Identification of key phenolic compounds responsible for antioxidant activities of free and bound fractions of blackberry varieties' extracts by boosted regression trees.

BACKGROUND: Free fractions of different blackberry varieties' extracts are high in phenolic compounds with antioxidant activities. However, the phenolic profiles and antioxidant activities against peroxyl radicals of bound fractions of different blackberry varieties' extracts have not been previously reported. In addition, what the key antioxidant phenolic compounds are in free and bound fractions of blackberry extracts remain unknown. This study aimed to investigate the phenolic profiles and antioxidant activities of free and bound fractions of eight blackberry varieties' extracts and reveal the key antioxidant phenolic compounds by boosted regression trees. RESULTS: Fifteen phenolics (three anthocyanins, four flavonols, three phenolic acids, two proanthocyanidins, and three ellagitannins) were identified in blackberry by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Ferulic acid, ellagic acid, procyanidin C1, kaempferol-O-hexoside, ellagitannins hex, and gallic acid were major bound phenolics. Bound fractions of eight blackberry varieties' extracts were high in phenolics and showed great antioxidant activity. Boosted regression trees analysis showed that cyanidin-3-O-glucoside and chlorogenic acid were the most significant compounds, contributing 48.4% and 15.9% respectively to the antioxidant activity of free fraction. Ferulic acid was the most significant antioxidant compound in bound fraction, with a contribution of 61.5%. Principal component analysis showed that Kiowa was the best among the eight varieties due to its phenolic profile and antioxidant activity. CONCLUSION: It was concluded that blackberry varieties contained high amounts of bound phenolics, which confer health benefits through reducing oxidative stress. Ferulic acid was the key compound to explain the antioxidant activities of bound fractions. © 2021 Society of Chemical Industry.

Preparative Purification of Polyphenols from Aronia melanocarpa (Chokeberry) with Cellular Antioxidant and Antiproliferative Activity.

The aim of this study was the purification process of polyphenols from Aronia melanocarpa (chokeberry), and the purification parameters were optimised by adsorption and desorption tests. By comparing adsorption and desorption ability of polyphenols from chokeberry on six kinds of macroporous resin, XAD-7 resin was selected. Experiments prove that the best purification parameters of static adsorption and desorption were sample pH = 4.0 with 4 h of adsorption; and desorption solvent is 95% ethanol (pH = 7.0) with 2 h of desorption. The best dynamic parameters were 9.3 bed volume (BV) of sample loading amount at a feeding flow rate of 2 BV/h, and washing the column with 5.8 BV of water, followed by subsequent elution with an eluent volume of 5.0 mL at an elution flow rate of 2 BV/h. Next the antioxidant and antiproliferative activity of polyphenols from chokeberry, blueberries, haskap berries was studied on HepG2 human liver cancer cells. The results show that polyphenol from chokeberry has a strong antioxidant effect. Taking into account the content of polyphenols in fruit, polyphenols from chokeberry represent a very valuable natural antioxidant source with antiproliferative products.

Complexes of glycated casein and carboxymethyl cellulose enhance stability and control release of anthocyanins.

To improve the stability and sustained-release property of anthocyanins (ACNs), casein (CA) - dextran (DEX) glycated conjugates (UGCA) and carboxymethyl cellulose (CMC) were used to prepare ACNs-loaded binary and ternary complexes. The ACNs-loaded binary complexes (ACNs-UGCA) and ternary complexes (ACNs-UGCA-CMC) achieved by 8 min' ultrasonic treatment with 40 % amplitude. The binary and ternary complexes showed spherical structure and good dispersibility, with the average size of 121.2 nm and 132.4 nm respectively. The anthocyanins encapsulation efficiency of ACNs-UGCA-CMC increased almost 20 % than ACNs-UGCA. ACNs-UGCA-CMC had better colloidal stabilities than ACNs-UGCA, such as thermal stability and dilution stability. Simultaneously, both of the binary and ternary complexes significantly prevented anthocyanins from being degraded by heat treatment, ascorbic acid, sucrose and simulated gastrointestinal environment. The protective effect of ACNs-UGCA-CMC was more significant. Furthermore, ACNs-UGCA-CMC showed slower anthocyanins release in simulated releasing environment in vitro and a long retention time in vivo. Our current study provides a potential delivery for improving the stability and controlling release of anthocyanins.

