Bioaccessibility of polyphenolic compounds of six quinoa seeds during in vitro gastrointestinal digestion

Evaluation of biological activity and prebiotic properties of proanthocyanidins with different degrees of polymerization through simulated digestion and in vitro fermentation by human fecal microbiota

The bioactive activity of proanthocyanidins (PAs) is closely associated with their degree of polymerization (DP), however, the effects of PAs with different DP on digestion and gut microbiota have remained unclear. To investigate this, we conducted in vitro simulated digestion and colonic fermentation studies on samples of PAs with different DP. The results showed that PAs was influenced by both protein precipitation and enzymolysis, resulting in a decrease in functional activity. PAs with a high DP were more sensitive to the gastrointestinal environment. The significant clustering trend in colonic fermentation verified the reliability of multivariate statistical techniques for screening samples with distinct functional differences. The gut microbiota analysis showed that oligomeric PAs had a stronger promoting effect on beneficial bacteria, while high polymeric PAs had a greater inhibitory effect on harmful bacteria. This study offers new insights into the biological activity and microbiological mechanisms of PAs with different DP.

Metabolomics Characterization of Phenolic Compounds in Colored Quinoa and Their Relationship with In Vitro Antioxidant and Hypoglycemic Activities

Chenopodium quinoa Willd. is rich in phenolic compounds and exhibits diverse biological activities. Few studies have focused on the effect of colored quinoa's phenolic profile on potential biological activity. This study used a UPLC-MS/MS-based metabolomic approach to examine the quinoa phenolics and their association with in vitro antioxidant and hypoglycemic properties. In total, 430 polyphenols, mainly phenolic acids, flavonoids, and flavonols, were identified. Additionally, 121, 116, and 148 differential polyphenols were found between the white and black, white and red, and black and red comparison groups, respectively; 67 polyphenols were screened as shared key differential metabolites. Phenylalanine, tyrosine, and the biosynthesis of plant secondary metabolites were the main differently regulated pathways. Black quinoa had better total phenolic contents (643.68 mg/100 g DW) and antioxidant capacity, while white quinoa had better total flavonoid contents (90.95 mg/100 g DW) and in vitro α-amylase (IC50 value of 3.97 mg/mL) and α-glucosidase (IC50 value of 1.08 mg/mL) inhibition activities. Thirty-six polyphenols, including epicatechin and linarin, etc., were highly correlated with in vitro antioxidant activity, while six polyphenols, including tiliroside and chrysoeriol, etc., were highly correlated with in vitro hypoglycemic activity. This study may provide important information for colored quinoa resources to develop their healthy food applications.

Wild and Micropropagated Artemisia eriantha Infusions: In Vitro Digestion Effects on Phenolic Pattern and Antioxidant Activity

This study investigated the in vitro simulated gastrointestinal digestion (GID) effects on wild and micropropagated Apennines Genepì infusions. Wild and micropropagated infusions were compared for their antioxidant activity, phenolic contents, and polyphenolic profiles before and after GID. Before digestion, the wild infusions had higher amounts of phenolic compounds and antioxidant activity than the micropropagated ones. Instead, after digestion, the differences in the total phenolic content (TPC) and antioxidant activity between wild and micropropagated infusions were less pronounced. The changes in the TPC and phenolic profiles revealed the presence of several chemical transformations and rearrangements that resulted in compounds with different reactivity and antioxidant potential. Without enzyme actions, the wild infusion digest undergoes higher modifications than those obtained from the micropropagated ones. The current study offers the first concrete proof of the impact of GID on the polyphenolic chemicals present in infusions of wild and micropropagated Apennines Genepì and their antioxidant properties. Our findings are essential for future in-depth analyses of Apennine Genepì infusions and their potential impacts on human health.

Gastrointestinal digestion assays for evaluating the bioaccessibility of phenolic compounds in fruits and their derivates: an overview

Fruits and their derivatives are sources of phenolic compounds, which contribute to the maintenance of health benefits. In order to exert such properties, these compounds must be exposed to gastrointestinal conditions during digestion. In vitro methods of gastrointestinal digestion have been developed to simulate and evaluate the changes that compounds undergo after being exposed to various conditions. We present, in this review, the major in vitro methods for evaluating the effects of gastrointestinal digestion of phenolic compounds in fruits and their derivatives. We discuss the concept of bioaccessibility, bioactivity, and bioavailability, as well as the conceptual differences and calculations among studies. Finally, the main changes caused by in vitro gastrointestinal digestion in phenolic compounds are also discussed. The significant variation of parameters and concepts observed hinders a better evaluation of the real effects on the antioxidant activity of phenolic compounds, thus, the use of standardized methods in research would contribute for a better understanding of these changes.

