Digestion support catechins -
After the addition of β-lactoglobulin β-Lg , epigallocatechin gallate EGCG , epigallocatechin EGC , and epicatechin EC bioaccessibility increased by The addition of β-casein β-CN negatively affected EGCG and EGC bioaccessibility but significantly increased EC bioaccessibility.
The addition of β-Lg and β-CN showed better protective effects on antioxidant activity. The bioaccessibility of tea catechins mixed with β-Lg is significantly higher than that of tea catechins mixed with β-CN in the gastrointestinal digestion stage, except for the mixture of EC and β-CN.
The increase in catechin bioaccessibility and antioxidant activity was positively correlated to the binding affinity of catechins-proteins. Keywords: Antioxidant activity; Bioaccessibility; Catechins; Competitive interactions; Digestive enzymes; Milk protein; Protein digestibility.
Honda and Hara have previously reported that GTE inhibited human salivary α-amylase Another study evaluated the inhibitory effects of GTE and its catechins on α-amylase and α-glucosidase activity in comparison with acarbose.
GTE especially EGCG was a stronger inhibitor than the latter Similar results evaluating EGCG activity were obtained in starch-fed mice Despite a few studies conducted in animal models 24 , 25 , 26 , 27 , little is known about the impact of pure GTE on starch digestion and absorption in humans.
The research carried out in healthy Asians provided evidence that a beverage containing 0. Although suggestive of an influence of green tea on inhibiting starch digestion and absorption, this data is confounded by the complicated mixture of three teas and the use of a rice-based meal rather than pure starch.
In contrast to the aforementioned study we used GTE alone. We avoided different biological interactions between compounds of three teas this way. The variety of green tea extract components as well as their effects on humans have been extensively studied. The study of Gao et al. shows that GTE and its polyphenols namely EGCG, strongly suppress the α-glucosidase in vitro Based on the half maximal inhibitory concentration IC 50 values, GTE, green tea polyphenols and EGCG alone demonstrate — times the efficacy of acarbose IC 50 values of GTE, green tea polyphenols and EGCG against α-glucosidase were 4.
In regard to α-amylase, it was not strongly inhibited by these substances. Similar results were obtained in the study of Yang et al. who proved, consistently with the previous report, that the inhibition of α-glucosidase by tea polyphenols is noncompetitive 13 , Furthermore, Gao et al.
also reported that the combination of acarbose and GTE, EGCG, or green tea polyphenols show combined inhibitory effects at certain concentrations Therefore, it could be expected that joined therapy with GTE or green tea polyphenols or EGCG may diminish the dose of acarbose needed in therapy, hence weaken the side effects of acarbose alone.
The aforesaid findings indicate that green tea or functional food based on green tea could be applicable for complementary therapy in postprandial hyperglycemia. We used naturally 13 C abundant cornflakes as a source of starch. The physical form of starch, the method of its processing or the size of the particle are a vital factors that may influence the hydrolysis and glycemic response in subjects Commercially available cereals used in the study, were produced via an extrusion process, which gives starch a high degree of gelatinization.
Based on the study of Hiele et al. starch in this formation is more rapidly hydrolysed than native starch Maize, a representative of C4 photosynthesizing plants incorporates more 13 C atoms into the starch than C3 plants do e.
European grain, potatoes, rice. The typical Polish diet in contrast to the American diet contains foodstuffs like potatoes, rye, wheat, beet sugar and to lesser extent maize, therefore maintaining the conditions of the test was easier. Our data suggest that the use of GTE is a viable alternative to pharmaceutical inhibitors of glucoside hydrolase enzymes.
This plant extract is widely available, inexpensive and well tolerated, so it has potential utility for weight control and the treatment of diabetes.
Our study supports the concept that pure GTE inhibits starch digestion and absorption. However, the clinical significance of each green tea catechin and the exact mechanism responsible for this action in humans remain to be determined. The study comprised of 28 healthy, adult volunteers 19 women and 9 men, aged 19—26 years old recruited from Vocational Technical High School for Computer Science in Nakło nad Notecią, Poland Table 3.
All subjects were recruited after they presented at an appointed meeting and showed willingness to participate the study, which was thereafter confirmed by informed written consent.
The health status was defined as such: no physical complaints in the month preceding the study, no acute or chronic disease, no current pharmacotherapy, no past hospitalizations for gastroenterological indications and good nutritional status defined as weight, height and BMI within normal reference values.
