Non-extractable Polyphenols Research Articles

Extraction, phytochemicals characterization, in vivo and in vitro anti-diabetic ability of non-extractable polyphenols from Undaria pinnatifida

Undaria pinnatifida (Up) is an edible seaweed known for its abundant nutrients and active compounds. In this research, six different methods, including acid hydrolysis extraction (AHE), alkaline hydrolysis extraction (LHE), enzymatic hydrolysis extraction (EHE), as well as their combinations with ultrasonic assisted extraction (AHE-U, LHE-U, EHE-U), were applied to extract non-extractable polyphenols from Up (UNEPPs). Results revealed that LHE-U was the most effective way to extract UNEPPs, it gave the highest yield (1.26 %) and total phenolics content (29.88 μg GAE/mg E), as well as considerable antioxidant and in vitro hypoglycemic effects. HPLC-Q-TOF-MS/MS analysis revealed the identification of 36 compounds from ULNEPPs, ferulic acid, p-coumaric acid and ferulic acid 4-O-glucuronide were the major compounds. In vivo study found that ULNEPPs could reduce fasting blood glucose (FBG) level, ameliorate abnormal glucose metabolism and dyslipidemia, repair insulin resistance and pancreas islet damage in type 2 diabetes (T2D) mice. Additionally, RT-qPCR analysis revealed that ULNEPPs improved glucose metabolism through the up-regulation of gene expression levels of Pi3k, Glut4, Akt, Ampk and the down-regulation of gene expression levels of Foxo1, Pgc-1α, Gsk-3β, Glut4, and G6pc. These results evidence that has the potential as dietary ingredients for preventing and treating T2D.

Extractable and Non-extractable Polyphenols in Berry Fibers

Extractable and Non-extractable Polyphenols in Berry Fibers

Nonextractable Polyphenols from Fu Brick Tea Alleviates Ulcerative Colitis by Controlling Colon Microbiota-Targeted Release to Inhibit Intestinal Inflammation in Mice.

This study was designed to elucidate the colon microbiota-targeted release of nonextractable bound polyphenols (NEPs) derived from Fu brick tea and to further identify the possible anti-inflammatory mechanism in dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mice. 1.5% DSS drinking water-induced C57BL/6J mice were fed rodent chow supplemented with or without 8% NEPs or dietary fibers (DFs) for 37 days. The bound p-hydroxybenzoic acid and quercetin in NEPs were liberated up to 590.5 ± 70.6 and 470.5 ± 51.6 mg/g by in vitro human gut microbiota-simulated fermentation, and released into the colon of the mice supplemented with NEPs by 4.4- and 1.5-fold higher than that of the mice supplemented without NEPs, respectively (p < 0.05). Supplementation with NEPs also enhanced the colonic microbiota-dependent production of SCFAs in vitro and in vivo (p < 0.05). Interestingly, Ingestion of NEPs in DSS-induced mice altered the gut microbiota composition, reflected by a dramatic increase in the relative abundance of Dubosiella and Enterorhabdus and a decrease in the relative abundance of Alistipes and Romboutsia (p < 0.05). Consumption of NEPs was demonstrated to be more effective in alleviating colonic inflammation and UC symptoms than DFs alone in DSS-treated mice (p < 0.05), in which the protective effects of NEPs against UC were highly correlated with the reconstruction of the gut microbiome, formation of SCFAs, and release of bound polyphenols. These findings suggest that NEPs as macromolecular carriers exhibit targeted delivery of bound polyphenols into the mouse colon to regulate gut microbiota and alleviate inflammation.

Unveiling the bioactivity and bioaccessibility of phenolic compounds from organic coffee husks using an in vitro digestion model.

