In vitro evaluation of the effects of protein-polyphenol-polysaccharide interactions on (+)-catechin and cyanidin-3-glucoside bioaccessibility

The role of processing on phenolic bioaccessibility and antioxidant capacity of apple derivatives

Fruit derivatives are commonly obtained by applying processing operations deemed responsible for the loss of phenol compounds, but very little information is available on the fate of phenols upon digestion of these products. The present study evaluated the effect of thermal and mechanical treatments, commonly applied to turn apple pulp into puree and homogenate, on phenolic bioaccessibility and antioxidant activity. Despite a 20 % decrease in polyphenols due to processing, their bioaccessibility was higher in apple derivatives (>20 %) compared to pulp (∼2 %). Polyphenol oxidase (PPO), inactivated by thermal treatments in apple derivatives but not in the pulp, was hypothesized to be responsible for this difference. Results acquired on an unprocessed PPO-free apple model, only featuring quercetin-3-glucoside and pectin, actually exhibited similar bioaccessibility as processed derivatives. The radical scavenging capacity was unaffected by the structural integrity of apples, indicating independence from the plant tissue's hierarchical arrangement. After digestion, radical scavenging capacity decreased in the real apple matrices, correlating with phenolic content, while it was retained in the apple model, further suggesting the pivotal food matrix role in modulating polyphenols bioaccessibility and subsequent biological activity. Translating these results to an industrial scale, processing conditions can be optimized not only to guarantee that the quality requirements are met, but also to achieve desired nutritional benefits.

Nano techniques: an updated review focused on anthocyanin stability

Anthocyanins (ACNs) are one of the subgroups of flavonoids and getting intensive attraction due to the nutritional values. However, their application of ACNs is limited due to their poor stability and bioavailability. Accordingly, nanoencapsulation has been developed to enhance its stability and bio-efficacy. This review focuses on the nano-technique applications of delivery systems that be used for ACNs stabilization, with an emphasis on physicochemical stability and health benefits. ACNs incorporated with delivery systems in forms of nano-particles and fibrils can achieve advanced functions, such as improved stability, enhanced bioavailability, and controlled release. Also, the toxicological evaluation of nano delivery systems is summarized. Additionally, this review summarizes the challenges and suggests the further perspectives for the further application of ACNs delivery systems in food and medical fields.

The interaction of polyphenols-polysaccharides and their applications: A review

Polyphenols, as important secondary metabolites in nature, are widely distributed in vegetables, fruits, grains, and other foods. Polyphenols have attracted widespread attention in the food industry and nutrition due to their unique structure and various biological activities. However, the health benefits of polyphenols are compromised owing to their structural instability and sensitivity to the external environment. The interaction between polyphenols and polysaccharides largely determined the stability and functional characteristics of polyphenols in food processing and storage. Thus, this topic has attracted widespread attention in recent years. The main purposes of this article are as follows: 1) to review the interaction mechanisms of polyphenols and polysaccharides including non-covalent and covalent bonds; 2) to comprehensively analyze the influencing factors of the interaction between polyphenols and polysaccharides, and introduce the effects of their interaction on the properties of polyphenols; 3) to systematically summarize the applications of interaction between polyphenols and polysaccharides. The findings can provide the important reference and theoretical support for the application of polyphenols and polysaccharides in food industry.

In vitro digestion and antioxidant activity of Xuan-Mugua (Chaenomeles fruit) peel and pulp phenolics

Since time immortal, people have used the well-known Chinese Chaenomeles fruit Xuan-Mugua for both traditional medicine and nourishment. With an aim to explore the digestive and antioxidant properties of the phenolics, Xuan-Mugua peel and pulp were extracted, digested and analyzed in vitro. Our results indicated that the total phenolics content (TPC), total flavonoids content (TFC) and the antioxidant activity of the peel were 3.24-8.89 times higher than that of pulp. The contents and activity of the peel and pulp consistently dropped in the sequence of oral, gastric, and small intestine digestions, from 22.78 % to 52.16 %. With a level of 1.590 ± 0.060 and 0.395 ± 0.015 mg g-1 dried weight in the peel and pulp, respectively, chlorogenic acid was the primary phenolic ingredient in Xuan-Mugua, with a promising recovery (81.39-82.23 %) during the digestion. According to these results, Xuan-Mugua exhibited an appreciable level of phenolic content and antioxidant activity during digestion, making it a suitable ingredient for use in functional foods.

Stabilization effect and interaction mechanism of mannoprotein on anthocyanins in mulberry juice

This study aimed to investigate the problem of color instability in mulberry juice, examine the effect of mannoprotein (MP) dosage on improving the stability of anthocyanins in mulberry juice, and explore the molecular binding mechanism between them. As the mass ratio of anthocyanins to MP of 1.07 × 10-3: 1-1.65 × 10-3: 1, the retention rates of anthocyanins in mulberry juice and simulated system were significantly improved in the photostability experiment, with the highest increase of 128.89 % and 24.11 %, respectively. In the thermal stability experiment, it increased by 7.96 % and 18.49 %, respectively. The synergistic effect of combining MP with anthocyanins has been demonstrated to greatly enhance their antioxidant capacity, as measured by ABTS, FRAP, and potassium ferricyanide reduction method. Furthermore, MP stabilized more anthocyanins to reach the intestine in simulated in vitro digestion. MP and cyanidin-3-glucoside (C3G) interacted with each other through hydrogen bonding and hydrophobic interactions. Specific amino acid residues involved of MP in binding process were identified as threonine (THR), isoleucine (ILE) and arginine (ARG). The identification of the effective mass concentration ratio range and binding sites of MP and anthocyanins provided valuable insights for the application of MP in mulberry juice.

