Effects of α-casein and β-casein on the stability, antioxidant activity and bioaccessibility of blueberry anthocyanins with an in vitro simulated digestion

Digestive recovery of polyphenols, antioxidant activity, and anti-inflammatory activity of selected edible flowers from the family Fabaceae

Edible flowers are regaining popularity as therapeutic agents, due to their phytochemical composition. The present study assessed the recovery of phenolics along with the antioxidant and anti-inflammatory properties of seven edible flowers of the Fabaceae family after being subjected to simulated gastrointestinal conditions and dialysis. The total phenolic content of all the flowers decreased after the gastric phase, whereas the total flavonoid content increased. The total anthocyanin content of four flower species decreased after the intestinal phase of digestion. Cassia auriculata expressed the highest hydrogen peroxide and nitric oxide scavenging activities in the dialyzed fraction. Bauhinia racemose had the highest activity in the inhibition of heat-induced hemolysis of red blood cells after dialysis (4.43 ± 01.5%). In general, the results suggest a reduction in the phenolic contents after gastrointestinal digestion and dialysis; however, phenolics, flavonoids and anthocyanins were sufficiently available to be absorbed with the dialysis to exert antioxidant and anti-inflammatory activities. PRACTICAL APPLICATION: The presence of various phenolic compounds in edible flowers has attracted the attention of consumers as well as the food industry, due to their potential to be incorporated in functional foods and drugs. However, the availability of phenolics after digestion is an important measure to get a realistic view of the health effects exerted upon the consumption of these edible flowers. The present study provides new information on the antioxidant and anti-inflammatory potential of selected edible flowers before and after in vitro digestion. This would be more useful for nutritionists, policymakers and consumers to effectively utilize edible flowers by understanding the changes undergone by the phenolic compounds upon digestion.

In Situ Stability of Anthocyanins in Lycium ruthenicum Murray

In this research, the effects of drying method, storage temperature, and color protector glucose on anthocyanin preservation in the Lycium ruthenicum Murr. fruit were studied. Compared with hot-air drying, vacuum freeze-drying preserved about 5.8-fold more anthocyanins. The half-life of anthocyanins in the freeze-dried fruit samples with glucose was 3.6 days, 1.8 days, and 1.7 days at 4 °C, 20 °C, and 37 °C, respectively. On the other hand, the half-life values without glucose addition were 2.2 days, 2.3 days, and 2.1 days at each temperature, respectively, indicating that glucose protected anthocyanins at low temperature. The composition and contents of anthocyanins and anthocyanidins in the freeze-dried Lycium ruthenicum Murr., stored for 20 days, were investigated with a HPLC-MS/MS setup. It was found that most anthocyanidins in Lycium ruthenicum Murr. are linked with coumaroyl glucose to form anthocyanins, while glycosylated and acetyl-glycosylated anthocyanins were also detected. Five anthocyanidins were detected: delphinidin, cyanidin, petunidin, malvidin, and peonidin, and delphinidin accounts for about half of the total amount of anthocyanidins. It is much more economic to conserve anthocyanins in situ with freeze-drying methods and to store the fruits at low temperatures with glucose.

Bioaccessibility of Anthocyanins on in vitro Digestion Mmodels: Factors Implicated and Role in Functional Foods Development

BACKGROUND

Worldwide, the prevalence of obesity and related non-communicable chronic diseases is high and continues to grow. In that sense, anthocyanins (ANC) have shown beneficial health effects in preventing obesity and metabolic risk factors. Moreover, the demand for functional foods incorporating these compounds has risen significantly in the past years. Thus, there is a need for validations of the functional properties of these formulations; nevertheless, in vivo assays are complex and require a lot of resources. One approach for estimating bioactive compounds' functionality and health benefits is to evaluate their bioaccessibility on a specific food matrix, determined by various factors. This article aims to review different factors influencing the bioaccessibility of ANC evaluated on in vitro digestion models as a functionality parameter, elucidating the effect of chemical composition, raw materials, food matrices, and vehicles for the delivery of ANC.