As the subjects were to ingest milk, a hydrogen-methane breath test was performed in each subject, to exclude lactose malabsorption. In the first week of study, some of the participants ingested the test meal with GTE while the others ingested placebo.
The second test followed in a crossover manner. One week later, subjects who took GTE in the previous test were given placebo and those receiving placebo in the previous week were given GTE. In this way subjects were internal self-controls to themselves.
Exclusion criteria comprised: celiac disease, exocrine pancreatic insufficiency 32 , 33 and other gastrointestinal diseases, pharmacotherapeutics that might affect digestion and absorption of carbohydrates, antibiotic therapy within the preceding month and the use of beverages composed of green tea within the preceding month.
All subjects fasted for hours. The subjects were assigned to the groups randomly. One week later, the procedure was repeated, though the subjects ingested the opposite preparation from that ingested in the initial study. The subjects were also instructed to not eat any food with a naturally increased 13 C content, such as products made of maize, cane sugar, pineapple, kiwi fruit for 5 days preceding the examination.
The participants were asked not to consume any additional food or beverages and not to perform any physical activity in order to limit the glucose oxidation level and to only obtain the rate of starch hydrolysis.
CPDR was considered to reflect digestion and absorption of dietary starch. GTE was prepared according to the protocol described by Bajerska et al.
Elena, Zelazkow, Poland. One gram of green tea aqueous extract dry matter contained 7. The study was carried out in accordance with the Declaration of Helsinki. Every subject provided written consent to participate after being informed about the aim and protocol of the research. Results are expressed as medians and interquartile ranges.
The statistical significance of differences between GTE and placebo tests was determined with the use of the Wilcoxon rank-sum test. How to cite this article : Lochocka, K. et al. Green tea extract decreases starch digestion and absorption from a test meal in humans: a randomized, placebo-controlled crossover study.
Ng, M. Global, regional and national prevalence of overweight and obesity in children and adults during — a systematic analysis for the Global Burden of Disease Study The Lancet , — Article Google Scholar. Aller, E. Starches, sugars and obesity.
Nutrients 3, — Article CAS Google Scholar. Saris, W. Simple carbohydrates and obesity: Fact, Fiction and Future. Rains, T. Antiobesity effects of green tea catechins: a mechanistic review. Suzuki, Y. Health-promoting effects of green tea. B Phys. Wolfram, S. Anti-obesity effects of green tea: from bedside to bench.
Food Res. Collins, Q. Raederstorff, D. Effect of EGCG on lipid absorption and plasma lipid levels in rats. Juśkiewicz, J.
Extract of green tea leaves partially attenuates streptozotocin-induced changes in antioxidant status and gastrointestinal functioning in rats. Sabu, M. Anti-diabetic activity of green tea polyphenols and their role in reducing oxidative stress in experimental diabetes.
Epigallocatechin gallate supplementation alleviates diabetes in rodents. Polychronopoulos, E. Effects of black and green tea consumption on blood glucose levels in non-obese elderly men and women from Mediterranean Islands MEDIS epidemiological study. Yang, X. Evaluation of the in vitro α-glucosidase inhibitory activity of green tea polyphenols and different tea types.
Food Agric. Kanwar, J. Recent advances on tea polyphenols. Elite Ed. Jonderko, K. Feasibility of a breath test with a substrate of natural 13C-abundance and isotope-selective non-dispersive infrared spectrometry: A preliminary study.
Walkowiak, J. Single dose of green tea extract decreases lipid digestion and absorption from a test meal in humans. Acta Biochim. Chow, H. Phase I pharmacokinetic study of tea polyphenols following single-dose administration of epigallocatechin gallate and polyphenon E.
Cancer Epidemiol. Cancer Res. Cosponsored Am. CAS Google Scholar. Lacroix, M. Glucose naturally labeled with carbon use for metabolic studies in man.
Science , — Article ADS CAS Google Scholar. Hiele, M. Gut 31, — Yilmazer-Musa, M. Grape Seed and Tea Extracts and Catechin 3-Gallates Are Potent Inhibitors of α-Amylase and α-Glucosidase Activity.
Food Chem. McDougall, G. Different polyphenolic components of soft fruits inhibit alpha-amylase and alpha-glucosidase. Hara, Y. The inhibition of. Forester, S. Honda, M. Inhibition of Rat Small Intestinal Sucrase and α -Glucosidase Activities by Tea Polyphenols.
