Absorption and metabolism of proanthocyanidins

Hydroethanolic extracts from Bauhinia guianensis: a study on acute toxicity in Zebrafish embryos and adults

CONTEXT

The botanical species Bauhinia guianensis Aublet (Leguminosae-Cercidoideae) is traditionally used in the Amazon for medicinal purposes.

OBJECTIVE

The acute toxicity of the hydroethanolic extracts from B. guianensis leaves and stems (HELBg and HESBg) was evaluated in zebrafish (Danio rerio), with emphasis on the embryonic developmental stage and adult alterations.

MATERIALS AND METHODS

Extracts were analyzed on LC-DAD-MS/MS. Zebrafish eggs were inoculated individually with concentrations of HELBg and HESBg (0.25, 0.5, 0.75, 1.0, and 1.5 µg/mL), observed for 96 h. Adult zebrafish were treated with a single oral dose (100, 200, 500, 1000, and 2000 mg/kg) of HELBg and HESBg, observed for 48 h.

RESULTS

HELBg and HESBg analysis detected 55 compounds. Both extracts exhibited toxicity, including embryo coagulation at higher doses of HELBg and absence of heartbeats in embryos at all doses of HESBg. Behavioral variations were observed; tissue alterations in adult zebrafish were found at the highest doses, primarily in the liver, intestine, and kidneys because of HELBg and HESBg effects. The LD50 of HESBg was 1717 mg/kg, while HELBg exceeded the limit dose of 2000 mg/kg.

CONCLUSIONS

The study on acute toxicity of B. guianensis extracts exhibits significant toxic potential, emphasizing effects on embryonic and adult zebrafish. The results suggest relative safety of the species preparations, encouraging further clinical trials on potential biological activities.

Procyanidine alleviates bisphenol A-induced apoptosis in TM3 cells via the Nrf2 signaling pathway

Contaminated foods are a major source of bisphenol A (BPA) and are widely used in food packaging. Prolonged exposure to BPA can cause reproductive dysfunction in humans. Procyanidine (PC) is a potent natural antioxidant; however, the exact mechanism by which PC mitigates Leydig cell damage caused by BPA is unknown. In this study, the protective effect of PC against BPA-induced TM3 cell damage was investigated, and the underlying mechanism was assessed. PC treatment attenuates BPA-induced TM3 cell damage by suppressing oxidative stress and inhibiting TM3 apoptosis. In addition, PC upregulates the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream antioxidant target genes. Treatment with the NRF2 inhibitor ML385 reversed the PC-induced upregulation of the mRNA expression of these genes. Overall, PC may mitigate BPA-induced cell damage by activating the Nrf2 signaling pathway, suggesting that PC supplementation may alleviate BPA toxicity in TM3 cells.

Apple polyphenols prevent patulin-induced intestinal damage by modulating the gut microbiota and metabolism of the gut-liver axis

Patulin (PAT), a foodborne toxin, causes severe intestinal damage. To mitigate this health threat, mice were pretreated with apple polyphenols (AP) in their drinking water (0.01 % and 0.05 %) for eight weeks, followed by exposure to PAT during the last two weeks. Subsequently, histopathological and biochemical evaluations of intestinal tissues were conducted, alongside assessments of alterations in gut microbiota, colonic content metabolome, and hepatic metabolome. Consequently, AP alleviated PAT-induced villus and crypt injury, mucus depletion, GSH level decline, GSH-Px and SOD activity reduction, and MPO activity elevation. Notably, AP counteracted PAT-mediated microbiota disruptions and promoted the abundance of beneficial bacteria (Dubosiella, Akkermansia, Lachnospiraceae, and Lactobacillus). Furthermore, AP counteracted PAT-induced metabolic disorders in the colonic contents and liver. Ultimately, AP prevented intestinal injury by regulating the gut microbiota and amino acid, purine, butanoate, and glycerophospholipid metabolism in the gut-liver axis. These results underscore the potential of AP to prevent foodborne toxin-induced intestinal damage.

Cocoa and Polyphenol-Rich Cocoa Fractions Fail to Improve Acute Colonic Inflammation in Dextran Sulfate Sodium-Treated Mice

SCOPE

A study is conducted to determine the anti-inflammatory effects of cocoa and polyphenol-rich cocoa fractions in the dextran sulfate sodium (DSS)-induced mouse model of acute colonic inflammation.

METHODS AND RESULTS

Male C57BL/6J mice are treated with dietary cocoa powder, an extractable cocoa polyphenol fraction, or a non-extractable cocoa polyphenol fraction for 2 weeks prior to treatment with 2.5% DSS in the drinking water for 7 days to induce colonic inflammation. Cocoa treatment continues during the DSS period. Cocoa and/or cocoa fractions exacerbate DSS-induced weight loss and fail to mitigate DSS-induced colon shortening but do improve splenomegaly. Cocoa/cocoa fraction treatment fails to mitigate DSS-induced mRNA and protein markers of inflammation. Principal component analysis shows overlap between cocoa or cocoa fraction-treated mice and DSS-induced controls, but separation from mice not treated with DSS.

CONCLUSION

The results suggest cocoa and cocoa polyphenols may not be useful in mitigating acute colonic inflammation.

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.

Influence of fecal fermentation on the anthelmintic activity of proanthocyanidins and ellagitannins against human intestinal nematodes and Caenorhabditis elegans

Some tannin-rich plants such as Combretum mucronatum and Phyllanthus urinaria are widely used in Africa for the control of parasitic nematodes in both humans and livestock. Tannins have been recognized as an alternative source of anthelmintic therapies, and hence, recent studies have focused on both the hydrolyzable and condensed tannins. These groups of compounds, however, have poor oral bioavailability and are metabolized by gut microbiota into lower molecular weight compounds. The role of these metabolites in the anthelmintic activities of tannins has not been explored yet. This study investigated the effects of fecal metabolism on the anthelmintic potential of procyanidin C1 (PC1) and geraniin and the tannin-enriched extracts of C. mucronatum (CML) and P. urinaria (PUH), which contain these compounds, respectively. Metabolites were formed by anaerobic fermentation of the test compounds and extracts in a fresh human fecal suspension for 0 h, 4 h, and 24 h. Lyophilized samples were tested in vitro against hookworm larvae and whipworm (Trichuris trichiura) larvae obtained from naturally infected human populations in Pru West District, Bono East Region, Ghana, and against the wildtype strain of Caenorhabditis elegans (L4). Both extracts and compounds in the undegraded state exhibited concentration-dependent inhibition of the three nematodes. Their activity, however, significantly decreased upon fecal metabolism. Without fermentation, the proanthocyanidin-rich CML extract was lethal against hookworm L3 (LC50 = 343.5 μg/mL, 95% confidence interval (CI) = 267.5-445.4), T. trichiura L1 (LC50 = 230.1 μg/mL, CI = 198.9-271.2), and C. elegans (LC50 = 1468.1 μg/mL, CI = 990.3-1946.5). PUH, from which the ellagitannin geraniin was isolated, exhibited anthelmintic effects in the unfermented form with LC50 of 300.8 μg/mL (CI = 245.1-374.8) against hookworm L3 and LC50 of 331.6 μg/mL (CI = 290.3-382.5) against T. trichiura L1, but it showed no significant activity against C. elegans L4 larvae at the tested concentrations. Similarly, both compounds, procyanidin C1 and geraniin, lost their activity when metabolized in fecal matter. The activity of geraniin at a concentration of 170 μg/mL against C. elegans significantly declined from 30.4% ± 1.8% to 14.5% ± 1.5% when metabolized for 4 h, whereas that of PC1 decreased from 32.4% ± 2.3% to 8.9% ± 0.9% with similar treatment. There was no significant difference between the anthelmintic actions of metabolites from the structurally different tannin groups. The outcome of this study revealed that the intact bulky structure of tannins (hydrolyzable or condensed) may be required for their anthelmintic action. The fermented products from the gut may not directly contribute toward the inhibition of the larvae of soil-transmitted helminths.