Nanoencapsulation and bioaccessibility of polyphenols of aqueous extracts from Bauhinia forficata link

Bauhinia forficata Link is a plant rich in polyphenols that has been used mainly for its hypoglycemic activity, which is related to its antioxidant and anti-inflammatory potential. However, the beneficial effect of these bioactive compounds is directly dependent on their bioaccessibility and bioavailability, requiring processing techniques that can improve and preserve their biological activities. This work aimed to obtain nanocapsulated extracts from the infusion (ESIN) and decoction (ESDC) of B. forficata Link leaves, by spray drying. The encapsulating agents used were maltodextrin and colloidal silicon dioxide. The nanocapsules were characterized by HPLC-PDA-ESI-IT-MS ⁿ , evaluated the bioaccessibility of polyphenols after simulated digestion and their antioxidant activity. Additionally, an extensive physicochemical characterization of the nanocapsulated extracts was carried out and their stability and technological parameters were evaluated. The ESIN and ESDC extracts had yields of 57.3 % and 62.7 %, with average nanocapsules sizes of 0.202 μm and 0.179 μm, low humidity and water activity (<0.5), powder density and proper flow properties (Hausner ratio ≤ 1.25; Carr index 18-19 %). Scanning electron microscopy showed a spherical and amorphous morphology and low viscosity, which may have favored the solubility profile. The phenolic compounds of the nanocapsules degraded after 400 °C, showing high thermal stability. The infrared spectra identified the presence of maltodextrin and phenolic compounds and that there were no reactions between them. Chromatography confirmed the presence of phenolic compounds, mainly flavonols and their O-glycosylated derivatives, as well as carbohydrates, probably maltodextrin. Simulated in vitro digestion showed that polyphenols and flavonoids from ESIN and ESDC nanocapsules were bioaccessible after the gastric phase (49.38 % and 64.17 % of polyphenols and 64.08 % and 36.61 % of flavonoids) and duodenal (52.68 % and 79.06 % of polyphenols and 13.24 % and 139.03 % of flavoids), with a variation from 52.27 % to 70.55 % of the antioxidant activity maintained, by the ORAC method, after gastric digestion and still 25 %, after duodenal. Therefore, the nanoencapsulation of extracts of B. forficata is a viable option for the preservation of their bioactive compounds, making them bioaccessible and with antioxidant activity, which make them suitable for incorporation into various nutraceutical formulations, such as capsules, tablets and sachets.

Effect of in vitro gastrointestinal digestion on the chemical composition and antioxidant properties of Ginkgo biloba leaves decoction and commercial capsules

In this study Ginkgo biloba leaves (GBL) decoction and commercial capsules were digested using an in vitro model. Thirty-six active compounds were identified and quantified by HPLC-ESI-MS analysis based on the MS/MS patterns (precursor ions and product ions) and retention times, in comparison with reference standards. Most compounds in GBL showed a significant decrease during intestinal digestion, with an exception of vanillic acid and biflavonoids. Bioaccessibility values of chemical compositions varied between decoction and capsules samples. Also, significant reductions of total flavonoids and total phenolic content was observed after in vitro digestion. Both, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazo-line-6-sulfonic acid (ABTS) scavenging capacity decreased after gastric digestion, but increased during intestinal digestion. Nevertheless, different behaviour was observed in reducing antioxidant power (FRAP) assay. Compared to the pH of digestion, the influence of digestive enzymes on the chemical composition and antioxidant activity of GBL was relatively minor. Overall, these results may help provide a valid foundation for further investigations on bioactive compounds and the pharmacodynamics of GBL.

Effects of colonic fermentation on the stability of fresh and black onion bioactives

The health properties related to onion intake are attributed mainly to the presence of bioactive compounds, particularly phenolic and organosulfur compounds (OSCs). The aim of this study was to investigate, for the first time, the effect of an in vitro colonic fermentation on the stability of phenolic and OSCs of fresh and black onion by ultra-high-performance liquid chromatography coupled with mass spectrometry with a linear ion trap (UHPLC-LIT-MS). Throughout colonic fermentation, fresh onion showed an increase in the total phenolic content of 45%, mainly due to an increase in the content of the flavonoid family, while the OSCs remained stable along the fermentation. Black onion presented a different behaviour, showing significant decreases in total (poly)phenol and OSC content, 22 and 48%, respectively. The main compounds found after the in vitro colonic fermentation of fresh onion were isorhamnetin (141 μmol L^-1), quercetin (95 μmol L^-1), 3,4-dihydroxybenzoic acid (53 μmol L^-1), methionine sulfoxide (100 μmol L^-1) and S-allylcysteine (SAC) (21.7 μmol L^-1), whereas 3,4-dihydroxybenzoic acid (70 μmol L^-1), 4-hydroxyphenylacetic acid (68 μmol L^-1), methionine sulfoxide (82 μmol L^-1) and S-propylmercapto-L-cysteine (SPMC) (10.1 μmol L^-1) accounted for the highest concentrations of phenolics and OSCs in fermented black onion. These compounds, presumably present for their absorption and action at the colonic level, could be related to the health benefits of regular consumption of fresh and black onion.