Novel inhibitory effect of black chokeberry (Aronia melanocarpa) from selected eight berries extracts on advanced glycation end-products formation and corresponding mechanism study.

Numerous health hazards have been connected to advanced glycation end products (AGEs). In this investigation, using reaction models including BSA-fructose, BSA- methylglyoxal (MGO), and BSA-glyoxal (GO), we examined the anti-glycation potential of eight different berry species on AGEs formation. Our results indicate that black chokeberry (Aronia melanocarpa) exhibited the highest inhibitory effects, with IC50 values of 0.35 ± 0.02, 0.45 ± 0.03, and 0.48 ± 0.11 mg/mL, respectively. Furthermore, our findings suggest that black chokeberry inhibits AGE formation by binding to BSA, which alleviates the conformation alteration, prevents protein cross-linking, and traps reactive α-dicarbonyls to form adducts. Notably, three major polyphenols, including cyanidin-3-O-galactoside, cyanidin-3-O-arabinoside, and procyanidin B2 from black chokeberry, showed remarkably inhibitory effect on MGO/GO capture, and new adducts formation was verified through LC-MS/MS analysis. In summary, our research provides a theoretical basis for the use of berries, particularly black chokeberry, as natural functional food components with potential anti-glycation effects.

Polyphenol nanoparticles based on bioresponse for the delivery of anthocyanins.

Anthocyanin (AN) has good antioxidant and anti-inflammatory bioactivities, but its poor biocompatibility and low stability limit the application of AN in the food industry. In this study, core-shell structured carriers were constructed by noncovalent interaction using tannic acid (TA) and poloxamer 188 (F68) to improve the biocompatibility, stability and smart response of AN. Under different treatment conditions, TA-F68 and AN were mainly bound by hydrophobic interaction. The PDI is less than 0.1, and the particle size of nanoparticles (NPs) is uniform and concentrated. The retention of the complex was 15.50 % higher than that of AN alone after 9 d of light treatment. After heat treatment for 180 min, the retention rate after loading was 13.87 % higher than that of AN alone. The carrier reduce the damage of AN by the digestive environment, and intelligently and sustainedly release AN when the esterase is highly expressed. In vitro studies demonstrated that the nanocarriers had good biocompatibility and significantly inhibited the overproduction of reactive oxygen species induced by oxidative stress. In addition, AN-TA-F68 has great potential for free radical scavenging at sites of inflammation. In conclusion, the constructed nano-delivery system provides a potential application for oral ingestion of bioactive substances for intervention in ulcerative colitis.

Effects of sucrose degradation product furfural on cyanidin-3-O-glucoside: Mechanism of action, stability, and identification of products in sugar solutions.

Anthocyanins are often affected by the sweetener sucrose during processing, which is closely related to its typical degradation product, furfural (Ff). However, the specific mechanism is unclear. In this study, Ff and cyanidin-3-O-glucoside (C3G) were used to explain the mechanism of the effect. The results showed that Ff destabilized anthocyanins by chemically reacting with C3G to generate three new adducts. Meanwhile, the color of the C3G solution changed from bright red to dark purple, and the value of the color difference (ΔE) increased significantly by 2.69. Furthermore, the new adducts were less stable than C3G and continued to promote the degradation of C3G when they coexisted with it. The above adducts were also detected in sugar solutions supplemented with C3G, and these adducts were more likely to accumulate under light storage conditions. These results provide a theoretical basis for reducing anthocyanin loss in food processing.

Comparative study on alleviating effect of kiwi berry (Actinidia arguta) polysaccharide and polyphenol extracts on constipated mice.

