Polyphenols Research Articles

Assessing Antioxidant and Pour Point Depressant Capacity of Turmeric Rhizome Extract in Biolubricants

Natural polyphenols found in plants are secondary metabolites and act as natural antioxidants. Phenols prevent lipid oxidation by donating their hydrogen to free radicals generated between reactions of oxygen with unsaturated fatty acids. This work aims to examine turmeric extract for its capacity to act as an antioxidant and pour point depressant additive in biolubricants. The study involved extracting turmeric rhizome and analyzing the extract using the gas chromatography-mass spectrometry (GC-MS) and Fourier-transform infrared spectroscopy (FTIR) techniques to identify phenolic compounds and the nature of bonds in terms of abundance peak areas. The yield of concentrated turmeric rhizome extract by weight was 3.7%. The FTIR analysis revealed O-H band at 3336 cm−1, C-H asymmetric and symmetric stretching at 2940 and 2834 cm−1, C=C cyclic ring at 1680–1515 cm−1. The phenols detected by the GC-MS technique are phenol, 2 -methoxy-3-(2-propenyl) occupying 36.3% area at 16.5 min retention time and Phenol, 2-methoxy-4-(2-propenyl)-, acetate having 3.8% area at 3.8 min retention time. The results show promising capacity of turmeric rhizome extract to act as antioxidant and pour point depressant additive in biolubricants.

Natural Polyphenol Delivered Methylprednisolone Achieve Targeted Enrichment for Acute Spinal Cord Injury Therapy.

The strong anti-inflammatory effect of methylprednisolone (MP) is a necessary treatment for various severe cases including acute spinal cord injury (SCI). However, concerns have been raised regarding adverse effects from MP, which also severely limits its clinical application. Natural polyphenols, due to their rich phenolic hydroxyl chemical properties, can form dynamic structures without additional modification, achieving targeted enrichment and drug release at the disease lesion, making them a highly promising carrier. Considering the clinical application challenges of MP, a natural polyphenolic platform is employed for targeted and efficient delivery of MP, reducing its systemic side effects. Both in vitro and SCI models demonstrated polyphenols have multiple advantages as carriers for delivering MP: (1) Achieved maximum enrichment at the injured site in 2 h post-administration, which met the desires of early treatment for diseases; (2) Traceless release of MP; (3) Reducing its side effects; (4) Endowed treatment system with new antioxidative properties, which is also an aspect that needs to be addressed for diseases treatment. This study highlighted a promising prospect of the robust delivery system based on natural polyphenols can successfully overcome the barrier of MP treatment, providing the possibility for its widespread clinical application.

Curcumin Inhibits the Development of Pancreatic Cancer by Targeting the circ_0079440/miR-522-3p/EIF4A1 Pathway.

Pancreatic cancer (PC) is a common gastrointestinal cancer with high invasiveness and high mortality. Curcumin is a natural polyphenol with anti-tumor activity against different cancers, including PC. Curcumin has been verified to mediate the expression of circular RNAs (circRNAs) to inhibit tumor development. This study aimed to explore the function and regulatory mechanism of curcumin on circ_0079440 in PC. PC cells were treated with different concentrations of curcumin (0, 5, 10 or 15 μM) for 24 h. Gene expression in PC cells and tissues was detected using RT-qPCR. Cell malignant phenotypes were determined by functional assays. The levels of EMT-related proteins were tested using western blot. RNA interaction was determined using RNA pulldown assay, luciferase reporter assay and RIP assay. The results showed that curcumin suppressed cell proliferative, migratory, and invasive capabilities, and weakened epithelial-mesenchymal transition (EMT) in a concentration-dependent way. Circ_0079440 was expressed at a high level in PC and its level was reduced via curcumin administration in PC cells. Rescue assays showed that circ_0079440 overexpression reversed the suppressive effects of curcumin on PC cell malignant phenotypes. Furthermore, in the xenograft mouse models, curcumin treatment inhibited tumor growth and metastasis, and circ_0079440 upregulation reversed the function of curcumin. Additionally, circ_0079440 was revealed to bind to miR-522-3p to upregulate eukaryotic initiation factor 4A1 (EIF4A1) expression in PC cells. EIF4A1 expression was also downregulated by curcumin, and EIF4A1 overexpression abolished the suppressive functions of curcumin. Moreover, EIF4A overexpression or miR-522-3p inhibition counteracted the anti-tumor effects of circ_0079440 depletion on PC development. To sum up, curcumin suppresses PC development by targeting the circ_0079440/miR-522-3p/EIF4A1 pathway, which might provide novel therapeutic targets for treatment of PC.