Exploring the Impact of Solid-State Fermentation on Macronutrient Profile and Digestibility in Chia (Salvia hispanica) and Sesame (Sesamum Indicum) Seeds

Fermentation of plant-based substrates with edible fungi enhances the nutrient profile and digestibility, but it has been scarcely applied to edible seeds, which are rich in healthy lipids. In this study, chia and sesame seeds were solid-state fermented with Pleurotus ostreatus, followed by drying and milling. Fermentation led to increased content of lipid and protein in both seeds' products, and a change in fatty acid profile in favor of increased polyunsaturated fatty acids. Then, the samples were subjected to in vitro digestion. Lipolysis, determined by nuclear magnetic resonance, was higher in sesame than in chia products, and the fermented counterparts had increased values compared to the controls. In terms of physical properties, fermentation showed reduced particle size and increased matrix degradation and decreased viscosity of the digestion medium, which were related to increased lipolysis. In conclusion, applying solid-state fermentation on chia and sesame seeds could be a recommendable approach.

Modelling and Optimization of Ultrasound-Assisted Extraction of Phenolic Compounds from Black Quinoa by Response Surface Methodology

Phenolic compounds are currently the most investigated class of functional components in quinoa. However, great variability in their content emerged, because of differences in sample intrinsic and extrinsic characteristics; processing-induced factors; as well as extraction procedures applied. This study aimed to optimize phenolic compound extraction conditions in black quinoa seeds by Response Surface Methodology. An ultrasound-assisted extraction was performed with two different mixtures; and the effect of time; temperature; and sample-to-solvent ratio on total phenolic content (TPC) was investigated. Data were fitted to a second-order polynomial model. Multiple regression analysis and analysis of variance were used to determine the fitness of the model and optimal conditions for TPC. Three-dimensional surface plots were generated from the mathematical models. TPC at optimal conditions was 280.25 ± 3.94 mg of Gallic Acid Equivalent (GAE) 100 g⁻¹ dm upon extraction with aqueous methanol/acetone, and 236.37 ± 5.26 mg GAE 100 g⁻¹ dm with aqueous ethanol mixture. The phenolic profile of extracts obtained at optimal conditions was also investigated by HPLC. The two extracting procedures did not show different specificities for phenolic compounds but differed in the extraction yield.

Probiotic red quinoa drinks for celiacs and lactose intolerant people: study of functional, physicochemical and probiotic properties during fermentation and gastrointestinal digestion

The consumption of probiotic foods is rather limited for many sectors of the population (vegans, lactose intolerant and celiacs). Therefore, it is necessary to offer functional alternatives for these sectors. Different red quinoa drinks were fermented with L. plantarum (QLPBB) and B. longum (QBLBB) at different times. Results showed that microbial concentration reached high levels (6-8 Log CFU/mL) after 6 h and probiotic viability was very high (6 Log CFU/mL) after gastrointestinal digestion (GD). However, QBLBB reached the best probiotic concentration at 24 h. From 6 h of fermentation, probiotic resistance to some antibiotics, especially B. longum, could have a great potential to restore the intestinal microbiota during and after treatment with certain antibiotics. QLPBB showed the highest levels of total polyphenols and antioxidant capacity (AOC) after GD. Therefore, these red quinoa drinks have potential as functional probiotic beverages for vegans, celiacs and allergic to milk protein and lactose-intolerant people.

Effect of in vitro gastro-intestinal digestion on the phenolic composition and antioxidant capacity of Burdock roots at different harvest time

The current study aimed to evaluate how the harvest time affects the phenolic composition in Burdock root flours (BRF) and how these phenolics are influenced by the gastro-intestinal digestive environment. Burdock roots were harvested in 2020 in Jiangsu Province in June (B1), July (B2) and August (B3). The main phenolic, 5-O-caffeoylquinic acid (5-CQA) decreased after in vitro digestion from 1.14 to 0.22 mg/g (B1 < B2 < B3). Total phenolic content of BRF was 61% lower after in vitro digestion whereas 5-CQA bioaccessibility remained at about 60%. Twelve other phenolic compounds were tentatively identified after in vitro digestion. An average reduction in antioxidant capacity of 27% and 10% was observed for DPPH and ABTS, respectively. In conclusion, data demonstrated that phenolic composition, bioaccessibility and antioxidant capacity of Burdock roots harvested at different times were subject to the influence of in vitro gastrointestinal digestion.

