, such as endogenous polyphenols and acids, often decrease the sensitivity of PCR assays and immunoassays, thus routinely requiring laborious cell separation steps to increase the sensitivity. In the current study, polyethylene glycol (PEG)–derivatized liposomes encapsulating sulforhodamine B were tagged with anti–E. coli O157:H7 antibodies and used in an immunoliposome sandwich assay for the detection of E. coli O157:H7 in apple cider. Even without prior separation, this assay can detect E. coli O157:H7 in apple cider samples inoculated with as few as 1 CFU/ml after an 8-h enrichment period. The lower limit of detection in pure cultures without enrichment was 7 × 103 CFU/ml (280 CFU/40-μl sample). PEGylated immunoliposomes are suitable as an analytical reagent for the detection of E. coli O157:H7 in fruit juices containing polyphenols.

THE USE OF CHEMICAL MARKERS AND MODEL STUDIES TO ASSESS THE IN VITRO PRO- AND ANTIOXIDATIVE PROPERTIES OF METHYLXANTHINE-RICH BEVERAGES

Chemical markers and model studies are useful in predicting the stability and shelf life of foods and beverages in food technology and chemistry. Chemical modification induced by food processing has an impact on the reactivity and chemical properties of the food constituents, frequently giving rise to new molecules with enhanced antioxidative activity and potential health benefit. In the case of coffee, tea, and cocoa, these positive characteristics are often associated with dietary polyphenols. In particular, the often referred to “paradox” behavior of endogenous polyphenols to act as anti- and/or prooxidants is demonstrated with the aid of in vitro model studies. Furthermore, in-situ chemical markers such as 8-oxocaffeine are described in methylxanthine-rich beverages that reflect oxidative reactions. Such chemicals can be employed to help assess the impact of processing conditions on food quality as well as to predict the stability of the final product.

Adsorption of endogenous polyphenols relieves the inhibition by fruit juices and fresh produce of immuno-PCR detection of Escherichia coli O157:H7.

The immuno-polymerase chain reaction (PCR) approaches facilitate rapid (8 h) detection of Escherichia coli O157:H7 in contaminated dairy products and ground beef samples with detection sensitivities approaching 1 colony forming unit (cfu) g-1 ml-1. However, no PCR products were obtained when the method was applied to identify E. coli O157:H7 in tainted apple juice. Enzyme-linked immuno-assay (ELISA) results suggested non-specific binding of endogenous polyphenols (ubiquitous in plant products) to antibodies present on the surface of the immunobeads, making the latter unavailable for capturing the target bacteria Treatment of the test sample, prior to IMS, with a synthetic fining agent, polyvinylpyrrolidone, restored the full function and sensitivity of the immuno-PCR. The study demonstrates the suitability of the improved method as a generic strategy for rapid screening of fruit juices and plant produce for E. coli O157:H7.