The large quantities of by-products generated in the coffee industry are a problem. Studies related to the biological potential of organic coffee husks are still limited. The aim of this work was to investigate the occurrence of phenolic compounds in organic coffee husks and to evaluate their potential as a source of bioactive dietary components. To achieve this objective, three extracts were prepared, namely extractable polyphenols (EPs), hydrolyzable non-extractable polyphenols (H-NEPs), and non-extractable polyphenols (NEPs). These extracts were characterized and evaluated for their bioactive properties after simulated gastrointestinal digestion. The results show that the extraction process affected the occurrence of phenols from coffee peels, especially for caffeic acid, gallic acid, and chlorogenic acid. The free and bound polyphenols found in the extracts and digests not only showed antioxidant properties against 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals but were also strongly bioavailable and had good anticoagulant potential. These results highlight the potential health benefits of phytochemicals from coffee husks and open new perspectives for the use of such compounds in dietary supplements. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effect of lactic acid bacteria fermentation on extractable and non-extractable polyphenols of soybean milk: Influence of β-glucosidase and okara

Polyphenols and isoflavones are the main bioactive components of soybean. During traditional processing, many active compounds are lost because of filtration and discard of okara. However, reports on changes in phenolic compounds, especially bound phenolic compounds (BPC), during the fermentation of whole soybean milk (WSM) are few. In this paper, three lactic acid bacterias (LABs) with different β-glucosidase activities were used to evaluate the effect of β-glucosidase and different okara contents in soybean milk on the conversion of extractable and non-extractable polyphenols during fermentation. The results showed that the action of β-glucosidase improved the release of BPC and isoflavones. During WSM fermentation, the β-glucosidase-producing capacity of LABs strongly correlated with both the decrease in conjugated phenolic compounds and isoflavone glycosides, and the increase in free phenolic compounds and isoflavone aglycones. With the increase of okara content, the acid tolerance of Lactobacillus delbrueckii b8 was enhanced and the viability increased. During L. delbrueckii b8-mediated fermentation, the β-glucosidase activity of soy milk with high okara content (59.07 ± 1.48 U/mL) was 1.62 times that of soy milk with low okara content (36.43 ± 1.38 U/mL). As the okara concentration increased, the release of soybean polyphenols increased. Moreover, high okara content and high β-glucosidase activity mutually promote polyphenol conversion in soy yogurt. Therefore, WSM fermentation by β-glucosidase-producing LAB is a method for increasing the phenolic compound content in soymilk. This approach can offer a theoretical guide for efficiently utilizing soybean polyphenols and developing phenolic compound-rich soymilk.

Non-extractable polyphenols from blue honeysuckle fruit pomace with strong antioxidant capacity: Extraction, characterization, and their antioxidant capacity

The aim of this study was to investigate a more practical method for obtaining non-extractable polyphenols (NEPPs) from blue honeysuckle fruit pomace. Three methods, namely acid, alkaline, and enzymatic hydrolysis, were utilized to extract NEPPs. The findings indicated that alkaline hydrolysis was the most effective method for releasing NEPPs, which demonstrated higher levels of total flavonoid content (TFC) and total phenolic content (TPC) from blue honeysuckle fruit pomace. Additionally, higher TPC and TFC levels were related to a stronger antioxidant capacity. Qualitative and quantitative analysis using HPLC-HR-TOF-MS/MS revealed that acid hydrolysis resulted in a greater concentration of certain phenolic acids, while alkaline hydrolysis yielded a higher concentration of flavonoids, and enzymatic hydrolysis produced a wider range of phenolic compositions. Despite the fact that enzymatic hydrolysis is considered a gentler method, the researchers concluded that alkaline hydrolysis was the most appropriate method for obtaining NEPPs from blue honeysuckle fruit pomace.

Colon-Targeted Release of Turmeric Nonextractable Polyphenols and Their Anticolitis Potential via Gut Microbiota-Dependent Alleviation on Intestinal Barrier Dysfunction in Mice.

