Highly selective separation and purification of anthocyanins from bilberry based on a macroporous polymeric adsorbent

Development of a scalable, high-anthocyanin and low-acidity natural red food colorant from Hibiscus sabdariffa L

The hibiscus calyx contains 0.3-2.4% total anthocyanins, and is a promising source for naturally red food colorants. In this study, commercially available hibiscus calyces were subjected to ethanolic-aqueous extraction and chromatographic enrichment with the XAD-7HP resin, to create scalable, high-anthocyanin and low-acidity natural food colorants. Anthocyanins, organic and phenolic acids were monitored after each step using UHPLC-DAD and UHPLC-QQQ/MS. 75.67% total anthocyanins were recovered from calyces after double extractions, and the content increased by 8.50-14.90 times after the column enrichment, reaching 14.51-31.90% (by dry weight) in the final product. Chromatographic fractionation was also shown to effectively increase the total phenolic acids by 11.01-16.22 times, and remove an average of 98.58% of the total organic acids. High intensity redness at pH 2.5-3.5 indicated that the final product may be a promising, versatile natural food and beverage colorant in low pH products.

Polyphenol-Rich Extract of Apocynum venetum L. Leaves Protects Human Retinal Pigment Epithelial Cells against High Glucose-Induced Damage through Polyol Pathway and Autophagy

Diabetic retinopathy (DR) is a specific microvascular problem of diabetes, which is mainly caused by hyperglycemia and may lead to rapid vision loss. Dietary polyphenols have been reported to decrease the risk of DR. Apocynum venetum L. leaves are rich in polyphenolic compounds and are popular worldwide for their health benefits as a national tea drink. Building on previous findings of antioxidant activity and aldose reductase inhibition of A. venetum, this study investigated the chemical composition of polyphenol-rich extract of A. venetum leaves (AVL) and its protective mechanism on ARPE-19 cells in hyperglycemia. Ninety-three compounds were identified from AVL by LC-MS/MS, including sixty-eight flavonoids, twenty-one organic acids, and four coumarins. AVL regulated the polyol pathway by decreasing the expression of aldose reductase and the content of sorbitol, enhancing the Na+K+-ATPase activity, and weakening intracellular oxidative stress effectively; it also could regulate the expression of autophagy-related proteins via the AMPK/mTOR/ULK1 signaling pathway to maintain intracellular homeostasis. AVL could restore the polyol pathway, inhibit oxidative stress, and maintain intracellular autophagy to protect cellular morphology and improve DR. The study reveals the phytochemical composition and protective mechanisms of AVL against DR, which could be developed as a functional food and/or candidate pharmaceutical, aiming for retina protection in diabetic retinopathy.

Green Solvents for Extraction of Natural Food Colorants from Plants: Selectivity and Stability Issues

Consumers associate the color of food with its freshness and quality. More and more attention is being paid to natural colorants that bring additional health benefits to humans. Such natural substances are the carotenoids (yellow to orange), the anthocyanins (red to blue), and the betalains (red and yellow), which are very sensitive to exposure to light, air, high temperatures, and chemicals. Stability and diversity in terms of color can be optimized by using environmentally friendly and selective extraction processes that provide a balance between efficacy, safety, and stability of the resulting extracts. Green solvents like water, supercritical fluids, natural deep eutectic solvents, and ionic liquids are the most proper green solvents when combined with different extraction techniques like maceration, supercritical extraction, and ultrasound-assisted or microwave-assisted extraction. The choice of the right extracting agent is crucial for the selectivity of the extraction method and the stability of the prepared colorant. The present work reviews the green solvents used for the extraction of natural food colorants from plants and focuses on the issues related to the selectivity and stability of the products extracted.

Gingerols synergize with anthocyanins to induce antioxidant activity in vitro

Oxidative stress caused by free radicals contributes to the pathogenesis of multiple chronic health conditions. Phytochemicals protect against oxidative stress; however, low bioavailability from dietary sources limits their health benefits. This study aimed to assess the effects of anthocyanins and gingerols' combination on the cellular antioxidant response of Caco-2 cells against oxidative stress. A strong synergism was observed for anthocyanin-gingerol (Ac-G) w/w combined ratios of 8:1 and 2:1 (dosages of (1 + 0.125) and (1 + 0.5) μg/mL) in the cellular antioxidant activity (CAA) and cytoprotective effects, with synergistic effect indicator (SE) values of 1.41 and 1.61, respectively. The synergism of Ac-G combinations promoted cellular antioxidant defense systems and cytoprotective effects by reducing the induced GPx enzyme activity, protecting SOD enzyme activity, reducing cellular ROS generation, increasing glutathione content, and inhibiting lipid peroxidation. Thus, Ac-G combinations showed potential in supporting the endogenous antioxidant systems to protect cells from oxidation and restore physiological redox status. The Ac-G formulation is a promising healthy option that can be developed into functional foods or nutraceutical products. Furthermore, it could help address the low bioavailability of these phenolics, as higher effects were achieved when combining the same doses.