Therapeutic Effect of Resveratrol and its Novel Formulations on Lung Cancer: Focus on Biological Aspects and Underlying Pathways.

Lung cancer is a leading cause of mortality and morbidity worldwide. Due to significant advances in therapeutic strategies, patients' survival and life quality have been improved, however there is still an urgent requirement for developing more effective therapeutic methods. Resveratrol, a natural polyphenol with numerous biological potentials, has been widely studied. It has shown therapeutic potetial in various diseases including neurodegenerative diseases, cardiovascular disorders, and cancers through the regulation of key cellular signaling such as apoptosis, as well as molecular pathways such as microRNA modulation. It has been reported that resveratrol acts as an anticancer agent against lung cancer in vivo and in vitro. Resveratrol could combat against lung cancer by modulating various molecular targets and signaling pathways involved in oxidative stress, inflammation, apoptosis and autoghagy and also microRNAs expression. Moreover, novel delivery systems and analogs have recently been introduced to promote the anticancer impacts of resveratrol. In this article, we review current evidence on the anticancer effects of resveratrol and its novel formulations in the treatment of lung cancer with a focus on underlying mechanisms.

Antibacterial evaluation of polyvinyl alcohol/polyvinyl pyrrolidone/chitosan nanocomposite embedded curcumin@zinc oxide

This study focuses on the fabrication and characterization of PVA/PVP/Cs (Polyvinyl alcohol/Polyvinyl Pyrrolidone/Chitosan) composite membranes embedded with ZnO (zinc oxide) nanoparticles and curcumin as a natural polyphenol with well-known antimicrobial properties. A series of nanocomposite membranes were successfully developed via a solution casting method with varying ZnO loading (2–20 wt%) and fixed 5 wt% curcumin content and physiochemically characterized. Structural and compositional analyses using XRD, FESEM, EDX, and TEM characterizations confirmed the successful incorporation and homogeneous distribution of crystalline ZnO nanoparticles within the amorphous PVA/PVP/Cs polymer matrix. The estimated size of the synthesized ZnO nanoparticles was measured to be around 18–22 nm. TGA thermograms revealed the nanoparticles catalyzed minor reductions in thermal stability while enhancing the residual char at elevated temperatures, a function of their increasing loading fractions. These compositionally tuned PVA/PVP/Cs-ZnO-curcumin nanocomposites exhibited potent antimicrobial efficacy against selected Gram-positive and Gram-negative bacterial strains. The PVA/PVP/Cs-ZnO-curcumin nanocomposites demonstrated tunable antimicrobial activity against bacterial strains, which pave the foundation of eco-friendly, sustainable materials for addressing antimicrobial challenges in biomedical and environmental disinfection applications.

Synthesis of plyphenol-containing cationic linear and dendrimeric peptides with anti-oxidant activity

Natural polyphenols are of great interest from the point of view of their use for the pharmacological control of oxidative stress and many diseases. However, the low bioavailability and rapid metabolism of polyphenols in the form of glycosides or aglycones stimulates the search for effective means of delivery into systemic circulation. Conjugation of polyphenols with cationic amphiphilic peptides can result in compounds with strong antioxidant activity and the ability to cross biological barriers. Such compounds may be in demand as drugs for antioxidant therapy, including for the treatment of viral, oncological and neurodegenerative diseases due to the diverse range of biological activities inherent in polyphenols and peptides. In this work, cationic linear and dendrimer amphiphilic cationic peptides were synthesized by the solid phase method, and a number of peptides were conjugated to gallic acid (Ga). Ga is a non-toxic natural phenolic acid and an important functional element of many flavonoids with high antioxidant activity. It was shown that the resulting Ga-peptide conjugates exhibited antioxidant (antiradical) activity that was 2-3 times higher than that of ascorbic acid. Other tests indicated that the addition of Ga did not affect the toxicity and hemolytic activity of the conjugates. Ga-modified peptides stimulated the transmembrane transfer of the pGL3 plasmid encoding the luciferase reporter gene; however, the addition of Ga to the N-terminus of the peptide reduced its transfection activity. Some of the resulting compounds had noticeable inhibitory activity against theE. сoli-Dh5α strain.