Solid evidence has emerged supporting the role of nonextractable polyphenols (NEPs) and dietary fibers (DFs) as gut microbiota modulators. This study aims to elucidate gut microbiota-dependent release of turmeric NEPs and examine the possible anti-inflammatory mechanism in the dextran sulfate sodium-induced ulcerative colitis (UC) model. 1.5% DSS drinking water-induced C57BL/6J mice were fed a standard rodent chow supplemented with or without 8% extractable polyphenols (EPs), NEPs, or DFs for 37 days. The bound curcumin, demethoxycurcumin, and bisdemethoxycurcumin in NEPs were released up to 181.5 ± 10.6, 65.2 ± 6.0, and 69.5 ± 7.6 μg/mL by in vitro gut microbiota-simulated fermentation and released into the colon of NEP-supplemented mice by 5.7-, 11.0-, and 7.8-fold higher than pseudo germ-free mice, respectively (p < 0.05). NEPs also enhanced the colonic microbiota-dependent production of short-chain fatty acids in vitro and in vivo (p < 0.05). Interestingly, NEP feeding significantly improved the DSS-caused gut microbiota disorder, epithelial barrier damage, and inflammation of UC mice better than EPs or DFs (p < 0.05). Meanwhile, the pseudo germ-free mice supplemented with NEPs failed to ameliorate UC symptoms. These findings manifest that turmeric NEPs as macromolecular carriers exert the target delivery of polyphenols into the colon for regulating gut microbiota to restore the impaired gut barrier function for alleviation of inflammation.

The synergistic ramification of insoluble dietary fiber and associated non-extractable polyphenols on gut microbial population escorting alleviation of lifestyle diseases.

Most of the pertinent research which aims at exploring the therapeutic effects of polyphenols usually misapprehends a large fraction of non-extractable polyphenols due to their poor aqueous-organic solvent extractability. These polymeric polyphenols (i.e., proanthocyanins, hydrolysable tannins and phenolic acids) possess a unique property to adhere to the food matrix polysaccharides and protein sowing to their structural complexity with high glycosylation, degree of polymerization, and plenty of hydroxyl groups. Surprisingly resistance to intestinal absorption does not hinder its bioactivity but accelerates its functionality manifolds due to the colonic microbial catabolism in the gastrointestinal tract, thereby protecting the body from local and systemic inflammatory diseases. This review highlights not only the chemistry, digestion, colonic metabolism of non-extractable polyphenols (NEPP) but also summarises the synergistic effect of matrix-bound NEPP exerting local as well as systemic health benefits.

Vacuum Impregnation of Polyphenols in Yam Bean: Effect on Sensory Acceptability, Antioxidant Capacity, and Potential Absorption Ability

The aim of this study was to evaluate the effect of vacuum impregnation (VI) of an ultrasound-assisted mango seed phenolic extract on antioxidant capacity (AOX), phenolic content, proximal composition, sensory acceptability, and in vitro polyphenols potentially available for absorption (PPAA) in the yam bean slice. The final parameters of VI optimizations by response surface were: slice thickness (1.5 mm), vacuum time (15 min), and restoration time (5 min). The optimal treatment (OT) showed a 412% increase in total soluble polyphenols (TSP), as well as a general increase in DPPH, ABTS, and FRAP (20.26, 129.99, and 64.52 μmol TE/g respectively), in relation to the control. However, VI increased the amount of nonextractable polyphenols in the indigestible fraction of yam bean slices and reduced the PPAA compared to the control. Therefore, it is concluded that the application of VI increases TSP and AOX, maintains sensory parameters, and decreases the PPAA in yam bean.

Chestnut shell represents a rich source of polyphenols: preparation methods, antioxidant activity and composition analysis of extractable and non-extractable polyphenols

Chestnut shell represents a rich source of polyphenols: preparation methods, antioxidant activity and composition analysis of extractable and non-extractable polyphenols

Polyphenol-Dietary Fiber Conjugates from Fruits and Vegetables: Nature and Biological Fate in a Food and Nutrition Perspective.