Newly formed phenolics selectively bound to the graded polysaccharides of lychee pulp during heat pump drying using UPLC-ESI-QqQ-TOF-MS/MS

Our study investigated heat pump drying (HPD) effects on phenolic-polysaccharide adducts of three lychee pulp grades, their composition and bound phenolic contents. During HPD, the hexose content in water soluble polysaccharide (WSP) increased continuously, and the pentose and glucuronic acid contents in WSP and dilute alkali soluble pectin (ASP) together with the hexose content in ASP increased initially and then decreased due to polysaccharide hydrolases pectinase, polygalacturonase and cellulase. After HPD, the bound phenolic content in WSP, ASP and water unextractable polysaccharide (WUP) significantly increased. Protocatechualdehyde and 3,4-dihydroxybenzeneacetic acid were newly generated phenolics and the former combined with all the three polysaccharide grades, while the latter selectively combined with only WSP. During HPD, WSP and ASP surface structures were gradually broken and became loose, but WUP surface structure was a complete and rough sheet structure. Alkaline hydrolysis caused sparser, more porous surfaces of the three polysaccharide grades. The polyphenol selectivity could be related to substrate selectivity of endogenous oxidases and the type of phenolic compounds.

Ultrasonic-assisted nanoencapsulation of kiwi leaves proanthocyanidins in liposome delivery system for enhanced biostability and bioavailability

The poor biostability and bioavailability of proanthocyanidins limit their application. In this study, it was hypothesized that encapsulation in lecithin-based nanoliposomes using ultrasonic technology improves the above properties. Based on preliminary experiments, the effects of lecithin mass ratio (1-9%, wt.), pH (3.2-6.8), ultrasonic power (0-540 W), and time (0-10 min) on biostability and bioavailability of purified kiwi leaves proanthocyanidins (PKLPs) were determined. Nanoliposomes prepared optimally with lecithin (5%, wt.), pH = 3.2, ultrasonic power (270 W), and time (5 min) demonstrated a significantly (p < 0.05) improved physicochemical stability, homogeneity, and high encapsulation efficiency (73.84%) relative to control. The PKLPs bioaccessibility during in vitro digestion increased by 2.28-3.07-fold, with a remarkable sustained release and delivery to the small intestine. Similar results were obtained by in vivo analyses, showing over 200% increase in PKLPs bioaccessibility compared to the control. Thus, PKLPs-loaded nanoliposomes are promising candidates for foods and supplements for novel applications.

Exploring the Impact of Cyanidin-3-Glucoside on Inflammatory Bowel Diseases: Investigating New Mechanisms for Emerging Interventions

Cyanidin-3-O-glucoside (C3G), the most widely distributed anthocyanin (ACN) in edible fruits, has been proposed for several bioactivities, including anti-inflammatory, neuro-protective, antimicrobial, anti-viral, anti-thrombotic and epigenetic actions. However, habitual intake of ACNs and C3G may vary widely among populations, regions, and seasons, among individuals with different education and financial status. The main point of C3G absorption occurs in the small and large bowel. Therefore, it has been supposed that the treating properties of C3G might affect inflammatory bowel diseases (IBD), such as ulcerative colitis (UC) and Crohn's disease (CD). IBDs develop through complex inflammatory pathways and sometimes may be resistant to conventional treatment strategies. C3G presents antioxidative, anti-inflammatory, cytoprotective, and antimicrobial effects useful for IBD management. In particular, different studies have demonstrated that C3G inhibits NF-κB pathway activation. In addition, C3G activates the Nrf2 pathway. On the other hand, it modulates the expression of antioxidant enzymes and cytoprotective proteins, such as NAD(P)H, superoxide dismutase, heme-oxygenase (HO-1), thioredoxin, quinone reductase-oxide 1 (NQO1), catalase, glutathione S-transferase and glutathione peroxidase. Interferon I and II pathways are downregulated by C3G inhibiting interferon-mediating inflammatory cascades. Moreover, C3G reduces reactive species and pro-inflammatory cytokines, such as C reactive protein, interferon-γ, tumor necrosis factor-α, interleukin (IL)-5, IL-9, IL-10, IL-12p70, and IL-17A in UC and CD patients. Finally, C3G modulates gut microbiota by inducing an increase in beneficial gut bacteria and increasing microbial abundances, thus mitigating dysbiosis. Thus, C3G presents activities that may have potential therapeutic and protective actions against IBD. Still, in the future, clinical trials should be designed to investigate the bioavailability of C3G in IBD patients and the proper therapeutic doses through different sources, aiming to the standardization of the exact clinical outcome and efficacy of C3G.