Room-Temperature Cascade Electrophilic Addition/Cyclization/Oxidation Reactions: Divergent Selective Synthesis of Brominated 2H-Chromenes, 2H-Chromen-2-ols and 2H-Chromen-2-ones

The room temperature metal-free cascade electrophilic addition/cyclization/oxidation reactions of (3-phenoxyprop-1-yn-1-yl)benzenes to divergently synthesize various brominated benzopyran derivatives (3-bromo-2H-chromenes, 3-bromo-2H-chromen-2-ols and 3-bromo coumarins) by tuning the amount of Br2 and H2O have been developed. The method exhibited high selectivity, mild reaction conditions, broad substrate scope, high efficiency, and the applicability for derivatization of the brominated products. The importance of the strategies provides a great advantage for selective synthesis of brominated benzopyran derivatives.

A-type proanthocyanidins: Sources, structure, bioactivity, processing, nutrition, and potential applications

A-type proanthocyanidins (PAs) are a subgroup of PAs that differ from B-type PAs by the presence of an ether bond between two consecutive constitutive units. This additional C-O-C bond gives them a more stable and hydrophobic character. They are of increasing interest due to their potential multiple nutritional effects with low toxicity in food processing and supplement development. They have been identified in several plants. However, the role of A-type PAs, especially their complex polymeric form (degree of polymerization and linkage), has not been specifically discussed and explored. Therefore, recent advances in the physicochemical and structural changes of A-type PAs and their functional properties during extraction, processing, and storing are evaluated. In addition, discussions on the sources, structures, bioactivities, potential applications in the food industry, and future research trends of their derivatives are highlighted. Litchis, cranberries, avocados, and persimmons are all favorable plant sources. Α-type PAs contribute directly or indirectly to human nutrition via the regulation of different degrees of polymerization and bonding types. Thermal processing could have a negative impact on the amount and structure of A-type PAs in the food matrix. More attention should be focused on nonthermal technologies that could better preserve their architecture and structure. The diversity and complexity of these compounds, as well as the difficulty in isolating and purifying natural A-type PAs, remain obstacles to their further applications. A-type PAs have received widespread acceptance and attention in the food industry but have not yet achieved their maximum potential for the future of food. Further research and development are therefore needed.

Glucose-modified BSA/procyanidin C1 NPs penetrate the blood-brain barrier and alleviate neuroinflammation in Alzheimer's disease models

Alzheimer's disease (AD) is a chronic neurodegenerative disease with high prevalence, long duration and poor prognosis. The blood-brain barrier (BBB) is a physiologic barrier in the central nervous system, which hinders the entry of most drugs into the brain from the blood, thus affecting the efficacy of drugs for AD. Natural products are recognized as one of the promising and unique therapeutic approaches to treat AD. To improve the efficiency and therapeutic effect of the drug across the BBB, a natural polyphenolic compound, procyanidin C-1 (C1) was encapsulated in glucose-functionalized bovine serum albumin (BSA) nanoparticles to construct Glu-BSA/C1 NPs in our study. Glu-BSA/C1 NPs exhibited good stability, slow release, biocompatibility and antioxidant properties. In addition, Glu-BSA/C1 NPs penetrated the BBB, accumulated in the brain by targeting Glut1, and maintained the BBB integrity both in vitro and in vivo. Moreover, Glu-BSA/C1 NPs alleviated memory impairment of 5 × FAD mice by reducing Aβ deposition and Tau phosphorylation and promoting neurogenesis. Mechanistically, Glu-BSA/C1 NPs significantly activated the PI3K/AKT pathway and inhibited the NLRP3/Caspase-1/IL-1β pathway thereby suppressing neuroinflammation. Taken together, Glu-BSA/C1 NPs could penetrate the BBB and mitigate neuroinflammation in AD, which provides a new therapeutic approach targeting AD.

Bioavailability and mechanisms of dietary polyphenols affected by non-thermal processing technology in fruits and vegetables

Plant polyphenols play an essential role in human health. The bioactivity of polyphenols depends not only on their content but also on their bioavailability in food. The processing techniques, especially non-thermal processing, improve the retention and bioavailability of polyphenolic substances. However, there are limited studies summarizing the relationship between non-thermal processing, the bioavailability of polyphenols, and potential mechanisms. This review aims to summarize the effects of non-thermal processing techniques on the content and bioavailability of polyphenols in fruits and vegetables. Importantly, the disruption of cell walls and membranes, the inhibition of enzyme activities, free radical reactions, plant stress responses, and interactions of polyphenols with the food matrix caused by non-thermal processing are described. This study aims to enhance understanding of the significance of non-thermal processing technology in preserving the nutritional properties of dietary polyphenols in plant-based foods. It also offers theoretical support for the contribution of non-thermal processing technology in improving food nutrition.

Intestinal Microbiome Metabolism of Cranberry (Vaccinium macrocarpon) Proanthocyanidin Dimers, but Not Trimers, Is Altered by Dysbiosis in Ulcerative Colitis Ex Vivo

Cranberries contain proanthocyanidins with different interflavan bond types and degrees of polymerization. These chemical differences may impact the metabolism of proanthocyanidins by the intestinal microbiome. In our previous study, we found that healthy microbiomes produced higher concentrations of the phenolic acid metabolites 5-(3',4'-dihydroxyphenyl)-g-valerolactone and 3-hydroxyphenylacetic acid from the cranberry extract in comparison to ulcerative colitis (UC) microbiomes ex vivo. To understand this difference, LC-ESI-MS/MS was utilized to characterize the metabolism of the precursor proanthocyanidins. Healthy microbiomes metabolized procyanidin A2, procyanidin B2, and procyanidin dimeric intermediates but not A-type trimers, to a greater extent than UC microbiomes. The metabolism of procyanidin A2 and procyanidin B2 by fecal microorganisms was then compared to identify their derived phenolic acid metabolites. 5-(3',4'-Dihydroxyphenyl)-g-valerolactone and 3-hydroxyphenylacetic acid were identified as unique metabolites of procyanidin B2. Based on these results, the metabolism of procyanidin B2 contributed to the differential metabolism observed between healthy and UC microbiomes.