Kiwi berry (Actinidia arguta) is beneficial for relieving constipation, but the mechanism of easing constipation is still unknown. The alleviating effects of kiwi berry polysaccharide and polyphenol extracts on loperamide induced constipation were studied. Administration with polysaccharide extract of kiwi berry in loperamide-induced constipation mice distinctly decreased the body weight gain by 124.0%, the number and the water content of feces was decreased by 152.4% and 107.0% respectively, gastrointestinal (GI) transit rate was decreased by 39.5% and the time to the first dark stool was largen by 56.2% as compared with those in the loperamide group, respectively. The levels of excitability neurotransmitters were increased, and the inhibitory neurotransmitter was decreased in the kiwi berry extracts groups compared with the loperamide group. The levels of aquaporins were decreased to ameliorate constipation. Moreover, kiwi berry extracts can protect colon smooth muscle cells from apoptosis and help to restore colon health. Interstitial cells of Cajal (ICC) and animal experiments suggested that kiwi berry extracts can up-regulate the expression levels of stem cell factors (SCF)/c-kit protein. Kiwi berry can remodel the structure of microbial communities. All findings suggest that kiwi berry polysaccharide and polyphenol especially its polysaccharide extract, can effectively alleviate constipation induced by loperamide. Kiwi berry is a promising food supplement that can be used to relieve constipation.

Combined effect of thermosonication and high hydrostatic pressure on bioactive compounds, microbial load, and enzyme activities of blueberry juice.

The current study is aimed to evaluate the combined effect of thermosonication (TS) and high hydrostatic pressure (HHP) on enzyme activities (polyphenolase and peroxidase), microbial load and phenolic compounds (phenols, flavonoids, and anthocyanins) of blueberry juice. Blueberry juice has been treated with TS (40 kHz and 240 W) at different temperatures (25 °C and 45 °C) for 15 mins with subsequent different HHP (200, 400 and 600 MPa) for 5 mins at room temperature. The results revealed that a combined use of HHP of 400 MPa and 600 MPa with TS at 45 °C not only reduced microorganisms below 1 logCFU/mL, but also significantly inactivated enzymes. The treatments also increased the phenolic compounds, peroxyl radical scavenging capacity (PSC), and DPPH free radical scavenging activity to a higher level without causing any changes in soluble solids and pH. Therefore, the combination of HHP and TS can be used as a novel alternative nonthermal technology to improve the nutritional qualities of blueberry juice, which produces a desirable, healthy juice for consumers.

Protective effects and mechanism of amino acids as chokeberry cyanidin and its glycoside protectant under the condition of vitamin C coexistence.

In the presence of vitamin C, cyanidin and cyanidin glycosides are degraded during the processing and storage of food products. To solve this issue, we investigated the protective effects and mechanism of action of five amino acids on the stability of cyanidin and its glycosides from chokeberry. The results showed that 0.3% tryptophan most effectively inhibited the degradation of cyanidin and its glycosides in the presence of vitamin C, under ultraviolet, dark, and sucrose-rich conditions. Fluorescence spectrum analysis showed that tryptophan could form noncovalent binding complexes with cyanidin-3-O-galactoside and cyanidin through hydrophobic and electrostatic forces and hydrogen bonds. Molecular docking results showed that the indole structure of tryptophan could form hydrophobic interactions with cyanidin-3-O-galactoside and cyanidin via hydrogen bonding, resulting in greater protection. Therefore, tryptophan could effectively protect cyanidin and its glycosides in cyanidin- and cyanidin glycoside-rich food products.

Conversion of condensed tannin from chokeberry to cyanidin: Evaluation of antioxidant activity and gut microbiota regulation.

Chokeberries contain a large amount condensed tannin. In this study, hot acid-alcohol treatment was used to convert the condensed tannin into cyanidin, so as to give them higher antioxidant activity and improve the function of gut microbiota. The total cyanidins yield was taken as the index. The effects of various factors on the total cyanidins yield were analysed by the single factor experiment and factor design experiment. In addition, the response surface methodology was used to obtain the optimal conversion conditions. The cyanidin composition and cellular antioxidant activity of products was detected. Through simulated digestion and fermentation in vitro, improvement of gut microbiota was evaluated. The results show that the product obtained by the optimal conversion treatment conditions, which could increase total cyanidins yield 1.50 folds to 28.88 mg/g. The total antioxidant activity and cellular antioxidant activity increased by 1.85 folds and 1.56 folds, reaching 3905.48 (µmol Vit C equiv./100 g FW) and 2329.31 (µmol QE/100 g FW), respectively. Conversion treatment could change the some negative effect of chokeberry on gut microbiota diversity into the positive effect.

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.

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 and ß-casein on the stability, antioxidant activity and bioaccessibility of blueberry anthocyanins with an in vitro simulated digestion.