Nanoformulations for the Delivery of Dietary Anthocyanins for the Prevention and Treatment of Diabetes Mellitus and Its Complications

Diabetes mellitus (DM) is a metabolic disease characterized by abnormal blood glucose levels-hyperglycemia, caused by a lack of insulin secretion, impaired insulin action, or a combination of both. The incidence of DM is increasing, resulting in billions of dollars in annual healthcare costs worldwide. Current therapeutics aim to control hyperglycemia and reduce blood glucose levels to normal. However, most modern drugs have numerous side effects, some of which cause severe kidney and liver problems. On the other hand, natural compounds rich in anthocyanidins (cyanidin, delphinidin, malvidin, pelargonidin, peonidin, and petunidin) have also been used for the prevention and treatment of DM. However, lack of standardization, poor stability, unpleasant taste, and decreased absorption leading to low bioavailability have hindered the application of anthocyanins as therapeutics. Therefore, nanotechnology has been used for more successful delivery of these bioactive compounds. This review summarizes the potential of anthocyanins for the prevention and treatment of DM and its complications, as well as the strategies and advances in the delivery of anthocyanins using nanoformulations.

Optimization of Supercritical Carbon Dioxide Extraction of Polyphenols from Black Rosehip and Their Bioaccessibility Using an In Vitro Digestion/Caco-2 Cell Model

The fruits of Rosa pimpinellifolia are rich sources of (poly)phenols, however they are underutilized due to the limited information available. The influence of the pressure, temperature, and co-solvent concentration (aqueous ethanol) of the supercritical carbon dioxide extraction (SCO₂-aqEtOH) on the extraction yield, total phenolic-, total anthocyanin-, catechin-, cyanidin-3-O-glucoside contents, and total antioxidant activity of black rosehip was investigated simultaneously. The maximum obtained total phenolic and total anthocyanin contents under the optimized extraction conditions (280 bar, 60 °C and 25% ethanol, v/v) were 76.58 ± 4.25 mg gallic acid equivalent and 10.89 ± 1.56 mg cyanidin-3-O-glucoside equivalent per g of the dry fruits, respectively. The optimal extract obtained by SCO₂-aqEtOH was compared to two other extraction procedures: ultrasonication using ethanol as solvent (UA-EtOH) and pressurized hot water extraction (PH-H₂O). The bioaccessibility and cellular metabolism of the phenolic compounds in the different black rosehip extracts were assessed using an in vitro digestion coupled with a human intestinal Caco-2 cell model. The in vitro digestive stability and cellular uptake of the phenolic compounds had no significant difference among the different extraction methods. The results of this study confirm the efficiency of SCO₂-aqEtOH extraction for phenolic compounds and, in particular, for anthocyanins, and could be used to produce new functional food ingredients from black rosehip with high antioxidant power containing both hydrophilic and lipophilic compounds.

Influence of Green Tea Added to Cherry Wine on Phenolic Content, Antioxidant Activity and Alpha-Glucosidase Inhibition during an In Vitro Gastrointestinal Digestion

Cherries are a good source of bioactive compounds, with high antioxidant activity as well as nutritional and therapeutic importance. In this study, cherry wines enriched with green tea infusion (mild and concentrated) were produced, and their biological properties were evaluated. During winemaking, the main vinification parameters (alcohol, reducing sugars, acidity, total polyphenol content) as well biological activity (antioxidant activity, alpha-glucosidase inhibition potential) were determined. An in vitro digestion process was also performed to evaluate the impact of the gastrointestinal environment on the biological stability of the wines, and to analyze the interactions of wine-intestinal microflora. The addition of green tea to the cherry wine significantly increased the total polyphenol content (up to 2.73 g GAE/L) and antioxidant activity (up to 22.07 mM TE/L), compared with the control wine. However, after in vitro digestion, a reduction in total polyphenols (53–64%) and antioxidant activity (38–45%) were noted. Wines fortified with green tea expressed a stronger inhibition effect on intestinal microflora growth, of which E. coli were the most sensitive microorganisms. The tea-derived bioactive compounds significantly increased the potential of alpha-glucosidase inhibition. The proposed wines could be a good alternative type of wine, with an increased polyphenol content and the potential to control the insulin response supporting therapy for diabetes.

The effects of β-lactoglobulin on cyanidin-3-O-glucoside antioxidant activity and bioaccessibility after heat treatment

The impact of heat treatment at different temperatures on the interaction of β-lactoglobulin (β-Lg) and anthocyanin-3-O-glucoside (C3G) was studied. Heat treatment and the addition of C3G changed the secondary structure of β-Lg with decreasing β-sheets and increasing random coils. Interactions between C3G and β-Lg were mainly via hydrogen bonds and van der Waals forces at 25 °C. The elevated temperature promoted hydrophobic interactions between C3G and β-Lg due to an increase in the hydrophobic groups and amino groups on the surface of β-Lg molecules. The addition of β-Lg to the C3G eliminated heat-induced thermal degradation of C3G. The β-Lg-C3G interactions accompanied with increased particle size and constant zeta potential could increase the antioxidant capacity of C3G approximately by 4% to 10% and protect the colour of C3G from degradation under heat treatment. The C3G bioaccessibility with β-Lg addition increased by 26.08%, 33.45%, 83.09%, 72.27%, and 354.62% compared with C-25, C-60, C-85, C-100, and C-121, respectively. The protective effect of the non-covalent interactions on C3G at high temperatures (85 °C to 121 °C) was significantly stronger than at 25 °C and 60 °C. The application of β-Lg in foodstuffs could enhance the antioxidant activity and bioaccessibility of C3G.

