Molecular interactions between (-)-epigallocatechin gallate analogs and pancreatic lipase

Natural compounds as obesity pharmacotherapies

Obesity has become a serious global public health problem, affecting over 988 million people worldwide. Nevertheless, current pharmacotherapies have proven inadequate. Natural compounds have garnered significant attention due to their potential antiobesity effects. Over the past three decades, ca. 50 natural compounds have been evaluated for the preventive and/or therapeutic effects on obesity in animals and humans. However, variations in the antiobesity efficacies among these natural compounds have been substantial, owing to differences in experimental designs, including variations in animal models, dosages, treatment durations, and administration methods. The feasibility of employing these natural compounds as pharmacotherapies for obesity remained uncertain. In this review, we systematically summarized the antiobesity efficacy and mechanisms of action of each natural compound in animal models. This comprehensive review furnishes valuable insights for the development of antiobesity medications based on natural compounds.

Ultrasonic-assisted enzymatic improvement of polyphenol content, antioxidant potential, and in vitro inhibitory effect on digestive enzymes of Miang extracts

The aims of this research were to optimize the ultrasonic-assisted enzymatic extraction of polyphenols under Miang and tannase treatment conditions for the improvement of antioxidant activity of Miang extracts via response surface methodology. Miang extracts treated with and without tannase were investigated for their inhibitory effects on digestive enzymes. The optimal conditions for ultrasonic-assisted enzymatic extraction of the highest total polyphenol (TP) (136.91 mg GAE/g dw) and total flavonoid (TF) (5.38 mg QE/g dw) contents were as follows: 1 U/g cellulase, 1 U/g xylanase, 1 U/g pectinase, temperature (74 °C), and time (45 min). The antioxidant activity of this extract was enhanced by the addition of tannase obtained from Sporidiobolus ruineniae A45.2 undergoing ultrasonic treatment and under optimal conditions (360 mU/g dw, 51 °C for 25 min). The ultrasonic-assisted enzymatic extraction selectively promoted the extraction of gallated catechins from Miang. Tannase treatment improved the ABTS and DPPH radical scavenging activities of untreated Miang extracts by 1.3 times. The treated Miang extracts possessed higher IC₅₀ values for porcine pancreatic α-amylase inhibitory activity than those that were untreated. However, it expressed approximately 3 times lower IC₅₀ values for porcine pancreatic lipase (PPL) inhibitory activity indicating a marked improvement in inhibitory activity. The molecular docking results support the contention that epigallocatechin, epicatechin, and catechin obtained via the biotransformation of the Miang extracts played a crucial role in the inhibitory activity of PPL. Overall, the tannase treated Miang extract could serve as a functional food and beneficial ingredient in medicinal products developed for obesity prevention.

Cross-linking effects of EGCG on myofibrillar protein from common carp (Cyprinus carpio) and the action mechanism

The cross-linking effects and action mechanism of epigallocatechin gallate (EGCG) on myofibrillar protein from common carp (Cyprinus carpio) were investigated. According to particle size, zeta potential, and atomic force microscopy, EGCG could cause the aggregation of myofibrillar protein, while hydrogen bonds and electrostatic interactions were the main molecular forces. With the measurement of Fourier transform infrared spectrum, surface hydrophobicity, fluorescence spectrum, circular dichroism spectrum, and molecular dynamics simulation, EGCG could make the spatial configuration of myofibrillar protein loose, enhance the exposure of amino acid residues, and further change its secondary and tertiary structures by forming intermolecular and intramolecular hydrogen bonds with myofibrillar protein. In addition, the gel properties of myofibrillar protein were improved by EGCG. All results suggested that EGCG had the cross-linking effects on myofibrillar protein in carp meat and could further improve its properties, which showed the potential to improve the qualities of fish meat in food industry. PRACTICAL APPLICATIONS: Compared with other meat, fish meat is particularly easy to break and deteriorate during its processing and sales due to the short length and low cross-linking degree of fish myofibrillar protein, which shows some negative impacts on the quality of fish meat. In the present study, epigallocatechin gallate (EGCG) showed the significant cross-linking effects on carp myofibrillar protein and further improved its physicochemical properties. All results suggested that EGCG had the potential to increase the cross-linking degree of fish myofibrillar protein and improve its properties, so as to ameliorate the quality of fish meat during processing and storage.

