Monomeric catechin and dimeric procyanidin B2 against human norovirus surrogates and their physicochemical interactions

Bioguided fractionation of procyanidin B2 as potent anti coxsackie virus B and Herpes simplex from cypress (Cupressus sempervirens L.)

The methanolic extracts of cypress (Cupressus sempervirens L.) collected at three phenological stages were evaluated for their cytotoxicity on Vero cells by MTT test as well as on Herpes simplex (HSV-2) and coxsackie (CVB-3) viruses by plaque reduction assay. The methanolic extract exhibited the highest cytotoxicity against HSV-2 (IC50 = 20.40 µg/mL) and CVB-3 (IC50 = 47.50 µg/mL) at the flowering stage. This extract also exhibited a virucidal action both during the entry of viruses and the release of newly formed virions. The methanolic extract bioguided purification showed that the ethyl-acetate fraction was responsible for virucidal activity. This fraction was endowed with more important selectivity index of 8.15 for HSV-2 and 4.40 for CVB-3. The ethyl acetate fraction was subjected to thin layer chromatography fractionation and identification by HPLC-DAD-ESI-MSn. Results showed that the condensed tannin procyanidin B2 was identified for the first time responsible of the antiviral activity of cypress.

Procyanidin B2: A promising multi-functional food-derived pigment for human diseases

Natural edible pigments play a paramount part in the food industry. Procyanidin B2 (PB2), one of the most representative naturally occurring edible pigments, is usually isolated from the seeds, fruits, and leaves of lots of common plants, such as grapes, Hawthorn, black soybean, as well as blueberry, and functions as a food additive in daily life. Notably, PB2 has numerous bioactivities and possesses the potential to treat/prevent a wide range of human diseases, such as diabetes mellitus, diabetic complications, atherosclerosis, and non-alcoholic fatty liver disease, and the underlying mechanisms were partially elucidated, including mediating signaling pathways like NF-κB, MAPK, PI3K/Akt, apoptotic axis, and Nrf-2/HO-1. This paper presents a review of the natural sources, bioactivities, and the therapeutic/preventive potential of PB2 and the possible mechanisms, with the aim of promoting the development of PB2 as a functional food and providing references for its clinical application in the treatment of diseases.

Structure-activity relationship, bioactivities, molecular mechanisms, and clinical application of nuciferine on inflammation-related diseases

Nuciferine aporphine alkaloid mainly exists in Nelumbo nucifera Gaertn and is a beneficial to human health, such as anti-obesity, lowering blood lipid, prevention of diabetes and cancer, closely associated with inflammation. Importantly, nuciferine may contribute to its bioactivities by exerting intense anti-inflammatory activities in multiple models. However, no review has summarized the anti-inflammatory effect of nuciferine. This review critically summarized the information regarding the structure-activity relationships of dietary nuciferine. Moreover, biological activities and clinical application on inflammation-related diseases, such as obesity, diabetes, liver, cardiovascular diseases, and cancer, as well as their potential mechanisms, involving oxidative stress, metabolic signaling, and gut microbiota has been reviewed. The current work provides a better understanding of the anti-inflammation properties of nuciferine against multiple diseases, thereby improving the utilization and application of nuciferine-containing plants across functional food and medicine.

Proanthocyanidin Structure-Activity Relationship Analysis by Path Analysis Model

To fully explore the influence mechanism of interactions between different monomer units of proanthocyanidins (PAs) on biological activity, a path analysis model of the PA structure-activity relationship was proposed. This model subdivides the total correlation between each monomer unit and activity into direct and indirect effects by taking into account not only each monomer unit but also the correlation with its related monomer units. In addition, this method can determine the action mode of each monomer unit affecting the activity by comparing the direct and total indirect effects. Finally, the advantage of this model is demonstrated through an influence mechanism analysis of Rhodiola crenulata PA monomer units on antioxidant and anti-diabetes activities.