Pork Liver Pâté Enriched with Persimmon Coproducts: Effect of In Vitro Gastrointestinal Digestion on Its Fatty Acid and Polyphenol Profile Stability

Agrofood coproducts are used to enrich meat products to reduce harmful compounds and contribute to fiber and polyphenol enrichment. Pork liver pâtés with added persimmon coproducts (3 and 6%; PR-3 and PR-6, respectively) were developed. Therefore, the aim was to study the effect of their in vitro gastrointestinal digestion on: the free and bound polyphenol profile (HPLC) and their colon-available index; the lipid oxidation (TBARs); and the stability of the fatty acid profile (GC). Furthermore, the effect of lipolysis was investigated using two pancreatins with different lipase activity. Forty-two polyphenols were detected in persimmon flour, which were revealed as a good source of bound polyphenols in pâtés, especially gallic acid (164.3 µg/g d.w. in PR-3 and 631.8 µg/g d.w. in PR-6). After gastrointestinal digestion, the colon-available index in enriched pâté ranged from 88.73 to 195.78%. The different lipase activity in the intestinal phase caused significant differences in bound polyphenols' stability, contributing to increased lipid oxidation. The fatty acids profile in pâté samples was stable, and surprisingly their PUFA content was raised. In conclusion, rich fatty foods, such as pâté, are excellent vehicles to preserve bound polyphenols, which can reach the colon intact and be metabolized by the intestinal microbiome.

Viscozyme L hydrolysis and Lactobacillus fermentation increase the phenolic compound content and antioxidant properties of aqueous solutions of quinoa pretreated by steaming with α-amylase

In this work, red quinoa was successively subjected to α-amylase steaming, complex enzyme Viscozyme (R) L hydrolysis, and lactic acid bacteria (LAB) fermentation. The total phenolic compound content (TPC), flavonoid content (TFC), and antioxidant capacities of the solvent-extractable (free) and bound fractions and the individual phenolic compounds released were determined. Compared to steaming with α-amylase, enzymatic hydrolysis and fermentation of quinoa resulted in approximately 82.6, 26.9, 36.3, and 45.2% increases in the TPC (the sum of free and bound fractions), TFC, DPPH, and ORAC values, respectively. HPLC-QqQ-MS/MS analysis showed that enzymolysis and fermentation increased the content of protocatechuic acid, catechin, procyanidin B₂ , and quercetin by 126.3, 101.9, 524, and 296.3%, respectively. Moreover, a major proportion of individual phenolic compounds existed as bound form. The results indicated that complex enzymatic hydrolysis and LAB fermentation were practical and useful to release promising polyphenols. This research provides a basis for the processing of quinoa beverages rich in phenolic compounds. PRACTICAL APPLICATION: In this work, liquefying with α-amylase, hydrolyzing with cellulolytic enzyme mixture, and fermenting with Lactic acid bacteria (LAB), successively, were exploited to process quinoa. This is an innovative method of quinoa processing to produce beverage products. Complex enzymatic hydrolysis and fermentation with LAB can significantly enhance phenolic compound, especially protocatechuic acid, catechin, procyanidin B₂ , and quercetin. In additional, LAB fermentation is very beneficial to improve the antioxidant activity of quinoa. We also found that a major proportion of phenolic compounds existed as bound forms in quinoa.

Specialty seeds: Nutrients, bioactives, bioavailability, and health benefits: A comprehensive review

Seeds play important roles in human nutrition and health since ancient time. The term "specialty" has recently been applied to seeds to describe high-value and/or uncommon food products. Since then, numerous studies have been conducted to identify various classes of bioactive compounds, including polyphenols in specialty seeds. This review discusses nutrients, fat-soluble bioactives, polyphenols/bioactives, antioxidant activity, bioavailability, health benefits, and safety/toxicology of commonly consumed eight specialty seeds, namely, black cumin, chia, hemp, flax, perilla, pumpkin, quinoa, and sesame. Scientific results from the existing literature published over the last decade have been compiled and discussed. These specialty seeds, having numerous fat-soluble bioactives and polyphenols, together with their corresponding antioxidant activities, have increasingly been consumed. Hence, these specialty seeds can be considered as a valuable source of dietary supplements and functional foods due to their health-promoting bioactive components, polyphenols, and corresponding antioxidant activities. The phytochemicals from these specialty seeds demonstrate bioavailability in humans with promising health benefits. Additional long-term and well-design human intervention trials are required to ascertain the health-promoting properties of these specialty seeds.