Polysaccharides improved the viscoelasticity, microstructure, and physical stability of ovalbumin-ferulic acid complex stabilized emulsion

This study explored the mechanism underlying the interactions between polysaccharides and ovalbumin-ferulic acid (OVA-FA) and the effect of polysaccharides on OVA-FA-stabilized emulsions. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to study the polysaccharide OVA-FA interactions mechanism and to resolve the changes in the protein secondary structure and crystal structure. OVA-FA-polysaccharide-stabilized emulsions were studied using confocal laser scanning microscopy (CLSM), and their rheological properties and stability were determined. The results showed that the non-covalent interactions between polysaccharides and OVA-FA led to an increase in the β-sheet content of OVA and a decrease in the α-helix and random coil contents. The stability of the OVA-FA-polysaccharide-stabilized emulsions was better compared with that of the OVA-FA-stabilized emulsions. By comparing the different OVA-FA-polysaccharide-stabilized emulsions, we observed that OVA-FA-agar did not stabilize the emulsion well, while the OVA-FA-SA- and OVA-FA-KC-stabilized emulsions had good elasticity, and the microstructure and storage stability of the OVA-FA-KC-stabilized emulsion were better. Our findings provide a new perspective for the application of OVA-FA-KC in complex food emulsions.

Stability, Morphology, and Effects of In Vitro Digestion on the Antioxidant Properties of Polyphenol Inclusion Complexes with β-Cyclodextrin

Polyphenols are inversely associated with the incidence of chronic diseases, but therapeutic use is limited by poor stability and bioaccessibility. Encapsulation has been shown to overcome some of these limitations. A selection of polyphenols (catechin, gallic acid, and epigallocatechin gallate) and their combinations were encapsulated in beta-cyclodextrin (βCD). Encapsulation was characterized and the thermal and storage stability was evaluated using the 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. The samples were then subjected to in vitro digestion using a simple digestion (SD) model (gastric and duodenal phases) and a more complex digestion (CD) model (oral, gastric, and duodenal phases). Thereafter, the chemical (oxygen radical absorbance capacity assay) and cellular (dichlorofluorescein diacetate assay in Caco-2 cells) antioxidant and antiglycation (advanced glycation end-products assay) activities were determined. Inclusion complexes formed at a 1:1 molar ratio with a high encapsulation yield and efficiency. Encapsulation altered the morphology of the samples, increased the thermal stability of some and the storage stability of all samples. Encapsulation maintained the antioxidant activity of all samples and significantly improved the antiglycation and cellular antioxidant activities of some polyphenols following SD. In conclusion, the formed inclusion complexes of βCD with polyphenols had greater storage stability, without altering the beneficial cellular effects of the polyphenols.

A Novel Hyaluronic Acid-Black Rice Anthocyanins Nanocomposite: Preparation, Characterization, and Its Xanthine Oxidase (XO)-Inhibiting Properties

To promote the normal metabolism of human uric acid, high-performance hyaluronic acid-black rice anthocyanins (HAA) nanocomposite particles were successfully prepared by a simple crosslinking method as a novel xanthine oxidase inhibitor. Its structure and properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), and X-ray diffraction (XRD). SEM and TEM electron microscopy showed an obvious double-layer spherical structure with a particle size of ~298 nm. FT-IR and XRD analysis confirmed that black rice anthocyanins (ATC) had been successfully loaded into the hyaluronic acid (HA) structure. Nanocomposite particles (embedded form) showed higher stability in different environments than free black rice ATC (unembedded form). In addition, the preliminary study showed that the inhibition rate of the nanocomposite particles on Xanthine oxidase (XO) was increased by 40.08%. These results indicate that HAA nanocomposite particles can effectively improve black rice ATC's stability and activity, creating an ideal new material for inhibiting XO activity that has a broad application prospect.

Antioxidant activity, stability, in vitro digestion and cytotoxicity of two dietary polyphenols co-loaded by β-lactoglobulin

The combination of multiple dietary polyphenols may have synergistic beneficial effects. And the beneficial effects can be further improved by the encapsulation of proteins. The interactions of procyanidin B2 (PB2) and/or dihydromyricetin (DMY) with β-lactoglobulin (β-LG) were investigated using multi-spectroscopic techniques and molecular docking. The structural change of β-LG in the presence of PB2 and/or DMY was demonstrated by dynamic light scattering, Fourier transform infrared spectroscopy and circular dichroism spectroscopy. Response surface analysis was used to optimize the synergistic antioxidant activity between PB2 and DMY. Besides, the antioxidant activity, stability, in vitro digestion and cytotoxicity of PB2 and DMY in the binary and ternary systems were investigated. These studies will elucidate the interaction mechanism of PB2 and/or DMY with β-LG. The research results can provide theoretical support for the development of functional foods and beverages with synergistic activity, improved stability and bioaccessibility, thereby promoting human health and preventing diseases.