The Research Progress of Extraction, Purification and Analysis Methods of Phenolic Compounds from Blueberry: A Comprehensive Review

Blueberry is the source of a variety of bioactive substances, including phenolic compounds, such as anthocyanins, pterostilbene, phenolic acids, etc. Several studies have revealed that polyphenols in blueberry have important bioactivities in maintaining health, such as antioxidant and anti-tumor activities, immune regulation, the prevention of chronic diseases, etc. Therefore, these phenolic compounds in blueberries have been widely used in the field of healthcare, and the extraction, isolation, and purification of phenolic compounds are the prerequisites for their utilization. It is imperative to systematically review the research progress and prospects of phenolic compounds present in blueberries. Herein, the latest progress in the extraction, purification, and analysis of phenolic compounds from blueberries is reviewed, which can in turn provide a foundation for further research and usage of blueberries.

Comprehensive resistance evaluation of 15 blueberry cultivars under high soil pH stress based on growth phenotype and physiological traits

High soil pH is one of the main abiotic factors that negatively affects blueberry growth and cultivation. However, no comprehensive evaluation of the high soil pH tolerance of different blueberry cultivars has been conducted. Herein, 16 phenotypic and physiological indices of 15 blueberry cultivars were measured through pot experiments, and the high-pH soil tolerance coefficient (HSTC) was calculated based on these indices to comprehensively evaluate the high-soil-pH tolerance of plants. The results demonstrated that high soil pH stress inhibited blueberry 77.growth, and MDA, soluble sugar (SS), and soluble protein (SP) levels increased in leaves. Moreover, in all cultivars, CAT activity in the antioxidant system was enhanced, whereas SOD activity was reduced, and the relative expression levels of the antioxidant enzyme genes SOD and CAT showed similar changes. In addition, the leaf chlorophyll relative content (SPAD), net photosynthetic rate (P_n), transpiration rate (E), and stomatal conductance (G_s) decreased, while changes in the intercellular CO₂ concentration (C_i) were noted in different cultivars. Finally, according to the comprehensive evaluation value D obtained from the combination of principal component analysis (PCA) and membership function (MF), the 15 blueberry cultivars can be divided into 4 categories: high soil pH-tolerant type ['Briteblue' (highest D value 0.815)], intermediate tolerance type ('Zhaixuan 9', 'Zhaixuan 7', 'Emerald', 'Primadonna', 'Powderblue' and 'Chandler'), low high soil pH-tolerant type ('Brightwell', 'Gardenblue', 'Plolific' and 'Sharpblue') and high soil pH-sensitive type ['Legacy', 'Bluegold', 'Baldwin' and 'Anna' (lowest D value 0.166)]. Stepwise linear regression analysis revealed that plant height, SS, E, leaf length, C_i, SOD, and SPAD could be used to predict and evaluate the high soil pH tolerance of blueberry cultivars.

Anthocyanins in Different Food Matrices: Recent Updates on Extraction, Purification and Analysis Techniques

Anthocyanins (ANCs), a kind of natural pigments, are widely present in food substrates. Evidence has shown that ANCs can promote health in terms of anti-oxidation, anti-tumor, and anti-inflammation. However, the oxidative stability of ANCs limits accurate quantitation and analysis. Therefore, faster, more accurate, and highly sensitive extraction and determination methods are necessary for understanding the role of ANCs in medicine and food. This review presents an updated overview of pretreatment and detection techniques for ANCs in various food substrates since 2015. Liquid-liquid extraction and various green solvent extraction methods, such as accelerated solvents extraction, deep eutectic solvents extraction, ionic liquids extraction, and supercritical fluid extraction, are commonly used pretreatment methods for extraction and purification of ANCs. Liquid chromatography coupled with different detectors (tandem mass spectrometry and UV detectors) and spectrophotometry methods are some of the determination methods for ANC. This study has updated, compared, and discussed different pretreatment and analysis methods. Moreover, the advanced methods and development prospects in this field are comprehensively summarized, which can provide references for further utilization of ANCs.