Screening of natural extracts with anti-norovirus effects and analysis of this mechanism in grape seed extract

Norovirus (NoV）is a major causative virus of viral gastroenteritis and requires a general disinfection method because it is resistant to common disinfectants such as ethanol and chlorhexidine. This study aimed to find natural extracts as candidates for versatile disinfectant ingredients. The antiviral effect of natural extracts against NoV can be evaluated using the feline calicivirus (FCV）-inactivation test and NoV virus-like particle (NoV-VLP）-binding inhibition test. In this study, screening of natural extracts with anti- NoV effects was performed using these two methods. Of the 63 natural extracts examined, 14 were found to have high FCV-inactivation and NoV-VLP-binding inhibitory effects. In addition, we evaluated the NoV-VLPbinding inhibitory effect of grape seed extract（GSE）containing proanthocyanidins under multiple concentration conditions and treatment times and determined that the binding inhibitory effect of GSE was concentration- and time-dependent. Electron microscopy showed that GSE-treated NoV-VLPs aggregated, distorted, and swelled, suggesting that GSE directly interacts with NoV particles. The results suggest that some natural extracts containing GSE can be used as components of disinfectants against NoV.

Bioactivities and mechanisms of dietary proanthocyanidins on blood pressure lowering: A critical review of in vivo and clinical studies

Proanthocyanidins, widespread in natural plant sources, are bioactive substances that exhibit broad benefits to human health. Of note, proanthocyanidins have been reported to lower blood pressure and prevent hypertension, but a critical review of this is lacking. In this review, information on the basic structures and absorption of dietary proanthocyanidins as well as their bioactivities and related mechanisms on the lowering of blood pressure derived via in vivo and clinical studies are summarized. Clinical studies have shown that proanthocyanidins have a pronounced blood pressure-lowering effect, effectively preventing hypertension and reducing the occurrence of cardiovascular and cerebrovascular diseases. The potential mechanisms, which are herein reviewed in detail, involve the improvement of vascular function, reduction of oxidative stress and inflammation, and modulation of lipid metabolism. Taken together, this work provides information for a better understanding of the antihypertensive effects of proanthocyanidins, which may promote their use to reduce the risk of developing hypertension.

Investigation of binding interaction between bovine α-lactalbumin and procyanidin B2 by spectroscopic methods and molecular docking

The interactions between bovine α-lactalbumin and procyanidin B2 were fully investigated by spectroscopic methods and molecular docking. This study hypothesized that ALA could spontaneously interact with procyanidin B2 to form protein-based complex delivery carrier. Far UV CD and FTIR data demonstrated ALA's secondary structures were altered and intrinsic fluorescence quenching suggested ALA conformation was changed with procyanidin B2. Calorimetric technique illustrated ALA-procyanidin B2 complexation was a spontaneous and exothermic process with the number of binding site (n, 3.53) and the binding constant (K_b, 2.16 × 10⁴ M^-1). A stable nano-delivery system with ALA can be formed for encapsulating, stabilizing and delivering procyanidin B2. Molecular docking study further elucidated that hydrogen bonds dominated procyanidin B2 binding to ALA in a hydrophobic pocket. This study shows great potential in using ALA as protein-based nanocarriers for oral delivery of hydrophilic nutraceuticals, because procyanidin B2-loaded ALA complex delivery systems can be spontaneously formed.

Anti-HCV Tannins From Plants Traditionally Used in West Africa and Extracted With Green Solvents

Millions of people are still infected with hepatitis C virus (HCV) nowadays. Although recent antivirals targeting HCV proteins are very efficient, they are not affordable for many people infected with this virus. Therefore, new and more accessible treatments are needed. Several Ivorian medicinal plants are traditionally used to treat “yellow malaria”, a nosological category including illness characterized by symptomatic jaundice such as hepatitis. Therefore, some of these plants might be active against HCV. An ethnobotanical survey in Côte d’Ivoire allowed us to select such medicinal plants. Those were first extracted with methanol and tested for their anti-HCV activity. The most active ones were further studied to specify their IC50 and to evaluate their toxicity in vitro. Greener solvents were tested to obtain extracts with similar activities. Following a phytochemical screening, tannins of the most active plants were removed before re-testing on HCV. Some of these tannins were identified by UPLC-MS and pure molecules were tested against HCV. Out of the fifteen Ivorian medicinal plants selected for their putative antiviral activities, Carapa procera DC. and Pericopsis laxiflora (Benth. ex Baker) Meeuwen were the most active against HCV (IC50: 0.71 and 0.23 μg/ml respectively) and not toxic for hepatic cells. Their crude extracts were rich in polyphenols, including tannins such as procyanidins A2 which is active against HCV. The same extracts without tannin lost their anti-HCV activity. Replacing methanol by hydro-ethanolic solvent led to tannins-rich extracts with similar antiviral activities, and higher than that of aqueous extracts.