Extraction of Anthocyanins from Borage (Echium amoenum) Flowers Using Choline Chloride and a Glycerol-Based, Deep Eutectic Solvent: Optimization, Antioxidant Activity, and In Vitro Bioavailability

Borage flower (Echium amoenum), an annual herb native to the Mediterranean region, is an excellent source of anthocyanins and is widely used in various forms due to its biological activities. In the present study, a choline chloride and glycerol (CHGLY)-based natural deep eutectic solvent (NADES) was applied in order to extract the anthocyanins from borage flowers. The traditional solvents, including water, methanol, and ethanol, were used to evaluate the efficiency of CHGLY. The results showed that CHGLY was highly efficient compared to the traditional solvents, providing the highest amounts of the total anthocyanin content (TAC), total phenolic content (TPC), total flavonoid content (TFC), individual anthocyanins, and antioxidant activity (DPPH radical scavenging (DPPH) and ferric-reducing antioxidant power (FRAP) assays). The most dominant anthocyanin found in studied borage was cyanidin-3-glucoside, followed by cyanin chloride, cyanidin-3-rutinoside, and pelargonidin-3-glucoside. The bioavailability % was 71.86 ± 0.47%, 77.29 ± 0.57%, 80.22 ± 0.65%, and 90.95 ± 1.01% for cyanidin-3-glucoside, cyanidin-3-rutinoside, by pelargonidin-3-glucoside and cyanin chloride, respectively. However, cyanidin-3-glucoside was the anthocyanin compound showing the highest stability (99.11 ± 1.66%) in the gastrointestinal environment. These results suggested that choline chloride and glycerol-based NADES is not only an efficient, eco-friendly solvent for the extraction of anthocyanins but can also be used to increase the bioavailability of anthocyanins.

Effect of dietary fiber addition on the content and in vitro bioaccessibility of antioxidants in red raspberry puree

The aim of the present study was to understand how the addition of pectin (2.5% and 5%) affected the content and bioaccessibility of phenolics in red raspberry puree. The results showed that the concentration of antioxidants in red raspberry puree was reduced with the addition of pectin. Similarly, addition of pectin to red raspberry puree significantly reduced the total phenolic content (15-20%), total antioxidant capacity (18-70%), and total monomeric anthocyanin (25-30%) after in vitro digestion. On the other hand, significant decreases in the bioaccessible amount of cyanidin (41%), cyanidin-3-glucoside (14%), cyanidin-3-rutinoside (17%), pelargonidin 3-glucoside (16%), and peonidin (28%) were observed after the addition of pectin (5% (w/w)) compared to the control (p < 0.05) as analyzed with the HPLC method. According to the LC-MS/MS analysis of red raspberry samples, five flavonoids (rutin, quercetin, kaempferol, myricetin, and phlorizin) and six phenolic acids (gallic acid, caffeic acid, chlorogenic acid, sinapic acid, p-coumaric acid, and ferulic acid) were detected. The effect of in vitro gastrointestinal digestion varied depending on the type of the phenolic compounds. Sinapic acid and phlorizin were not detected at all in the intestinal phase, indicating that they were completely degraded during digestion. The percentage bioaccessibility of gallic acid (49-88%), rutin (6-16%), and quercetin (23-33%) was decreased proportionally with the increase in the pectin content in red raspberry purees (p < 0.05). On the other hand, only 5% pectin addition to red raspberry puree resulted with a significant decrease in the amount of bioaccessible caffeic acid (8% to 5%), kaempferol (24% to 13%), ferulic acid (26% to 10%), and myricetin (91% to 57%) (p < 0.05). Overall, the present study highlighted that incorporation of pectin to red raspberry puree reduced the amount of bioaccessible polyphenols.

Advanced approaches for improving bioavailability and controlled release of anthocyanins

Anthocyanins are a group of phytochemicals responsible for the purple or red color of plants. Additionally, they are recognized to have health promoting functions including anti-cardiovascular, anti-thrombotic, anti-diabetic, antimicrobial, neuroprotective, and visual protective effect as well as anti-cancer activities. Thus, consumption of anthocyanin supplement or anthocyanin-rich foods has been recommended to prevent the risk of development of chronic diseases. However, the low stability and bioavailability of anthocyanins limit the efficacy and distribution of anthocyanins in human body. Thus, strategies to achieve target site-local delivery with good bioavailability and controlled release rate are necessary. This review introduced and discussed the latest advanced techniques of designing lipid-based, polysaccharide-based and protein-based complexes, nano-encapsulation and exosome to overcome the limitation of anthocyanins. The improved bioavailability and controlled release of anthocyanins have great significance for gastrointestinal tract absorption, transepithelial transportation and cellular uptake. The techniques of applying different biocompatible materials and modifying the solubility of anthocyanins complex could achieve target site-local delivery with negligible degradation and good bioavailability in human body.