Chemistry and Pharmacological Actions of Delphinidin, a Dietary Purple Pigment in Anthocyanidin and Anthocyanin Forms

Anthocyanins are naturally occurring water-soluble flavonoids abundantly present in fruits and vegetables. They are polymethoxyderivatives of 2-phenyl-benzopyrylium or flavylium salts. Delphinidin (Dp) is a purple-colored plant pigment, which occurs in a variety of berries, eggplant, roselle, and wine. It is found in a variety of glycosidic forms ranging from glucoside to arabinoside. Dp is highly active in its aglycone form, but the presence of a sugar moiety is vital for its bioavailability. Several animal and human clinical studies have shown that it exerts beneficial effects on gut microbiota. Dp exhibits a variety of useful biological activities by distinct and complex mechanisms. This manuscript highlights the basic characteristics, chemistry, biosynthesis, stability profiling, chemical synthesis, physicochemical parameters along with various analytical methods developed for extraction, isolation and characterization, diverse biological activities and granted patents to this lead anthocyanin molecule, Dp. This review aims to open pathways for further exploration and research investigation on the true potential of the naturally occurring purple pigment (Dp) in its anthocyanidin and anthocyanin forms beyond nutrition.

Valorization of Fig (Ficus carica L.) Waste Leaves: HPLC-QTOF-MS/MS-DPPH System for Online Screening and Identification of Antioxidant Compounds

Fig (Ficus carica L.) leaves are produced each year and often disposed, resulting in a waste of resources. Fig waste leaves are rich in flavonoids, which have strong antioxidant activity; however, the variety and chemical structure of antioxidants in fig leaves have not been reported in detail. To take full advantage of fig waste leaves, antioxidant capacity of different extracts (petroleum ether, ethyl acetate, and water) was evaluated by 1, 1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS), and ferric-ion-reducing antioxidant power (FRAP) methods. The results showed that flavonoids in ethyl acetate extraction had the highest content (83.92 ± 0.01 mg/g), maximum DPPH scavenging activity (IC₅₀ 0.54 mg/mL), highest ABTS scavenging rate (80.28%), and FRAP (3.46 mmol/g). Furthermore, an HPLC-QTOF-MS/MS-DPPH method was developed to identify 11 flavonoids in fig waste leaves. This rapid and efficient method can not only be used for screening the antioxidant components in fig waste leaves, but also can be combined with mass spectrometry to identify the compounds with antioxidant capacity. There are three flavonoids with significant antioxidant capacity, which are 3-O-(rhamnopyranosyl-glucopyranosyl)-7-O-(glucopyranosyl)-quercetin, isoschaftoside, and rutin. The results confirmed that fig waste leaves contain a variety of antioxidant components, which contributed to increase the value of fig waste leaves as antioxidants.

Carbon Nanofibers-Based Nanoconfined Liquid Phase Filtration for the Rapid Removal of Chlorinated Pesticides from Ginseng Extracts

A rapid nanoconfined liquid phase filtration system (NLPF) based on solvent-confined carbon nanofibers/carbon fiber materials (CNFs/CFs) was proposed to effectively remove chlorinated pesticides from ginsenosides-containing ginseng extracts. A series of major parameters that may affect the separation performance of the CNFs-NLPF method were extensively investigated, including the water solubility of nanoconfined solvents, filtration rate, ethanol content of the ginseng extracts, and reusability of the material for repeated adsorption. The developed method showed a high removal efficiency of pesticides (85.5-97.5%), high retainment rate of ginsenosides (95.4-98.9%), and consistent reproducibility (RSD < 11.8%). Furthermore, the feasibility of the CNFs-NLPF technique to be scaled-up for industrial application was systematically explored by analyzing large-volume ginseng extract (1 L), which also verified its excellent modifiable characteristic. This filtration method exhibits promising potential as a practical tool for removing pesticide residues and other organic pollutants in food samples to assure food quality and safeguard human health.