Matsumoto, N. Reduction of Blood Glucose Levels by Tea Catechin. Heber, D. Green Tea, Black Tea and Oolong Tea Polyphenols Reduce Visceral Fat and Inflammation in Mice Fed High-Fat, High-Sucrose Obesogenic Diets.
Liu, J. Effect of green tea catechins on the postprandial glycemic response to starches differing in amylose content.
Zhong, L. An extract of black, green and mulberry teas causes malabsorption of carbohydrate but not of triacylglycerol in healthy volunteers. Gao, J. Combined effects of green tea extracts, green tea polyphenols or epigallocatechin gallate with acarbose on inhibition against α-amylase and α-glucosidase in vitro.
Basel Switz. Gamberucci, A. Green tea flavonols inhibit glucosidase II. Snow, P. Factors affecting the rate of hydrolysis of starch in food. The changing face of the exocrine pancreas in cystic fibrosis: pancreatic sufficiency, pancreatitis and genotype.
Assessment of maldigestion in cystic fibrosis. Bajerska, J. Green tea aqueous extract reduces visceral fat and decreases protein availability in rats fed with a high-fat diet.
N 31, — Download references. Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, Poznan, Poland.
Catehins are provided in two different Antioxidant supplements for aging for consumer and professional Digestion support catechins. These resources are produced by Dr. Actechins Scherr and her research staff. Produced by Michelle Chellino, Hanee Hyun Hee Park, Janice Ho, BS, Rachel E. Scherr, PhD, Carl L. Keen, PhD, Sheri Zidenberg-Cherr, PhD, Center for Nutrition in Schools, Department of Nutrition, University of California, Davis,Digestion support catechins -
In a randomized study conducted on individuals with controlled Type II Diabetes, the catechins in the red wine were reported t significantly increase plasma HDL levels by 2.
Lung Cancer: Research studies have focused on the correlation of COPD Chronic Obstructive Pulmonary Disease and increased lung cancer risk.
Consistent with its putative antioxidant abilities, moderate consumption of red wine has been associated with a reduced risk of lung cancer in comparison to individuals who do not consume red wine 8.
Prostate Cancer: There have been contradicting results regarding consumption of red wine and cancer. Results from some studies suggest that consumption of red wine over a lifetime posed increased risks of prostate cancer.
Further research is needed to better understand the amount and time period of red wine consumption and the associated risks to prostate cancer 9. Conclusions: In light of this research, the American Heart Association does not recommend consumption of alcohol to reduce risk of cardiovascular disease and the American Cancer Society recommends limiting consumption of alcoholic beverages.
If adults choose to drink alcoholic beverages, the Dietary Guidelines for Americans, recommends they do so in moderation. Moderation is considered 1 drink defined as 12 ounces of beer, 5 ounces of wine, 1. Some short term research suggests that percent purple grape juice may be an alcohol free alternative to red wine for those interested in the cardiovascular and anticancer effects of this beverage; however a reduction in development of chronic disease and mortality due to consumption of grape juice has yet to be confirmed 11, If choosing to consume purple grape juice, it is important to follow the Dietary Guidelines for Americans, , and limit juice consumption by choosing whole fruit for the majority of your daily fruit servings 8.
Chocolate Antioxidant capacity is the ability for a compound or compounds to reduce the concentration of free radicals in a given system. Table 1: What is the antioxidant capacity of chocolate? Prev Med. Isbrucker RA, Bausch J, Edwards JA, Wolz E.
Safety studies on epigallocatechingallate EGCG preparations. Part 1: genotoxicity. Food Chem Toxicol. Isbrucker RA, Edwards JA, Wolz E, Davidovich A, Bausch J. Part 2: dermal, acute and short-term toxicity studies.
Part 3: teratogenicity and reproductive toxicity studies in rats. Cellular and in vivo hepatotoxicity caused by green tea phenolic acids and catechins. Free Radic Biol Med. Takami S, Imai T, Hasumura M, Cho YM, Onose J, Hirose M. Evaluation of toxicity of green tea catechins with day dietary administration to F rats.
Ullmann U, Haller J, Decourt JP, Girault N, Girault J, Richard-Caudron AS. A single ascending dose study of epigallocatechingallate in healthy volunteers. J Int Med Res.
