Search

Flavonoids present promising potential as α -glucosidase inhibitors, with potential benefits in lowering blood glucose levels. In our previous study, apigenin, quercetin, and phloretin obtained from whole-grain highland barley demonstrated notable efficacy as α -glucosidase inhibitors. Therefore, in this study, we used enzyme kinetics, fluorescence spectroscopy, circular dichroism, and molecular docking to explore the interactions between apigenin, quercetin, and phloretin, and α -glucosidase. With the addition of three flavonoids, the inhibitory effect of all the flavonoids on α -glucosidase activity was reversible and exhibited a mixed-type pattern. Molecular docking analysis revealed that the three flavonoids predominantly bind to yeast-derived α -glucosidase mainly through hydrophobic interactions and van der Waals forces, whereas the interaction with human-derived α -glucosidase involved hydrophobic interactions. Further experiments revealed that the flavonoids quenched the fluorescence of α -glucosidase due to the complex formation between the flavonoids and α -glucosidase, leading to changes in the protein secondary structure and conformational changes, which was further supported by molecular dynamics simulations. These results provided insights into the mechanism of the flavonoid inhibition of α -glucosidase. These findings could promote the consumption of whole-grain highland barley and the development of hypoglycemic foods rich in flavonoids. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the inhibitory impacts of chlorogenic acid (CGA), ferulic acid (FA), and vanillic acid (VA) on advanced lipid oxidation end products (ALEs) generation in bovine serum albumin-linoleic acid models. The addition of 160 μg/mL CGA and VA significantly blocked the formation of lipofuscin-like pigments (LFLP), reducing them by 22.141% ± 1.823% and 12.156% ± 1.296% respectively. It is worth noting that the best inhibition of LFLP by FA was observed at 40 μg/mL (13.105% ± 0.731%). Compared to the control (25.280 ± 1.580 mg/kg protein), thiobarbituric acid reactive substances values were the lowest in the samples containing 160 μg/mL CGA (2.107 ± 0.912 mg/kg protein), 40 μg/mL FA (6.847 ± 1.824 mg/kg protein), and 160 μg/mL VA (10.007 ± 0.912 mg/kg protein) (P < 0.05). These results suggest that CGA has a more potent inhibitory effect on ALEs formation compared to FA and VA. Therefore, CGA, FA, and VA can be considered as safe dietary phenolic acids for reducing ALEs formation. [Display omitted] • Chlorogenic acid (CGA), ferulic acid (FA), and vanillic acid (VA) reduced advanced lipid oxidation end products (ALEs) formation. • CGA, FA, and VA protected bovine serum albumin conformational changes oxidation-induced by linoleic acid. • Reactive carbonyl species were effectively scavenged by CGA, FA, and VA. • Compared with FA and VA, CGA had the best inhibitory effect on ALEs generation. • CGA, FA, and VA may be used to inhibit ALEs formation during food processing. [ABSTRACT FROM AUTHOR]

Although herbal medicines (HMs) are widely used in the prevention and treatment of obesity and obesity-associated disorders, the key constituents exhibiting anti-obesity activity and their molecular mechanisms are poorly understood. Recently, we assessed the inhibitory potentials of several HMs against human pancreatic lipase (hPL, a key therapeutic target for human obesity), among which the root-extract of Rhodiola crenulata (ERC) showed the most potent anti-hPL activity. In this study, we adopted an integrated strategy, involving bioactivity-guided fractionation techniques, chemical profiling, and biochemical assays, to identify the key anti-hPL constituents in ERC. Nine ERC fractions (retention time = 12.5–35 min), obtained using reverse-phase liquid chromatography, showed strong anti-hPL activity, while the major constituents in these bioactive fractions were subsequently identified using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS/MS). Among the identified ERC constituents, 1,2,3,4,6-penta -O -galloyl-β- d -glucopyranose (PGG) and catechin gallate (CG) showed the most potent anti-hPL activity, with pIC 50 values of 7.59 ± 0.03 and 7.68 ± 0.23, respectively. Further investigations revealed that PGG and CG potently inhibited hPL in a non-competitive manner, with inhibition constant (K i) values of 0.012 and 0.082 μM, respectively. Collectively, our integrative analyses enabled us to efficiently identify and characterize the key anti-obesity constituents in ERC, as well as to elucidate their anti-hPL mechanisms. These findings provide convincing evidence in support of the anti-obesity and lipid-lowering properties of ERC. [Display omitted] • The root-extract of Rhodiola crenulata (ERC) potently inhibits hPL. • The hPL inhibitors in ERC were characterized using an integrated panel of assays. • Six constituents in ERC were identified as hPL inhibitors. • PGG and CG are potent non-competitive hPL inhibitors (K i < 0.1 μM). • The binding modes of PGG and CG were examined based on docking simulations. [ABSTRACT FROM AUTHOR]