Polyphenols and Lactobacillus reuteri in oral health

Oral health is one of the necessary preludes to the overall quality of life. Several medical procedures and therapies are available to treat oral diseases in general and periodontal diseases in particular, yet caries, periodontitis, oral cancer, and oral infections remain a global concern. Natural molecules, with their anti-oxidant, anti-inflammatory, and anti-microbic properties, are one of the main sources of oral health and dental health care, and should be supplemented to exploit their beneficial effects. A possible way to improve the intake of these molecules is adhering to a diet that is rich in fruits, vegetables, and probiotics, which has many beneficial properties and can improve overall health and wellbeing. The Mediterranean diet, in particular, provides several beneficial natural molecules, mainly because of the precious nutrients contained in its typical ingredients, mainly plant-based (olives, wine, citrus fruits, and many more). Its beneficial effects on several diseases and in increasing the overall wellbeing of the population are currently being studied by physicians. Among its nutrients, polyphenols (including, among other molecules, lignans, tannins, and flavonoids) seem to be of outmost importance: several studies showed their anticariogenic properties, as well as their effects in decreasing the incidence of non-communicable diseases. Therefore, plant-derived molecules - such as polyphenols - and probiotics - such as Lactobacillus reuteri - have shown a significant potential in treating and curing oral diseases, either alone or in combination, owing to their antioxidant and antimicrobial properties, respectively.

The In Vitro Inhibitory Effect of Selected Asteraceae Plants on Pancreatic Lipase Followed by Phenolic Content Identification through Liquid Chromatography High Resolution Mass Spectrometry (LC-HRMS)

Pancreatic lipase (PNLIP, EC 3.1.1.3) plays a pivotal role in the digestion of dietary lipids, a metabolic pathway directly related to obesity. One of the effective strategies in obesity treatment is the inhibition of PNLIP, which is possible to be achieved by specific phenolic compounds occurring in high abundance in some plants. In this study, a multidisciplinary approach is presented investigating the PNLIP inhibitory effect of 33 plants belonging in the Asteraceae botanical family. In the first stage of the study, a rapid and cost-efficient PNLIP assay in a 96-microwell plate format was developed and important parameters were optimized, e.g., the enzyme substrate. Upon PNLIP assay optimization, aqueous and dichloromethane Asteraceae plant extracts were tested and a cut-off inhibition level was set to further analyze only the samples with a significant inhibitory effect (inhibitory rate > 40%), using an ultra-high-performance liquid chromatography hybrid quadrupole time-of-flight mass spectrometry (UHPLC-q-TOF-MS) method. Specifically, a metabolomic suspect screening was performed and 69 phenolic compounds were tentatively identified, including phenolic acids, flavonoids, flavonoid-3-O-glycosides, and flavonoid-7-O-glycosides, amongst others. In the case of aqueous extracts, phytochemicals known for inducing PNLIP inhibitory effect, e.g., compounds containing galloyl molecules or caffeoylquinic acids, were monitored in Chrysanthemum morifolium, Grindella camporum and Hieracium pilosella extracts. All in all, the presented approach combines in vitro bioactivity measurements to high-end metabolomics to identify phenolic compounds with potential medicinal and/or dietary applications.

4″-Sulfation Is the Major Metabolic Pathway of Epigallocatechin-3-gallate in Humans: Characterization of Metabolites, Enzymatic Analysis, and Pharmacokinetic Profiling

Epigallocatechin-3-gallate (EGCG), a major green tea polyphenol, has beneficial effects on human health. This study aimed to elucidate the detailed EGCG sulfation process to better understand its phase II metabolism, a process required to maximize its health benefits. Results show that kinetic activity of sulfation in the human liver and intestinal cytosol is 2-fold and 60- to 300-fold higher than that of methylation and glucuronidation, respectively, suggesting sulfation as the key metabolic pathway. Moreover, SULT1A1 and SULT1A3 are responsible for sulfation in the liver and intestine, respectively. Additionally, our human ingestion study revealed that the concentration of EGCG-4″-sulfate in human plasma (C_max: 177.9 nmol·L^-1, AUC: 715.2 nmol·h·L^-1) is equivalent to free EGCG (C_max: 233.5 nmol·L^-1, AUC: 664.1 nmol·h·L^-1), suggesting that EGCG-4″-sulfate is the key metabolite. These findings indicate that sulfation is a crucial factor for improving EGCG bioavailability, while also advancing the understanding of the bioactivity and toxicity of EGCG.