Investigation of peanut allergen-procyanidin non-covalent interactions: Impact on protein structure and in vitro allergenicity

Interactions between plant polyphenols and food allergens may be a new way to alleviate food allergies. The non-covalent interactions between the major allergen from peanut (Ara h 2) with procyanidin dimer (PA2) were therefore characterized using spectroscopic, thermodynamic, and molecular simulation analyses. The main interaction between the Ara h 2 and PA2 was hydrogen bonding. PA2 statically quenched the intrinsic fluorescence intensity and altered the conformation of the Ara h 2, leading to a more disordered polypeptide structure with a lower surface hydrophobicity. In addition, the in vitro allergenicity of the Ara h 2-PA2 complex was investigated using enzyme-linked immunosorbent assay (ELISA) kits. The immunoglobulin E (IgE) binding capacity of Ara h 2, as well as the release of allergenic cytokines, decreased after interacting with PA2. When the ratio of Ara h 2-to-PA2 was 1:50, the IgE binding capacity was reduced by around 43 %. This study provides valuable insights into the non-covalent interactions between Ara h 2 and PA2, as well as the potential mechanism of action of the anti-allergic reaction caused by binding of the polyphenols to the allergens.

The Use of Fruit and Vegetable by-Products as Enhancers of Health Status of Piglets after Weaning: The Role of Bioactive Compounds from Apple and Carrot Industrial Wastes

At weaning, piglets are exposed to a large variety of stressors, from environmental/behavioral factors to nutritional stress. Weaning transition affects the gastrointestinal tract especially, resulting in specific disturbances at the level of intestinal morphology, barrier function and integrity, mucosal immunity and gut microbiota. All these alterations are associated with intestinal inflammation, oxidative stress and perturbation of intracellular signaling pathways. The nutritional management of the weaning period aims to achieve the reinforcement of intestinal integrity and functioning to positively modulate the intestinal immunity and that of the gut microbiota and to enhance the health status of piglets. That is why the current research is focused on the raw materials rich in phytochemicals which could positively modulate animal health. The composition analysis of fruit, vegetable and their by-products showed that identified phytochemicals could act as bioactive compounds, which can be used as modulators of weaning-induced disturbances in piglets. This review describes nutritional studies which investigated the effects of bioactive compounds derived from fruit (apple) and vegetables (carrot) or their by-products on the intestinal architecture and function, inflammatory processes and oxidative stress at the intestinal level. Data on the associated signaling pathways and on the microbiota modulation by bioactive compounds from these by-products are also presented.

The regulatory role of MdNAC14-Like in anthocyanin synthesis and proanthocyanidin accumulation in red-fleshed apples

Flavonoids, such as anthocyanins and proanthocyanidins (PAs), play essential roles in plant growth, development, and stress response. Red-fleshed apples represent a valuable germplasm resource with high flavonoid content. Understanding and enriching the regulatory network controlling flavonoid synthesis in red-fleshed apples holds significant importance for cultivating high-quality fruits. In this study, we successfully isolated an NAC transcription factor, MdNAC14-Like, which exhibited a significant negative correlation with the content of anthocyanin. Transient injection of apple fruit and stable expression of callus confirmed that MdNAC14-Like acts as an inhibitor of anthocyanin synthesis. Through yeast monohybrid, electrophoretic mobility shift, and luciferase reporter assays, we demonstrated the ability of MdNAC14-Like to bind to the promoters of MdMYB9, MdMYB10, and MdUFGT, thus inhibiting their transcriptional activity and subsequently suppressing anthocyanin synthesis. Furthermore, our investigation revealed that MdNAC14-Like interacts with MdMYB12, enhancing the transcriptional activation of MdMYB12 on the downstream structural gene MdLAR, thereby promoting PA synthesis. This comprehensive functional characterization of MdNAC14-Like provides valuable insights into the intricate regulatory network governing anthocyanin and PA synthesis in apple.

Antinutrients and metabolomic compounds of Bambara groundnut (Vigna subterranean) as affected by traditional processing by smallholder farmers

Bambara groundnut (BG) (Vigna subterranean) is an underutilized, indigenous crop in South Africa that has nutritional and associated health benefits. Decreasing the antinutrients in food sources can potentially increase the digestibility of proteins and mineral absorption. To determine the effect of traditional processing (cooking) on the antinutrient content and metabolome of this crop, BG was sampled from 12 rural farms in three districts of the Mpumalanga province, South Africa. The four main colors that were identified (cream, orange, brown, and purple) were pooled together according to the district they were obtained from. One-half of each color sample obtained from each of the three districts was dehulled, color sorted, milled, and subjected to subsequent antinutrient and metabolome analyses, while the other half was cooked, air-dried, and milled prior to analyses. Samples were analyzed for phytate and tannins (antinutrients) by hydrochloric acid extraction methods as well as metabolome constituents by ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). Phytate, tannins, as well as other metabolomic constituents, namely, catechin, epicatechin, procyanidin, as well as citric acid, were identified in all raw and cooked BG samples. The cooking process resulted in a significant decrease (p < 0.05) in the phytate and tannin content as well as an increase in the health-associated phenolic compounds.

Ultrasonic-assisted nanoencapsulation of kiwi leaves proanthocyanidins in liposome delivery system for enhanced biostability and bioavailability

The poor biostability and bioavailability of proanthocyanidins limit their application. In this study, it was hypothesized that encapsulation in lecithin-based nanoliposomes using ultrasonic technology improves the above properties. Based on preliminary experiments, the effects of lecithin mass ratio (1-9%, wt.), pH (3.2-6.8), ultrasonic power (0-540 W), and time (0-10 min) on biostability and bioavailability of purified kiwi leaves proanthocyanidins (PKLPs) were determined. Nanoliposomes prepared optimally with lecithin (5%, wt.), pH = 3.2, ultrasonic power (270 W), and time (5 min) demonstrated a significantly (p < 0.05) improved physicochemical stability, homogeneity, and high encapsulation efficiency (73.84%) relative to control. The PKLPs bioaccessibility during in vitro digestion increased by 2.28-3.07-fold, with a remarkable sustained release and delivery to the small intestine. Similar results were obtained by in vivo analyses, showing over 200% increase in PKLPs bioaccessibility compared to the control. Thus, PKLPs-loaded nanoliposomes are promising candidates for foods and supplements for novel applications.

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.