Functional Components and Anti-Nutritional Factors in Gluten-Free Grains: A Focus on Quinoa Seeds

Quinoa (Chenopodium quinoa Willd.) has recently received increasing interest from both scientists and consumers due to its suitability in gluten-free diets, its sustainability, and its claimed superfood qualities. The aim of this paper is to systematically review up-to-date studies on quinoa functional components and anti-nutritional factors, in order to define a baseline for food scientists approaching the investigation of quinoa phytochemicals and providing evidence for the identification of healthier sustainable foods. State of the art evaluations of phytochemical contents in quinoa seeds were obtained. It emerged that phenolic compounds are the most investigated functional components, and spectrophotometric methods have been mostly applied, despite the fact that they do not provide information about single components. Saponins are the most studied among anti-nutritional factors. Betalains, tannins, and phytoecdysteroids have been poorly explored. Information on factors affecting the phytochemical content at harvesting, such as quinoa ecotypes, crop geographical location and growing conditions, are not always available. A comprehensive characterization, encompassing several classes of functional components and anti-nutritional factors, is mainly available for quinoa varieties from South America. However, defining a standard of quality for quinoa seeds is still challenging and requires a harmonization of the analytical approaches, among others.

Changes in the Organosulfur and Polyphenol Compound Profiles of Black and Fresh Onion during Simulated Gastrointestinal Digestion

This study aims to determine the changes in, and bioaccessibility of, polyphenols and organosulfur compounds (OSCs) during the simulated gastrointestinal digestion of black onion, a novel product derived from fresh onion by a combination of heat and humidity treatment, and to compare it with its fresh counterpart. Fresh and black onions were subjected to in-vitro gastrointestinal digestion, and their polyphenol and OSC profiles were determined by ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS). Although to a lesser extent than in the fresh onion, the phenolic compounds in the black variety remained stable during the digestion process, presenting a higher bioaccessibility index (BI) with recovery corresponding to 41.1%, compared with that of fresh onion (23.5%). As for OSCs, apart from being more stable after the digestion process, with a BI of 83%, significantly higher quantities (21 times higher) were found in black onion than in fresh onion, suggesting that the black onion production process has a positive effect on the OSC content. Gallic acid, quercetin, isorhamnetin, and ɣ-glutamyl-S-(1-propenyl)-L-cysteine sulfoxide were the most bioaccessible compounds in fresh onion, while isorhamnetin, quercetin-diglucoside, ɣ-glutamyl-S-methyl-L-cysteine sulfoxide and methionine sulfoxide were found in black onion. These results indicate that OSCs and polyphenols are more bioaccessible in black onion than in fresh onion, indicating a positive effect of the processing treatment.

Effect of in vitro gastrointestinal digestion on phenolic compounds and antioxidant properties of soluble and insoluble dietary fibers derived from hulless barley

In this study, the bioaccessibility and antioxidant activity of phenolic compounds in insoluble dietary fiber (IDF) and soluble dietary fiber (SDF) derived from hulless barley were evaluated by an in vitro gastrointestinal (GI) digestion model. The total phenolic and flavonoid contents, as well as antioxidant activity of phenolic compounds in IDF and SDF following GI digestion were studied. The results obtained showed an increase in total phenolic and flavonoid contents, as well antioxidant activity compared with undigested extracts. Moreover, the bioaccessibility indexes of phenolic compounds in IDF and SDF were 490.90 ± 3.10% and 1608.79 ± 40.63% respectively, after GI digestion. Similarly, the bioaccessibility indexes of flavonoids in IDF and SDF were 179.20 ± 15.16% and 814.36 ± 26.31%, respectively. Based on our findings, individual phenolic compounds show different stability in the digestion process. The content of ferulic acid has different trends in IDF and SDF during GI digestion. This study could provide a scientific basis for hulless barley DF as valuable food additives. PRACTICAL APPLICATION: Hulless barley is a unique cereal with potential health benefits due to high dietary fiber (DF) content and phenolic compounds. Phenolic compounds could be linked to DF through chemical bonds. Phenolic compounds in DF can be slowly and continuously released under acidic, alkaline, and enzymatic conditions by in vitro gastrointestinal digestion, which could maintain a higher phenolic concentration in the bloodstream and be beneficial for human health. This study could provide a scientific basis for hulless barley DF as valuable food additives.