Ultrasonic-assisted modifications of macroporous resin to improve anthocyanin purification from a Pyrus communis var. Starkrimson extract

The present study presents an attempt to modify the surface properties of macroporous resins (MRs) in order to improve anthocyanin adsorption and desorption from Pyrus communis var Starkrimson fruit peel extract. A number of MRs were tested to optimise the ultrasonic-assisted adsorption (UAA) conditions; including ultrasonic power (100-400 W), resin-to-extract ratio (1-3 g/50 mL) and temperature (20-40 °C). Similarly, varying ultrasonic-assisted desorption (UAD) conditions were optimised; including ultrasonic power (200-600 W), resin-to-solvent ratio (1-4 g/50 mL), ethanol concentration (60-90% v/v) and temperature (20-40 °C). The Amberlyst 15 (H) cationic resin was found to be superior to the other tested resins. The maximum adsorption capacity (659 µg/g) of cyanidin 3-galactoside (Cy 3-gal) was achieved under the optimised UAA conditions (400 W, 20 °C and 1 g/50 mL), while 616 µg/g of Cy 3-gal was recovered under the optimised UAD conditions (582 W, 1 g/50 mL, 60% and 20 °C). Moreover, titratable-acid and total-sugar contents were found to be significantly lower under UAA than under conventional-assisted adsorption (CAA). ANOVA revealed that process factors had significant effects on the Cy 3-gal purification, as depicted by their linear, quadratic and interactive effects. While anthocyanin adsorption was found to be significantly improved at lower ultrasonic power, higher power promoted the desorption process. Adsorption under optimized UAA conditions followed pseudo second-order kinetics and multilayer adsorption (Freundlich isotherm) onto the Amberlyst 15 (H) resin surface was observed. The particle-size distribution curve and scanning electron microscopic images also revealed higher resin-surface roughness, peeling and the appearance of pores on the surface under ultrasonication.This is the first study to use ultrasonication to modify a cationic exchange resin for the improvement of Cy 3-gal purification from a fruit extract. This study can recommend the use of ultrasonication as a low-cost green technique that can improve macroporous resin characteristics for better purification of compounds from an extract.

Microencapsulation of Pigments by Directly Spray-Drying of Anthocyanins Extracts from Blueberry Pomace: Chemical Characterization and Extraction Modeling

The aim of this study was to develop an environmentally friendly process to extract anthocyanins from blueberry pomace using water as a solvent and directly microencapsulate anthocyanins by spray drying. The anthocyanins in water and ethanol extracts were characterized by high-performance liquid chromatography and mass spectrometry. The malvidin-3-O-galactoside and malvidin-3-O-glucoside were identified as the main anthocyanins in the blueberry pomace. The anthocyanins profiles of water extracts were similar to that by ethanol extraction. The effects of extraction parameters including solid-to-liquid ratio and temperature on the extraction efficiency and anthocyanins concentration were studied. The blueberry anthocyanins degraded at temperatures higher than 60 °C and all anthocyanins showed similar degradation tendency. The result showed that the artificial neural network (ANN) modeling could be well used to portray the effects of these parameters. Finally, the water extracts were successfully spray dried to produce microencapsulation of blueberry anthocyanins with maltodextrin (MD) as wall materials.

Modeling of the Adsorption/Desorption Characteristics and Properties of Anthocyanins from Extruded Red Cabbage Juice by Macroporous Adsorbent Resin

The adsorption/desorption characteristics, modeling and properties of anthocyanins from extruded red cabbage juice by macroporous resins were investigated. The static adsorption and desorption capacities of red cabbage anthocyanins on five macroporous resins were measured and compared. The X-5 resin showed the best capacities and was selected for the adsorption kinetics, isotherms and elution studies. The pseudo-second-order kinetic model and Langmuir isotherm model were used to describe the adsorption process and mechanism. Dynamic adsorption and desorption tests were performed on a fixed-bed column, and the loading and eluent conditions were optimized. The purity of anthocyanins in freeze-dried purified powder by the resin adsorption process is 21.3 ± 0.9 wt % and shows better stability in the air than the unpurified one. Finally, the antioxidant activity and color properties including color density, color intensity, color tonality and degradation index of the purified powders were measured.

Polysaccharide-based cationic hydrogels for dye adsorption

With advances in soft material design and engineering, naturally resourced polysaccharides have frequently been used to construct hydrogels because of their unique properties such as renewability, biodegradability and biocompatibility. In this work, we use a water-soluble microbial polysaccharide, salecan as a trapped natural polymer, poly(acrylamide-co-diallyldimethylammonium chloride) (PAD) as a functional matrix to prepare salecan/PAD hydrogels through a facile one-pot method. We employed a variety of spectroscopic techniques to probe the physicochemical properties of the designed hydrogels. The results demonstrated that salecan not only tuned the polarity of the PAD hydrogels, but also endowed them with adjustable water content. Subsequently, the adsorption performance of these hydrogels to methyl orange (MO) dye was investigated in detail. It was found that the salecan/PAD had the ability to remove MO from the surrounding aqueous solutions. In addition, adsorption kinetic data were nicely described by pseudo-second-order model and the adsorption isotherm data fitted well with the Freundlich equation. Having tailorable physicochemical properties coupled with the ability to uptake dye, these salecan-incorporated hydrogels could be promising platform for wastewater treatment and removal of heavy metal ions.