Boosting the Antioxidant Potential of Polymeric Proanthocyanidins in Litchi (Litchi chinensis Sonn.) Pericarp via Biotransformation of Utilizing Lactobacillus Plantarum

In order to enhance the efficient utilization of polymeric proanthocyanidins from litchi pericarp, a process for transforming litchis' polymeric proanthocyanidins (LPPCs) by using Lactobacilli has been established for products with highly antioxidative properties. Lactobacillus plantarum was selected to enhance the transformation effect. The transformation rate of LPPCs reached 78.36%. The content of litchis' oligomeric proanthocyanidins (LOPCs) in the products achieved 302.84 μg grape seed proanthocyanidins (GPS)/mg DW, while that of total phenols was 1077.93 gallic acid equivalents (GAE) μg/mg DW. Seven kinds of substances have been identified in the products by using the HPLC-QTOF-MS/MS method, among which 4-hydroxycinnamic acid, 3,4-dihydroxy-cinnamic acid, and proanthocyanidin A2 were major components. The in vitro antioxidative activity of the products after transformation was significantly (p < 0.05) higher than those of LOPCs and LPPCs. The scavenging activity of the transformed products for DPPH free radicals was 1.71 times that of LOPCs. The rate of inhibiting conjugated diene hydroperoxides (CD-POV) was 2.0 times that of LPPCs. The scavenging activity of the products for ABTS free radicals was 11.5 times that of LPPCs. The ORAC value of the products was 4.13 times that of LPPCs. In general, this study realizes the transformation of polymeric proanthocyanidins into high-activity small-molecule substances.

Magnetic nanometer combined with microwave: Novel rapid thawing promotes phenolics release in frozen-storage lychee

Magnetic nanometer combined with microwave thawing (MN-MT) could become a novel solution to challenges uneven and overheating of microwave thawing (MT), while retaining high thawing efficiency, compared to conventional water immersion thawing (WT). In this study, MN-MT was applied to thaw fruit (lychee as an example) for the first time, and was evaluated by comparison with WT, MT and water immersion combined with microwave thawing (WI-MT). Results showed that MN-MT could significantly shorten the thawing time of frozen lychee by 80.67%, 25.86% and 18.83% compared to WT, MT and WI-MT, respectively. Compared to WT, MN-MT was the only thawing treatment which significantly enhanced the release of quercetin-3-O-rutinose-7-O-α-l-rhamnoside, according to HPLC-DAD. Meanwhile, thermal-sensitive procyanidin B2, phenylpropionic acid and protocatechuic acid were found to be protected from degradations only by MN-MT based on UPLC-ESI-QTOF-MS/MS results. In summary, MN-MT is a potential novel treatment for rapid thawing and quality maintenance of frozen fruits.

Accounting Gut Microbiota as the Mediator of Beneficial Effects of Dietary (Poly)phenols on Skeletal Muscle in Aging

Sarcopenia, the age-related loss of muscle mass and function increasing the risk of disability and adverse outcomes in older people, is substantially influenced by dietary habits. Several studies from animal models of aging and muscle wasting indicate that the intake of specific polyphenol compounds can be associated with myoprotective effects, and improvements in muscle strength and performance. Such findings have also been confirmed in a smaller number of human studies. However, in the gut lumen, dietary polyphenols undergo extensive biotransformation by gut microbiota into a wide range of bioactive compounds, which substantially contribute to bioactivity on skeletal muscle. Thus, the beneficial effects of polyphenols may consistently vary across individuals, depending on the composition and metabolic functionality of gut bacterial communities. The understanding of such variability has recently been improved. For example, resveratrol and urolithin interaction with the microbiota can produce different biological effects according to the microbiota metabotype. In older individuals, the gut microbiota is frequently characterized by dysbiosis, overrepresentation of opportunistic pathogens, and increased inter-individual variability, which may contribute to increasing the variability of biological actions of phenolic compounds at the skeletal muscle level. These interactions should be taken into great consideration for designing effective nutritional strategies to counteract sarcopenia.

Proanthocyanins and anthocyanins in chestnut (Castanea mollissima) shell extracts: biotransformation in the simulated gastrointestinal model and interaction with gut microbiota in vitro

BACKGROUND

Chestnut (Castanea mollissima) shell is rich in flavonoids and our previous studies showed that proanthocyanins and anthocyanins were the two markedly varied flavonoids in chestnut shell extracts (CSE) during digestion. Here, the biotransformation of proanthocyanins and anthocyanins in a simulated gastrointestinal model, and the interactions between non-absorption CSE (NACSE) and gut microbiota in vitro, were investigated by ultra-high-performance liquid chromatography combined with triple-quadrupole mass spectrometry and 16S rRNA sequencing.

RESULTS

Chestnut shell was richer in proanthocyanins and anthocyanins, while the loss of proanthocyanins was greater after digestion. Additionally, the content of anthocyanin decreased after gastric digestion but increased after intestinal digestion and remained stable after fermentation. After fermentation, delphinidin-3-O-sambubioside and pelargonidin-3-O-galactoside were newly formed. Furthermore, microbiome profiling indicated that NACSE promoted the proliferation of beneficial bacteria, while inhibiting pathogenic bacteria.

CONCLUSION

All these data suggest that CSE may be a promising candidate to protect gut health. © 2023 Society of Chemical Industry.

Investigation of bovine β-lactoglobulin-procyanidin complexes interactions and its utilization in O/W emulsion

Procyanidins are bioactive polyphenols that have a strong affinity to proteins. Beta-lactoglobulin (BLG) is widely used as an emulsifier in the food and other industries. This study evaluated the interaction between BLG and A-type procyanidin dimer (PA2) using the spectroscopic, thermodynamic, and molecular simulation. PA2 decreased the transmissivity and quenched the intrinsic fluorescence of BLG, suggesting that the two molecules formed a complex. The binding of PA2 reduced the surface hydrophobicity and altered the conformation of BLG with increasing the random coil regions. Thermodynamic and isothermal titration calorimetry analyses suggested that the main driving force of PA2-BLG interaction was hydrophobic attraction. Molecular docking simulations were used to identify the main interaction sites and forces in the BLG-PA2 complexes, which again indicated that hydrophobic interactions dominated. In addition, the influence of PA2 on the ability of BLG to form and stabilize O/W emulsions was analyzed. Emulsions formulated using BLG-PA2 complexes contained relatively small droplets (D_4,3 ≈ 0.7 μm) and high surface potentials (absolute value >50 mV). Compared to BLG alone, BLG-PA2 complexes improved the storage stability of the emulsions. This study provides valuable new insights into the formation, properties, and application of protein-polyphenol complexes as functional ingredients in foods.

Chemical Characterization and Antioxidant Activity of Nine Hypericum Species from Greece

Hypericum L. comprises about 500 species distributed almost worldwide. Research has mainly focused on H. perforatum with confirmed biological activity on the alleviation of depression symptoms, among others. The compounds responsible for such activity are considered naphthodianthrones and acylphloroglucinols. Other Hypericum species are less studied or not studied, and further research is needed to complete the characterization of the genus. In this study we evaluated the qualitative and quantitative phytochemical profile of nine Hypericum species native to Greece, namely H. perforatum, H. tetrapterum, H. perfoliatum, H. rumeliacum subsp. apollinis, H. vesiculosum, H. cycladicum, H. fragile, H. olympicum and H. delphicum. Qualitative analysis was performed using the LC/Q-TOF/HRMS technique, while quantitative data were calculated with the single point external standard method. Additionally, we estimated the antioxidant activity of the extracts using DPPH and ABTS assays. Three species endemic to Greece (H. cycladicum, H. fragile, H. delphicum) were studied for the first time. Our results indicated that all studied species are rich in secondary metabolites, mainly of the flavonoids family, with strong antioxidant activity.