Catechins as a Potential Dietary Supplementation in Prevention of Comorbidities Linked with Down Syndrome

Plant-derived polyphenols flavonoids are increasingly being recognized for their medicinal potential. These bioactive compounds derived from plants are gaining more interest in ameliorating adverse health risks because of their low toxicity and few side effects. Among them, therapeutic approaches demonstrated the efficacy of catechins, a major group of flavonoids, in reverting several aspects of Down syndrome, the most common genomic disorder that causes intellectual disability. Down syndrome is characterized by increased incidence of developing Alzheimer's disease, obesity, and subsequent metabolic disorders. In this focused review, we examine the main effects of catechins on comorbidities linked with Down syndrome. We also provide evidence of catechin effects on DYRK1A, a dosage-sensitive gene encoding a protein kinase involved in brain defects and metabolic disease associated with Down syndrome.

( -)-Epicatechin and cardiometabolic risk factors: a focus on potential mechanisms of action

This review summarizes experimental evidence on the beneficial effects of ( -)-epicatechin (EC) attenuating major cardiometabolic risk factors, i.e., dyslipidemias, obesity (adipose tissue dysfunction), hyperglycemia (insulin resistance), and hypertension (endothelial dysfunction). Studies in humans are revised and complemented with experiments in animal models, and cultured cells, aiming to understand the molecular mechanisms involved in EC-mediated effects. Firstly, an assessment of EC metabolism gives relevance to both conjugated-EC metabolites product of host metabolism and microbiota-derived species. Integration and analysis of results stress the maintenance of redox homeostasis and mitigation of inflammation as relevant processes associated with cardiometabolic diseases. In these processes, EC appears having significant effects regulating NADPH oxidase (NOX)-dependent oxidant production, nitric oxide (NO) production, and energy homeostasis (mitochondrial biogenesis and function). The potential participation of cell membranes and membrane-bound receptors is also discussed in terms of direct molecular action of EC and EC metabolites reaching cells and tissues.

Gut microbiota as a driver of the interindividual variability of cardiometabolic effects from tea polyphenols

Tea polyphenols have been extensively studied for their preventive properties against cardiometabolic diseases. Nevertheless, the evidence of these effects from human intervention studies is not always consistent, mainly because of a large interindividual variability. The bioavailability of tea polyphenols is low, and metabolism of tea polyphenols highly depends on individual gut microbiota. The accompanying reciprocal relationship between tea polyphenols and gut microbiota may result in alterations in the cardiometabolic effects, however, the underlying mechanism of which is little explored. This review summarizes tea polyphenols-microbiota interaction and its contribution to interindividual variability in cardiometabolic effects. Currently, only a few bacteria that can biodegrade tea polyphenols have been identified and generated metabolites and their bioactivities in metabolic pathways are not fully elucidated. A deeper understanding of the role of complex interaction necessitates fully individualized data, the ntegration of multiple-omics platforms and development of polyphenol-centered databases. Knowledge of this microbial contribution will enable the functional stratification of individuals in the gut microbiota profile (metabotypes) to clarify interindividual variability in the health effects of tea polyphenols. This could be used to predict individual responses to tea polyphenols consumption, hence bringing us closer to personalized nutrition with optimal dose and additional supplementation of specific microorganisms.

Camellia nitidissima Chi leaf as pancreatic lipase inhibitors: Inhibition potentials and mechanism