Tomato is an important vegetable crop in the world, with rich nutritional value. Clavibacter michiganensis subsp. michiganensis (Cmm) can cause infection to tomato, reduce the yield and quality of tomato, and seriously affect the sale and consumption of tomato. Protocatechuic acid (PCA), a natural phenolic compound, has been proved to have excellent antibacterial effects, possessing higher food safety and environmental friendliness than chemical bactericides. Therefore, PCA was chosen to be the potential bactericide to against Cmm and further applied into the investigation on its mechanism. The minimum inhibitory concentration (MIC) of PCA on Cmm was 0.156 mg/mL. The preventive activity of PCA on Cmm was 60.00%–70.00%, and the therapeutic activity was 64.70%–74.51%. Cmm treated with PCA showed a significant increase in surface potential and surface hydrophobicity compared to the untreated ones. In addition, it was observed in this study that PCA could damage the cell wall, damage the cell membrane by enhancing cell membrane permeability and reducing membrane potential, cause the leakage of intracellular ions, lead to a large accumulation of reactive oxygen species (ROS), and inhibit the activities of total atpase (T-ATPase), pyruvate kinase (PK) and succinate dehydrogenase (SDH). In summary, these studies indicated that PCA had good antibacterial activity against Cmm and had great potential to be applied to tomato as a natural antibacterial agent. [Display omitted] • Protocatechuic acid had a good control effect on tomato canker caused by Cmm. • Protocatechuic acid affected the cell surface of Cmm. • Cell wall and membrane were targets of protocatechuic acid inhibiting Cmm. • Protocatechuic acid caused leakage of functional ions in Cmm cells. • The respiratory metabolism of Cmm cells could be affected by protocatechuic acid. [ABSTRACT FROM AUTHOR]

Dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides exhibit great potential to alleviate type II diabetes. This study aimed to prepare, identify and explore the molecular mechanism of DPP-IV inhibitory peptides from eggshell membrane (ESM), an abundant byproduct of the food industry, based on combining in silico and in vitro assessments. In silico evaluation of ten major ESM proteins revealed the great potential of ESM as a novel source of DPP-IV inhibitors. Moreover, the optimal combined-enzymatic strategy (alkaline protease + papain) for the efficient production of DPP-IV inhibitory peptides from ESM was designed by simulated proteolysis. Corresponding with in silico predictions, in vitro assessments confirmed that sodium sulfite assisted the screened dual enzymes led to better production of DPP-IV inhibitory peptides from ESM, with preferable total nitrogen recovery (86.61% ± 4.83%), DPP-IV inhibitory activity (64.61% ± 2.75%) and total antioxidant activity (215.27 ± 1.75 μg/mL). Due to the correlation between diabetes and oxidative stress, the antioxidant and DPP-IV inhibitory activities of the hydrolysate facilitate its amelioration of diabetes. Three novel DPP-IV inhibitory peptides with high abundance in ESM hydrolysates (YPEPPPQ, HDGADVS and VTDGQPH) were identified by LC-MS/MS, in silico characterization and molecular docking. These peptides were synthesized and confirmed to possess DPP-IV inhibitory activity, potentially relating to their stable binding with key residues within the S1, S2 pockets and catalytic triad of DPP-IV via hydrogen bonding and hydrophobic interaction. Overall, this research suggests an effective and time-saving strategy to investigate novel DPP-IV inhibitory peptides from ESM, as well as opens new opportunities for ESM application in antidiabetic foods. [Display omitted] • The discarded Eggshell membrane (ESM) is a novel source of DPP-IV inhibitory peptides. • In silico analysis provides guidance for in vitro exploration of ESM-derived peptides. • Na 2 SO 3 -assisted dual enzymatic hydrolysis was optimal for releasing DPP-IV inhibitors. • Three novel peptides were identified and validated experimentally the bioactivity. • H-bonds and hydrophobic interactions with DPP-IV were the key interaction modes. [ABSTRACT FROM AUTHOR]