Binding parameters and molecular dynamics of β-lactoglobulin-vanillic acid complexation as a function of pH - part B: Neutral pH

Interactions between the dimeric form of β-lactoglobulin and vanillic acid were investigated at pH 7.2, using a variety of spectroscopic techniques and molecular dynamics (MD) simulations. FTIR and CD studies showed alterations in the secondary structure of the protein upon its interaction with the ligand. Fluorescence measurements indicated that the dimeric complex with the phenolic acid produced a large dissociation constant (K_D) compared to the monomeric counterpart at acidic pH (part A of this series). Stoichiometry of 1:1 was identified for the β-lactoglobulin-vanillic acid complex by Job plot analysis at neutral pH suggesting two ligand molecules can participate in binding with the dimer. Molecular docking and MD simulations suggested that the top-ranked binding sites of the ligand were located at the entrance of each β-barrel structure of the dimer. These simulations also allowed identification of the contribution of water molecules, in the form of protein-water-ligand bridging interactions, to the complexes.

Identification and in vitro anti-inflammatory activity of different forms of phenolic compounds in Camellia oleifera oil

Camellia oleifera (C. oleifera) oil is known as "oriental olive oil". We previously reported the anti-inflammatory activity of C. oleifera oil was mainly attributed to the phenolic compounds, but the specific compounds remain uncovered. In this study, phenolic compounds in the form of free (11.92 μg GAE/g), esterified (37.57 μg GAE/g), glycosylated (128.71 μg GAE/g), and insoluble (47.53 μg GAE/g) were prepared from C. oleifera oil. Their anti-inflammatory activities were evaluated by lipopolysaccharide induced RAW 264.7 macrophage. Glycosylated fraction showed the highest anti-inflammatory activity as indicated by the low production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). Subsequently, 13 different glycosylated polyphenols were identified by UPLC-Q-TOF/MS, and the major compounds were purified for anti-inflammatory re-evaluation. Lower anti-inflammatory activities of compound 3 and compound 6 were observed when compared to kaempferol. Overall, these results would promote the utilization of phenolic compounds in C. oleifera oil.

Nanoencapsulation of anthocyanins-loaded β-lactoglobulin nanoparticles: Characterization, stability, and bioavailability in vitro

This work aims to investigate the effect of desolvation on the stability and bioavailability of nanoparticles of β-lactoglobulin (β-Lg) and anthocyanins (AC) extracted from red raspberry pomace. Interactions between the substrates were also studied using multispectral approaches. β-Lg-nanoparticles were fabricated via heat treatment at 85 °C for 30 min before initiating the desolvation method at pH 7. This method generated monodisperse particles, nano-scale size of β-Lg, and AC-β-Lg ranged from 129.13 to 351.85 nm with square morphology obtained by SEM. The AC extract was encapsulated successfully during desolvation process into β-Lg-nanoparticles with encapsulation efficiency (EE %) of ~77%. Results also showed that AC (from 1 to 13 × 10^-4 M) quenched the fluorescence intensity of de-solvated β-Lg estimated to be 98%, and a binding among them occurred with a K_a-value of 7.59 × 10⁸ M^-1 at 25 °C. Addition of AC also gradually increased the antioxidant activity of β-Lg-nanoparticles with values of 82.51% at the highest AC-concentration (13 × 10^-4 M) loaded on β-Lg-nanoparticles. AC-loaded β-Lg nanoparticles was more stable in mouth (pH 6.8), simulated gastric (SG, pH 2), and simulated intestinal (SI, pH 6.9) by showing high retention rate (%) than that of AC unencapsulated. Overall, de-solvated-β-Lg increased the heat-stability and bioavailability of AC, which could be further utilized in various food and pharmaceutical matrices. These findings recommend that β-Lg nanoparticles could be appropriated as delivery systems for anthocyanins.

Increased stability and intracellular antioxidant activity of chlorogenic acid depend on its molecular interaction with wheat gluten hydrolysate

Gastrointestinal stability and cell entry efficiency affect the biological accessibility of chlorogenic acid (CGA). Here, wheat gluten hydrolysate (WGH) was proven to improve the stability of CGA during simulated gastrointestinal digestion, promote the intestinal epithelial cell entry efficiency of CGA, and increase its intracellular antioxidant activity. The interaction between WGH and CGA was studied by fluorescence quenching and molecular dynamics simulations. The thermodynamic parameters and molecular dynamics simulation analysis showed that the interaction between WGH and CGA was dependent on hydrogen bonding and hydrophobic and electrostatic interactions. Analyses of the binding sites of WGH showed that Arg12, Arg49, Lys54, and Pro74-Gln89 had strong interactions with CGA molecules. This interaction between CGA and WGH was related to both electrostatic interactions and their respective concentrations. Taken together, the stability, intestinal epithelial cell entry, and antioxidant activity of CGA can be increased by its molecular interactions with WGH.

