Bioconversion of polyphenols and organic acids by gut microbiota of predigested Hibiscus sabdariffa L. calyces and Agave (A. tequilana Weber) fructans assessed in a dynamic in vitro model (TIM-2) of the human colon

Biotransformation of quercetin by Bacillus subtilis and anticancer activity evaluation: in vitro and in Silico

Biotransformation of quercetin by Bacillus subtilis ATCC 23,857 yielded a major metabolite; apigenin-7-O-pentoside (A7P) and 9 other phenolic metabolites. They were elucidated by LC-ESI-TOF-MS/MS analysis. Furthermore, the cytotoxic potential of the biotransformed products was compared to their parent substrate (S) using MTT assay against 2 cancer cell lines; A549 and Caco-2. After 72 h. incubation, the BPs showed concentration-dependent cytotoxic activity against Caco-2 and A549 with IC50 equal to 0.32 and 0.78 mg/ml, respectively. Both BPs and S were safe on the normal human skin fibroblast (hFB) cell line. Molecular docking confirmed the high binding affinity of A7P towards phosphatidyl inositide 3-kinase delta (PI3Kδ) and Cathepsin B protein (CatB) expressed in lung and colorectal cancer cells compared to quercetin suggesting higher anticancer activity. The present findings suggest that the application of biotransformation techniques using bacteria as B. subtilis can enhance the biological activity of flavonoids by generating bioactive metabolites.

Personalized nutrition studies of human gut microbiome-polyphenol interactions utilizing continuous multistaged in vitro fermentation models-a narrative review

The gut microbiota, a complex community of microorganisms primarily inhabiting the human large intestine, plays a crucial role in human health. Gut dysbiosis, characterized by an imbalance in gut bacterial populations, has been increasingly recognized as a significant factor in the pathogenesis of metabolic diseases such as type 2 diabetes, inflammatory bowel disease, and colorectal cancer. Polyphenols are critical modulators of gut microbial composition and metabolism. However, the extent of polyphenol-induced modulation of the gut microbiome remains largely unexplored. In vitro models offer a convenient and ethical alternative to in vivo studies for investigating nutrient-gut microbiome interactions, facilitating easy sampling and controlled experimental conditions. Among these, continuous multistaged in vitro fermentation models, which simulate different sections of the human gastrointestinal tract (e.g., proximal colon, transverse colon, and distal colon), provide a more accurate representation of the human gut environment compared to single-batch fermentation. Various configurations of these multistaged models have been developed and widely employed in studies examining the effects of polyphenols on the gut microbiome. This review aims to summarize the different configurations of multistaged in vitro fermentation models and recent advancements in their development, highlight key aspects of experimental design, outline commonly used analytical workflows with complementary analyses, and review the restorative effects of polyphenol interventions on dysregulated gut microbiota.

An untargeted metabolomics approach applied to the study of the bioavailability and metabolism of three different bioactive plant extracts in human blood samples

Advances in the understanding of bioavailability and metabolism of bioactive compounds have been achieved primarily through targeted or semi-targeted metabolomics approaches using the hypothesis of potential metabolized compounds. The recent development of untargeted metabolomics approaches can present great advantages in this field, such as in the discovery of new metabolized compounds or to study the metabolism of compounds from multiple matrices simultaneously. Thus, this study proposes the use of an untargeted metabolomics strategy based on HPLC-ESI-QTOF-MS for the study of bioavailability and metabolism of bioactive compounds from different vegetal sources. Specifically, this study has been applied to plasma samples collected in an acute human intervention study using three matrices (Hibiscus sabdariffa, Silybum marianum and Theobroma cacao). This approach allowed the selection of those significant variables associated with exogenous metabolites derived from the consumption of bioactive compounds for their subsequent identification. As a result, 14, 25 and 3 potential metabolites associated with supplement intake were significantly detected in the plasma samples from volunteers who ingested the H. sabdariffa (HS), S. marianum (SM) and T. cacao (TC) extracts. Furthermore, Tmax values have been computed for each detected compound. The results highlight the potential of untargeted metabolomics for rapid and comprehensive analysis when working with a wide range of exogenous metabolites from different plant sources in biological samples.

