The effect of simulated digestion on the composition of phenolic compounds and antioxidant activities in lychee pulp of different cultivars

Newly formed phenolics selectively bound to the graded polysaccharides of lychee pulp during heat pump drying using UPLC-ESI-QqQ-TOF-MS/MS

Our study investigated heat pump drying (HPD) effects on phenolic-polysaccharide adducts of three lychee pulp grades, their composition and bound phenolic contents. During HPD, the hexose content in water soluble polysaccharide (WSP) increased continuously, and the pentose and glucuronic acid contents in WSP and dilute alkali soluble pectin (ASP) together with the hexose content in ASP increased initially and then decreased due to polysaccharide hydrolases pectinase, polygalacturonase and cellulase. After HPD, the bound phenolic content in WSP, ASP and water unextractable polysaccharide (WUP) significantly increased. Protocatechualdehyde and 3,4-dihydroxybenzeneacetic acid were newly generated phenolics and the former combined with all the three polysaccharide grades, while the latter selectively combined with only WSP. During HPD, WSP and ASP surface structures were gradually broken and became loose, but WUP surface structure was a complete and rough sheet structure. Alkaline hydrolysis caused sparser, more porous surfaces of the three polysaccharide grades. The polyphenol selectivity could be related to substrate selectivity of endogenous oxidases and the type of phenolic compounds.

Lychee pulp phenolics fermented by mixed lactic acid bacteria strains promote the metabolism of human gut microbiota fermentation in vitro

Lychee pulp phenolics possess excellent biological activities, however, changes in phenolic substances after microbial treatments are unknown. Herein, lychee pulp was fermented by Lactobacillus plantarum, Lactobacillus rhamnosus, and a mixed strain of the two, followed by an investigation of the products' colonic fermentation. In comparison to single-strain fermentation, mixed-strain fermentation significantly increased catechin and quercetin. In addition, lychee phenolics fermented by mixed strains were more conducive to the growth of gut microbiota. The results of HPLC-DAD showed that colonic fermentation further promoted the release of lychee phenolics. There was a notable increase in the content of gallic acid and quercetin, while multiple phenolics were degraded. Quercetin-3-O-rutinose-7-O-α-L-rhamnoside (QRR) and rutin were catabolized into quercetin by gut microbiota, and 4-hydroxybenzoic acid was produced from the metabolism of QRR and procyanidin B2. Lychee phenolics fermented by mixed lactic acid bacteria were easily metabolized and transformed by gut microbiota. These findings indicate that lychee pulp fermented by mixed lactic acid bacteria possesses probiotic potential, which is of great significance for the development of functional probiotic products.

Changes of Bioactive Components and Antioxidant Capacity of Pear Ferment in Simulated Gastrointestinal Digestion In Vitro

Fruit ferment is rich in polyphenols, organic acids, enzymes, and other bioactive components, which contribute to their antioxidant ability. In this study, we investigated the effect of the simulated gastric and intestinal digestion in vitro on the total phenolic content (TPC), total flavonoid content (TFC), phenolic components content, organic acid content, protease activity, superoxide dismutase (SOD) activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (DPPH-RSA), hydroxyl (·OH) radical scavenging activity (·OH-RSA), and total reducing capacity in ‘Xuehua’ pear (Pyrus bretschneideri Rehd) ferment. The result showed that the TPC, TFC, protease activity, and phenolic components such as arbutin, protocatechuic acid, malic acid, and acetic acid showed a rising trend during the simulated gastric digestion in ‘Xuehua’ pear ferment, and these components might contribute to the increasing of ·OH-RSA and total reducing capacity. The SOD activity and epicatechin content showed an increasing trend at first and then a decreasing trend, which was likely associated with DPPH-RSA. During in vitro-simulated intestinal digestion, the majority of evaluated items reduced, except for protease activity, quercetin, and tartaric acid. The reason for the decreasing of bio-accessibility resulted from the inhibition of the digestive environment, and the transformation between substances, such as the conversion of hyperoside to quercetin. The correlation analysis indicated that the antioxidant capacity of ‘Xuehua’ pear ferment was mainly affected by its bioactive compounds and enzymes activity as well as the food matrices and digestive environment. The comparison between the digestive group with and without enzymes suggested that the simulated gastrointestinal digestion could boost the release and delay the degradation of phenolic components, flavonoids, and organic acid, protect protease and SOD activity, and stabilize DPPH-RSA, ·OH-RSA, and total reducing capacity in ‘Xuehua’ pear ferment; thus, the ‘Xuehua’ pear ferment could be considered as an easily digestible food.