METHODS

Study searches were performed using PubMed, Web of Science, Scopus, and Science Direct databases.

RESULTS

Different factors influenced bioaccessibility and stability of ANC studied by in vitro digestion which are: i) the raw material used for ANC obtention; ii) food processing; iii) other food components; iv) the extraction method and solvents used; v) the structure of ANC; vi) delivery system (e.g., microencapsulation); vii) pH of the medium; viii) the digestion stage.

CONCLUSION

Simulated digestion systems allow to determine free or encapsulated ANC bioaccessibility in different food matrices, which offers advantages in determining the potential functionality of a food product.

In vitro phenolic bioaccessibility of coffee beverages with milk and soy subjected to thermal treatment and protein-phenolic interactions

The effect of skimmed bovine milk and soy protein on the in vitro bioaccessibility of polyphenols in coffee beverages under thermal treatment (25, 90, and 121 °C) and the protein-phenolic interaction was investigated. Thermal treatment at 90 °C and 121 °C reduced the in vitro bioaccessibility of total and individual phenolic. Skimmed milk and soy protein addition increased the total (by 37.01%-64.21% and 24.74%-47.32%, respectively) and individual phenolic in vitro bioaccessibility (by 4.40%-27.29% and 12.02%-28.61%, respectively) of coffee beverages subjected to thermal treatment at 25, 90 and 121 °C. Compared with soy protein, skimmed milk significantly enhanced the in vitro bioaccessibility of coffee polyphenols, possibly owing to the presence of different types and strengths of noncovalent protein-phenolic interactions. These findings can provide certain theoretical knowledge for optimizing the processing technology and formula of the food industry to help improve the health benefits of milk coffee beverages.

Pharmacokinetic and excretion study of Aronia melanocarpa anthocyanins bound to amylopectin nanoparticles and their main metabolites using high-performance liquid chromatography-tandem mass spectrometry

Anthocyanins of Aronia melanocarpa are known for their therapeutic properties; however, they are unstable and easily degrade in the environment and in vivo. Herein, we investigated the stability and bioavailability of four anthocyanins bound to amylopectin nanoparticles (APNPs) through a pharmacokinetic and excretion study using high-performance liquid chromatography-tandem mass spectrometry. An EC-C18 column with methanol and 0.1% formic acid as the mobile phase was used during the analysis. After APNP treatment, anthocyanins and metabolites exhibited a marked increase, whereas their maximum oral bioavailability reached 440% and 593%, respectively. The delayed elimination half time demonstrated that APNPs had a sustained-release effect on anthocyanins. Pharmacokinetic results revealed that APNPs effectively protect anthocyanins in vivo. Excretion studies in urine and feces had shown a decrease in excretion of anthocyanins and most of the metabolites after APNP treatment. The results of excretion study further proved the protective effect of APNPs on anthocyanins in vivo.

Potential micro-/nano-encapsulation systems for improving stability and bioavailability of anthocyanins: An updated review

Anthocyanins (ACNs) are notable hydrophilic compounds that belong to the flavonoid family, which are available in plants. They have excellent antioxidants, anti-obesity, anti-diabetic, anti-inflammatory, anticancer activity, and so on. Furthermore, ACNs can be used as a natural dye in the food industry (food colorant). On the other hand, the stability of ACNs can be affected by processing and storage conditions, for example, pH, temperature, light, oxygen, enzymes, and so on. These factors further reduce the bioavailability (BA) and biological efficacy of ACNs, as well as limit ACNs application in both food and pharmaceutics field. The stability and BA of ACNs can be improved via loading them in encapsulation systems including nanoemulsions, liposomes, niosomes, biopolymer-based nanoparticles, nanogel, complex coacervates, and tocosomes. Among all systems, biopolymer-based nanoparticles, nanohydrogels, and complex coacervates are comparatively suitable for improving the stability and BA of ACNs. These three systems have excellent functional properties such as high encapsulation efficiency and well-stable against unfavorable conditions. Furthermore, these carrier systems can be used for coating of other encapsulation systems (such as liposome). Additionally, tocosomes are a new system that can be used for encapsulating ACNs. ACNs-loaded encapsulation systems can improve the stability and BA of ACNs. However, further studies regarding stability, BA, and in vivo work of ACNs-loaded micro/nano-encapsulation systems could shed a light to evaluate the therapeutic efficacy including physicochemical stability, target mechanisms, cellular internalization, and release kinetics.