• L-Pheand Zn(NO 3) 2 are efficient hybrid inhibitor for Mg alloys in NaCl solution. • Appropriate concentration and ratio between them are critical for inhibition effect. • The film is formed on metal surface including complicate composition. • Inhibition mechanism is proposed according to XPS and theoretical calculation. L-Phenylalanine (L-Phe) is a promising eco-friendly alternative to replace the conventional toxic inhibitors for magnesium alloys in NaCl solution. However, its inhibitory performance is not satisfied. The addition of slight amount Zn(NO 3) 2 would greatly refine the inhibitory efficiency. The inhibitory performance of hybrid inhibitor is explored by scanning electron microscopy (SEM) along with energy dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and various electrochemical measurements. The highest inhibitory efficiency of 93.2% is achieved for 0.30 mM L -Phe + 0.07 mM Zn(NO 3) 2. The amount of each inhibitor and the suitable match of two inhibitors are carefully determined, which are both critical items for the final performance. The possible inhibitory mechanism is conjectured by the XRD and XPS measurements along with the quantum chemical calculations. [Display omitted] [ABSTRACT FROM AUTHOR]

Maillard reaction occurs in bakery products during heating process, especially between reducing sugars carbonyls with amino compounds to produce pleasant aromas, favorable colors, and flavors. MR also produces toxic or harmful substances, including advanced glycosylation end products (AGEs) in the last stage of MR. Body AGEs can be divided into exogenous and endogenous sources. Food source AGEs inhibitors such as polyphenols can capture (or remove) active dicarbonyl groups and scavenging free radical, etc. New processing techniques and optimizing oven performance can also be applied to control AGEs. In this review, AGEs in bakery products were systematically described from the sources, formation mechanism, detection methods, influencing factors and inhibition mechanism and methods. Baking ingredients, processing conditions, types of ovens, process technologies (conduction, convection, radiation, vacuum-combined cooling), which contribute to AGEs generation and affect the AGEs content. This research provides new solution for AGEs control and its application in new processing technology. [Display omitted] • AGEs formation mechanism and detection in bakery products processing were summarized. • Ingredients, types of ovens, process technologies are related to AGEs formation. • The inhibition mechanism and pathway of food source AGEs inhibitors were introduced. • New baking technologies and equipment can reduce AGEs generation. [ABSTRACT FROM AUTHOR]

Abstract Flavonoids are natural polyphenolic compounds from plants. As a new biotechnological algaecide, the molecular mechanism of plant flavonoids on the inhibition of Microcystis aeruginosa is still unknown. Therefore, in this study, we analyzed the variation of expressions of photosynthesis-related genes, microcystin synthesis-related genes and the genes involved in N and P acquisition in M. aeruginosa under the flavonoids stress. The results showed that the expression of psb D1, psa B and rbc L related to photosynthesis were influenced by three flavonoids but with different changing tendencies. The transcription of mcy A, mcy D and mcy H related to microcystin synthesis were decreased after 5-d of exposure, which could block microcystin synthesis. Meanwhile, flavonoids treatments resulted in the inhibition of N and P acquisition related genes transcription to affect the absorption of N and P in algal cells, and further influenced the physiological metabolic process of M. aeruginosa. Graphical abstract Image 1 Highlights • M. aeruginosa had different response to 5, 4′-dihydroxyflavone (DHF), apigenin and luteolin. • 5, 4′-dihydroxyflavone (DHF) had a strong inhibitory effect on M. aeruginosa. • 5, 4′-DHF significantly inhibited the expressions of photosynthesis-related genes, N and P acquisition related genes. • The three flavonoids can down-regulate the expression of microcystin synthesis-related gene (mcy A, mcy D and mcy H). [ABSTRACT FROM AUTHOR]