In this study, Camellia nitidissima Chi leaf extract was investigated for its compounds and pancreatic lipase inhibitory potentials. The interaction was determined using ultraviolet (UV) spectroscopy, circular dichroism (CD), fluorescence spectroscopy (FS), and molecular docking to understand the inhibiton, kinetic, and conformation of extraction-pancreatic lipase complex. C. nitidissima Chi leaf extraction inhibited the pancreatic lipase activity in a dose-dependent manner at the concentration of 1-12 mg/ml. The Lineweaver-Burk plots indicated that the inhibition on pancreatic lipase by extraction was noncompetitive. In addition, the decrease in α-helix contents, increase in β-sheet and β-turn, and decrease in fluorescence intensity after extraction treatment indicated that the conformation of pancreatic lipase was changed. This work revealed that C. nitidissima Chi leaf extraction played a significant role in inhibiting pancreatic lipase activity and brought out a solution of delay fat accumulation. PRACTICAL APPLICATIONS: This study reports the components in the extract of C. nitidissima Chi leaf and its inhibitory effect and mechanism of pancreatic lipase. C. nitidissima Chi leaf is a good source of bioactive components, including multiflorin B, kaempferol-3-O-rutinoside, vicenin-2, apigenin-6-C-pentosyl-8-C-hexosyl, vitexin, kaempferol, and other ingredients. It can inhibit pancreatic lipase and be used to control obesity and treat hyperlipidemia. This study also revealed the structure changes of C. nitidissima Chi leaf extract on pancreatic lipase, and further revealed the inhibitory mechanism of C. nitidissima Chi leaf extract on lipase, which provides a theoretical basis for C. nitidissima Chi leaf as a lipase inhibitor.

Discovery of anthocyanins from cranberry extract as pancreatic lipase inhibitors using a combined approach of ultrafiltration, molecular simulation and spectroscopy

Obesity is a chronic disease that has been causing serious problems all over the world. However, there is a lack of available therapeutic approaches to treat obesity. The FDA-approved drug orlistat has severe side effects, such as abdominal pain, flatulence and oily stool. As the therapeutic target of orlistat is pancreatic lipase, there is an urgent need for discovery of new pancreatic lipase inhibitors from natural sources that have reduced side effects compared with orlistat. In this study, ultrafiltration in combination with molecular simulation and spectroscopy was reported as an effective approach for identifying new pancreatic lipase inhibitors from anthocyanin-rich berry sources. Using this approach, four monomeric anthocyanins cyanidin-3-O-arabinoside (C3A), cyanidin-3-O-galactoside (C3Ga), peonidin-3-O-arabinoside (Pn3A) and peonidin-3-O-galactoside (Pn3Ga) from cranberries were discovered as potent pancreatic lipase inhibitors. These four cranberry anthocyanins were shown to form hydrophobic interactions and hydrogen bonds with pocket amino acid residues in molecular docking and molecular dynamics simulations. C3A showed greater impact on secondary structures of the enzyme and showed higher binding capacity with the enzyme compared with C3Ga, Pn3A and Pn3Ga as observed by CD and fluorescence spectroscopy. The structure-activity relationships were then investigated and summarized as both the structures of the B ring and glycosyl group were related to the inhibitory activities of anthocyanins. In short, our results suggested that cranberry anthocyanins could be developed as food supplements to facilitate the prevention and treatment of obesity.

Targeting Carbohydrates and Polyphenols for a Healthy Microbiome and Healthy Weight

Purpose of Review

In this review, we focus on microbiota modulation using non-digestible carbohydrate and polyphenols (i.e., prebiotics) that have the potential to modulate body weight.

Recent Findings

Prebiotics derived from plants have gained the interest of public and scientific communities as they may prevent diseases and help maintain health.

Summary

Maintaining a healthy body weight is key to reducing the risk of developing chronic metabolic complications. However, the prevalence of obesity has increased to pandemic proportions and is now ranked globally in the top five risk factors for death. While diet and behavioral modification programs aiming to reduce weight gain and promote weight loss are effective in the short term, they remain insufficient over the long haul as compliance is often low and weight regain is very common. As a result, novel dietary strategies targeting the gut microbiota have been successful in decreasing obesity and metabolic disorders via different molecular mechanisms.

Inhibitory effects of a sulfated polysaccharide isolated from edible red alga Bangia fusco-purpurea on α-amylase and α-glucosidase

In this study, a sulfated polysaccharide (BFP) was isolated from the edible red alga Bangia fusco-purpurea. Gel-filtration and thin layer chromatographically analyses suggested that BFP was a homogenous polysaccharide. The chemical structural analysis revealed that BFP mainly consisted of galactose together with a small amount of uronic acid, mannose, and glucose. Its molecular mass was estimated to be 133.18 kDa by high-performance liquid chromatography (HPLC) analysis. BFP inhibited α-amylase and α-glucosidase in a concentration-dependent manner. The IC50 values of BFP against α-amylase and α-glucosidase were estimated to be 1.26 ± 0.11 mg/mL and 1.34 ± 0.07 mg/mL, respectively. Kinetic analyses suggested that BFP showed competitive and non-competitive inhibition against α-amylase and α-glucosidase, respectively. Circular dichroism spectral and fluorescence spectral analyses suggested that BFP affects the conformational structures of these enzymes, which may lead to the inhibition of the enzymatic activities.