Tea polyphenols nanoparticles integrated with microneedles multifunctionally boost 5-aminolevulinic acid photodynamic therapy for skin cancer

5-aminolevulinic acid photodynamic therapy (ALA-PDT) is an emerging therapeutic strategy for skin cancer due to its noninvasiveness and high spatiotemporal selectivity. However, poor skin penetration, poor intratumoral delivery, the instability of aqueous ALA, and the tumor’s inherent hypoxia microenvironment are major hurdles hindering the efficacy of ALA-PDT. Herein, we aim to address these challenges by using microneedles (MNs) to assist in delivering nanoparticles based on natural polymeric tea polyphenols (TP NPs) to self-assemble and load ALA (ALA@TP NPs). The TP NPs specifically increase cellular uptake of ALA by A375 and A431 cells and reduce mitochondrial membrane potential. Subsequently, the photosensitizer protoporphyrin IX derived from ALA accumulates in the tumor cells in a dose-dependent manner with TP NPs, generating reactive oxygen species to promote apoptosis and necrosis of A375 and A431 cells. Interestingly, TP NPs can ameliorate the tumor’s inherent hypoxia microenvironment and rapid oxygen consumption during PDT by inhibiting hypoxia inducible factor-1α, thereby boosting reactive oxygen species (ROS) generation and enhancing ALA-PDT efficacy through a positive feedback loop. After ALA@TP NPs are loaded into MNs to fabricate ALA@TP NPs@MNs, the MNs enhance skin penetration and storage stability of ALA. Importantly, they exhibit remarkable antitumor efficacy in A375-induced melanoma and A431-induced squamous cell carcinoma with a reduced dose of ALA and reverse hypoxia in vivo. This study provides a facile and novel strategy that integrates MNs and green NPs of TP for addressing the bottlenecks of ALA-PDT and enhancing the ALA-PDT efficacy against skin cancers for future clinical translation.

In silico investigation on the inhibitory potential of natural polyphenolics against Lanosterol 14α-Demethylase to discover novel antifungal lead compounds

Lanosterol 14α-Demethylase is considered one of the main targets for the development of novel therapeutics against fungal diseases. In this research, more than 100 natural polyphenolic compounds from honeybee propolis were introduced to blind and targeted molecular docking protocols to investigate their antifungal potential against the fungal enzyme. Finally, the compounds with the lowest binding energies were subjected to 250 ns molecular dynamics (MD) simulations. Accordingly, it turns out that three compounds, Dehydroabietic acid (DAA), 3-Hydroxy-2,2-dimethyl-8-prenylchromane-6-propenoic acid (3HPP), and (2R,3R)-6[1-(4′-Hydroxy-3′-methoxyphenyl) (HYM), bound to the catalytic pocket with the lowest binding energies of −10.4, −10.0, −9.8 kcal/mol, respectively. According to MD simulations results, binding of these three compounds to the receptor changed the RMSF magnitudes of residues in the catalytic pocket. Also, DAA and 3HPP significantly changed the structural dynamics of the protein, especially in regions vital for substrate binding and enzymatic activity, suggesting potential disruption of the enzyme's function and hindrance to fungal growth. These compounds caused notable decreases in Rg and SASA of the protein, indicating increased structural compactness. Furthermore, DAA and 3HPP significantly impacted the protein's mobility patterns, potentially impeding its function. Binding free energy calculations also revealed DAA's superior affinity, making it the top candidate among the studied ligands. According to their predicted pharmacokinetics and toxicity properties, DAA and 3HPP, with good pharmacokinetic properties and low toxicities, caused the highest instability in the protein structure, so they can be nominated as the most effective antifungal agents against Lanosterol 14α-Demethylase to further investigations to prove their efficiencies.

Porous Silica Nanomaterials as Carriers of Biologically Active Natural Polyphenols: Effect of Structure and Surface Modification.