Metabolic profiling of (poly)phenolic compounds in mouse urine following consumption of hull-less and purple-grain barley

The present study attempted for the first time to investigate the metabolic fate of (poly)phenolic compounds provided by a hull-less and purple grain barley genotype biofortified in anthocyanins. Balb/c mice were supplemented either with standard purified diet (SD) or whole-grain barley supplemented diet (WGB) for six weeks. Subsequently, (poly)phenolic metabolites were determined in urine samples by UPLC-MS/MS, and the principal metabolic pathways were elucidated. Thirty-nine (poly)phenolics compounds were identified in WGB which were distributed between the free (58%) and bound (42%) fractions, encompassing anthocyanins, phenolic acids, flavan-3-ols and flavones. Upon WGB intake, forty-two (poly)phenolic metabolites were identified, predominantly comprising phase-II sulphate, glucuronide, and/or methylated conjugates, along with colonic catabolites. Noteworthy metabolites included peonidin-3-O-glucuronide, peonidin-3-O-6''-O-malonylglucoside, and peonidin-3-O-glucoside among anthocyanins; hydroxyphenylpropanoic acid-O-sulphate among phenolic acids; and 5-(3',4'-dihydroxyphenyl)-γ-valerolactone-O-sulphate among flavan-3-ols. Metabolites like phenylpropionic, phenylacetic, hydroxybenzoic, and hippuric acids were found in both WGB and SD groups, with higher levels after barley consumption, indicating both endogenous and polyphenolic metabolism origins. Overall, this study offers valuable insights into the metabolism of (poly)phenols in purple barley, setting the stage for future investigations into the health benefits linked to the consumption of purple grain barley.

Bioavailability of bioactive compounds in Hibiscus sabdariffa beverage as a potential anti-inflammatory

The absorption and metabolism of bioactive compounds (BCs) in a Hibiscus sabdariffa drink (HbD) were evaluated by the in vivo bioavailability of organic acids (OA) and phenolic compounds (PC's). An acute single-blind clinical study in humans was conducted. Twelve volunteers consumed a HbD and a control drink (CD). Urine and plasma samples were taken after consuming both beverages. OA and PC's of the beverages (HbD and CD) and the biological samples (urine and plasma) were characterized by HPLC-DAD-MS. Thirthy-eight compounds in HbD and four CD were detected and quantified, equivalent to 937.37 mg and 1.22 mg per 60 mL, respectively. Hibiscus acid was the most abundant OA in both drinks. Additionally, hydroxycinnamic acids, flavonoids, anthocyanins, and anthocyanidins were also detected in HbD, although their amount represented 10% of the total BCs. 25 different metabolites were identified, 15 in urine and 23 in plasma. The microbiota extensively biotransformed PCs and their amount was lower than organic acids, particularly hibiscus acid and hydroxycitric acid. The colonic metabolites derived from PCs and organic acids would be behind the anti-inflammatory bioactivity described for Hibiscus sabdariffa L. (Malvaceae family). However, further studies are necessary to evaluate the metabolites responsible for their anti-inflammatory activity.

Plant fructans: Recent advances in metabolism, evolution aspects and applications for human health

Fructans, fructose polymers, are one of the three major reserve carbohydrate in plants. The nutritional and therapeutic benefits of natural fructans in plants have attracted increasing interest by consumers and food industry. In the course of evolution, many plants have developed the ability of regulating plant fructans metabolism to produce fructans with different structures and chain lengths, which are strongly correlated with their survival in harsh environments. Exploring these evolution-related genes in fructans biosynthesis and de novo domestication of fructans-rich plants based on genome editing is a viable and promising approach to improve human dietary quality and reduce the risk of chronic disease. These advances will greatly facilitate breeding and production of tailor-made fructans as a healthy food ingredient from wild plants such as huangjing (Polygonatum cyrtonema). The purpose of this review is to broaden our knowledge on plant fructans biosynthesis, evolution and benefits to human health.

Effects of Fermentation on Bioactivity and the Composition of Polyphenols Contained in Polyphenol-Rich Foods: A Review

Polyphenols, as common components with various functional activities in plants, have become a research hotspot. However, researchers have found that the bioavailability and bioactivity of plant polyphenols is generally low because they are usually in the form of tannins, anthocyanins and glycosides. Polyphenol-rich fermented foods (PFFs) are reported to have better bioavailability and bioactivity than polyphenol-rich foods, because polyphenols are used as substrates during food fermentation and are hydrolyzed into smaller phenolic compounds (such as quercetin, kaempferol, gallic acid, ellagic acid, etc.) with higher bioactivity and bioavailability by polyphenol-associated enzymes (PAEs, e.g., tannases, esterases, phenolic acid decarboxylases and glycosidases). Biotransformation pathways of different polyphenols by PAEs secreted by different microorganisms are different. Meanwhile, polyphenols could also promote the growth of beneficial bacteria during the fermentation process while inhibiting the growth of pathogenic bacteria. Therefore, during the fermentation of PFFs, there must be an interactive relationship between polyphenols and microorganisms. The present study is an integration and analysis of the interaction mechanism between PFFs and microorganisms and is systematically elaborated. The present study will provide some new insights to explore the bioavailability and bioactivity of polyphenol-rich foods and greater exploitation of the availability of functional components (such as polyphenols) in plant-derived foods.