In the past few years, numerous studies have investigated the correlation between polyphenol intake and the prevention of several chronic diseases. Research regarding the global biological fate and bioactivity has been directed to extractable polyphenols that can be found in aqueous-organic extracts, obtained from plant-derived foods. Nevertheless, significant amounts of non-extractable polyphenols, closely associated with the plant cell wall matrix (namely with dietary fibers), are also delivered during digestion, although they are ignored in biological, nutritional, and epidemiological studies. These conjugates have gained the spotlight because they may exert their bioactivities for much longer than extractable polyphenols. Additionally, from a technological food perspective, polyphenols combined with dietary fibers have become increasingly interesting as they could be useful for the food industry to enhance technological functionalities. Non-extractable polyphenols include low molecular weight compounds such as phenolic acids and high molecular weight polymeric compounds such as proanthocyanidins and hydrolysable tannins. Studies concerning these conjugates are scarce, and usually refer to the compositional analysis of individual components rather than to the whole fraction. In this context, the knowledge and exploitation of non-extractable polyphenol-dietary fiber conjugates will be the focus of this review, aiming to access their potential nutritional and biological effect, together with their functional properties.

Characterization and potential bioactivity of polyphenols of Rosa rugosa

Rosa rugosa is widely cultivated in China, and the blossom of R. rugosa is used to extract rose essential oil or directly make into various foods, such as mei gui hua cake, mei gui hua sauce. Rose dregs are mostly used as fertilizer after extracting essential oil and the polar part has not been fully utilized. There is still much to be done in the products and deep processing of rose. In this study the content of total flavonol glycosides, the extractable polyphenols, the non-extractable polyphenols, the total phenolic and the total anthocyanins in R. rugosa from five major production areas in China was analyzed; the biological activities of the total extract, the polyphenols fraction, the flavonol glycosides fraction and the isolated compounds of R. rugosa were evaluated, including antioxidant, anti-ultraviolet, inhibitory activities of α-glucosidase, lipase, alveolar epithelial cell senescence and tyrosinase, together with regulating activities on intestinal flora. The components content of R. rugosa in different producing areas was significantly different. The total flavonol glycosides in Yunnan, the extractable polyphenols and the total phenolics in Shandong, the non-extractable polyphenols in Xinjiang, the total anthocyanins in Gansu was the higher than other areas. The polyphenols fraction showed antioxidant and anti-ultraviolet properties, inhibition of alveolar epithelial cell senescence, lipase and tyrosinase activities, and regulation of intestinal flora. The flavonol glycosides fraction showed α-glucosidase inhibitory activity. The results showed the polyphenols fraction and the flavonol glycosides fraction of R. rugosa could be used as skin care products and healthy food ingredient.

Bioaccessibility of phenolic compounds in Psidium guajava L. varieties and P. friedrichsthalianum Nied. after gastrointestinal digestion

Psidium guajava L. and Psidium friedrichsthalianum Nied are part of the Psidium species native to America. Nowadays, it is essential to study the phenolic compound (PC) profile and their changes during digestion and the fractions available for absorption. This study aimed to characterize the PC profile in some Psidium species and their bioaccessibility (BA). Fifty-seven compounds were identified, and forty-six belonged to ten different phenolic classes. PC profiles showed significant differences between the species and the intestinal fraction P. friedrichsthalianum Nied. showed the highest PC content, although it mostly belonged to non-extractable polyphenols. This leads to the lowest BA (37%); P. guajava L. ‘Morada’ showed the highest (47%). Hydroxycinnamic acids were the most stable PC after gastrointestinal digestion. This study showed relevant differences in the PC content and profile of different Psidium species and changes between the PC in the original matrix and those released in the different stages of gastrointestinal digestion.

Composition of Nonextractable Polyphenols from Sweet Cherry Pomace Determined by DART-Orbitrap-HRMS and Their In Vitro and In Vivo Potential Antioxidant, Antiaging, and Neuroprotective Activities

Sweet cherry pomace is an important source of phenolic compounds with beneficial health properties. As after the extraction of phenolic compounds, a phenolic fraction called nonextractable polyphenols (NEPs) remains usually retained in the extraction residue, alkaline and acid hydrolyses and enzymatic-assisted extraction (EAE) were carried out in this work to recover NEPs from the residue of conventional extraction from sweet cherry pomace. In vitro and in vivo evaluation of the antioxidant, antihypertensive, antiaging, and neuroprotective capacities employing Caenorhabditis elegans was achieved for the first time. Extractable phenolic compounds and NEPs were separated and identified by families by high-performance thin-layer chromatography (HPTLC) with UV/Vis detection. A total of 39 phenolic compounds were tentatively identified in all extracts by direct analysis in real-time high-resolution mass spectrometry (DART-Orbitrap-HRMS). EAE extracts presented the highest in vitro and in vivo antioxidant capacity as well as the highest in vivo antiaging and neuroprotective capacities. These results showed that NEPs with interesting biological properties are retained in the extraction residue, being usually underestimated and discarded.