Blueberry stem extract and stem active components prevent blue light-emitting diode light-induced retinal photoreceptor cell damage in vitro

Blue light causes retinal damage that can lead to ocular diseases such as age-related macular degeneration. In this study, we determined the protective effect of blueberry stem extract (BStEx) and active components on blue light-emitting diode (LED) light-induced retinal photoreceptor cell damage in vitro. Photoreceptor cells cultured in the presence of BStEx or components were exposed to blue light to induce cell damage. BStEx, fractions of BStEx containing proanthocyanidins, chlorogenic acid, catechin, and epicatechin prevented the cell damage and/or inhibited the generation of reactive oxygen species (ROS). Furthermore, BStEx reduced apoptosis and cell death, and inhibited the phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase leading to cellular apoptosis induced by blue light exposure. These findings suggest that BStEx and components exert a protective effect against blue light-induced photoreceptor cell damage through the inhibition of MAPK phosphorylation and ROS production.

Coupling Hydrophilic Interaction Chromatography and Reverse-Phase Chromatography for Improved Direct Analysis of Grape Seed Proanthocyanidins

Acid-catalyzed depolymerization is recognized as the most practical method for analyzing subunit composition and the polymerization degree of proanthocyanidins, involving purification by removing free flavan-3-ols, as well as acid-catalyzed cleavage and the identification of cleavage products. However, after the removal of proanthocyanidins with low molecular weights during purification, the formation of anthocyanidins from the extension subunits accompanying acid-catalyzed cleavage occurred. Thus, grape seed extract other than purified proanthocyanidins was applied to acid-catalyzed depolymerization. Hydrophilic interaction chromatography was developed to quantify free flavan-3-ols in grape seed extract to distinguish them from flavan-3-ols from terminal subunits of proanthocyanidins. Reverse-phase chromatography was used to analyze anthocyanidins and cleavage products at 550 and 280 nm, respectively. It is found that the defects of the recognized method did not influence the results of the subunit composition, but both altered the mean degree of polymerization. The established method was able to directly analyze proanthocyanidins in grape seed extract for higher accuracy and speed than the recognized method.

Hepatotoxicity of polymeric proanthocyanidins is caused by translocation of bacterial lipopolysaccharides through impaired gut epithelium

Polymeric proanthocyanidins (P-PAC) induced hepatotoxicity in C57BL/6 mice. Mice were supplemented with P-PAC alone or with a mixture of probiotic bacteria (PB), Lactobacillus, Bifidobacterium, and Akkermansia muciniphila for 14 consecutive days. The liver tissues of sacrificed mice were analyzed by mass spectrometry to identify and quantify the P-PAC metabolites. Potential P-PAC metabolites, 2-hydroxyphenylacetic acid and pyrocatechol were detected in higher concentrations and 4-hydroxybenzoic acid was detected exclusively in the mice supplemented with P-PAC and PB. Supplementation with P-PAC alone or with PB caused no shift in the α-diversity of mice gut microbiota. P-PAC induced nonalcoholic steatohepatitis in mice through increasing liver exposure to intestinal bacterial lipopolysaccharides by reducing expression of gut epithelial tight junction proteins, claudin-3 and occludin. Lipopolysaccharide concentrations in the livers of mice supplemented with P-PAC were significantly high compared to the control mice. Furthermore, P-PAC downregulated the expressions of claudin-3 and claudin-4 tight junction proteins in cultured Caco-2 cell monolayers. PB biotransformed P-PAC into bioavailable metabolites and potentially reduced the toxicity of P-PAC. The toxicity of P-PAC and their synbiotics need to be critically evaluated for the safety of human consumption.

Proanthocyanidins: Impact on Gut Microbiota and Intestinal Action Mechanisms in the Prevention and Treatment of Metabolic Syndrome

The metabolic syndrome (MS) is a cluster of risk factors, such as central obesity, hyperglycemia, dyslipidemia, and arterial hypertension, which increase the probability of causing premature mortality. The consumption of high-fat diets (HFD) is a major driver of the rising incidence of MS. In fact, the altered interplay between HFD, microbiome, and the intestinal barrier is being considered as a possible origin of MS. Consumption of proanthocyanidins (PAs) has a beneficial effect against the metabolic disturbances in MS. However, there are no conclusive results in the literature about the efficacy of PAs in improving MS. This review allows a comprehensive validation of the diverse effects of the PAs on the intestinal dysfunction in HFD-induced MS, differentiating between preventive and therapeutic actions. Special emphasis is placed on the impact of PAs on the gut microbiota, providing a system to facilitate comparison between the studies. PAs can modulate the microbiome toward a healthy profile and strength barrier integrity. Nevertheless, to date, published clinical trials to verify preclinical findings are scarce. Finally, the preventive consumption of PAs in MS-associated dysbiosis and intestinal dysfunction induced by HFD seems more successful than the treatment strategy.

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.

A label-free LC/MS-based enzymatic activity assay for the detection of PDE5A inhibitors

Phosphodiesterase type 5 (PDE5), a cyclic nucleotide phosphodiesterase, controls the duration of the cyclic guanosine monophosphate (cGMP) signal by hydrolyzing cGMP to GMP. Inhibiting the activity of PDE5A has proven to be an effective strategy for treating pulmonary arterial hypertension and erectile dysfunction. Current enzymatic activity assay methods for PDE5A mainly use fluorescent or isotope-labeled substrates, which are expensive and inconvenient. Here, we developed an LC/MS-based enzymatic activity assay for PDE5A without labeling, which detects the enzymatic activity of PDE5A by quantifying the substrate cGMP and product GMP at a concentration of 100 nM. The accuracy of this method was verified by a fluorescently labeled substrate. Moreover, a new inhibitor of PDE5A was identified by this method and virtual screening. It inhibited PDE5A with an IC₅₀ value of 870 nM. Overall, the proposed strategy provides a new method for screening PDE5A inhibitors.