Assessment of the phytochemical profile and antioxidant activities of eight kiwi berry (Actinidia arguta (Siebold & Zuccarini) Miquel) varieties in China

The kiwi berry (Actinidia arguta) is a new product on the market that expanding worldwide acceptance and consumption. This widespread interest has created an increasing demand to identify the nutritional and health benefits of kiwi berry. Many studies are being actively conducted to investigate the composition and health-promoting effects of kiwi berry. In this study, the phytochemical content of free and bound fractions of eight kiwi berry varieties were systematically investigated in order to better understand the potential of this superfood crop. Nine phenolic monomers were identified and quantified by ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and ultrahigh-performance liquid chromatography-PAD. Antioxidant activity was further determined via peroxyl radical scavenging capacity and cellular antioxidant activity assays. The free extracts had higher phytochemical contents and antioxidant activities than the corresponding bound extracts among the eight kiwi berry varieties. Bivariate Pearson's and multivariate correlation analyses showed that antioxidant activities were most related to the total phenolic, flavonoid, vitamin C, and phenolic acids contents. The results provide a theoretical basis for the selection of kiwi berry varieties and the utilization of functional foods.

Inhibition Mechanism of α-Amylase/α-Glucosidase by Silibinin, Its Synergism with Acarbose, and the Effect of Milk Proteins

As a natural flavonolignan, silibinin is reported to possess multiple biological activities, while the inhibitory potential of silibinin on carbohydrate-hydrolyzing enzymes is still unclear. Therefore, in this study, the inhibitory effect and underlying mechanism of silibinin against α-amylase/α-glucosidase were investigated. The results indicated that silibinin showed a strong inhibitory efficiency against α-amylase/α-glucosidase in noncompetitive manners and exhibited synergistic inhibition against α-glucosidase with acarbose. However, interestingly, the inhibitory effect of silibinin was significantly hindered in various milk protein-rich environments, but this phenomenon disappeared after simulated gastrointestinal digestion of milk proteins in vitro. Furthermore, silibinin could combine with the inactive site of α-amylase/α-glucosidase and change the microenvironment and secondary structure of the enzymes, thereby influencing the catalytic efficiency of enzymes. This research suggested that silibinin could be used as a novel carbohydrate-hydrolyzing enzyme inhibitor, and milk beverages rich in silibinin had the potential for further application in antidiabetic dietary or medicine.

Effects and interaction mechanism of soybean 7S and 11S globulins on anthocyanin stability and antioxidant activity during in vitro simulated digestion

The objective of this study was to investigate the effects of soybean 7S and 11S globulins on the stability and antioxidant capacity of cyanidin-3-O-glucoside (C3G) in the simulated gastrointestinal environment, and further to elucidate their interaction mechanism. The stability and total content of anthocyanins (ACNs) before and after simulated digestion were determined by Ultraviolet–visible (UV–Vis) spectroscopic and pH differential methods, respectively, and free radical scavenging activity of C3G after simulated digestion were measured using ABTS and DPPH assays. The interaction mechanism was further investigated using molecular docking and molecular dynamics simulation. The analysis results showed that soybean 7S and 11S globulins had a protective effect on the stability of C3G during simulated digestion and improved the antioxidant capacity of C3G after simulated digestion. Soybean 11S globulin had a better effect than soybean 7S globulin in protecting the stability and antioxidant capacity of C3G against simulated gastrointestinal environment. In silico results showed that the binding interactions between C3G and 7S and 11S globulins were mainly hydrogen bonds and van der Waals forces, followed by hydrophobic interactions. Among them, ASN69 and THR101 are the key amino acid residues for 7S–C3G binding, and THR82 and PRO86 are the key amino acid residues for 11S–C3G binding. The results suggested that it may be helpful to use soybean 7S and 11S globulins as carriers to improve the stability and antioxidant activity of ACNs.