Characterization of procyanidin extracts from hawthorn (Crataegus pinnatifida) in human colorectal adenocarcinoma cell line Caco-2, simulated Digestion, and fermentation identified unique and novel prebiotic properties

The health-promoting activities of procyanidin extracts from hawthorn (HPCs) are closely related to their digestive behaviors, absorption, and colonic metabolism, all of which remain unknown for now and thus hinder further exploration. This study aims to explore the dynamic changes of HPCs during in vitro digestion and fermentation, as well as their Caco-2 permeability, focusing mainly on the interaction between gut microbiota and HPCs. The results showed that the digested HPC samples had characteristic absorption peaks at 280 nm, and there were absorption peaks in the stretching vibration zone, including OH and CC on the benzene ring, which suggested that procyanidins were the main components in HPCs after in vitro digestion. Meanwhile, HPCs had the highest stability in the oral phase. However, the total procyanidin content of HPCs decreased during gastrointestinal digestion, and flavan-3-ol dimers and trimers in HPCs are partially degraded into epicatechin. Uptake of epicatechin (4.07 %), procyanidin B2 (2.15 %), and procyanidin B5 (39.44 %) through Caco-2 monolayer was also observed in HPC treatment, while there was still a large portion of procyanidins that was not absorbed. Subsequent fermentation resulted in a decrease in pH along with the production of short-chain fatty acids (SCFAs), mainly due to the degradation and utilization of HPC, as indicated by a reduction of total procyanidins. Furthermore, the HPCs modulated gut microbial populations: down-regulated the abundances of Bacteroides, Fusobacterium, Enterococcus, Parabacteroides, and Bilophila, and up-regulated Escherichia-Shigella, Klebsiella, Turicibacter, Actinobacillus, Roseburia, and Blautia. Ultimately, epicatechin and procyanidin B2, B5 and C1 were converted into phenolic acids through the metabolism of Bacteroides, Sutterella, Butyrobacter and Blautia. 4-ethylbenzoic acid, 4-hydroxyphenylpropionic acid, 3,4-dihydroxyphenyl acetic acid were confirmed as the significant metabolites in the fermentation. These results elucidated the potential mechanisms of HPCs metabolism and their beneficial effects on gut microbiota and colonic phenolic acids production.

Tackling the Future Pandemics: Broad-Spectrum Antiviral Agents (BSAAs) Based on A-Type Proanthocyanidins

A-type proanthocyanidins (PAC-As) are plant-derived natural polyphenols that occur as oligomers or polymers of flavan-3-ol monomers, such as (+)-catechin and (-)-epicatechin, connected through an unusual double A linkage. PAC-As are present in leaves, seeds, flowers, bark, and fruits of many plants, and are thought to exert protective natural roles against microbial pathogens, insects, and herbivores. Consequently, when tested in isolation, PAC-As have shown several biological effects, through antioxidant, antibacterial, immunomodulatory, and antiviral activities. PAC-As have been observed in fact to inhibit replication of many different human viruses, and both enveloped and non-enveloped DNA and RNA viruses proved sensible to their inhibitory effect. Mechanistic studies revealed that PAC-As cause reduction of infectivity of viral particles they come in contact with, as a result of their propensity to interact with virion surface capsid proteins or envelope glycoproteins essential for viral attachment and entry. As viral infections and new virus outbreaks are a major public health concern, development of effective Broad-Spectrum Antiviral Agents (BSAAs) that can be rapidly deployable even against future emerging viruses is an urgent priority. This review summarizes the antiviral activities and mechanism of action of PAC-As, and their potential to be deployed as BSAAs against present and future viral infections.

“K-Powder” Exposure during Adolescence Elicits Psychiatric Disturbances Associated with Oxidative Stress in Female Rats

Ketamine, also called ‘K-powder’ by abusers, an analog of phencyclidine, primarily acts as an antagonist of N-methyl-D-aspartic acid (NMDA) receptors, therapeutically used as an anesthetic agent. Ketamine also stimulates the limbic system, inducing hallucinations and dissociative effects. At sub-anesthetic doses, ketamine also displays hallucinatory and dissociative properties, but not loss of consciousness. These behavioral consequences have elicited its recreational use worldwide, mainly at rave parties. Ketamine is generally a drug of choice among teenagers and young adults; however, the harmful consequences of its recreational use on adolescent central nervous systems are poorly explored. Thus, the aim of the present study was to characterize the behavioral and biochemical consequences induced by one binge-like cycle of ketamine during the early withdrawal period in adolescent female rats. Adolescent female Wistar rats (n = 20) received intraperitoneally administered ketamine (10 mg/kg/day) for 3 consecutive days. Twenty-four hours after the last administration of ketamine, animals were submitted to behavioral tests in an open field, elevated plus-maze, and forced swimming test. Then, animals were intranasally anesthetized with 2% isoflurane and euthanized to collect prefrontal cortex and hippocampus to assess lipid peroxidation, antioxidant capacity against peroxyl radicals, reactive oxygen species, reduced glutathione, and brain-derived neurotrophic factor (BDNF) levels. Our results found that 24 h after recreational ketamine use, emotional behavior disabilities, such as anxiety- and depression-like profiles, were detected. In addition, spontaneous ambulation was reduced. These negative behavioral phenotypes were associated with evidence of oxidative stress on the prefrontal cortex and hippocampus.