Preparation and characterization of molecularly imprinted solid amine adsorbent for CO2 adsorption

A molecularly imprinted solid amine adsorbent was successfully synthesized and exhibited excellent CO₂ adsorption performance under simulated flue gas.

Simultaneous separation and purification of chlorogenic acid, epicatechin, hyperoside and phlorizin from thinned young Qinguan apples by successive use of polyethylene and polyamide resins

The method for separating and purifying chlorogenic acid (CA), epicatechin (EC), hyperoside (HY) and phlorizin (PH) simutaneously from young Qinguan apples by successive use of X-5 and polyamide resins has been developed in this study. The order of adsorption capacities of X-5 for the four phenolics was PH>HY>EC>CA, and the adsorption equilibriums of the four phenolics onto X-5 resin conformed to Langmuir isotherms preferentially. The adsorption kinetics of EC and CA onto X-5 conformed to the pseudo-first-order model, while that of HY and PH accorded with the pseudo-second-order model. Interestingly, the values of equilibrium adsorption capacities (Q_e) calculated in the preferential kinetics models were closer to that of theoretical maximum adsorption capacities (Q₀) calculated by Langmuir isotherms. Through dynamic adsorption and desorption using X-5 and polyamide resins with ethanol solution as strippant, CA, EC, HY and PH were obtained with purities of 96.21%, 95.34%, 95.36% and 97.36%, respectively.

Identification and Enrichment of α-Glucosidase-Inhibiting Dihydrostilbene and Flavonoids from Glycyrrhiza uralensis Leaves

To exploit Glycyrrhiza uralensis resources, we examined the bioactive constituents of G. uralensis leaves. Seven chemical components were isolated by repeat column chromatography, and using spectroscopic methods, their structures were determined to be a novel prenylated dihydrostilbene, α,α'-dihydro-3,5,3',4'-tetrahydroxy-2,5'-diprenylstilbene (1); a methylated flavonoid, quercetin-3-Me ether (4); and 5 prenylated flavonoids: 5'-prenylquercetin (3), 8-[(E)-3-hydroxymethyl-2-butenyl]eriodictyol (7), 6-prenyleriodictyol (5), 5'-prenyleriodictyol (6), and 6-prenylquercetin-3-Me ether (2). Compounds 1-7 and their unprenylated counterparts, glycosides, and other related compounds (8-13) were quantitatively analyzed. Using a macroporous resin column, most of these compounds could be enriched in the 40% to 60% ethanol-eluted fractions. Compounds 1-7 showed strong radical scavenging activity toward DPPH, and most of them demonstrated greater inhibitory activity against α-glucosidase than their unprenylated counterparts.

Using a novel adsorbent macrocyclic compound cucurbit[8]uril for Pb2+ removal from aqueous solution

In this study, cucurbit[8]uril (CB[8]) was utilized as a kind of new adsorbent to remove Pb²⁺ ions from aqueous solution. With the solution pH increased from 2 to 6, the removal efficiency of adsorption increased from 55.6% to 74.5%correspondingly. The uptake of Pb²⁺ increased rapidly in the initial 30min, and then the adsorption rate became slower. The Pseudo-second order model could be used to interpret the adsorption kinetics satisfactorily; and the rate determining step in Pb²⁺ adsorption onto CB[8] was the external mass transfer step. Equilibrium isotherm study reveals that the Langmuir model gave a better fitting result than Freundlich model. The maximum adsorption capacity calculated by the Langmuir model was 152.67mg/g for 298K, 149.70mg/g for 313K and 136.42mg/g for 323K, respectively. The adsorption is a spontaneous process of exothermic nature. The effect of the adsorbent dosage and the influences of solution pH and co-existing cations were also investigated. The CB[8] was synthesized and characterized by ¹H NMR, IR, ESI-MS spectra, SEM-EDAX, Zeta-potential and BET-analysis. The adsorption mechanism was due to the coordination between CB[8] molecule and Pb²⁺ ions.

Efficient separation and purification of anthocyanins from saskatoon berry by using low transition temperature mixtures

Separation of anthocyanins from saskatoon berry by using low transition temperature mixtures.