Pisters KM, Newman RA, Coldman B, et al. Phase I trial of oral green tea extract in adult patients with solid tumors. J Clin Oncol. PubMed CAS Google Scholar. Gloro R, Hourmand-Ollivier I, Mosquet B, et al. Fulminant hepatitis during self-medication with hydroalcoholic extract of green tea.
Eur J Gastroenterol Hepatol. Jimenez-Saenz M, Martinez-Sanchez MC. Acute hepatitis associated with the use of green tea infusions. J Hepatol. Bonkovsky HL. Hepatotoxicity associated with supplements containing Chinese green tea Camellia sinensis. Molinari M, Watt KD, Kruszyna T, et al.
Acute liver failure induced by green tea extracts: case report and review of the literature. Liver Transpl. Javaid A, Bonkovsky HL. Hepatotoxicity due to extracts of Chinese green tea Camellia sinensis : a growing concern.
Chalasani N, et al. Causes, clinical features, and outcomes from a prospective study of drug induced liver injury in the United States. Fontana RJ, Watkins PB, Bonkovsky HL, et al. Drug-induced liver injury network DILIN prospective study: rationale, design and conduct.
Drug Saf. Vega M, Vuppalanchi R, Bonkovsky H, et al. The US drug induced liver injury network: establishment of an herbal and dietary supplements HDS repository. Google Scholar. Hwang SI, Lee YY, Park JO, et al. Clin Chim Acta. Warning on Hydroxycut Products.
May 1, Seddick M, Lucidarme D, Creusy C, Filoche B. Is exolise hepatotoxic? Gastroenterol Clin Biol. Sarma DN, Barrett ML, Chavez ML, et al. Safety of green tea extracts: a systematic review by the US Pharmacopeia. Lambert JD, Kennett MJ, Sang S, Reuhl KR, Ju J, Yang CS.
Brown JC, Jiang X. Prevalence of antibiotic-resistant bacteria in herbal products. Initial structure of trypsin was taken from Protein Data Bank PDB [ 37 ] www.
org , i. Water molecules in the structure were removed and hydrogen atoms were added using Schrӧdinger[ 39 ]. The protonation states of residues His, Asp, Glu, Arg, Lys, N- and C-terminus were set at pH 7. All residues of protein were then parameterized using the AMBER03 force field[ 42 ].
The structures of EGC and EGCG were retrieved from PDB, and the structures of EC and ECG were obtained by replacing the corresponding hydroxyl group from EGC and EGCG with hydrogen atom, respectively. All these catechin structures then were optimized using B3LYP[ 43 — 48 ] with G d,p basis set implanted in Gaussin09[ 49 ].
The partial charges of atoms in catechins were determined by R. RESP ESP charge Derive [ 50 ], and other atomic parameters were assigned according to general AMBER force field GAFF [ 51 ]. Molecular docking of each catechin to trypsin was carried out by AutoDock Vina[ 52 ], in which the Iterated Local Search Globule Optimizer[ 53 , 54 ] was applied to locate the most favorable binding site.
Semi-flexible docking method was used, where trypsin was treated as a rigid body and all rotatable bonds in the catechins were sampled. Optimal binding sites were searched in a box of 60×60×60 Å 3 that covered the entire exterior of the protein. The box had 1.
In each docking experiment, top 20 models were selected according to the binding affinity calculated by the scoring function in AutoDock Vina. Trypsin-catechin complex structures from docking were further refined in a fully flexible atomic molecular dynamics simulation using NAMD version 2.
A cubic TIP3P water box was used to enclose structure models with a ~10 Å buffering in all three orthogonal dimensions. As a result, the water box size of all systems is ca. In order to exhaustively sample complex structures while keep protein structures close to the native conformation, six phases as listed in Table 1 were carried out.
All three phases of minimization run steps conjugate gradient energy minimization, including solvent relaxation with both protein and ligand structures fixed, ligand and protein side chain relaxation with protein backbone fixed, and relaxation of all atoms.
Then the system was gradually heated to K in a ps relaxation. Subsequently, NPT ensemble equilibration was carried out to achieve the initial configuration equilibrium before a 30 ns NVT dynamics simulation to generate the trajectories of complex structures for analysis.
Here it is worthy to note that we have run an 80 ns MD simulation on the complex. We found that the structural fluctuations of both protein and ligand revealed from the RMSD are quite small see S2 Fig and the binding state has no change during the simulation time, so we keep on 30 ns simulation through all this work.