In Silico Screening and In Vitro Assessment of Natural Products with Anti-Virulence Activity against Helicobacter pylori

Helicobacter pylori is one of the most frequent human pathogens and a leading etiological agent of various gastric diseases. As stringent response, coordinated by a SpoT protein, seems to be crucial for the survivability of H. pylori, the main goal of this article was to use in silico computational studies to find phytochemical compounds capable of binding to the active site of SpoT from H. pylori and confirm the ability of the most active candidates to interfere with the virulence of this bacterium through in vitro experiments. From 791 natural substances submitted for the virtual screening procedure, 10 were chosen and followed for further in vitro examinations. Among these, dioscin showed the most interesting parameters (the lowest MIC, the highest anti-biofilm activity in static conditions, and a relatively low stimulation of morphological transition into coccoids). Therefore, in the last part, we extended the research with a number of further experiments and observed the ability of dioscin to significantly reduce the formation of H. pylori biofilm under Bioflux-generated flow conditions and its capacity for additive enhancement of the antibacterial activity of all three commonly used antibiotics (clarithromycin, metronidazole, and levofloxacin). Based on these results, we suggest that dioscin may be an interesting candidate for new therapies targeting H. pylori survivability and virulence.

Omnifarious fruit polyphenols: an omnipotent strategy to prevent and intervene diabetes and related complication?

Diabetes mellitus is a metabolic syndrome which cannot be cured. Recently, considerable interest has been focused on food ingredients to prevent and intervene in complications of diabetes. Polyphenolic compounds are one of the bioactive phytochemical constituents with various biological activities, which have drawn increasing interest in human health. Fruits are part of the polyphenol sources in daily food consumption. Fruit-derived polyphenols possess the anti-diabetic activity that has already been proved either from in vitro studies or in vivo studies. The mechanisms of fruit polyphenols in treating diabetes and related complications are under discussion. This is a comprehensive review on polyphenols from the edible parts of fruits, including those from citrus, berries, apples, cherries, mangoes, mangosteens, pomegranates, and other fruits regarding their potential benefits in preventing and treating diabetes mellitus. The signal pathways of characteristic polyphenols derived from fruits in reducing high blood glucose and intervening hyperglycemia-induced diabetic complications were summarized.

Antiviral Properties of Polyphenols from Plants

Polyphenols are active substances against various types of viral infections. Researchers have characterized methods of how to isolate polyphenols without losing their potential to formulate pharmaceutical products. Researchers have also described mechanisms against common viral infections (i.e., influenza, herpes, hepatitis, rotavirus, coronavirus). Particular compounds have been discussed together with the plants in the biomass in which they occur. Quercetin, gallic acid and epigallocatechin are exemplary compounds that inhibit the growth cycle of viruses. Special attention has been paid to identify plants and polyphenols that can be efficient against coronavirus infections. It has been proven that polyphenols present in the diet and in pharmaceuticals protect us from viral infections and, in case of infection, support the healing process by various mechanisms, i.e., they block the entry into the host cells, inhibit the multiplication of the virus, seal blood vessels and protect against superinfection.

Towards a better understanding of Fagopyrum dibotrys: a systematic review

Fagopyrum dibotrys (F. dibotrys) (D.Don) H.Hara is a well-known edible herbal medicine in Asian countries. It has been widely used for the treatment of lung diseases, swelling, etc., and is also an important part of many Chinese medicine prescriptions. At present, more than 100 compounds have been isolated and identified from F. dibotrys, and these compounds can be primarily divided into flavonoids, phenols, terpenes, steroids, and fatty acids. Flavonoids and phenolic compounds are considered to be the main active ingredients of F. dibotrys. Previous pharmacological studies have shown that F. dibotrys possesses anti-inflammatory, anti-cancer, anti-oxidant, anti-bacterial, and anti-diabetic activities. Additional studies on functional genes have led to a better understanding of the metabolic pathways and regulatory factors related with the flavonoid active ingredients in F. dibotrys. In this paper, we systemically reviewed the research advances on the phytochemistry and pharmacology of F. dibotrys, as well as the functional genes related to the synthesis of active ingredients, aiming to promote the development and utilization of F. dibotrys.