In vitro assessment of the bioavailability of bioactive non-extractable polyphenols obtained by pressurized liquid extraction combined with enzymatic-assisted extraction from sweet cherry (Prunus avium L.) pomace

In vitro digestion and absorption simulation processes of non-extractable polyphenols (NEPs) obtained by pressurized liquid extraction combined with enzymatic-assisted extraction with Promod enzyme (PLE-EAE) from the residue of conventional extraction of sweet cherry pomace were studied. In general, total phenolic and proanthocyanidin contents decreased in each phase of the digestion. However, the antioxidant capacity increased when the digestion process progressed. In addition, the highest total phenolic and proanthocyanidin contents and antioxidant capacity were obtained in the absorbed fraction. NEPs from PLE-EAE extract, digestive fractions, absorbed and unabsorbed fractions were analyzed by ultra-high-performance liquid chromatography coupled to electrospray ionization quadrupole Exactive-Orbitrap mass spectrometry (UHPLC-ESI-Q-Orbitrap-MS). Fifteen NEPs were identified in the intestinal fraction and five in the absorbed fraction after the digestion process. Results obtained in this study define for the first time the bioavailability of antioxidant NEPs obtained from sweet cherry pomace.

Evaluation and Comparison of the Antioxidant Activity of Extractable Polyphenols and Non-extractable Polyphenols of Sour Orange Peel

Background and Objectives Research on food polyphenols has experienced a huge development during the last century. Most studies on polyphenolic compounds have focused on extractable polyphenols (EPP). However, an important polyphenolic fraction is ignored (Non-Extractable polyphenols (NEPP)) because they are trapped in the corresponding extraction residues. In this study, the antioxidant EPP and NEPP of sour orange peel, extracted by aqueous solvent and acid hydrolysis (with two different solvent systems) respectively, are evaluated and compared. Methods Antioxidant activity was evaluated by four tests of radical inhibition of 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP) and iron chelating. The amount of polyphenolic compounds, flavonoids, oligomeric proanthocyanidins, and flavanones were respectively determined by folin-ciocalteu, Aluminium chloride (AlCl3) and Ultraviolet–visible spectroscopy (UV-visible). Also, the anti-lipid peroxidation effect in rat liver was measured. Results The results of antioxidant analysis showed that NEPP with methanol/Sulfuric Acid Solvent had the highest level of antioxidant activity in sour orange peel. It can be due to the high polyphenolic compounds in this extraction compared to the others. Conclusion All extracts had antioxidant activity and can be suggested as a potential natural source in food and pharmaceutical industries.

Rapid fingerprinting of extractable and non-extractable polyphenols from tropical fruit peels using direct analysis in real time coupled to orbitrap mass spectrometry

A simple and rapid direct analysis in real-time coupled to high-resolution mass spectrometry (DART-HRMS) methodology was developed to generate the extractable and non-extractable polyphenols (NEPs) fingerprint for four different passion fruits, G. mangostana, and A. squamosa peels as case-study to investigate the influence of alkaline hydrolysis and enzymatic-assisted extraction (EAE) on the recovery of NEPs. The extraction residue obtained after these treatments was also analyzed by DART-HRMS. Data compiled from DART-HRMS mass spectra were processed with principal component analysis to discriminate among the different treatments. EAE with Depol enzyme enabled to obtain NEPs with the highest signal intensity in DART-HRMS analysis from all peels except for P. edulis and A. squamosa peels. In these two cases, NEPs were better extracted by EAE with Promod enzyme and alkaline hydrolysis. Results showed that the applied treatments were efficient to extract NEPs since their signal intensities in the extraction residues were very low compared with their extracts.