In each simulation trajectory, complex structures from the last 20 ns MD simulation at a time interval of 10 ps were extracted and used for complex structure analysis and binding free energy calculation.
Further, we clustered these structures using SPICKER[ 56 ] based on the RMSD value of backbone atoms, and the centroid structure of the largest cluster was selected as the typical model for illustrating complex structure.
Langevin thermostat was used to maintain the temperature at K with the dampening coefficient of 5 ps -. Pressure was scaled at 1 atm with Nosé-Hoover Langevin piston method [ 57 — 60 ] with the piston period of fs, the piston decay of 50 fs, and the piston temperature at K.
Periodic boundary conditions were applied and long-range electrostatics were treated using the particle-mesh Ewald PME method[ 61 , 62 ].
Non-bonded interactions were calculated using a cutoff of 12 Å without switch function, and a 14 Å neighbor list was updated every 10 steps of the dynamics. All covalent bonds involving hydrogen atoms were confined by SHAKE algorithm[ 63 , 64 ].
The integrated time step is set to 2 fs, and the coordinates of trajectories were saved every 1 ps throughout all MD simulations. The convergence of MD simulations on the trypsin-catechins complexes was evaluated by the root mean-square deviation RMSD of atoms after superposition, which is defined by 1 where N is the number of atoms, r i and r i , ref is the position of atom i in a structure and in a referent structure, respectively.
In the analysis of simulation trajectories, the PDB structure of trypsin and the best docking structure of catechins were selected as the referent structure. The conformation change and structure fluctuation of protein during simulations also can be traced by the radius of gyration R g , the solvent accessible surface area SASA and the B-factor.
The R g was calculated by 2 where m i and r i are the mass and the position of the i th atom, respectively, and is the mass center. The SASA was computed by the maximal speed molecular surfaces algorithm[ 65 ] implemented in visual molecular dynamics VMD[ 66 ] , using a probe radius of 1.
The B-factor was defined as 3 here, RMSF k is the root-mean-square fluctuation of the atom k. It can be calculated through Eq 1 , in which N is the number of trajectory and r i , ref is the average position of the atom k over all trajectories generated in a MD simulation.
We extracted the models evenly from the last 20 ns MD trajectories to compute the binding free energy between trypsin and catechins, using the molecular mechanics Poisson-Boltzmann solvent accessible surface area MM-PBSA method[ 67 ].
The total binding free energy can be calculated by 4 here, ΔE MM is the change of molecular mechanical energy, ΔG sol is the solvation free energy and TΔS considers the penalty of entropy. Considering that most protein-polyphenol complexes are enthalpy dominant[ 68 ] and the low reliability and high computationally cost[ 69 , 70 ] in entropy computation, we ignored the entropy contributions in the present work.
The ΔE MM includes non-bonded interaction, van der Waals ΔE vdW and electrostatic ΔE ele interactions, and local bonded interaction ΔE int. The last term, which is a sum of bond, angle, and dihedral contributions, is counteracted in single trajectory approach.
The nonpolar term can be further divided into the excluded volume contributed by repulsive interaction ΔG enpolar and the attractive interaction ΔG edisper aroused from the solute-solvent van der Waals dispersion interaction. The ΔE MM and ΔG sol were calculated using Amber[ 71 ] and the PBSA module in AmberTools[ 72 ], respectively.
In the MM-PBSA calculation, a grid spacing of 0. At last, free energy decomposition at residue level ΔG per-decomp also was carried out to provide detailed information of binding site and binding affinity.
Based on the 20 top ranked docking models for each complex, the strongest binding affinities and the occurrence of catechins in the S1 pocket with given orientations were computed and summarized in Table 2.
Typical models with the strongest binding affinities of different catechins were shown in S3 Fig. It can be seen that the majority of binding of catechins occurred at S1 pocket, ranging from For EC and EGC, ring B presents in the S1 pocket with higher probability, in agreement with our recent finding in Monte Carlo simulation of catechin-serum albumin complex[ 73 ].
By comparing catechins with and without the galloyl group, it can be found that the galloyl group can significantly enhance the binding affinity. This is consistent with that catechins with the galloyl group show much stronger binding and inhibitory ability to various functional proteins such as human serum albumin and dopa decarboxylase [ 19 , 74 , 75 ].
According to the structure models shown in S3 Fig , residues in or at the vicinity of binding site, i. With all the four catechins, residues Ser, Gln, Ser and ValSerTrp always contribute conserved hydrogen-bond interactions or hydrophobic contacts.