For centuries, humans have relied on natural products to prevent and treat numerous health issues. However, biologically active compounds from natural sources, such as polyphenols, face considerable challenges, due to their low solubility, rapid metabolism, and instability, which hinder their effectiveness. Advances in the nanotechnologies have provided solutions to overcoming these problems through the use of porous silica materials as polyphenol carriers. These materials possess unique properties, such as a high specific surface area, adjustable particle and pore sizes, and a surface that can be easily and selectively modified, which favor their application in delivery systems of polyphenols. In this review, we summarize and discuss findings on how the pore and particle size, structure, and surface modification of silica materials influence the preparation of efficient delivery systems for biologically active polyphenols from natural origins. The available data demonstrate how parameters such as adsorption capacity, release and antioxidant properties, bioavailability, solubility, stability, etc., of the studied delivery systems could be affected by the structural and chemical characteristics of the porous silica carriers. Results in the literature confirm that by regulating the structure and selecting the appropriate surface modifications, the health benefits of the loaded bioactive molecules can be significantly improved.

Acetamiprid induces cardiotoxicity in rats by dysregulating α7 nAChR and its downstream targets: The ameliorative role of resveratrol

Acetamiprid (ACP) is a novel neonicotinoid insecticide used for controlling insect pests. Resveratrol (RSV) is a natural polyphenol that possesses anti-oxidant, anti-inflammatory and anti-apoptotic actions. The current research explores the mechanism of ACP-induced cardiotoxicity and the alleviative effects of RSV. Male rats were allocated to four groups of ten each. Rats were treated daily for 90 days via oral route. Control rats received distilled water, ACP rats received 25 mg acetamiprid/kg, RSV rats received 20 mg resveratrol/kg and ACP + RSV rats received both ACP and RSV. ACP exposure increased serum creatine phosphokinase activity and cardiac troponin level. It also induced oxidative stress, as evidenced by the glutathione reduction, and malondialdehyde elevation, as well as the detrimental histopathological and immunohistochemical changes in the myocardium. Gene expression analysis revealed down-regulation in the mRNA expression of the survival-related genes α7 nAChR, Erk and Bcl-2, and up-regulation in the apoptosis-related genes Jnk, Bax and Caspase-3. Conversely, the concomitant administration of ACP with RSV alleviated most of the aforementioned toxic impacts. It can be concluded that ACP induces cardiotoxicity by dysregulating the mRNA expression of α7 nAChR and its downstream targets. Additionally, RSV is proved to be a promising ameliorative agent against ACP-induced cardiotoxicity.

Soy protein-polyphenols conjugates interaction mechanism, characterization, techno-functional and biological properties: An updated review

Soy protein is a promising nutritional source with improved functionality and bioactivities due to conjugation with polyphenols (PP)—the conjugates between soy protein and PP held by covalent and noncovalent bonds. Different approaches, including thermodynamics, spectroscopy, and molecular docking simulations, can demonstrate the outcomes and mechanism of these conjugates. The soy protein, PP structure, matrix properties (temperature, pH), and interaction mechanism alter the ζ-potential, secondary structure, thermal stability, and surface hydrophobicity of proteins and also improve the techno-functional properties such as gelling ability, solubility, emulsifying, and foaming properties. Soy protein-PP conjugates also reveal enhanced in vitro digestibility, anti-allergic, antioxidant, anticancer, anti-inflammatory, and antimicrobial activities. Thus, these conjugates may be employed as edible film additives, antioxidant emulsifiers, hydrogels, and nanoparticles in the food industry. Future research is needed to specify the structure-function associations of soy protein-PP conjugates that may affect their functionality and application in the food industry.

Influence of resveratrol on the sorption of phosphorylated tau protein and MAPT on the PVDF membrane in a mouse model of Alzheimer’s disease