Release of characteristic phenolics of quinoa based on extrusion technique

Quinoa is rich in phenolics which are benefit for human health for their outstanding antioxidant capacity, anti-inflammatory property and special biological functions. However, most of phenolics existed as bound form that with low bioavailability in quinoa. In this study, extrusion technique was applied for the release of bound phenolics in red quinoa (RQ), and effects of extruded temperature (120 °C, 140 °C, 160 °C and 180 °C) on the release of characteristic phenolics of RQ was investigated as well. Phenolics both presented as free and bound forms were identified in RQ and extruded quinoa samples, and result showed rutin, ferulic acid and vanillic acid were most common. The content of bound phenolics in RQ was 155.52 mg/kg, however, in extruded red quinoa (ERQ) was 77.25 mg/kg (ERQ-140 °C)-84.08 mg/kg (ERQ-120 °C). In corresponding, free phenolics in RQ was 22.15 mg/kg, while in ERQ was 41.04 mg/kg (ERQ-140 °C)-47.25 mg/kg (ERQ-160 °C). In conclusion, extrusion was excellent for the release of bound phenolics in quinoas and the best extruded temperature was 160 °C. Extrusion technique was potential in the processing of quinoa.

Rice and common bean blends: Effect of cooking on in vitro starch digestibility and phenolics profile

This study aims to evaluate the effects of in vitro digestion of rice and common bean blends on phenolics content and profile. Black and carioca beans were used as common bean sources. Blends consisted of 25:75, 50:50, and 75:25 polished rice:beans (w/w). Pure rice or pure beans were also analyzed. Phenolic compounds were determined in raw, cooked, and digested samples. The glucose release through in vitro digestion was slower as the proportion of black beans or carioca beans increased. Starch digestibility ranged between 41.1 in 100% carioca bean to 84.4% in 100% rice. Hydroxybenzoic acid, ferulic acid, p-coumaric acid, catechin, and epicatechin were the most abundant phenolics detected in the studied samples. Considering the content of phenolic compounds determined in the raw, cooked, and digested grains, only a small fraction was available for absorption in the gut, with amounts varying from 0.1 to 0.6 μg·g^-1.

Changes in bio-accessibility, polyphenol profile and antioxidants of quinoa and djulis sprouts during in vitro simulated gastrointestinal digestion

This study aimed to evaluate the bio-accessibility of the phenolics and flavonoid, the polyphenolic profile and the antioxidant activity of sprouts obtained from four different quinoa genotypes and one djulis cultivar during in vitro gastrointestinal digestion. Compared to their content in sprouts, the bioavailable phenolics after the oral phase, the gastric phase, the intestinal phase, and in the dialyzable fraction were in the ranges of 45.7%-63.5%, 87.6%-116.7%, 89.6%-124.5%, and 7.4%-10.9%, respectively. The trend in flavonoid bio-accessibility was similar to the polyphenols. The dialyzable flavonoid recoveries varied between 4.2% and 12.4%. Correspondingly, the free radical scavenging activity of the dialyzable phase decreased significantly from 84.7% to 96.5%. The main phenolic acids were vanillic acid, caffeic acid, and syringic acid during digestion. The results suggest that gastrointestinal digestion greatly affected the absorption of polyphenols and flavonoid of quinoa and djulis sprouts, as well as their antioxidant capacity.

Antioxidant activity and stability of the flavonoids from Lycium barbarum leaves during gastrointestinal digestion in vitro

In this study, stability including the total flavonoids content (TFC) and main monomers composition and antioxidant activity of the flavonoids extract (LBLF) from Lycium barbarum leaves were investigated in the process of simulated oral and gastrointestinal digestion in vitro. During digested through the simulated oral fluid (SOF), gastric fluid (SGF), and intestinal fluid (SIF) in order, TFC of LBLF in the lyophilized digestive fluid samples were determined at different time points. It was shown that compared with the initial TFC of 811.72 ± 0.72 mg RE/g DW, the total flavonoids did not change significantly during oral digestion, while definitely increased at gastric digestion stage (p < 0.05) where the pH value is the lowest in the digestive system, indicating that the release of flavonoids from LBLF was promoted by pepsin, trypsase, and bile, however decreased during intestinal digestion probably due to the instability of LBLF in weak alkali media. Moreover, the antioxidant capacity and bioaccessibility of LBLF were significantly improved by SGF and SIF digestion (p < 0.05). The scavenging effect of the fluid sample after gastric digestion on free radicals followed as O2−· > ABTS+· > DPPH > ·OH > FRAP, while the clearance effect of intestinal digestion sample expressed as ABTS+· > O2−· > DPPH > FRAP > ·OH. High performance liquid chromatography (HPLC) results suggested that chlorogenic acid and rutin in LBLF had low stability during the gastrointestinal digestion in vitro. Our study suggests that LBLF may show the instability in the contents of total flavonoids and some main monomers, but an enhancement in the antioxidant activity during gastrointestinal digestion, providing a reference for the stability improvement of LBLF in the next step.