Besides, Phe41, Cys42 and Leu99 are involved in hydrophobic interactions, and the backbone of Phe41 forms hydrogen-bond interaction with ECG and EGCG. Catechins, which occupy the catalytic pocket S1 with strong interaction with the residues, hinder the natural substrate binding to trypsin.
This indirectly implies that catechins can suppress the hydrolyzed activity of trypsin, in line with experimental observation[ 15 , 17 , 18 ]. Further, since the 2, 3 carbon atoms in catechins are chiral, each catechin has four stereoisomers, i.
The binding affinity and occurrence in the S1 pocket with given orientations for the stereoisomers of EGCG binding to trypsin were summarized in S1 Table , and the docking structure with the superposition of stereoisomers was illustrated in S4 Fig. The natural configuration in tea, 2R-3R EGCG, shows the strongest binding affinity to trypsin, and the S1 pocket is still a conservative binding site for different stereoisomers.
The 30 ns MD simulations initialized from representative trypsin-catechin complex structures from docking and the catechin-free trypsin structure were carried out. Time evolutions of RMSD and R g of trypsin were displayed in Fig 2. The RMSD vs. simulation time is an important profile to estimate the equilibration procedure in the simulation trajectory and the stability of protein structure upon the binding of ligand[ 76 — 78 ].
Our results indicate that the catechin-free and the catechin-complex systems achieve equilibrium in 10 ns simulation. Therefore, we evenly selected structure models from the last 20 ns to analyze the binding mode of catechins to trypsin. The average fluctuations represented by the RMSD for the catechin free-trypsin, EC-trypsin, EGC-trypsin, ECG-trypsin and EGCG-trypsin are 1.
The decrease of RMSD in the complex comparing to the catechin-free trypsin suggests that the stability of the trypsin structure is enhanced upon the binding of catechins.
While the fact that the R g values in the complex are always larger than the catechin-free trypsin suggests that the enhancement in the stability is not a result of protein becoming more compact, but a synergic conformation change to closely contact with catechins. The average solvent accessible surface area SASA of trypsin in the form of free-trypsin, EC-trypsin, EGC-trypsin, ECG-trypsin and EGCG-trypsin were , , , and Å 2 , respectively.
It further confirmed that protein have conformational changes at given regions to facilitate the binding with catechins, and fully flexible MD simulation is indispensible to reveal ligand binding to protein over semi-flexible molecular docking.
Time evolutions of a the backbone RMSD and b the radius of gyration R g of trypsin in MD simulations. Black color indicates trypsin in catechin-free form; red, blue, dark-cyan and magenta indicate trypsin in the complex with EC, ECG, EGC and EGCG, respectively.
To find out the flexibility of residues upon the binding of catechins, Cα B-factor for each residue in trypsin was computed and presented in Fig 3. It can be observed from Fig 3 that the B-factor profile of catechin-free trypsin is similar as the one from X-ray crystallographic measurement saved in the PDB file.
This confirms the reliability to assess flexibility of residues using MD simulation. Further, residues within coil always show higher B-factor value, in agreement with that the residues located at the coil are more flexible. Although binding of catechins only leads to slightly change the whole B-factor profile, B-factors of residues 24—27, 37—39 and 96—99 have a remarkable increase.
None of these regions is in, but at the vicinity of the S1 pocket. Instead, the majority of residues with close contact with catechins have low B-factor value. It clearly demonstrates that trypsin has a local synergic conformation change upon the binding of catechins.
The most protruding region is the residues from to in trypsin with high B-factor in any forms. The first motif of residues in the S1 pocket residues — with a low B-factor is similar both in the complex and catechin-free trypsin.
The other motif in S1 pocket of residues — has high B-factor values, and show fingerprints for catechins with different structures.
The Cα B-factor for each residue in trypsin computed from MD simulation trajectories in the form of catechin-free black and complex with EC red , ECG blue , EGC dark-cyan and EGCG magenta , respectively.
The orange line represents the Cα B-factor from PDB file. The wiring diagram shows the secondary structure of trypsin. The bar chart at the bottom of picture shows the distance range of the Cα atom to the nearest heavy atom of catechins.
The inset enlarges the sequence motifs in the S1 pocket. The most favorable complex structures were shown in Fig 4. This difference in the structure may result in stronger binding affinity of ECG and EGCG than that of EC and EGC without galloyl groups, in consistent with the results from docking.