Liquid submerged fermentation by selected microbial strains for onion skins valorization and its effects on polyphenols

Onion skins, actually recycled as organic fertilizers, could be used as a substrate in environmental-friendly bioprocesses to recover high-value bioactive compounds and food ingredients.In this work, a bioprospecting method was carried out including 94 bacterial and 45 yeast strains from several agri-food and environmental niches to verify their ability to grow on onion skins as unique nutrients source.Red and yellow onion skins were assessed by newly selected starter-driven liquid submerged fermentation assays mainly aimed at the release and modification of polyphenols through microbial activities. Fermented onion skins were also investigated as a inexpensive favourable source of microbial enzymes (amylases, proteases, lipases, esterases, cellulases, xylanases).In red onion skins, the treatment with Lactiplantibacillus plantarum TB 11-32 produced a slight increase of bioactive compounds in terms of total phenolics, whereas with the yeast strain Zygosaccharomyces mrakii CL 30 - 29 the quercetin aglycone content increased of about 25% of the initial raw material.In yellow onion skins inoculated, the highest content of phenolic compounds was detected with the yeast strain Saccharomyces cerevisiae En SC, while quercetin aglycone increased of about 60% of the initial raw material in presence of the bacterial strain L. plantarum C 180 - 34.In conclusion, the proposed microbial pre-treatment method can be a potential strategy to re-use onion skins as a fermentation substrate, and as a first step in the development of a biorefinery process to produce value-added products from onion by-products.

Extraction, Characterization, and Bioactivity of Phenolic Compounds-A Case on Hibiscus Genera

Phenolic compounds have recently gained interest, as they have been related to improvements in health and disease prevention, such as inflammatory intestinal pathologies and obesity. However, their bioactivity may be limited by their instability or low concentration in food matrices and along the gastrointestinal tract once consumed. This has led to the study of technological processing with the aim of optimizing phenolic compounds' biological properties. In this sense, different extraction systems have been applied to vegetable sources for the purpose of obtaining enriched phenolic extracts such as PLE, MAE, SFE, and UAE. In addition, many in vitro and in vivo studies evaluating the potential mechanisms of these compounds have also been published. This review includes a case study of the Hibiscus genera as an interesting source of phenolic compounds. The main goal of this work is to describe: (a) phenolic compound extraction by designs of experiments (DoEs) applied to conventional and advanced systems; (b) the influence of the extraction system on the phenolic composition and, consequently, on the bioactive properties of these extracts; and (c) bioaccessibility and bioactivity evaluation of Hibiscus phenolic extracts. The results have pointed out that the most used DoEs were based on response surface methodologies (RSM), mainly the Box-Behnken design (BBD) and central composite design (CCD). The chemical composition of the optimized enriched extracts showed an abundance of flavonoids, as well as anthocyanins and phenolic acids. In vitro and in vivo studies have highlighted their potent bioactivity, with particular emphasis on obesity and related disorders. This scientific evidence establishes the Hibiscus genera as an interesting source of phytochemicals with demonstrated bioactive potential for the development of functional foods. Nevertheless, future investigations are needed to evaluate the recovery of the phenolic compounds of the Hibiscus genera with remarkable bioaccessibility and bioactivity.

In Vitro Gastrointestinal Digestion Affects the Bioaccessibility of Bioactive Compounds in Hibiscus sabdariffa Beverages

Hibiscus sabdariffa possess great versatility to be used as an ingredient for a whole range of products with natural-based ingredients, which are growing in popularity due to the health benefits of bioactive compounds (BC). Therefore, the objective of this study was to characterize the BC content in Hibiscus beverages and to evaluate their in vitro bioaccessibility. Results showed significant differences (p < 0.05) in the total contents of BC prior to the in vitro intestinal digestion. Hibiscus acid was the most abundant compound identified. Thirty-five compounds were identified in the Hibiscus beverage at the initial stage, while a maximum of 15 compounds were quantified in the different fractions of gastrointestinal digestion. After digestion, significant differences were found compared with the initial content of BC. That phenolic acids were the less bioaccessible group, while flavonoids were the most diverse. Principal components analysis showed different clusters and changes in the profiles of BC present at the initial stage and those bioaccessible, showing that intestinal digestion significantly affects the BC profile of the beverage.