Blueberry anthocyanins are well-known for their diverse biological functions. However, the instability during digestion results in their weak bioavailability. The current study aimed to investigate the alteration in the stability, antioxidant capacity and bioaccessibility of blueberry anthocyanins with the addition of α-casein and ß-casein in a simulated digestion system using pH differential method, HPLC-MS analysis, peroxyl scavenging capacity (PSC) assay, cellular antioxidant activity (CAA) and penetration test. The results showed that both α-casein and ß-casein could increase the stability of blueberry anthocyanins during intestinal digestion and protect their antioxidant capacity. Moreover, the addition of α-casein or ß-casein would enhance the bioaccessibility of blueberry anthocyanins. In conclusion, our study highlights that the interaction between α-casein or ß-casein with blueberry anthocyanins can protect the compounds against influences associated with the simulated digestion.

Effect of whey protein isolate on the stability and antioxidant capacity of blueberry anthocyanins: A mechanistic and in vitro simulation study.

The processing stability and antioxidant capacity of blueberry anthocyanins (ANs) in the presence of whey protein isolate (WPI) were examined. WPI was found to enhance both the stability and antioxidant activity of ANs during processing and simulated in vitro digestion, especially at a concentration of 0.15 mg·mL-1. Fluorescence and ultraviolet-visible absorption spectroscopy showed that ANs were primarily stabilized by hydrophobic forces between WPI and malvidin-3-O-galactoside (M3G), the major anthocyanin monomer. Circular dichroism and Fourier-transform infrared spectroscopy confirmed that the structure of WPI changed and the microenvironments of certain amino acid residues were modulated by non-covalent binding to M3G; furthermore, fewer α-helices and more ß-sheets were formed. Molecular docking studies revealed that WPI, especially immunoglobulin (IgG), contributed the most to ANs stability via hydrogen bonds and hydrophobic forces according to molecular docking scores (-141.30 kcal/mol). These results provided an important fundamental basis for improving the stabilities of ANs in milk systems.

Effects of high hydrostatic pressure and thermal processing on anthocyanin content, polyphenol oxidase and ß-glucosidase activities, color, and antioxidant activities of blueberry (Vaccinium Spp.) puree.

Thermal processing (TP) and high hydrostatic pressure (HHP) are two important puree processing methods. In this study, the polyphenol oxidase (PPO) and ß-glucosidase activities, chromatic values, peroxide radical scavenging capacities (PSCs), cellular antioxidant activities (CAAs), and anthocyanin profiles were evaluated in blueberry puree following TP and HHP treatments. Nine anthocyanins were identified and cyanidin glycosides were the most abundant compounds in the blueberry puree sample. Petunidin-3-O-arabinoside, malvidin-3-O-galactoside, and malvidin-3-O-glucoside concentrations increased at temperatures of 70-90 °C (TP) and a pressure of 300 MPa (HHP). The highest total anthocyanin concentration (503.5 µg/mL) and PSC (13.45 µg VCE/mL) were observed following the TP (90 °C) treatment. Furthermore, a positive correlation was observed between the anthocyanin content and PSC (R2 = 0.655, P < 0.05). Finally, HHP treatment resulted in better puree color retention than TP treatment. The results of this study could provide valuable information for optimizing the processing methods for anthocyanin-rich products.

Effect of In Vitro Digestion on Phytochemical Profiles and Cellular Antioxidant Activity of Whole Grains.

Most of the previous in vitro digestion treatments were conducted directly to whole grains without extraction of free phenolics, thus the bioaccessible phenolics contained both free phenolics that survived the digestion and digested phenolics released by digestion. However, the profiles of digested phenolics released by digestion remain unknown. This study was designed to investigate the phytochemical contents, peroxyl radical scavenging capacities (PSCs), and cellular antioxidant activities (CAAs) of free, digested, and bound fractions of whole grains. Total phenolic contents of whole grains were highest in digested fraction, followed by free and bound fractions. The predominant phenolics were 12 phenolic acids and one flavonoid, which mostly existed in bound forms, then in digested and free forms. The digested phenolics bound to proteins were in conjugated form. The bound fractions had the highest PSCs, followed by free and digested fractions. CAAs were highest in bound fractions, followed by digested and free fractions.