Phytochemical Compounds and Antioxidant Activity Modified by Germination and Hydrolysis in Mexican Amaranth

Amaranth (Amaranthus spp.) grains have become essential for human health and nutrition; due to the presence of bioactive compounds that have shown some biological activities. This study aimed to evaluate the effect of germination, enzymatic hydrolysis, and its combination on the phytochemical compounds and antioxidant activity in Mexican amaranth. Germinated amaranth flours (GAF) exhibited increases in the concentrations of soluble protein (SP), total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC) and antioxidant activity (AOX) by 35.7, 17.2, 163.0, 1472.2, and 54.3%, respectively, compared with ungerminated amaranth flours (UAF). In SDS-PAGE, both hydrolysates of UAF and GAF exhibited low molecular weight bands (< 10 kDa). The hydrolysates of UAFH and GAFH had the highest degree of hydrolysis at 205 min of sequential hydrolysis (pepsin with pancreatin) time with 73.4 and 60.3%, respectively. Both hydrolysates obtained from GAF and UAF released significantly SP, TPC, TFC after sequential enzymatic hydrolysis (up 205 min), which led to a remarkable improvement of AOX when compared to nonhydrolyzed amaranth samples. The UAFH and GAFH had the best AOX at 270 min of enzymatic hydrolysis with 983.1 and 1304.9 μmol TE/mg SP, respectively. Hence, the combination of germination and enzymatic hydrolysis could be used to produce functional ingredients for food product development.

Impact of Processing and Intestinal Conditions on in Vitro Digestion of Chia (Salvia hispanica) Seeds and Derivatives

Chia seeds present with an excellent nutrient profile, including polyunsaturated fat, protein, fibre and bioactive compounds, which make them a potential food or ingredient to bring beneficial health effects. However, their tough structure could mean that these seeds remain hardly disrupted during digestion, thus preventing the release and digestibility of nutrients. In the present study, different chia products (seeds, whole flour, partially defatted flour and sprouts) were assessed in terms of proteolysis, lipolysis, calcium and polyphenols bioaccessibility and antioxidant activity. In vitro digestions were performed supporting standard intestinal (pH 7, bile salts concentration 10 mM) and altered (pH 6, bile salts concentration 1 mM) conditions. The altered conditions significantly reduced lipolysis, but not proteolysis. Regarding the food matrix, compared to the chia seeds, whole and partially defatted flour increased the hydrolysis of lipids and protein, relating to reduced particle size. Sprouting had an enhancing effect on proteolysis but prevented lipolysis. Calcium bioaccessibility dropped in all the samples in the two intestinal conditions. The digestion process led to increased polyphenols bioaccessibility in all the structures, but reduced antioxidant activity except in the milled structures. In conclusion, milling should be applied to chia seeds prior to consumption in cases where enhancing the potential uptake of macro and micronutrients is targeted, and sprouting is suitable to enhance protein digestibility and reduce lipolysis.

Phenolic profile and antioxidant properties of sand rice (Agriophyllum squarrosum) as affected by cooking and in vitro digestion

BACKGROUND

Sand rice (Agriophyllum squarrosum) is an underutilized pseudocereal bearing edible seeds. In this study, the phenolics and antioxidant activity of sand rice seeds after cooking and in vitro digestion were extensively investigated.

RESULTS

Total phenolic content (TPC) of the sand rice seeds was slightly increased whereas total flavonoid content (TFC) decreased after boiling. Furthermore, nine compounds were detected in the uncooked seeds, with hyperoside (169.19 ± 6.59 µg g^-1 dry weight (DW)), protocatechuic acid (167.46 ± 7.21 µg g^-1 DW), and rutin (83.15 ± 3.26 µg g^-1 DW) as the major components. Apart from the bioaccessible phenolics in the aqueous fraction, these compounds retained in the solid residue of the porridge were released to varying degrees during simulated digestion. In addition, these phenolic extracts also exerted considerable antioxidant potency, which was positively correlated with their corresponding TPC, TFC, and phenolic profiles.

CONCLUSION

These results indicated that both boiling and in vitro digestive treatments could considerably enhance the release of bioactive compounds and thus contribute antioxidant properties to sand rice porridge. These findings suggest that sand rice seed is a potential functional food and an excellent natural antioxidant source. © 2019 Society of Chemical Industry.

Effect of digestion on the phenolic content and antioxidant activity of celery leaf and the antioxidant mechanism via Nrf2/HO-1 signaling pathways against Dexamethasone