Enhanced peroxidase-like activity of 2(3), 9(10), 16(17), 23(24)-octamethoxyphthalocyanine modified CoFe LDH for a sensor array for reducing substances with catechol structure

Improving the catalytic activity of artificial nanozymes to realize the real-time detection of small molecules becomes an important task. Herein, a highly active nanozyme, 2(3), 9(10), 16(17), 23(24)-octamethoxyphthalocyanine (Pc(OH)₈) modified CoFe LDH microspheres (Pc(OH)₈-CoFe LDH) have been prepared by the two-step hydrothermal method. The 3,3',5,5'-tetramylbenzidine (TMB), a chromogenic substrate, was fast oxidized into blue oxTMB by H₂O₂ in the presence of Pc(OH)₈-CoFe LDH, indicating that Pc(OH)₈-CoFe LDH possesses high peroxidase-like activity rather than pure CoFe LDH. The enhancement peroxidase-like activity of the Pc(OH)₈-CoFe LDH is ascribed to the synergistic action between Pc(OH)₈ and CoFe LDH. Experimental results of radical scavenger and fluorescence probe verify that superoxide radical (•O₂^-) plays an important role during the catalytic reaction. Interestingly, the absorption intensity of reaction system has been enhanced largely, due to adding of the reducing substances containing catechol structure. Based on this, the three reducing substances (dopamine, procyanidin B2, catechins) containing catechol structure were distinguished from other reducing substances without catechol structure. Thus, a colorimetric array has been constructed using reaction time as the sensing element to realize the sensitive and selective recognition of catechol structures at a certain concentration.

Synthesis, characterization and in vitro digestion of folate conjugated chitosan-loaded proanthocyanidins nanoparticles

Proanthocyanidins have significant biological activity and pharmacological effects and are widely used in food, medicine, and cosmetics. Chitosan nanoparticles loaded with proanthocyanidins have been proven to improve their biological activity. Given some deficiencies of chitosan (CS), the modification of chitosan by folic acid (FA) can obtain new variants with different functions. For this objective, the folic acid conjugated chitosan was designed, and in vitro properties of proanthocyanidins loaded nanoparticles were studied systemically. Firstly, folic acid-chitosan conjugate (FA-CS) was synthesized and characterized. Folate-coupled chitosan-loaded proanthocyanidin nanoparticles (PC-CS/FA-NPs) were prepared by ionic gelation technique using FA-CS as a carrier. The successful nanoparticle synthesis was characterized by dynamic light scattering (DLS) techniques and Fourier transform infrared (FT-IR) spectroscopy. The synthesized nanoparticles exhibited a spherical shape and smooth and uniform distribution features with a size range of less than 300 nm, as observed by a scanning electron microscope (SEM). Meanwhile, PC-CS/FA-NPs had good thermal and gastrointestinal digestive stability and had a protective effect on AAPH-induced erythrocyte oxidative hemolysis. In conclusion, folic acid decorated chitosan nanoparticles improved the stability and bioavailability of proanthocyanidins in gastrointestinal digestion.

Insights on Chemical Crosslinking Strategies for Proteins

Crosslinking of proteins has gained immense significance in the fabrication of biomaterials for various health care applications. Various novel chemical-based strategies are being continuously developed for intra-/inter-molecular crosslinking of proteins to create a network/matrix with desired mechanical/functional properties without imparting toxicity to the host system. Many materials that are used in biomedical and food packaging industries are prepared by chemical means of crosslinking the proteins, besides the physical or enzymatic means of crosslinking. Such chemical methods utilize the chemical compounds or crosslinkers available from natural sources or synthetically generated with the ability to form covalent/non-covalent bonds with proteins. Such linkages are possible with chemicals like carbodiimides/epoxides, while photo-induced novel chemical crosslinkers are also available. In this review, we have discussed different protein crosslinking strategies under chemical methods, along with the corresponding crosslinking reactions/conditions, material properties and significant applications.

A Food-Grade Method for Enhancing the Levels of Low Molecular Weight Proanthocyanidins with Potentially High Intestinal Bioavailability

Proanthocyanidins (PACs) are a group of bioactive molecules found in a variety of plants and foods. Their bioavailability depends on their molecular size, with monomers and dimers being more bioavailable than those that have a higher polymerization degree. This study aimed to develop a method to convert high-molecular-weight PACs to low-molecular-weight ones in a grape seed extract (GSE) from Vitis vinifera L. Therefore, GSE was subjected to alkaline treatment (ATGSE), and its difference in chemical composition, compared to GSE, was evaluated using a molecular networking (MN) approach based on results obtained from HPLC-ESI HRMS/MS characterization analysis. The network analysis mainly noted the PAC cluster with about 142 PAC compounds identified. In particular, the obtained results showed a higher content of monomeric and dimeric PACs in ATGSE compared to GSE, with 58% and 49% monomers and 31% and 24% dimers, respectively. Conversely, trimeric (9%), polymeric (4%), and galloylated PACs (14%) were more abundant in GSE than in ATGSE (6%, 1%, and 4%, respectively). Moreover, in vitro antioxidant and anti-inflammatory activities were investigated, showing the high beneficial potential of both extracts. In conclusion, ATGSE could represent an innovative natural matrix rich in bioavailable and bioaccessible PACs for nutraceutical applications with potential beneficial properties.

Flavonoids bridging the gut and the brain: intestinal metabolic fate, and direct or indirect effects of natural supporters against neuroinflammation and neurodegeneration

In recent years, experimental evidence suggested a possible role of the gut microbiota in the onset and development of several neurodegenerative disorders, such as AD and PD, MS and pain. Flavonoids, including anthocyanins, EGCG, the flavonol quercetin, and isoflavones, are plant polyphenolic secondary metabolites that have shown therapeutic potential for the treatment of various pathological conditions, including neurodegenerative diseases. This is due to their antioxidant and anti-inflammatory properties, despite their low bioavailability which often limits their use in clinical practice. In more recent years it has been demonstrated that flavonoids are metabolized by specific bacterial strains in the gut to produce their active metabolites. On the other way round, both naturally-occurring flavonoids and their metabolites promote or limit the proliferation of specific bacterial strains, thus profoundly affecting the composition of the gut microbiota which in turn modifies its ability to further metabolize flavonoids. Thus, understanding the best way of acting on this virtuous circle is of utmost importance to develop innovative approaches to many brain disorders. In this review, we summarize some of the most recent advances in preclinical and clinical research on the neuroinflammatory and neuroprotective effects of flavonoids on AD, PD, MS and pain, with a specific focus on their mechanisms of action including possible interactions with the gut microbiota, to emphasize the potential exploitation of dietary flavonoids as adjuvants in the treatment of these pathological conditions.

Chemically Different but Often Mistaken Phenolic Polymers of Food Plants: Proanthocyanidins and Lignin in Seeds

Flavonoid based proanthocyanidins and cinnamyl alcohol based lignins are chemically complex phenolic oligomers/polymers that are found in food plants. Although structurally very different, these two biopolymers are often not distinguished, for example, in the (quantitative) compositional analysis of cell walls and dietary fiber. Here, we analytically distinguish lignin and proanthocyanidins in dietary fiber samples by using degradative and nondegradative techniques and provide information about their occurrence, abundance, and structural characteristics in seeds of chokeberries, cranberries, raspberries, red currants, and grapes. These data revealed that the seeds of botanically diverse fruits largely differ in terms of their phenolic fiber polymers. The mostly hardened tissue of the seeds is not necessarily based on lignified cell walls. For example, red currant and chokeberry seeds almost exclusively contain proanthocyanidins, and raspberry seeds were clearly lignified (G-H-lignin) but did not contain proanthocyanidins. Our data also allows for estimating the bias of proanthocyanidins on different approaches of lignin analysis.