Effect of digestion on bound phenolic content, antioxidant activity and hypoglycemic ability of insoluble dietary fibre from four Triticeae crops

To assess the physiological functions of bound phenols in insoluble dietary fiber (IDF) from different Triticeae crops, bound phenols in IDF were extracted from wheat, triticale, barley and quinoa. In addition, model in vitro was established and used in evaluating the release of bound phenols and changes in their physiological functions after simulated digestion. Results showed that bound phenol content in IDF from Triticeae crops before digestion was higher than which during digestion, and its physiological functions were also better (p < .05). Moreover, barley extracted before digestion, its bound phenolic content in IDF was higher than those in other three Triticeae crops, besides,its bound phenol also showed better antioxidant ability. Before digestion, bound phenols in IDF from triticale showed the best hypoglycemic ability (the inhibition rate of α-glucosidase was 95%; the inhibition rate of α-amylase was 97%). In the simulated digestion model, the bound phenols were mainly released during the intestinal digestion stage, they showed better physiological functions than which released at the gastric digestion stage. The bound phenol content in triticale was higher and its physiological functions was better than those in the other crops. PRACTICAL APPLICATIONS: The results of this experiment showed that the release of bound phenols measured by chemical extraction (i.e., before digestion) was higher than that by simulated gastrointestinal digestion. Compared with the chemical extraction method, in vitro gastro-intestinal digestion simulates the pH value and enzyme environment of food in the human body gastrointestinal digestion process more effectively. This study can provide reference for selecting Triticeae crops feeding in the future. To be more precise, bound phenol content in the insoluble dietary fiber of barley was the highest before digestion. The bound phenol in the insoluble dietary fiber of triticale had the best hypoglycemic ability. The bound phenolic compounds are mainly released during intestinal digestion, and their physiological functions are better than that in gastric digestion.

Functionalization of whey protein isolate fortified with blackcurrant concentrate by spray-drying and freeze-drying strategies

A solution of whey protein isolate was combined with blackcurrant concentrate via spray-drying and freeze-drying techniques separately to develop novel protein ingredients, (SWB and FWB). Chemical compositions, colour profiles, total anthocyanin content and encapsulation efficacy of the protein ingredients were evaluated. An in vitro digestion process was employed to observe the changes in total phenolic content, antioxidant activity, and predictive in vitro glycaemic response of the protein ingredients. The half maximal inhibitory concentration (IC₅₀) towards α-Amylase, and a molecular docking study on the interactions of α-Amylase with anthocyanins, were both performed to investigate the potential mechanisms of hypoglycaemic properties of these protein ingredients. The protein contents of SWB and FWB were 67.94 ± 0.47% and 68.16 ± 0.77%, respectively. Blackcurrant concentrate significantly (p < 0.001) changed the colour profiles of whey protein isolate. SWB obtained a higher total phenol content (3711.28 ± 4.36 μg/g), total anthocyanin content (85390.80 ± 162.81 μg/100 g), and greater encapsulation efficacy (99.64 ± 0.16%) than those of FWB (3413.03 ± 20.60 μg/g, 64230.24 ± 441.08 μg/100 g, and 95.43 ± 0.14%, respectively). Total phenolic content and antioxidant activities of SWB and FWB decreased after the in vitro digestion. The reducing sugar released during the in vitro digestion from SWB and FWB decreased compared with their corresponding controls (SWC and FWC). FWB (IC₅₀ = 73.46 μg/mL) exhibited stronger α-Amylase inhibitory activity than SWB (IC₅₀ = 81.46 μg/mL). Different anthocyanins differed from binding affinities to bind with the active sites of α-Amylase via formation of hydrogen bonds. This study suggested whey protein encapsulated-blackcurrant concentrate might be an innovative food product with improved nutritional profiles. Both spray- and freeze-drying are potential options to this encapsulation.

In vitro simulated digestion and colonic fermentation of lychee pulp phenolics and their impact on metabolic pathways based on fecal metabolomics of mice

Biochemical change and bioactivities of lychee pulp phenolics following simulated human digestion and in vivo metabolism in mice.

Comparative analysis of the morphological property and chemical composition of soluble and insoluble dietary fiber with bound phenolic compounds from different algae

The morphological, physicochemical, and biochemical properties of soluble and insoluble dietary fiber from seven types of algae were investigated. The soluble dietary fiber (SDF) contents (6.48 to 60.90% of the total fiber) in most of the investigated algae were significantly lower than the insoluble dietary fiber (IDF) contents (39.10 to 93.52% of the total fiber). It can be inferred from the infrared and UV-Vis spectra that the SDF and IDF of algae may contain cellulose, hemicellulose, various monosaccharides, phenolic compounds, and quinone pigments. The bound phenolic in the seven algae varied widely in contents (3.76 to 14.08 mg GAE/g in IDF and 1.94 to 8.61 mg GAE/g in SDF), whose antioxidant activities in the IDF were stronger than those in SDF because of different phenolic compositions. The HPLC-mass spectrometry (MS)/MS results showed that the IDF may contain methyl-8α-hydroxy-grindelate-7β-O-7'β-ether hydrate, hydroxydecanoic acid, and malyngic acid. PRACTICAL APPLICATION: Polysaccharides of high content in algae cannot be digested by humans, hence regarded as dietary fibers. A large amount of bound phenolic compounds in dietary fibers can add to the biological activities of dietary fibers. These topics are important to the development of seaweed-based functional foods.