The effect of digestion on the phenolic compounds and antioxidant activity of celery leaf were performed. In this work, 13 phenolic chemicals were discriminated by HPLC-MS, and content of phenolic and the antioxidant capacity were evaluated after digestion in vitro. After digestion, the content of phenols and flavonoids were increased by about 3-6-folds correlated with the average antioxidant activity (p < 0.05). It was found that the extraction of celery leaf (ET) decreased lipid peroxidation (MDA) and reactive oxygen species (ROS) level, and elevated the antioxidant activities of the liver, spleen, and thymus in Dexamethasone (Dex)-treated KM mice. Furthermore, ET increased the protein transcription of NF-E2-related factor 2 (Nrf2), hemeoxygenase-1 (HO-1) and glutathione s-transferase (GST) to against oxidation. These results suggested that ET can protect animals through the Nrf2/HO-1 signaling pathway from oxidative damage included by Dex. PRACTICAL APPLICATIONS: Celery is a daily edible vegetable with more pharmacological research focused on dietary fiber, yet fewer studies on the biological activity of small molecules, especially that in leaves. This study shows that the phenolic compounds from celery leaf have a distinct enhancement of oxidation after digestion in vitro, and the celery leaf reduces oxidative stress induced by Dex via Nrf2/HO-1 signaling pathway, indicating celery leaf or other food rich in phenolic compounds can be good source of functional food to fully use to promote the economic value. Moreover, it also provides theoretical information of celery leaf on digestion, which insinuates that food or Chinese medicine containing flavonoids, such as glycoside of apigenin or luteolin, have the similar digestion pattern, providing theoretical basis for later metabolism. Therefore, the absorption and metabolism of ET or flavonoids after digestion in body and the upstream signaling pathway activating Nrf2/HO-1, like PI3K or JNK phosphorylation, or downstream signaling pathway need further research.

Rheological properties and effects of in vitro gastrointestinal digestion on functional components and antioxidant activities of cooked yam flour

There is dearth of documented information on rheological behavior, bioaccessibility and antioxidant potential of cooked yam flour (CY). This study was carried out to evaluate rheological properties and effects of in vitro gastrointestinal digestion (GID) on functional compositions and antioxidant activities of CY. CY displayed enhanced pseudoplastic and ''gel-like" characteristics with incremental concentration (4.5-9.0%). After GID, contents of total polyphenols, flavonoids, sugar (TS), acidic polysaccharides (AP) and free amino acids (FAAs) significantly increased with maximal increment of 3.51-fold for TS followed by AP (3.05-fold), and DPPH, ABTS, FRAP and FIC assays pointed to a significant increase in antioxidant activity. Sixteen FAAs including 7 essential amino acids were detected with highest content of 9.81 mg/g for arginine. Large block remnants with a micro-porous structure were confirmed by scanning electron microscopy. Results indicate that CY with favourable swallowing performance can serve as a reliable source of bioaccessible and bioactive compounds with antioxidation.

Changes in bioaccessibility, polyphenol profile and antioxidant potential of flours obtained from persimmon fruit (Diospyros kaki) co-products during in vitro gastrointestinal digestion

The aim was to evaluate (i) the phenol and flavonoid recovery and bioaccessibility indexes, (ii) the stability of individual polyphenolic compounds and (iii) the antioxidant activity of persimmon flours (cultivars 'Rojo Brillante' and 'Triumph') during the in vitro digestion. The recovery index for phenolic and flavonoid content was dependent on flour type and digestion phase. After the dialysis phase, the bioaccessibility for phenolic compounds from both flours was similar; for flavonoids it was higher in 'Triumph' than 'Rojo Brillante' flour. After in vitro digestion, 13 polyphenolic compounds were detected in both flours, of which only six were detected in the intestinal phase. Their antioxidant activity (ABTS+, FRAP and DPPH) decreased after intestinal phase, while their chelating activity (FIC assay) increased in both flours. So, persimmon flours could be included in the formulation of foods to improve either their scarcity of bioactive compounds or an unbalanced nutritional composition.

Phytochemical analysis and biological activities of Hertia cheirifolia L. roots extracts

OBJECTIVE

To test the antioxidant, antimicrobial and α-glucosidase inhibitory activities of the roots extracts from Hertia cheirifolia (H. cheirifolia) L.

METHODS

Total phenolics and total flavonoids content of the different extracts were determined by colorimetric methods and reverse phase high-performance liquid chromatography (RP-HPLC) was performed to identify various chemical components. The different extracts were evaluated for antioxidant activities by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethylenebenzothiozoline-6-sulfonic acid (ABTS⁺) and β-carotene bleaching tests and α-glucosidase inhibitory properties. The antimicrobial activity was carried out in vitro by the broth dilution method.

RESULTS

Trans-cinnamic acid, rutin hydrate, naringin and quercetin were the main compounds of the ethyl acetate extract from H. cheirifolia L. This extract has significant scavenging activity to decrease free radicals especially for DPPH and ABTS radicals. As well as, the ethyl acetate extract exhibited an antimicrobial property against bacterial strains. Bacillus licheniformis and Salmonella enterica were the most sensitive strains with minimum inhibitory concentration values of 0.156 mg/mL.

CONCLUSION

The ethyl acetate extract was found to be selectively antioxidant and antimicrobial.