Transcriptional regulation of proanthocyanidin biosynthesis pathway genes and transcription factors in Indigofera stachyodes Lindl. roots

BACKGROUND

Proanthocyanidins (PAs) have always been considered as important medicinal value component. In order to gain insights into the PA biosynthesis regulatory network in I. stachyodes roots, we analyzed the transcriptome of the I. stachyodes in Leaf, Stem, RootI (one-year-old root), and RootII (two-year-old root).

RESULTS

In this study, a total of 110,779 non-redundant unigenes were obtained, of which 63,863 could be functionally annotated. Simultaneously, 75 structural genes that regulate PA biosynthesis were identified, of these 6 structural genes (IsF3'H1, IsANR2, IsLAR2, IsUGT72L1-3, IsMATE2, IsMATE3) may play an important role in the synthesis of PAs in I. stachyodes roots. Furthermore, co-expression network analysis revealed that 34 IsMYBs, 18 IsbHLHs, 15 IsWRKYs, 9 IsMADSs, and 3 IsWIPs hub TFs are potential regulators for PA accumulation. Among them, IsMYB24 and IsMYB79 may be closely involved in the PA biosynthesis in I. stachyodes roots.

CONCLUSIONS

The biosynthesis of PAs in I. stachyodes roots is mainly produced by the subsequent pathway of cyanidin. Our work provides new insights into the molecular pathways underlying PA accumulation and enhances our global understanding of transcriptome dynamics throughout different tissues.

Persimmon Proanthocyanidins with Different Degrees of Polymerization Possess Distinct Activities in Models of High Fat Diet Induced Obesity

Proanthocyanidins is a kind of polyphenol that had been found with strong prevention ability on high fat diet induced obesity. However, whether proanthocyanidins with different polymerization degree showed different anti-obesity ability is unclear. Therefore, in this study, the effects of persimmon proanthocyanidins (P-PCs) and persimmon oligo-proanthocyanidins (P-OPCs) on high-fat diet induced obesity were systematically investigated. The findings indicated that both of P-PCs and P-OPCs significantly reduced the body weight, and P-PCs showed stronger anti-obesity ability compared with P-OPCs, P-OPCs seemed with stronger ability on improvement of insulin resistance. Furthermore, gut microbiota results indicated that the composition of the gut microbiota was changed after P-PCs and P-OPCs intervention in C57BL/6J mice. In addition, P-PCs exhibited strong inhibitory on the digestion of starch and fat. Above all, this study indicated that P-PCs showed stronger anti-obesity ability compared with P-OPCs.

Tiliae flos metabolites and their beneficial influence on human gut microbiota biodiversity ex vivo

ETHNOPHARMACOLOGICAL RELEVANCE

The linden flower (Tiliae flos) has been used for centuries to treat and relieve symptoms of the common cold, throat irritation, and upper respiratory tract disturbances. Traditionally, this herb is administered orally, and thus it undergoes intestinal metabolism. Although it is pharmacopeial plant material, there are no reports about its interaction with human gut microbiota.

AIM OF THE STUDY

The study aimed to determine the interaction between human gut microbiota and the linden flower extracts, resulting in the biotransformation of the extract's constituents and changes in the microbiota composition.

MATERIAL AND METHODS

The linden flower metabolites were obtained by incubation of extract with human faecal slurries from 5 healthy donors. The UHPLC-DAD-MSⁿ analysis determined the composition of raw extract and analysis of microbial metabolites. The intestinal microbiota isolation and sequencing were used to determine changes in microbiota composition. The anti-inflammatory activity was tested using the LPS-stimulated human neutrophils model and ELISA test.

RESULTS

After incubation of linden flower extract with human gut microbiota, twenty metabolites were detected and characterized, and three among them were identified. The extract changed human gut microbiota composition but did not cause dysbiosis (change in the abundance of forty-three genera). Raw extract and their metabolites exhibit different levels of inhibition of cytokines production by LPS-stimulated neutrophils, but the reduction of TNF-α production was observed.

CONCLUSIONS

The linden flower extract has a beneficial influence on human gut microbiota because it promotes increasing the abundance of bacteria responsible for SCFAs production. The anti-inflammatory effect might be linked to both microbiota composition changes and direct activity of bioavailable metabolites. Increased abundance of SCFAs producers may inhibit the production of pro-inflammatory cytokines. A low concentration of phenolic compounds in metabolized linden flower extract and responsible for anti-inflammatory properties, and the multitude of biological and chemical particles and their interactions may weaken these properties.

Proanthocyanidins at the gastrointestinal tract: mechanisms involved in their capacity to mitigate obesity-associated metabolic disorders

The prevalence of overweight and obesity is continually increasing worldwide. Obesity is a major public health concern given the multiple associated comorbidities. Finding dietary approaches to prevent/mitigate these conditions is of critical relevance. Proanthocyanidins (PACs), oligomers or polymers of flavan-3-ols that are extensively distributed in nature, represent a major part of total dietary polyphenols. Although current evidence supports the capacity of PACs to mitigate obesity-associated comorbidities, the underlying mechanisms remain speculative due to the complexity of PACs' structure. Given their limited bioavailability, the major site of the biological actions of intact PACs is the gastrointestinal (GI) tract. This review discusses the actions of PACs at the GI tract which could underlie their anti-obesity effects. These mechanisms include: i) inhibition of digestive enzymes at the GI lumen, including pancreatic lipase, α-amylase, α-glucosidase; ii) modification of gut microbiota composition; iii) modulation of inflammation- and oxidative stress-triggered signaling pathways, e.g. NF-κB and MAPKs; iv) protection of the GI barrier integrity. Further understanding of the mechanisms and biological activities of PACs at the GI tract can contribute to develop nutritional and pharmacological strategies oriented to mitigate the serious comorbidities of obesity.

Advances in Evaluation of Antioxidant and Toxicological Properties of Stryphnodendron rotundifolium Mart. in Drosophila melanogaster Model

This study investigated the flavonoid content, antioxidant activity, and toxicological properties of the acetone–water fraction of stem bark of Stryphnodendron rotundifolium Mart. (TFSR). The total flavonoid content and antioxidant activity were determined, as typified by DPPH^● and ABTS^●+ radical scavenging abilities, Fe³⁺ reducing antioxidant power (FRAP), relative antioxidant capacity (RAC), and the inhibition of thiobarbituric acid reactive species (TBARs) in Drosophila melanogaster tissue. Toxicity and locomotor functions were evaluated in adult D. melanogaster flies through aging and survival assays, startle-induced negative geotaxis, and centrophobic responses with video-assisted open field motion tracking. The flavonoid content of dry TFSR (DF) was 3.36 mg quercetin/g. Furthermore, the significant antioxidant activity of TFSR was revealed through scavenging 95.3% of the ABTS^●+ radical and 82.4% of the DPPH^● radical, as well reducing 74.7% of Fe³⁺ in the FRAP assay and 80% Mo⁶⁺ in the RAC assay. TFSR conferred 70.25% protection against lipid peroxidation in Drosophila tissue. Survival rates ranged from 84.65 to 103.98% in comparison to the non-supplemented control and no evident deterioration of locomotor functions and centrophobia responses was observed. These results revealed that TFSR has potent antioxidant activity and low toxicity in vivo, profiling TFSR as a promising natural product in the treatment/management of iron overload and associated conditions.