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7S and 11S improved the stability of C3G during simulated digestion.

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7S and 11S improved the antioxidant capacity of C3G after simulated digestion.

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ASN69 and THR101 are the key amino acid residues for 7S–C3G binding.

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THR82 and PRO86 are the key amino acid residues for 11S–C3G binding.

Phenolics Profile and Antioxidant Activity Analysis of Kiwi Berry (Actinidia arguta) Flesh and Peel Extracts From Four Regions in China

The kiwi berry (Actinidia arguta) has been widely studied because of its rich phenolic, flavonoid, and vitamin C contents. Numerous reports have demonstrated that fruit peels contain higher phenolic content and antioxidant activity than that of flesh. In this study, the phytochemical content and antioxidant activities of peel and flesh extracts of six kiwi berries were analyzed from four regions (namely, Dandong, Benxi, Taian, and Tonghua) in China. The antioxidant activity was determined using the peroxyl radical scavenging capacity (PSC) and cellular antioxidant activity (CAA) assays. The phenolic, flavonoid, and vitamin C contents of kiwi berry peel were 10.77, 13.09, and 10.38 times richer than that of kiwi berry flesh, respectively. In addition, the PSC and CAA values of kiwi berry peel were higher than those of kiwi berry flesh. The analysis of the separation and contents of phenolics were performed by the high-performance liquid chromatography (HPLC)-diode-array detectormass spectrometry/mass (DAD-MS/MS) system, and the results illustrated that protocatechuic acid, caffeic acid, chlorogenic acid, and quinic acid were the major phenolic compounds. In conclusion, this study indicated that kiwi berry peel contains a rich source of antioxidants. These data are of great significance for the full development and utilization of kiwi berries in these four regions of China to produce nutraceutical and functional foods.

Effects of α-Casein on the Absorption of Blueberry Anthocyanins and Metabolites in Rat Plasma Based on Pharmacokinetic Analysis

Blueberry anthocyanins are well known for their beneficial biological activities. However, the poor bioavailability of anthocyanins limits their functional capacity in vivo. Our current study aimed to detect the effects of α-casein on the absorption of blueberry anthocyanins and their metabolites in rats. Blueberry anthocyanins with and without α-casein were intragastrically administered to two groups of rats and their blood samples were collected within 24 h. Results illustrated that rapid absorption of anthocyanins was observed in the rat plasma, but their concentration was relatively low. With the complexation of α-casein, the maximum concentration (C_max) of bioavailable anthocyanins and metabolites could increase by 1.5-10.1 times (P < 0.05 or P < 0.01). The promotional effect on the plasma absorption of malvidin-3-O-galactoside and vanillic acid was outstanding with the C_max increasing from 0.032 to 0.323 and from 0.360 to 1.902 μg/mL, respectively (P < 0.01). Besides, the molecular docking models presented that anthocyanins could enter the structural cavity and interact with amino acid residues of α-casein, which was in accordance with the improved bioavailability of anthocyanins. Therefore, α-casein could assist more blueberry anthocyanins and their metabolites to enter blood circulation.