Alzheimer’s disease is a complex neurodegenerative disease based on various processes associated with the accumulation and aggregation of defective proteins. Among them, the particularly important ones are the following: amyloid-β, which is formed by the breakdown of amyloid precursor protein, the accumulation of hyperphosphorylated tau proteins inside neurons that form neurofibrillary tangles, and aberrant aggregation and inclusion formation of microtubule-associated protein tau (MAPT). APP/PS1 transgenic mice act as a model of Alzheimer’s disease and express mutant human genes that cause the accumulation of amyloid-β peptides in the brain. The goal of this work was a quantitative assessment of the level of p-tau231 in the brain of transgenic mice with a model of AD using the sorption method. The objectives of the study also included testing the ability of the natural polyphenol resveratrol to reduce the concentration of p-tau231 in the brain of transgenic mice and improve their cognitive functions. Western blot is a widely used method for the immunodetection and in vitro quantitative determination of proteins. Western blot allows separating proteins based on their molecular weight with the further transfer to an adsorption membrane. In this case, the proteins are transferred from the gel to the PVDF membrane using electrophoretic elution. This method involves placing a protein-containing polyacrylamide gel in direct contact with a PVDF membrane represented by a linear polymer with repetitive links -(CF2-CH2)-. Proteins transferred to the membrane are well-retained on its surface during the whole immunodetection process due to a combination of dipole and hydrophobic interactions. Western blot showed that mice with impaired protein aggregation accumulated significantly more MAPT and phosphorylated tau protein in the brain as compared to wild mice. In addition, in the course of the Morris water maze test, these mice showed cognitive deficits, which manifested both in the difficulty of finding the platform and more anxious behaviour, which confirmed pronounced thigmotaxis. The natural polyphenol resveratrol partially reversed cognitive deficits, although this effect was not associated with decreased levels of phosphorylated tau and MAPT.

Dietary curcumin supplementation attenuates hepatic damage and function abnormality in a chronic corticosterone-induced stress model in broilers

Chronic stress refers to the activation of the hypothalamic-pituitary-adrenal (HPA) axis and elevated blood contents of ACTH and corticosterone (CORT), exhibiting significant adverse effects on health outcomes. Currently, natural polyphenol compounds are increasingly being explored as potential therapeutic agents and have been considered as a treatment option for a variety of stress-induced diseases. Curcumin (CUR) is the main substance in Curcuma longa (Zingiberacea) rhizome that has strong health-beneficial properties. The study aimed to assess the potential protective effects of CUR on hepatic oxidative stress damage and abnormal lipid deposition in a chronic CORT-induced stress (CCIS) model in broilers. One hundred and twenty experimental broilers were randomly divided into 1) control group (CON), 2) CUR group (200 mg/kg feed), 3) CORT group (4 mg/kg BW CORT) and 4) CORT+CUR group (200 mg/kg feed plus 4 mg/kg BW CORT). The liver histology, glycolipid metabolism and oxidative stress were determined. In addition, qPCR was performed to identify shifts in genes expression. Compared with CON group, broilers under CCIS showed a decreased body weight, body weight gain and average daily gain, while dietary CUR significantly reversed these adverse effects. Furthermore, the plasma contents of TCH, TG, HDL-C, LDL-C, TP, GLB and AST were all significantly increased in CCIS broilers, while dietary CUR obviously alleviated the increase of TCH, HDL-C, LDL-C and AST, and relieved the hepatic lipid deposition disorder and liver injury. Moreover, CCIS significantly increased the contents of MDA in both liver and plasma, and decreased the content of plasma SOD, while CUR obviously reversed these changes, showing reduced oxidative stress damage. Finally, the mRNA expressions of FAS, ACC, SCD and the protein level of PPAR-γ were significantly increased, meanwhile the mRNA expression of lipolytic genes ACOX1, ATGL and CPT as well as two major intracellular antioxidant enzymes SOD1 and GPX1 were obviously decreased, while CUR effectively reversed these effects. These results showed that dietary CUR effectively alleviated CCIS-induced body weight loss, hepatic oxidative damage and lipid deposition disorder, suggesting the possible therapeutic effectiveness of CUR against hepatic damage and function abnormality caused by CCIS.

Green Nanoengineered Fabrics: Waste-Derived Polyphenol-Zinc@ Silica Core-Shell Reactive Janus Nanoparticles for Functional Fabrics.

Fabricating Janus nanoparticle-functionalized fabrics with UV protection, strength enhancement, self-cleaning properties, and wash durability, with a biocompatible nature, is crucial in modern functional fabrics engineering. Particularly, tailoring multifunctional nanoparticles capable of exhibiting several distinct properties, utilizing low-cost raw materials, and adhering to green chemistry principles is pivotal. A fabrication strategy for developing multifunctional reactive Janus nanoparticles, utilizing waste-derived natural polyphenol (quercetin-3-glucuronide, myricetin-3-galactoside, gossypin, phlorizin, kaempferol, myricetin-3-arabinoside)-integrated zinc-silica core-shell Janus nanoparticles with UV protection, strength enhancement, and self-cleaning properties, is proposed. Polyphenols were utilized as sustainable precursors for synthesizing zinc-polyphenol complexes, which were then encapsulated within a silica shell to form a core-shell structure. Furthermore, Janus particles were created by introducing a bifunctional layer with half amine/carboxylic acid and half methyl terminals, imparting reactive hydrophilic and hydrophobic properties. Janus-coated textiles and leather exhibited significant attenuation of harmful UV radiation, with water contact angle measurements confirming improved water repellency. The coexistence of natural phenols and bifunctional groups within a material bolstered textile strength, fostering superior adhesion and markedly enhancing wash durability. This eco-friendly approach, utilizing waste-derived materials, presents a promising solution for sustainable textile engineering with enhanced performance in UV protection and water resistance, thereby contributing to the advancement of green nanotechnology in textile applications.