Contamination, bioaccumulation mechanism, detection, and control of human norovirus in bivalve shellfish: A review

Human norovirus (HuNoV) is a major foodborne pathogen that causes acute viral gastroenteritis, and bivalve shellfish are one of the main carriers of HuNoV transmission. A comprehensive understanding of bivalve shellfish-related HuNoV outbreaks focusing on contamination factors, bioaccumulation mechanisms, and pre- and post-harvest interventions is essential for the development of effective strategies to prevent contamination of shellfish. This review comprehensively surveys the current knowledge on global contamination and non-thermal treatment of HuNoV in bivalve shellfish. HuNoV contamination in bivalve shellfish is significantly related to the season and water. While evaluating the water quality of shellfish-inhabited waters is a key intervention, the development of non-heat treatment technology to effectively inactivate the HuNoV in bivalve shellfish while maintaining the flavor and nutrition of the shellfish is also an important direction for further research. Additionally, this review explores the bioaccumulation mechanisms of HuNoV in bivalve shellfish, especially the mechanism underlying the binding of histo-blood group antigen-like molecules and HuNoV. The detection methods for infectious HuNoV are also discussed. The establishment of effective methods to rapidly detect infectious HuNoV and development of biological components to inactivate or prevent HuNoV contamination in shellfish also need to be studied further.

Proanthocyanidins: Components, Pharmacokinetics and Biomedical Properties

Proanthocyanidins (PAs) are a group of polyphenols enriched in plant and human food. In recent decades, epidemiological studies have upheld the direct relationship between PA consumption and health benefits; therefore, studies on PAs have become a research hotspot. Although the oral bioavailability of PAs is quite low, pharmacokinetics data revealed that some small molecules and colonic microbial metabolites of PAs could be absorbed and exert their health beneficial effects. The pharmacological effects of PAs mainly include anti-oxidant, anticancer, anti-inflammation, antimicrobial, cardiovascular protection, neuroprotection, and metabolism-regulation behaviors. Moreover, current toxicological studies show that PAs have no observable toxicity to humans. This review summarizes the resources, extraction, structures, pharmacokinetics, pharmacology, and toxicology of PAs and discusses the limitations of current studies. Areas for further research are also proposed.

Effects of Infrared Radiation on Eggplant (Solanum melongena L.) Greenhouse Cultivation and Fruits' Phenolic Profile

The implementation of Infrared (IR) radiation in heated greenhouses possesses the advantage of high directional control and focused compensation of energy losses, appropriate for creating local microclimate conditions in highly energy-consuming systems, such as greenhouses. Moreover, it can efficiently maintain favorable environmental conditions at the plant canopy. The present study studies the application of Infrared (IR) heating in an experimental greenhouse with eggplant (Solanum melongena L.) cultivation. The experimental results are presented from a full cultivation period inside two identical, small scale experimental greenhouses, with IR and forced air heating system, respectively. The effects of IR heating over plant growth parameters, including the yield of the fruits as well as the total phenolic content and the antioxidant profile of eggplants fruits’ extracts are measured and discussed. The results indicate a greater uniformity production in the IR heating greenhouse in terms of antioxidant and radical scavenging activities, as well as the total phenolic content. Moreover, the phenolic profile of eggplant fruits from both greenhouses revealed the existence of numerous bioactive compounds, some of which were only characteristic of the eggplant fruits from IR heated greenhouses.

Grape Seed Procyanidins Attenuates Cisplatin-induced Human Embryonic Renal Cell Cytotoxicity by Modulating Heme Oxygenase-1 in Vitro

Cisplatin is a widely used anti-cancer drug. However, cisplatin is limited in clinical treatment because of its severe nephrotoxicity. This study reported whether O-GSP can antagonize the cisplatin-induced cytotoxicity in HEK293 cells through inducing HO-1 protein expression. We previously demonstrated O-GSP can increase the survival rate of HEK293 and have protective effect on HEK293 cells. Herein, We found that O-GSP can antagonize cisplatin nephrotoxicity through regulating the expression of HO-1. O-GSP promotes the translocation of Nrf2 in the nucleus, and activates the ERKN JNK pathway and p38 MAPK pathway. Interestingly, p38 MAPK plays a major role in HO-1 expression induced by O-GSP. And O-GSP can modulate the decrease of Nrf2 and HO-1 expression induced by cisplatin, and improve the cisplatin-induced activity and apoptosis rate of cells by stimulating the expression of HO-1. However, the protective effects of O-GSP are inhibited by ZnPP IX. Collectively, the results indicated that O-GSP induced the expression of HO-1 through p38MAPK and Nrf2 pathway in HEK293 cells.