Current progress on the mechanisms of hyperhomocysteinemia-induced vascular injury and use of natural polyphenol compounds

Cardiovascular disease is one of the most common diseases in the elderly population, and its incidence has rapidly increased with the prolongation of life expectancy. Hyperhomocysteinemia is an independent risk factor for various cardiovascular diseases, including atherosclerosis, and damage to vascular function plays an initial role in its pathogenesis. This review presents the latest knowledge on the mechanisms of vascular injury caused by hyperhomocysteinemia, including oxidative stress, endoplasmic reticulum stress, protein N-homocysteinization, and epigenetic modification, and discusses the therapeutic targets of natural polyphenols. Studies have shown that natural polyphenols in plants can reduce homocysteine levels and regulate DNA methylation by acting on oxidative stress and endoplasmic reticulum stress-related signaling pathways, thus improving hyperhomocysteinemia-induced vascular injury. Natural polyphenols obtained via daily diet are safer and have more practical significance in the prevention and treatment of chronic diseases than traditional drugs.

Effect of Chitosan/Nano-TiO2 Composite Coating on the Postharvest Quality of Blueberry Fruit

Blueberries are a rich source of health-promoting compounds such as vitamins and anthocyanins and show a high antioxidant capacity. Thus, considerable commercial and scientific interest exists in prolonging its postharvest life to meet the year-round demand for this fruit. In this investigation, the effect of a chitosan-based edible coating, as well as a chitosan-based edible coating containing nanosized titanium dioxide particles (CTS-TiO2), on the postharvest quality of blueberry fruit quality was evaluated during storage at 0 °C. The blueberries were treated with a chitosan coating (CTS) and a CTS-TiO2 composite, respectively. The most suitable chitosan and nano-TiO2 fraction concentrations to be incorporated in the coating formulation were prepared based on the wettability of the corresponding coating solutions. Changes in firmness, total soluble solids (TSS), titratable acidity (TA), ascorbic acid (VC), malondialdehyde (MDA), polyphenol oxidase (PPO), and peroxidase (POD) activities, anthocyanins, flavonoids, total phenolic content, and microbiological analysis were measured and compared. This combined treatment prevented product corruption. Compared with CTS, the CTS-TiO2 composite coating application effectively slowed down the decrease in firmness, TSS, VC, and TA in the blueberries. Additionally, changes in the total polyphenol, anthocyanin, and flavonoid contents and the antioxidant capacity of CTS-TiO2 composite coating blueberry fruits were delayed. Therefore, these results indicated that the chitosan/nano-TiO2 composite coating could maintain the nutrient composition of blueberries while playing a significant role in preserving the quality of fruit at 0 °C.

A molecular docking and molecular dynamics simulation study on the interaction between cyanidin-3-O-glucoside and major proteins in cow's milk

The objective of this study was to investigate the molecular interaction and complex stability of four major cow's milk (CM) proteins (α-LA, β-LG, α_s1 -CA, and β-CA) with cyanidin-3-O-glucoside (C3G) using computational methods. The results of molecular docking analysis revealed that hydrogen bond and hydrophobic interaction were the main binding forces to maintain the stability of the C3G-CM protein complexes. Molecular dynamics simulation results showed that all complexes except for C3G-α_s1 -CA were found to reach equilibrium within 50 ns of simulation. α_s1 -CA and β-CA switched to a more compact conformation after binding with C3G. Additionally, the radius of gyration, number of hydrogen bond, radial distribution function, and interaction energy showed that β-CA is the best C3G carrier protein among the four CM proteins. This study can provide valuable information for CM proteins to serve as C3G delivery carriers. PRACTICAL APPLICATIONS: Anthocyanins (ACNs) are flavonoid-based pigments that play an important functional role in regulating human's health. Cow's milk (CM) proteins are the most representative protein-based carriers that can improve the short-term bioavailability and stability of ACNs. Thus, it is important to study the interactions between ACNs and CM proteins at the molecular level for the development of effective ACNs delivery carriers. Our study showed that caseins (α_s1 -CA and β-CA) had more hydrophobic and hydrogen-bonding sites with cyanidin-3-O-glucoside (C3G) than whey proteins using computational methods. Among the four CM proteins, β-CA was the best C3G carrier protein showing the best interaction stability with C3G. Thus, it is helpful for us to screen effective ACNs carriers from multiple protein sources by computational methods.