Abbreviations: Ara: D-arabinose; AnGal: anhydro-L-galactose residues; CD spectroscopy: Circular Dichroism spectroscopy; DNS: dinitrosalicylic acid; FT-IR: fourier transform infrared spectra; Fuc: L-fucose; Gal: D-galactose; Glc: D-glucose; GlcA: D-Glucuronic acid; HPLC: high performance liquid chromatography; Man: D-mannose; pNPG: p-nitrophenyl-α-D-glucoside; TFA: trifluoroacetic acid; TLC: thin-layer chromatography; PMP: 1-phenyl-3-methyl-5-pyrazolone; Xyl: D-xylose

Inhibition of CpLIP2 Lipase Hydrolytic Activity by Four Flavonols (Galangin, Kaempferol, Quercetin, Myricetin) Compared to Orlistat and Their Binding Mechanisms Studied by Quenching of Fluorescence

The inhibition of recombinant CpLIP2 lipase/acyltransferase from Candida parapsiolosis was considered a key model for novel antifungal drug discovery and a potential therapeutic target for candidiasis. Lipases have identified recently as potent virulence factors in C. parapsilosis and some other yeasts. The inhibition effects of orlistat and four flavonols (galangin, kaempferol, quercetin and myricetin) characterized by an increasing degree of hydroxylation in B-ring, were investigated using ethyl oleate hydrolysis as the model reaction. Orlistat and kaempferol (14 µM) strongly inhibited CpLIP2 catalytic activity within 1 min of pre-incubation, by 90% and 80%, respectively. The relative potency of flavonols as inhibitors was: kaempferol > quercetin > myricetin > galangin. The results suggested that orlistat bound to the catalytic site while kaempferol interacted with W294 on the protein lid. A static mechanism of interactions between flavonols and CpLIP2 lipase was confirmed by fluorescence quenching analyses, indicating that the interactions were mainly driven by hydrophobic bonds and electrostatic forces. From the Lehrer equation, fractions of tryptophan accessibility to the quencher were evaluated, and a relationship with the calculated number of binding sites was suggested.

Thermodynamic and computational analyses reveal the functional roles of the galloyl group of tea catechins in molecular recognition

Catechins, biologically active polyphenols in green tea, exhibit various biological activities, such as anticancer and antiviral activities, arising from interactions with functional proteins. However, the molecular details of these interactions remain unclear. In this study, we investigated the interactions between human serum albumin (HSA) and various catechins, including some with a galloyl group, by means of isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), and docking simulations. Our results indicate that the galloyl group was important for recognition by HSA and was responsible for enthalpic gains derived from a larger buried surface area and more van der Waals contacts. Thus, our thermodynamic and computational analyses suggest that the galloyl group plays important functional roles in the specific binding of catechins to proteins, implying that the biological activities of these compounds may be due in part to the physicochemical characteristics of the galloyl group.

The Role of Polyphenols in Human Health and Food Systems: A Mini-Review

This narrative mini- review summarizes current knowledge of the role of polyphenols in health outcomes-and non-communicable diseases specifically-and discusses the implications of this evidence for public health, and for future directions for public health practice, policy, and research. The publications cited originate mainly from animal models and feeding experiments, as well as human cohort and case-control studies. Hypothesized protective effects of polyphenols in acute and chronic diseases, including obesity, neurodegenerative diseases, type 2 diabetes, and cardiovascular diseases, are evaluated. Potential harmful effects of some polyphenols are also considered, counterbalanced with the limited evidence of harm in the research literature. Recent international governmental regulations are discussed, as the safety and health claims of only a few specific polyphenolic compounds have been officially sanctioned. The implications of food processing on the bioavailability of polyphenols are also assessed, in addition to the health claims and marketing of polyphenols as a functional food. Finally, this mini-review asserts the need for increased regulation and guidelines for polyphenol consumption and supplementation in order to ensure consumers remain safe and informed about polyphenols.