Freezing-Tolerant Supramolecular Adhesives from Tannic Acid-Based Low-Transition-Temperature Mixtures.

Natural polyphenols like tannic acid (TA) have recently emerged as multifunctional building blocks for designing advanced materials. Herein, we show the benefits of having TA in a dynamic liquid state using low-transition-temperature mixtures (LTTMs) for developing freezing-tolerant glues. TA was combined with betaine or choline chloride to create LTTMs, which direct the self-assembly of guanosine into supramolecular viscoelastic materials with high adhesion. Molecular dynamics simulations showed that the structural properties of the material are linked to strong hydrogen bonding in TA-betaine and TA-choline chloride mixtures. Notably, long-term and repeatable adhesion was achieved even at -196 °C due to the binding ability of TA's catechol and gallol units and the mixtures' glass transition temperature. Additionally, the adhesives demonstrated injectability and low toxicity against fibroblasts in vitro. These traits reveal the potential of these systems as bioadhesives for tissue repair, opening new avenues for creating multifunctional soft materials with bioactive properties.

Simultaneous High-Performance Recovery and Extended Acid-Catalyzed Hydrolysis of Oleuropein and Flavonoid Glycosides of Olive (Olea europaea) Leaves: Hydrothermal versus Ethanol Organosolv Treatment.

Olive leaves (OLLs) are an exceptional bioresource of natural polyphenols with proven antioxidant activity, yet the applicability of OLL extracts is constrained by the relatively high polarity of the major polyphenols, which occur as glycosides. To overcome this limitation, OLLs were subjected to both hydrothermal and ethanol organosolv treatments, fostered by acid catalysis to solicit in parallel increased polyphenol recovery and polyphenol modification into simpler, lower-polarity substances. After an initial screening of natural organic acids, oxalic acid (OxAc) was found to be the highest-performing catalyst. The extraction behavior using OxAc-catalyzed hydrothermal and ethanol organosolv treatments was appraised using kinetics, while treatment optimization was accomplished by deploying response-surface methodology. The comparative assessment of the composition extracts produced under optimal conditions of residence time and temperature was performed with liquid chromatography-tandem mass spectrometry and revealed that OLLs treated with 50% ethanol/1.5% HCl suffered extensive oleuropein and flavone glycoside hydrolysis, affording almost 23.4 mg hydroxytyrosol and 2 mg luteolin per g dry weight. On the other hand, hydrothermal treatment with 5% OxAc provided 20.2 and 0.12 mg of hydroxytyrosol and luteolin, respectively. Apigenin was in all cases a minor extract constituent. The study presented herein demonstrated for the first time the usefulness of using a natural, food-grade organic acid to perform such a task, yet further investigation is needed to maximize the desired effect.

Evaluation of the stabilizing effect and ageing time indicator properties of poly(flavonoids) in a cyclic olefin copolymer

Few studies are concerned with the stabilization of polymers using natural polymeric polyphenols. There are no literature reports on the use of poly(flavonoids) produced by bio-chemical polymerization as stabilizers. The aim of the research was to analyse the stabilizing potential (anti-ageing UV) of poly(catechin) and poly(naringenin) in polymer compositions based on the thermoplastic elastomer of ethylene-norbornene copolymer (TOPAS Elastomer E-140). Poly(flavonoids) were obtained in a polymerization reaction with a cross-linking compound and then introduced into cyclic olefin copolymer TOPAS. For comparison, materials with monomeric catechin and naringenin were also prepared. The scope of research included the thermal analysis of the polymer compositions (Oxidation induction time OIT, Thermogravimetry TG), determination of carbonyl indices and ageing coefficients K (based on changes in mechanical properties) after UV ageing (400 h). In addition, the colour change after ageing of the samples was investigated. Samples containing polymeric forms of catechin and naringenin were more susceptible to degradation than samples with monomeric flavonoids. Inferior stabilizing properties of poly(flavonoids) were associated with steric hindrances and limited availability of hydroxyl groups to provide the antioxidant activity of the polymeric compounds. The work extends the literature data by providing an analysis of the stabilizing effect of synthetic poly(flavonoids) in polymer compositions.