Bioaccessibility and biotransformation of anthocyanin monomers following in vitro simulated gastric-intestinal digestion and in vivo metabolism in rats

Anthocyanins (ANCs) are phytochemicals with several health effects and undergo significant degradation and subsequent biotransformation during complex metabolic processes. The aim of the present study was to determine the bioaccessibility and biotransformation of cyanidin-3-glucoside (C3G) during the simulated gastric-intestinal digestion in vitro and the metabolism in rats in vivo. Characterization of C3G and its metabolites was conducted by HPLC-ESI-MS/MS. After gastric-intestinal digestion, C3G was detected with a recovery of 88.31% in the gastric-digestive system, and a small amount of methylated-C3G occurred. In the intestinal-digestive system, C3G occurred with a recovery of 6.05%, and mainly decomposed into protocatechuic acid (PCA) and 2,4,6-trihydroxybenzaldehyde. The pharmacokinetic trial of C3G in rats showed rapid elimination in plasma. In tissues, C3G underwent rapid absorption and metabolism into phenolic acids or their derivatives. C3G and methylated-C3G passed through the blood-brain barrier and caused rapid distribution of C3G in the brain. Understanding the conversion of C3G and its metabolites helps in the future design of dietary interventions and the exploration of biological activities of ACNs.

Blueberry pectin and increased anthocyanins stability under in vitro digestion

Pectin was extracted from blueberry powder as water soluble fraction (WSF), rich in branched regions, and chelator soluble fraction (CSF), linear, with strong negative charge. Binding of pectins with three anthocyanin standards (malvidin-3-glucoside; M3G, cyanidin-3-glucoside; C3G, and delphinidin-3-glucoside; D3G) and blueberry extract (BBE) were used. Without blueberry pectin, M3G was the most stable followed by C3G, whereas D3G completely disappeared after gastrointestinal digestion. CSF prevented M3G and C3G degradation more than WSF, the in vitro stability was highest with CSF and C3G. Increased stability of anthocyanins after simulated gastrointestinal digestion suggests that anthocyanins can be transported to colon where gut microbiota actively produce anthocyanin metabolites. The amount of bound anthocyanins that interacted with blueberry pectin increased as the number of hydroxyl groups increased on anthocyanins. Hydrogen bonding in addition to electrostatic interaction contribute to stability of pectin-anthocyanins interaction at pH 4.0 and contribute to stability under gastrointestinal simulation.

Dietary polyphenols modulate starch digestion and glycaemic level: a review

Polyphenols, as one group of secondary metabolite, are widely distributed in plants and have been reported to show various bioactivities in recent year. Starch digestion not only is related with food industrial applications such as brewing but also plays an important role in postprandial blood glucose level, and therefore insulin resistance. Many studies have shown that dietary phenolic extracts and pure polyphenols can retard starch digestion in vitro, and the retarding effect depends on the phenolic composition and molecular structure. Besides, dietary polyphenols have also been reported to alleviate elevation of blood glucose level after meal, indicating the inhibition of starch digestion in vivo. This review aims to analyze how dietary polyphenols affect starch digestion both in vitro and in vivo. We can conclude that the retarded starch digestion in vitro by polyphenols results from inhibition of key digestive enzymes, including α-amylase and α-glucosidase, as well as from interactions between polyphenols and starch. The alleviation of postprandial hyperglycemia by polyphenols might be caused by both the inhibited starch digestion in vivo and the influenced glucose transport. Therefore, phenolic extracts or pure polyphenols may be alternatives for preventing and treating type II diabetes disease.

Effect of the in vitro gastrointestinal digestion on free-phenolic compounds and mono/oligosaccharides from Moringa oleifera leaves: Bioaccessibility, intestinal permeability and antioxidant capacity

Moringa oleifera is a plant recognized for its compounds such as dietary fiber (oligosaccharides, amongst others) and polyphenols, with biological activities. These properties depend on bioactive compounds (BC) interactions with food matrix/digestion conditions, which have not been evaluated. Thus, the aim of this study was to evaluate the bioaccessibility, intestinal permeability and antioxidant capacity of BC (free-phenolic compounds (PC); and mono/oligosaccharides (MOS)) from Moringa oleifera leaves (ML) powder during in vitro gastrointestinal digestion. The gallic/caffeic acids, morin, kaempferol, mannose and stachyose showed the highest bioaccessibilities (~6-210%). The PC correlated with the antioxidant capacity (R²: 0.59-0.98, p < .05), whereas gallic/caffeic acids were the highest. The apparent permeability coefficients of bioactive compounds (0.62-36.65 × 10^-4 cm/s) and water flux/glucose transport confirmed the model similarity to in vivo experiments. The results suggest that ML digestion dynamically modifies PC/MOS bioaccessibility/antioxidant capacity while most of them are not completely absorbed in the small intestine.