Comparing with docking structure, other noticeable difference is that residues 41 and 42 no longer show strong interaction with ring B in catechins.
Meanwhile, catechins also have synergic conformation changes to accommodate the binding pocket of trypsin. The change of conformation can be viewed from the changes of distances among the rings in catechins, in comparison with their native structure as shown in Fig 5.
The change of distance between ring A and ring B is significant with the change of 0. Ring G is always stretched to form strong hydrogen bond with the residues in the binding pocket. These results clearly demonstrate that both protein and ligand have remarkable conformation changes to facilitate the binding, and fully flexible simulation is necessary to explore the detailed complex structure.
In addition, time evolutions of RMSD of catechins are also plotted in the S5 Fig. It can be seen that the average fluctuations of EC, ECG and EGCG are larger than that of trypsin, while lower for EGC. This indicates that EC, ECG and EGCG are more flexible than trypsin in the complex, while it is trypsin in the trypsin-EGC complex.
Representative structure models clustered from MD simulation trajectories for trypsin complex with a EC, b EGC, c ECG and d EGCG. Catechins are shown as ball-and-stick model, trypsin as cartoon. The catalytic triad Asp, His57, Ser is shown in stick.
Residues interact with catechins by hydrogen bond and hydrophobic interaction highlighted by lines. Based on the MD simulation trajectories, binding free energies of catechins to trypsin were calculated using MM-PBSA method.
Since the enthalpy dominates the binding of polyphenol to protein in most instances[ 68 ] and low reliability and high cost in entropy computation, the contributions of entropy in the binding free energy were neglected in this investigation. The free energy components were decomposed.
The binding free energy and the contributions of its components for each complex were summarized in Table 3. The lowest binding free energies of EC, EGC, ECG and EGCG to trypsin were EGCG and ECG have stronger binding affinity than EC and EGC, which is consistent with previous docking results.
The native stereoisomer of EGCG 2R-3R EGCG also shows the lowest binding free energy. In order to shed light on the dominant interaction for driving catechins binding to trypsin, it is essential to decompose the binding free energy into individual energy components.
The contributions of each component were presented in Fig 6. The van der Waals interaction ΔE vdW and the electrostatic interaction ΔE ele in the complex are the favorable for binding, while the polar and the nonpolar solvation terms show unfavorable contributions.
The electrostatic interaction and polar solvation free energy are reversely correlated in ECG and EGCG-trypsin complex. It is reasonable considered that the polar solvation screens the electrostatic interactions between trypsin and ECG or EGCG[ 79 ].
Usually, the van der Waals interactions and the nonpolar solvation energies are closely correlated with the hydrophobic interactions responsible for the burial of hydrophobic groups of catechins. This shows beneficial contributions for binding free energies, indicating that the hydrophobic interaction drives catechins binding to trypsin.
The aromatic ring is responsible for the hydrophobic interaction, thus ECG and EGCG with more aromatic ring have stronger binding affinity than EC and EGC. Comparison of the binding free energy components of trypsin binding with EC red , EGC blue , ECG dark cyan and EGCG magenta.
Further, the contributions of each residue for binding free energy, ΔG per-decomp was shown in Fig 7. The contributions of van der Waals interaction and the electrostatic interaction ascribe to each residue were also plotted in S6 and S7 Figs.
Residues with energies no less than 1. Residues in or at the vicinity of the three motifs in S1 pocket play an important role in binding catechins to trypsin.
Asp has strong electrostatic contribution to catechins that overwhelmed the unfavorable van der Waals interaction, and thus becomes the strongest site to bind catechins. Since hydrogen bond is enclosed in electrostatic attraction, further analysis of hydrogen bonding was carried out. A hydrogen bond was defined as the distance of the heavy atoms between donor and acceptor is less than 3.
The occurrence and geometry of hydrogen bonds between trypsin and catechin were listed in S2 Table. As illustrated in Fig 4 , the side-chain in Asp can form two stable hydrogen bonds with catechins, and they are also stable in whole MD simulation with high occurrence.
Other residues such as Gln, Trp and Gly with strong hydrophobic side-chains exhibit strong van der Waals interaction with catechins. The aromatic ring in Trp also provides π-stacking interaction to bind catechins.