Pressurized Liquid Extraction Combined with Enzymatic-Assisted Extraction to Obtain Bioactive Non-Extractable Polyphenols from Sweet Cherry (Prunus avium L.) Pomace.

Sweet cherry generates large amounts of by-products within which pomace can be a source of bioactive phenolic compounds. Commonly, phenolic compounds have been obtained by conventional extraction methodologies. However, a significant fraction, called non-extractable polyphenols (NEPs), stays held in the conventional extraction residues. Therefore, in the present work, the release of NEPs from cherry pomace using pressurized liquid extraction (PLE) combined with enzyme-assisted extraction (EAE) using PromodTM enzyme is investigated for the first time. In order to study the influence of temperature, time, and pH on the NEPs extraction, a response surface methodology was carried out. PLE-EAE extracts displayed higher TPC (75 ± 8 mg GAE/100 g sample) as well as, PA content, and antioxidant capacity than the extracts obtained by PLE (with a TPC value of 14 ± 1 mg GAE/100 g sample) under the same extraction conditions, and those obtained by conventional methods (TPC of 8.30 ± 0.05 mg GAE/100 g sample). Thus, PLE-EAE treatment was more selective and sustainable to release NEPs from sweet cherry pomace compared with PLE without EAE treatment. Besides, size-exclusion chromatography profiles showed that PLE-EAE allowed obtaining NEPs with higher molecular weight (>8000 Da) than PLE alone.

Chemical Composition and Functional Properties of Dietary Fibre Concentrates from Winemaking By-Products: Skins, Stems and Lees.

The objective of this study was to evaluate, from a technological and nutritional point of view, the chemical composition and functional properties of the industrial winemaking by-products, namely skins, stems and lees. The chemical and physical characteristics, as well as the functional properties (fat and water retention and swelling capacity, antioxidant capacity, and their prebiotic effect), of the dietary fibre of these by-products were studied. The results showed that the skins, stems, and lees are rich in fibre, with the stem fibre containing the highest amounts of non-extractable polyphenols attached to polysaccharides with high antioxidant activity and prebiotic effect. Lee fibre had the highest water retention capacity and oil retention capacity. The results reveal that winemaking by-products could be used as a source of dietary fibre with functional characteristics for food applications.

A Sustainable Approach for Extracting Non-Extractable Phenolic Compounds from Mangosteen Peel Using Ultrasound-Assisted Extraction and Natural Deep Eutectic Solvents

Mangosteen (Garcinia mangostana L.) peel is a potential source of phenolic compounds with beneficial properties. Natural deep eutectic solvents (NaDES) have been considered an environmentally friendly and cheap alternative to conventional organic solvents. In this work, a green extraction methodology was developed using ultrasound-assisted extraction (UAE) and NaDES for the extraction of antioxidant non-extractable polyphenols (NEPs) from mangosteen peel. To select the best NaDES to extract NEPs from mangosteen peel, seven NaDES were studied. Antioxidant capacity and total phenolic and proanthocyanidin contents were determined for the extracts. The molecular weights for the NEPs present in those extracts were evaluated by size exclusion chromatography. Experimental results showed that choline chloride–lactic acid (1:2) was the NaDES allowing the highest antioxidant proanthocyanidin content in the extracts. A Box–Behnken experimental design was employed to optimize the main parameters in UAE with NaDES: water percentage, ultrasound amplitude, and extraction time. The optimal extraction conditions were 18.8% (v/v) water, 60% ultrasound amplitude, and 15 min as the extraction time. In addition, the cytotoxicity of the NEP extracts obtained under optimal extraction conditions was evaluated. Results indicated for the first time that the use of NaDES in combination with UAE could be a sustainable alternative for the extraction of antioxidant NEPs from mangosteen peel for important applications in the food, pharmaceutical, agrochemical, and cosmetic fields, as the extracts presented low cytotoxicity.