Nano- and micro-particles for delivery of catechins: Physical and biological performance

Catechins, present in many fruits and vegetables, have many health benefits, but they are prone to degradation. Nano- and micro-particle systems have been used to stabilise catechins when exposed to adverse environments and to improve their bioavailability after ingestion. This review discusses the inherent properties of various catechins, the design of delivery formulations and the properties of catechin-loaded nano- and micro-particles. The protection afforded to catechins during exposure to harsh environmental conditions and gastrointestinal tract transit is reviewed. The bioavailability and efficacy of encapsulated catechins, as assessed by various in vitro and in vivo conditions, are discussed. Bioavailability based on uptake in the upper gut alone underestimates the bioavailability as polyphenols. The caveats with interpretation of bioavailability based on various tests are discussed, when taking into consideration the pathways of catechin metabolism including the role of the gut microflora. However, taken together, the weight of the evidence suggests that there are potentially improved health benefits with the use of appropriately designed nano- and micro-particles for delivery of catechins. Further systematic studies on the metabolism and physiological effects of encapsulated catechins in vivo and clinical trials are needed to validate the bioefficacy of the encapsulated catechins.

Interactions between cell wall polysaccharides and polyphenols

In plant-based food systems such as fruits, vegetables, and cereals, cell wall polysaccharides and polyphenols co-exist and commonly interact during processing and digestion. The noncovalent interactions between cell wall polysaccharides and polyphenols may greatly influence the physicochemical and nutritional properties of foods. The affinity of cell wall polysaccharides with polyphenols depends on both endogenous and exogenous factors. The endogenous factors include the structures, compositions, and concentrations of both polysaccharides and polyphenols, and the exogenous factors are the environmental conditions such as pH, temperature, ionic strength, and the presence of other components (e.g., protein). Diverse methods used to directly characterize the interactions include NMR spectroscopy, size-exclusion chromatography, confocal microscopy, isothermal titration calorimetry, molecular dynamics simulation, and so on. The un-bound polyphenols are quantified by liquid chromatography or spectrophotometry after dialysis or centrifugation. The adsorption of polyphenols by polysaccharides is mostly driven by hydrophobic interactions and hydrogen bonding, and can be described by various isothermal models such as Langmuir and Freundlich equations. Quality attributes of various food and beverage products (e.g., wine) can be significantly affected by polysaccharide-polyphenol interactions. Nutritionally, the interactions play an important role in the digestive tract of humans for the metabolism of both polyphenols and polysaccharides.

Grape skin phenolics as inhibitors of mammalian α-glucosidase and α-amylase--effect of food matrix and processing on efficacy

Type-2 diabetes is continuously increasing worldwide. Hence, there is a need to develop functional foods that efficiently alleviate damage due to hyperglycaemia complications while meeting the criteria for a sustainable food processing technology. Inhibition of mammalian α-amylase and α-glucosidase was studied for white grape skin samples recovered from wineries and found to be higher than that of the drug acarbose. In white grape skins, quercetin and kaempferol derivatives, analysed by UPLC-DAD-MS, and the oligomeric series of catechin/epicatechin units and their gallic acid ester derivatives up to nonamers, analysed by MALDI-TOF-MS were identified. White grape skin was then used for enrichment of a tomato puree (3%) and a flat bread (10%). White grape skin phenolics were found in the extract obtained from the enriched foods, except for the higher mass proanthocyanidin oligomers, mainly due to their binding to the matrix and to a lesser extent to heat degradation. Proanthocyanidin solubility was lower in bread, most probably due to formation of binary proanthocyanin/protein complexes, than in tomato puree where possible formation of ternary proanthocyanidin/protein/pectin complexes can enhance solubility. Enzyme inhibition by the enriched foods was significantly higher than for unfortified foods. Hence, this in vitro approach provided a platform to study potential dietary agents to alleviate hyperglycaemia damage and suggested that grape skin phenolics could be effective even if the higher mass proanthocyanidins are bound to the food matrix.

Cyanidin-3-O-glucoside: Physical-Chemistry, Foodomics and Health Effects

Anthocyanins (ACNs) are plant secondary metabolites from the flavonoid family. Red to blue fruits are major dietary sources of ACNs (up to 1 g/100 g FW), being cyanidin-3-O-glucoside (Cy3G) one of the most widely distributed. Cy3G confers a red hue to fruits, but its content in raspberries and strawberries is low. It has a good radical scavenging capacity (RSC) against superoxide but not hydroxyl radicals, and its oxidative potential is pH-dependent (58 mV/pH unit). After intake, Cy3G can be metabolized (phases I, II) by oral epithelial cells, absorbed by the gastric epithelium (1%-10%) and it is gut-transformed (phase II &amp; microbial metabolism), reaching the bloodstream (<1%) and urine (about 0.02%) in low amounts. In humans and Caco-2 cells, Cy3G's major metabolites are protocatechuic acid and phloroglucinaldehyde which are also subjected to entero-hepatic recycling, although caffeic acid and peonidin-3-glucoside seem to be strictly produced in the large bowel and renal tissues. Solid evidence supports Cy3G's bioactivity as DNA-RSC, gastro protective, anti-inflammatory, anti-thrombotic chemo-preventive and as an epigenetic factor, exerting protection against Helicobacter pylori infection, age-related diseases, type 2 diabetes, cardiovascular disease, metabolic syndrome and oral cancer. Most relevant mechanisms include RSC, epigenetic action, competitive protein-binding and enzyme inhibition. These and other novel aspects on Cy3G's physical-chemistry, foodomics, and health effects are discussed.