Computational Molecular Docking and X-ray Crystallographic Studies of Catechins in New Drug Design Strategies

Epidemiological and laboratory studies have shown that green tea and green tea catechins exert beneficial effects on a variety of diseases, including cancer, metabolic syndrome, infectious diseases, and neurodegenerative diseases. In most cases, (-)-epigallocatechin gallate (EGCG) has been shown to play a central role in these effects by green tea. Catechins from other plant sources have also shown health benefits. Many studies have revealed that the binding of EGCG and other catechins to proteins is involved in its action mechanism. Computational docking analysis (CMDA) and X-ray crystallographic analysis (XCA) have provided detailed information on catechin-protein interactions. Several of these studies have revealed that the galloyl moiety anchors it to the cleft of proteins through interactions with its hydroxyl groups, explaining the higher activity of galloylated catechins such as EGCG and epicatechin gallate than non-galloylated catechins. In this paper, we review the results of CMDA and XCA of EGCG and other plant catechins to understand catechin-protein interactions with the expectation of developing new drugs with health-promoting properties.

In Vitro and In Silico Studies of the Molecular Interactions of Epigallocatechin-3-O-gallate (EGCG) with Proteins That Explain the Health Benefits of Green Tea

Green tea has been shown to have beneficial effects on many diseases such as cancer, obesity, inflammatory diseases, and neurodegenerative disorders. The major green tea component, epigallocatechin-3-O-gallate (EGCG), has been demonstrated to contribute to these effects through its anti-oxidative and pro-oxidative properties. Furthermore, several lines of evidence have indicated that the binding affinity of EGCG to specific proteins may explain its mechanism of action. This review article aims to reveal how EGCG-protein interactions can explain the mechanism by which green tea/EGCG can exhibit health beneficial effects. We conducted a literature search, using mainly the PubMed database. The results showed that several methods such as dot assays, affinity gel chromatography, surface plasmon resonance, computational docking analyses, and X-ray crystallography have been used for this purpose. These studies have provided evidence to show how EGCG can fit or occupy the position in or near functional sites and induce a conformational change, including a quaternary conformational change in some cases. Active site blocking, steric hindrance by binding of EGCG near an active site or induced conformational change appeared to cause inhibition of enzymatic activity and other biological activities of proteins, which are related to EGCG’s biological oligomer and formation of their toxic aggregates, leading to the prevention of neurodegenerative diseases and amyloidosis. In conclusion, these studies have provided useful information on the action of green tea/catechins and would lead to future studies that will provide further evidence for rational EGCG therapy and use EGCG as a lead compound for drug design.

A Review on the Weight-Loss Effects of Oxidized Tea Polyphenols

The mechanistic systems in the body through which tea causes weight loss are complex and multi-dimensional. Additionally, the bioactive components in tea such as catechins, caffeine, and products of tea polyphenol oxidation vary greatly from one major tea type to the next. Green tea has been the primary subject of consideration for investigation into the preventative health effects of tea because it contains the highest levels of phenolic compounds and retains the highest antioxidant capabilities of any major tea type. However, recent research suggests decreasing body fat accumulation has little to do with antioxidant activity and more to do with enzyme inhibition, and gut microbiota interactions. This paper reviews several different tea polyphenol-induced weight-loss mechanisms, and purposes a way in which these mechanisms may be interrelated. Our original 'short-chain fatty acid (SCFA) hypothesis' suggests that the weight-loss efficacy of a given tea is determined by a combination of carbohydrate digestive enzyme inhibition and subsequent reactions of undigested carbohydrates with gut microbiota. These reactions among residual carbohydrates, tea polyphenols, and gut microbiota within the colon produce short-chain fatty acids, which enhance lipid metabolism through AMP-activated protein kinase (AMPK) activation. Some evidence suggests the mechanisms involved in SCFA generation may be triggered more strongly by teas that have undergone fermentation (black, oolong, and dark) than by non-fermented (green) teas. We discussed the mechanistic differences among fermented and non-fermented teas in terms of enzyme inhibition, interactions with gut microbiota, SCFA generation, and lipid metabolism. The inconsistent results and possible causes behind them are also discussed.