Evaluation of Different Advanced Approaches to Simulation of Dynamic In Vitro Digestion of Polyphenols from Different Food Matrices-A Systematic Review

Phenolic compounds have become interesting bioactive antioxidant compounds with implications for obesity, cancer and inflammatory gastrointestinal pathologies. As the influence of digestion and gut microbiota on antioxidant behavior is yet to be completely elucidated, and due to limitations associated to in vivo studies, dynamic in vitro gastrointestinal models have been promoted. A systematic review was conducted of different databases (PubMed, Web of Science and Scopus) following PRISMA guidelines to assess different dynamic digestion models and assay protocols used for phenolic compound research regarding bioaccesibility and interaction with colonic microbiota. Of 284 records identified, those including dynamic multicompartmental digestion models for the study of phenolic compound bioaccesibility, bioactivity and the effects of microbiota were included, with 57 studies meeting the inclusion criteria. Different conditions and experimental configurations as well as administered doses, sample treatments and microbiological assays of dynamic digestion studies on polyphenols were recorded and compared to establish their relevance for the dynamic in vitro digestion of phenolic compounds. While similarities were observed in certain experimental areas, a high variability was found in others, such as administered doses. A description of considerations on the study of the digestion of phenolic compounds is proposed to enhance comparability in research.

Catabolism of polyphenols released from mung bean coat and its effects on gut microbiota during in vitro simulated digestion and colonic fermentation

Mung bean coat is a good source of dietary polyphenols. In this study,in vitro simulated digestion and colonic fermentation were performed to investigate the release of polyphenols from mung bean coat and their bioactivities. Polyphenols released by colonic fermentation were much higher than those released by digestion and reached a peak at 12 h, resulting in higher antioxidant capacities (DPPH, ORAC, FRAP assays). About 49 polyphenols and metabolites including quercetin, vanillin, catechin and p-hydroxybenzoic acid were identified, and possible biotransformation pathways were postulated. Moreover, the relative abundance of beneficial bacteria (such as Lactococcus and Bacteroides) was improved during colonic fermentation. Altogether, gut microbiota could release polyphenols, the released polyphenols and their catabolic metabolites, alongside dietary fiber in mung bean coat selectively regulated the composition of gut microbiota and promoted the synthesis of SCFAs. These findings indicated that polyphenols in mung bean coat potentially contributed to gastrointestinal and colonic health.

Artificial Gastrointestinal Models for Nutraceuticals Research—Achievements and Challenges: A Practical Review

Imitating the human digestive system as closely as possible is the goal of modern science. The main reason is to find an alternative to expensive, risky and time-consuming clinical trials. Of particular interest are models that simulate the gut microbiome. This paper aims to characterize the human gut microbiome, highlight the importance of its contribution to disease, and present in vitro models that allow studying the microbiome outside the human body but under near-natural conditions. A review of studies using models SHIME, SIMGI, TIM-2, ECSIM, EnteroMix, and PolyfermS will provide an overview of the options available and the choice of a model that suits the researcher’s expectations with advantages and disadvantages.

Physiological Effects and Human Health Benefits of Hibiscus sabdariffa: A Review of Clinical Trials

Hibiscus sabdariffa Linn. Malvaceae (HS) is characterized by its edible calyxes. The HS calyxes are widely used for cosmetic, food, and medicinal applications. According to ethnobotanical evidence, decoction, infusion, or maceration extracts from HS calyxes have been used in folk medicine to treat many ailments. Moreover, several in vitro and in vivo studies have demonstrated the pharmacological properties and potential human health benefits of HS consumption. On the other hand, the evaluation of the physiological effects and health benefits of HS in clinical studies is most challenging. Therefore, this narrative review summarizes and discusses the physiological effects and health benefits of HS calyxes reported in clinical trials. Preparations obtained from HS calyxes (extracts, infusions, decoction, teas, beverages, capsules, and pills) are used as non-pharmacological therapies to prevent/control diverse chronic non-communicable diseases. The most-reported HS health benefits are its antihypertensive, antidyslipidemic, hypoglycemic, body fat mass reduction, nephroprotective, antianemic, antioxidant, anti-inflammatory, and anti-xerostomic activities; these effects are associated with the phytochemicals found in HS. Moreover, no adverse effects were reported during the clinical trials. However, clinical studies exhibited some limitations; thus, further studies are required to validate the clinical efficacy of HS in large-scale studies with higher doses and a good experimental design