Antiviral effects of blueberry proanthocyanidins against Aichi virus

Blueberry polyphenols are known for their high antioxidant and antimicrobial potential. Aichi virus (AiV) is an emerging human enteric virus that causes gastroenteritis outbreaks worldwide. This study aimed to (1) determine the time- and dose-dependent effects of blueberry proanthocyanidins (B-PAC) against AiV over 24 h at 37 °C; (2) gain insights on their mode of action using pre- and post-treatment of host cells and Transmission Electron Microscopy; and (3) determine their anti-AiV effects in model foods and under simulated gastric conditions. AiV at ∼5 log PFU/ml was incubated with equal volumes of commercial blueberry juice (BJ, pH 2.8), neutralized BJ (pH 7.0), B-PAC (2, 4, and 10 mg/ml) prepared either in 10% ethanol, apple juice (AJ), 2% milk, simulated gastric fluid (SGF, pH 1.5) or simulated intestinal fluid (SIF, pH 7.5), and controls (malic acid (pH 3.0), phosphate buffered saline (pH 7.2), apple juice (pH 3.6) and 2% milk) over 24 h at 37 °C, followed by standard plaque assays. Each experiment was replicated thrice and data were statistically analyzed. Differences in AiV titers with 1 mg/ml B-PAC were 2.13 ± 0.06 log PFU/ml lower after 24 h and ≥3 log PFU/ml (undetectable levels) lower with 2 and 5 mg/ml B-PAC compared to AiV titers in PBS after 24 h and 3 h, respectively. BJ at 37 °C resulted in titer differences (lower titers compared to PBS) of 0.17 ± 0.06, 1.27 ± 0.01, and 1.73 ± 0.23 log PFU/ml after 1, 3, and 6 h and ≥3 log PFU/ml after 24 h. Pre- and post-treatment of host cells with 0.5 mg/ml B-PAC caused titer decreases of 0.62 ± 0.33 and 0.30 ± 0.06 log PFU/ml, respectively suggesting a moderate effect on viral-host cell binding. B-PAC at 2 mg/ml in AJ caused titer differences of ≥3 log PFU/ml after 0.5 h, while differences of 0.84 ± 0.03 log PFU/ml with 5 mg/ml B-PAC in milk, and ≥3 log PFU/ml with B-PAC at 5 mg/ml in SIF after 30 min were obtained. This study shows the ability of BJ and B-PAC to decrease AiV titers to potentially prevent AiV-related illness and outbreaks.

Antiviral activity of aged green tea extract in model food systems and under gastric conditions

Aged-green tea extract (GTE) is known to reduce the infectivity of hepatitis A virus (HAV) and murine norovirus (MNV), a human norovirus surrogate, in vitro and in washing solutions. Initially, the effect of aged-GTE was evaluated on virus like particles (VLPs) of human norovirus (HuNoV) genogroup I (GI) by a porcine gastric mucine (PGM)-enzyme-linked immunosorbent assay (ELISA) and transmission electron microscopy (TEM), and on HuNoV GI suspensions by an in situ capture-RT-qPCR method, suggesting that HuNoVs are very sensitive to aged-GTE treatment at 37 °C. Moreover, the potential application of aged-GTE was evaluated using model foods and simulated gastric conditions. Then, aged-GTE samples prepared in orange juice, apple juice, horchata, and milk, respectively, were individually mixed with each virus and incubated overnight at 37 °C. Aged-GTE at 5 mg/ml in apple juice reduced MNV infectivity to undetectable levels and from 1.0 to 1.8 log in milk, horchata and orange juice. Aged-GTE at 5 mg/ml in orange juice, apple juice, horchata and milk reduced HAV infectivity by 1.2, 2.1, 1.5, and 1.7 log, respectively. Additionally, aged-GTE at 5 mg/ml in simulated intestinal fluid reduced MNV titers to undetectable levels and reduced HAV infectivity by ca. 2.0 log. The results show a potential for aged-GTE as a suitable natural option for preventive strategies for foodborne viral diseases.