Chlorogenic acid permeation across intestinal cell monolayers: Influence by circadian rhythms in the presence of other natural polyphenols and by dopaminergic neuronal-like cells

Poor oral bioavailability limits chlorogenic acid (CGA) benefits on the gut-brain axis. In this study we demonstrate the existence of an active circadian-dependent efflux for the CGA intestinal permeation, leading to greater bioavailability in the evening rather than in the morning. As therapeutic/nutraceutical polyphenols can mutually influence their intestinal absorption following circadian rhythms, we also evaluated the effects of other polyphenols on CGA permeation/bioavailability. The results indicate that gallic acid reducedin vitroCGA permeation across IEC-6 cell monolayers, as well as rat oral CGA bioavailability. On the contrary, arbutin, caffeic acid and ferulic acid did not modifyin vitroCGA permeation. Finally, 60 mM KCl-evoked dopamine release from PC12 cells significantly increased intestinal CGA permeation, likely by downregulating the expression/activity of efflux transporters, as confirmed by western blot analysis. Dopamine released from theenteric nervous systemmay therefore increase the dependence of oral bioavailability of CGA on circadian rhythms.

The Effects of a Natural Citrus Phenolic Extract on the Quality Attributes and Oxidative Stability of Pariza-Type Meat Emulsion Product

Several synthetic food additives that bear an E-number are used by the meat industry as antioxidants/preservatives of cured meat products, such as pariza-type meat emulsion products. However, these agents have been associated with health problems, namely cardiovascular disease, metabolic syndrome, and potential carcinogenic effects. As a result, natural alternatives are constantly under evaluation with the intention of replacing/minimizing their applications in the meat industry. The aim of the present study was therefore to evaluate the effects of a natural citrus phenolic complex extract on the quality characteristics of pariza-type meat emulsion products. The following three batches of pariza were produced based on the same raw material and recipe: a control group without natural antioxidants and two groups with the addition of the polyphenol complex at the levels of 500 and 1000 ppm. The pH, color, tenderness, and oxidative stability of the meat products were assessed immediately after pariza manufacture (day 0), and 30 and 72 days after the start of its refrigerated storage. As indicated, the oxidative stability of pariza was improved as a result of the natural polyphenol complex addition, since the values of malondialdehyde (MDA), an index of lipid peroxidation, were linearly decreased. Parameters such as pH, lightness (L), and yellowness (b*) were linearly increased, while redness (a*) was linearly decreased, and tenderness was not significantly influenced in the treatment groups compared to the control group. It can be concluded that the natural polyphenol complex under examination can be utilized for the improvement of oxidative stability in pariza.

Inhibition mechanism of different structural polyphenols against α-amylase studied by solid-state NMR and molecular docking

Polyphenol has the considerable effects for inhibition of digestive enzymes, however, inhibition mechanism of molecular size-dependent polyphenols on enzyme activity is still lacking. Herein, inhibition effect and binding interactions of three different structural polyphenols (catechol, quercetin and hesperidin) on α-amylase were studied. Inhibition assays proved that polyphenols significantly inhibited α-amylase and their effects were increased with their molecular sizes. Hesperidin showed the highest inhibition ability of α-amylase, which was determined as IC50 = 0.43 mg/mL. Fluorescence and FT-IR spectroscopy proved that inter-molecular interactions between polyphenols and α-amylase occurred through non-covalent bonds. Besides, the secondary structure of α-amylase was obviously changed after binding with polyphenols. Inter-molecular interactions were investigated using solid-state NMR and molecular docking. Findings proved that hydrogen bonds and π-π stacking interactions were the mainly inter-molecular interactions. We hope this contribution could provide a theoretical basis for developing some digestive enzyme inhibitors from natural polyphenols.