Flavonoid Intake From Cocoa-Based Products and Adiposity Parameters in Adolescents in Spain

Background

Cocoa-based products are a good source of flavonoids, which may have beneficial effects on metabolic health.

Objective

The aim of this study is to assess the relationship between flavonoids from cocoa-based products and adiposity parameters in adolescents.

Methods

A cross-sectional study was conducted involving 944 adolescents aged 11-14 years enrolled in the SI! Program for Secondary Schools trial in Spain with available baseline data from food frequency questionnaires and anthropometric measurements [weight, height, waist circumference (WC), and fat mass percentage (% FM) by bioimpedance analysis]. Fat mass index (FMI) and waist-to-height ratio (WHtR) were obtained by dividing fat mass by height and WC by height, respectively. Body mass index (BMI), WC, and FMI for age and gender z-score were calculated. Overweight/obesity was defined as BMI ≥ 85th percentile and excess adiposity as %FM or FMI ≥ 75th percentile. WC ≥ 90th percentile and WHtR with a 0.5 threshold were considered as criteria of abdominal obesity. Multilevel mixed-effect regressions were used to evaluate the association between flavonoids from cocoa-based products and adiposity parameters. Municipalities and schools were considered random effects.

Results

Participants with a higher flavonoid intake from cocoa-based products had lower WC z-score [B = -0.04, 95% CI (-0.07; -0.01), P-for trend = 0.045] and WHtR [B = -0.01, 95% CI (-0.02; -0.01), P- for trend < 0.001]. They also had lower probability of having abdominal obesity [OR 0.66, 95% CI (0.52; 0.85), P- for trend = 0.001]. Inverse associations were observed between flavonoids from cocoa powder and BMI z-score [B = -0.08, 95% CI (-0.12; -0.05), P < 0.001], WC z-score [B = -0.06, 95% CI (-0.11; -0.02), P = 0.003], WHtR [B = -0.01, 95% CI (-0.01; -0.00), P < 0.001], %FM [B = -1.11, 95% CI (-1.48; -0.75), P < 0.001], and FMI z-score [B = -0.18, 95% CI (-0.20; -0.17), P < 0.001]. Regarding dark chocolate, an inverse association only with WC z-score [B = -0.06, 95% CI (-0.08; -0.05), P < 0.001] was found. However, no association was observed between flavonoids from milk chocolate intake and anthropometric parameters.

Conclusions

A higher intake of flavonoids from cocoa-based products was associated with lower adiposity parameters and a lower probability of presenting abdominal obesity.

Food Industry Byproducts as Starting Material for Innovative, Green Feed Formulation: A Sustainable Alternative for Poultry Feeding

Rising global populations and enhanced standards of living in so-called developing countries have led to an increased demand of food, in particular meat, worldwide. While increasing the production of broiler meat could be a potential solution to this problem, broiler meat is plagued by health concerns, such as the development of antimicrobial resistance and lower meat quality. For this reason, the supplementation of poultry feed with vitamins and antioxidant compounds, such as polyphenols, has become an attractive prospect for research in this sector. Such supplements could be obtained by extraction of agricultural byproducts (in particular, grape pomaces and artichoke leaves and bracts), thus contributing to reductions in the total amount of waste biomass produced by the agricultural industry. In this review, the effects of poultry feed supplementation with bioactive extracts from grape pomace (skins and/or seeds), as well as extracts from artichoke leaves and bracts, were explored. Moreover, the various methods that have been employed to obtain extracts from these and other agricultural byproducts were listed and described, with a particular focus on novel, eco-friendly extraction methods (using, for example, innovative and biocompatible solvents like Deep Eutectic Solvents (DESs)) that could reduce the costs and energy consumption of these procedures, with similar or higher yields compared to standard methods.

Evaluation of Proanthocyanidins from Kiwi Leaves (Actinidia chinensis) against Caco-2 Cells Oxidative Stress through Nrf2-ARE Signaling Pathway

Proanthocyanidins (PAs) are considered to be effective natural byproduct and bioactive antioxidants. However, few studies have focused on their mode of action pathways. In this study, reactive oxygen species (ROS), oxidative stress indices, real-time PCR, Western blotting, confocal microscopy, and molecular docking were used to investigate the protective effect of purified kiwi leaves PAs (PKLPs) on Caco-2 cells’ oxidative stress mechanisms. The results confirmed that pre-treatment with PKLPs significantly reduced H2O2-induced oxidative damage, accompanied by declining ROS levels and malondialdehyde (MDA) accumulation in the Caco-2 cells. The PKLPs upregulated the expression of antioxidative enzymes (GSH-px, CAT, T-SOD) and the relative mRNA (Nrf, HO-1, SOD-1, CAT) of the nuclear factor erythroid 2-related factor (Nrf2) signaling pathway. The protein-expressing level of the Nrf2 and its relative protein (NQO-1, HO-1, SOD-1) were significantly increased (p < 0.05) in the PKLPs pre-treatment group compared to the model group. In conclusion, the novelty of this study is that it explains how PKLPs’ efficacy on the Nrf2-ARE signaling pathway, in protecting vital cells from oxidative stress, could be used for cleaner production.

Chocolate and Cocoa-Derived Biomolecules for Brain Cognition during Ageing

Cognitive decline is a common problem in older individuals, often exacerbated by neurocognitive conditions, such as vascular dementia and Alzheimer’s disease, which heavily affect people’s lives and exert a substantial toll on healthcare systems. Currently, no cure is available, and commonly used treatments are aimed at limiting the progressive loss of cognitive functions. The absence of effective pharmacological treatments for the cognitive decline has led to the search for lifestyle interventions, such as diet and the use of nutraceuticals that can prevent and limit the loss of cognition. Cocoa and chocolate are foods derived from cocoa beans, commonly used in the population and with good acceptability. The purpose of this review was to collect current experimental evidence regarding the neuroprotective effect of chocolate and cocoa (or derived molecules) in the elderly. From a systematic review of the literature, 9 observational studies and 10 interventional studies were selected, suggesting that the biomolecules contained in cocoa may offer promising tools for managing cognitive decline, if provided in adequate dosages and duration of treatment. However, the molecular mechanisms of cocoa action on the central nervous system are not completely understood.