The Inhibitory Effects of Anthocyanin-Rich Sunrouge Tea on Pancreatic Lipase Activity

This study investigated the in vitro and in vivo effects of Sunrouge (SR), which is an anthocyaninrich green tea. Hot and cold water extracts (CWEX) of Yabukita (YK; regular green tea), SR second crop (SR2), and SR third crop (SR3) were prepared. The 50% inhibitory concentrations for YK, SR2, and SR3 CWEXs against pancreatic lipase in vitro were 12.3±2.8, 6.2±0.3, and 4.0±1.1 mg/mL, respectively. Epigallocatechin gallate (EGCG) accounted for 4.3%, 6.0%, and 6.3% of YK, SR2, and SR3 CWEXs, respectively. SR2 had the highest anthocyanin content of these three samples. In vivo, the increase in the plasma triacylglycerol (TG) concentration following oral administration of oil to mice was significantly suppressed at 60 and 120 min in animals treated with SR2. No significant differences were observed between the plasma TG concentration in the YK and control groups. These results suggested that concomitant administration of SR with oil may suppress lipid absorption and that EGCG may exert this effect.

Antioxidants from black and green tea: from dietary modulation of oxidative stress to pharmacological mechanisms

The consumption of tea (Camellia sinensis) has been correlated with a low incidence of chronic pathologies, such as cardiovascular disease and cancer, in which oxidative stress plays a critical role. Tea catechins and theaflavins are, respectively, the bioactive phytochemicals responsible for the antioxidant activity of green tea (GT) and black tea (BT). In addition to their redox properties, tea catechins and theaflavins could have also pharmacological activities, such as the ability to lower glucose, lipid and uric acid (UA) levels. These activities are mediated by pharmacological mechanisms such as enzymatic inhibition and interaction with transporters. Epigallocatechin gallate is the most active compound at inhibiting the enzymes involved in cholesterol and UA metabolism (hydroxy-3-methyl-glutaryl-CoA reductase and xanthine oxidase respectively) and affecting glucose transporters. The structural features of catechins that significantly contribute to their pharmacological effect are the presence/absence of the galloyl moiety and the number and positions of the hydroxyl groups on the rings. Although the inhibitory effects on α-glucosidase, maltase, amylase and lipase, multidrug resistance 1, organic anion transporters and proton-coupled folate transport occur at higher concentrations than those apparent in the circulation, these effects could be relevant in the gut. In conclusion, despite the urgent need for further research in humans, the regular consumption of moderate quantities of GT and BT can effectively modulate their antioxidant capacity, mainly in people subjected to oxidative stress, and could improve the metabolism of glucose, lipid and UA.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Polyphenolic Compounds and Digestive Enzymes: In Vitro Non-Covalent Interactions

The digestive enzymes–polyphenolic compounds (PCs) interactions behind the inhibition of these enzymes have not been completely studied. The existing studies have mainly analyzed polyphenolic extracts and reported inhibition percentages of catalytic activities determined by UV-Vis spectroscopy techniques. Recently, pure PCs and new methods such as isothermal titration calorimetry and circular dichroism have been applied to describe these interactions. The present review focuses on PCs structural characteristics behind the inhibition of digestive enzymes, and progress of the used methods. Some characteristics such as molecular weight, number and position of substitution, and glycosylation of flavonoids seem to be related to the inhibitory effect of PCs; also, this effect seems to be different for carbohydrate-hydrolyzing enzymes and proteases. The digestive enzyme–PCs molecular interactions have shown that non-covalent binding, mostly by van der Waals forces, hydrogen binding, hydrophobic binding, and other electrostatic forces regulate them. These interactions were mainly associated to non-competitive type inhibitions of the enzymatic activities. The present review emphasizes on the digestive enzymes such as α-glycosidase (AG), α-amylase (PA), lipase (PL), pepsin (PE), trypsin (TP), and chymotrypsin (CT). Existing studies conducted in vitro allow one to elucidate the characteristics of the structure–function relationships, where differences between the structures of PCs might be the reason for different in vivo effects.