His57 in the catalytic triad also has strong interaction through hydrogen bond to catechins. Binding free energies contributed from each residue to stabilize the trypsin-catechin complex.
a trypsin-EC; b trypsin-EGC; c trypsin-ECG; and d trypsin-EGCG. Overall, the binding free energy calculation indicates that hydrophobic interaction together with hydrogen bonding dominates the binding of catechins to trypsin.
The van der Waals and electrostatic interaction majorly from hydrogen bonding show favorable contributions, while the solvation component has unfavorable contribution in the formation of trypsin-catechin complexes.
In this work, we investigated the binding of catechins to trypsin using an integration of semi-flexible molecular docking, fully flexible molecular dynamics simulation and free energy calculation. Catechins could bind to the active pocket S1 of trypsin with prone orientations.
The binding affinity is dependent on the number and arrangement of hydroxyl and aromatic groups in catechins. Functional groups in catechins are stretched in the binding.
Meanwhile, given residue motifs in trypsin, especially those in or at the vicinity of the S1 pocket and the catalytic triad, and the structures of catechins all have synergic conformation change to facilitate the binding.
Hydrophobic interaction through the van der Waals interaction, and hydrogen bonding enclosed in electrostatic attraction overwhelmed the unfavorable solvation contribution to stabilize trypsin-catechin complex.
These findings could provide a detailed understanding from energetic and structural aspects for protein-ligand binding and a molecular basis for rational design of new potent inhibitors to regulate the bioactivity of trypsin. Time evolutions of the RMSD in an 80 ns MD simulation on the trypsin-EGCG complex for the backbone of trypsin and EGCG.
Docking structures of trypsin with a : EC, b : EGC, c : ECG, and d : EGCG. Hydrogen bonds and hydrophobic interactions have important contribution in binding are highlighted.
The catalytic triad AspHisSer is shown in stick and the ligands are shown in stick-ball. The docking structure with the superposition of four steroisomers of EGCG in the S1 pocket: 2R, 3R-EGCG green ; 2R, 3S-EGCG cyan ; 2S, 3R-EGCG magenta ; 2S, 3S-EGCG yellow. Trypsin is represented by cartoon model, while the steroisomers of EGCG are represented by stick model with different size.
Time evolutions of RMSD of four types of catechins with respect to their initially docking positions: EC red , ECG blue , EGC dark cyan and EGCG magenta , respectively.
Antioxidant supplements for aging work aimed to study suoport effects of the Antioxidant supplements for aging interaction cxtechins tea catechins, milk catecjins, and digestive enzymes on Digesion digestibility, catechin bioaccessibility, Digesrion antioxidant All-natural weight loss supplements by simulating in vitro digestion. Catechns inhibitory effect Digestion support catechins catechins on digestive enzymes was positively Digesrion with the binding affinity of catechins to digestive enzymes. The interaction between tea catechins and milk proteins or digestive enzymes resulted in the reduction of protein digestibility. The bioaccessibility of catechins and antioxidant activity of the milk tea beverage were reduced by protein-catechin interaction, but they increased via competition among proteins, catechins, and digestive enzymes. After the addition of β-lactoglobulin β-Lgepigallocatechin gallate EGCGepigallocatechin EGCand epicatechin EC bioaccessibility increased by The addition of β-casein β-CN negatively affected EGCG and EGC bioaccessibility but significantly increased EC bioaccessibility. Many Dugestion dietary Amazon Jewelry Collections HDS contain green tea extract GTE and its component catechins, although their presence Digestion support catechins not Antioxidant supplements for aging cafechins indicated on the product label. Because Digsstion and catechins have been implicated Antioxidant supplements for aging human hepatotoxicity in several catecyins reports, our objective was to determine whether su;port were present in Digfstion that were implicated in hepatotoxicity, even if not identified among the labeled ingredients, and whether these compounds could be associated with liver injury. We found that 29 of 73 HDS Among patients with confirmed hepatotoxicity, there was no statistically significant association between the presence of catechin or the dose consumed and liver injury causality score, severity, or pattern of liver injury. Catechin levels tended to be highest in products used for weight loss, although catechin concentrations were low in most products. Many HDS commonly contain catechins that are implicated in hepatotoxicity, although their presence may not be indicated on the product label.
Sie lassen den Fehler zu. Schreiben Sie mir in PM, wir werden reden.
Ja, ich verstehe Sie. Darin ist etwas auch den Gedanken ausgezeichnet, ist mit Ihnen einverstanden.
man kann sagen, diese Ausnahme:)