Inhibition of pancreatic lipase by black tea theaflavins: Comparative enzymology and in silico modeling studies

Few studies have examined the effect of black tea (Camellia sinensis) theaflavins on obesity-related targets. Pancreatic lipase (PL) plays a central role in fat metabolism and is a validated target for weight loss. We compared the inhibitory efficacy of individual theaflavins and explored the underlying mechanism. Theaflavin-3,3'-digallate (TFdiG), theaflavin-3'-gallate, theaflavin-3-gallate, and theaflavin inhibited PL with IC50 of 1.9, 4.2, 3.0, and >10μmol/L. The presence and location of the galloyl ester moiety were essential for inhibitory potency. TFdiG exhibited mixed inhibition with respect to substrate concentration. In silico modeling showed that theaflavins bind to Asn263 and Asp206, which form a pocket adjacent to the active site, and galloyl-containing theaflavins are then predicted to perturb the protonation of His264. These data provide a putative mechanism to explain the anti-obesity effects of tea.

Advancing insights on the anti-obesity biochemical mechanism of (−)-epigallocatechin gallate (EGCG) by inhibiting α-amylase activity

The biochemical mechanisms of EGCG against human salivary α-amylase are comprehensively investigated in vitro as well as histological analyses and physiological indexes of obesity mice in vivo after 30 day EGCG oral administration.

Preliminary investigations on a polygalacturonase from Aspergillus fumigatus in Chinese Pu’er tea fermentation

Background

Polygalacturonase is one kind of pectinases which hydrolyze the alpha-1,4 glycosidic bond between galacturonic acid residue. Polygalacturonase has been widely used in the fields of food, biofuel, and textile industries, in which thermostable polygalacturonase is often demanded at high temperatures of 50–60 °C. Herein, we reported a thermostable polygalacturonase producing from Aspergillus fumigatus isolated from the pile fermentation of Pu’er tea in China.

Results

The thermophilic polygalacturonase-producing strain was identified as A. fumigatus L45 on basis of its morphology, physicochemical properties, and 18S rDNA analysis. The crucial fermentation parameters affecting polygalacturonase activity were optimized by response surface methodology (RSM); the optimum fermentation parameters were the following: inoculums concentration of 0.07 % (v/v), fermentation time of 36 h, pH of 5.0, and temperature of 45 °C. Under the optimized conditions, the highest polygalacturonase activity of 359.1 ± 10.1 U/mL was obtained. The polygalacturonase showed good thermostability and pH stability. The enzyme was activated by metal ions Zn2+ and Mg2+, but inhibited by K+. However, Na+ and Ca2+ showed little effects on its activity. K m and V max values were estimated to be 35.0 mg/mL and 7.69 μmol/mL/min, respectively.

Conclusions

A polygalacturonase from A. fumigatus L45 was preliminarily investigated, the crucial fermentation parameters were optimized by RSM, and the properties of polygalacturonase was examined. The polygalacturonase showed good thermostability and pH stability, which suggested the enzyme has potential applications in the biofuel and textile industries.

Epigallocatechin Gallate: A Review of Its Beneficial Properties to Prevent Metabolic Syndrome

Obesity and being overweight are linked with a cluster of metabolic and vascular disorders that have been termed the metabolic syndrome. This syndrome promotes the incidence of cardiovascular diseases that are an important public health problem because they represent a major cause of death worldwide. Whereas there is not a universally-accepted set of diagnostic criteria, most expert groups agree that this syndrome is defined by an endothelial dysfunction, an impaired insulin sensitivity and hyperglycemia, dyslipidemia, abdominal obesity and hypertension. Epidemiological studies suggest that the beneficial cardiovascular health effects of diets rich in green tea are, in part, mediated by their flavonoid content, with particular benefits provided by members of this family such as epigallocatechin gallate (EGCG). Although their bioavailability is discussed, various studies suggest that EGCG modulates cellular and molecular mechanisms of various symptoms leading to metabolic syndrome. Therefore, according to in vitro and in vivo model data, this review attempts to increase our understanding about the beneficial properties of EGCG to prevent metabolic syndrome.

Structural characteristics of (−)-epigallocatechin-3-gallate inhibiting amyloid Aβ42 aggregation and remodeling amyloid fibers

To elucidate the structural requirements of EGCG analogs inhibiting Aβ42 protein aggregation and remodeling amyloid fibers, the interactions mechanism between Aβ42 and four EGCG analogs, EGCG, GCG, ECG and EGC, were investigated in this work.