Graphical abstract Gallocatechin gallate can inhibit the activity of α-amylase and α-glucosidase relevant to postprandial hyperglycemia. Highlights • GCG inhibited a -amylase and a -glucosidase by mixed and non-competitive type, respectively. • The combination of GCG with acarbose increased the inhibition of α- amylase and α- glucosidase. • GCG binding to α- amylase or α- glucosidase induced an unfolding of enzymatic structures. • GCG interacted with some amino acid residues located in active site pocket of α- amylase. • GCG bound to a site close to the active pocket of α- glucosidase. Abstract The postprandial hyperglycemia of diabetic patients is associated with a -amylase and a -glucosidase, searching safer enzyme inhibitors and deciphering their inhibition mechanism are important. In this study, gallocatechin gallate (GCG) was found to exert strong inhibition on α- amylase and α- glucosidase in the mixed-type and non-competitive manners, respectively. GCG could bind with α- amylase and α- glucosidase to form the complexes, which induced conformational changes of the two carbohydrate digestive enzymes. Docking analysis verified that GCG interacted with pivotal amino acids within the active site of α- amylase, while it bound to a site close to the active site of α- glucosidase, which might affect active site, causing declines in a -amylase and α- glucosidase activities. Moreover, the combination of GCG with acarbose increased the inhibition of α- amylase and α- glucosidase and reduced the dosage of acarbose. This study may provide theoretical basis for designing novel functional foods of GCG for the prevention and treatment of diabetes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ginsenoside Rg1 was determined as an uncompetitive α-glucosidase inhibitor. • The stable complex between ginsenoside Rg1 and α-glucosidase was mainly formed by hydrogen bonds and hydrophobic forces. • Ginsenoside Rg1 reduced the postprandial blood glucose in normal and db/db mice. • Caco-2 cell model emphasised that ginsenoside Rg1 reduced glucose uptake and transport. One of the most effective therapeutic proposals for type 2 diabetes mellitus (T2DM) is regulation of postprandial blood glucose (PBG) level by inhibiting α-glucosidases. In this study, we firstly investigated the influence of ginsenoside Rg1 (Rg1) on activity of α-glucosidase in vitro. The results revealed that Rg1 had a reversible inhibition on α-glucosidase activity in an uncompetitive manner. Fluorescence spectrum and circular dichroism (CD) analysis indicated that the stable complex between Rg1 and α-glucosidase was mainly formed by hydrogen bonds and hydrophobic forces. In addition, the anti-hyperglycemic effect of Rg1 was confirmed by the sucrose tolerance test in normal and db/db mice. Caco-2 monolayer cell model further emphasized that decreasing effect of Rg1 on PBG may be achieved by reducing glucose uptake and transport which is accounted for inhibition of α-glucosidase. Taken together, those results suggested that Rg1 may be used as a promising α-glucosidase inhibitor to decrease PBG. [ABSTRACT FROM AUTHOR]

The mechanism of inhibitory effects of liquor cultured Hydrodictyon reticulatum (LCH) on the growth of Microcystis aeruginosa was studied in present study. The results showed that the growth of M. aeruginosa was inhibited by the LCH markedly, with the highest suppression ratio of 93% at 20% concentration of LCH. The high concentration of the LCH had caused decreased contents of chlorophyll a of M. aeruginosa, increased EC and OD260 value of algal extracellular fluid, increased contents of O2- and MDA as well as SOD activities of M. aeruginosa, indicating that liquor cultured H. reticulatum hindered generation of chlorophyll a and caused damage to photosynthesis. Meanwhile, it induced algal cells to generate plenty of O2-, which caused lipid peroxidation and damaged the cellular membrane structure when it exceeded the clearance ability of SOD. The main product of lipid peroxidation, MDA, also had altered the membrane permeability and caused intracellular compounds (cytoplasm, nucleic acid, et al) being released, resulted in the disintegration of M. aeruginosa. [ABSTRACT FROM AUTHOR]

[Display omitted] • • The IC 50 value of ACEI activity of HWS and VLSGF in vitro were 0.640 ±0.016 mg/mL and 0.328 ± 0.040 mg/mL. • • The ACEI kinetic of HWS was competitive inhibition and VLSGF was mixed-type inhibition. • • HWS and VLSGF had a high binding affinity with ACE sites by hydrogen bonds. • • HWS and VLSGF could increase the production of NO, upregulated the expression of eNOS, and decreased ROS production in HUVEC. In this work, four novel angiotensin I-converting enzyme inhibitory (ACEI) peptides were isolated and identified from peony (Paeonia suffruticosa Andr.) seed hydrolysate (PSH) by consecutive chromatography and UPLC-ESI-QTOF-MS/MS. The IC 50 values of HWS (0.640 ±0.016 mg/mL) and VLSGF (0.328 ± 0.040 mg/mL) were significantly (p < 0.05) lower than those of the other two peptides. The Lineweaver-Burk plots showed that VLSGF is competitive inhibition against ACE and HWS acted as a mixed-type inhibitor. Meanwhile, the results of molecular docking showed hydrogen interactions between VLSGF/HWS and ACE. In human endothelial cells, the pretreatments of VLSGF and HWS could increase the production of nitric oxide (NO) and the expression of endothelial nitric oxide synthase (eNOS). In addition, they also decreased the reactive oxygen species (ROS) production. These results indicated that it may be possible to use peony seed protein hydrolysate to create ingredients for functional foods. [ABSTRACT FROM AUTHOR]

The harvested loquat fruits are prone to browning, leading to a decline in fruit quality. Inhibiting activity of polyphenol oxidase (PPO) is an important way to prevent browning. In this study, we evaluated the inhibitory impact of oligomeric procyanidins (OPC) on hydroxylation of monophenol and oxidation of o-diphenol catalyzed by PPO and effect of OPC on loquat fruits storage. The obtained results revealed that OPC could attenuate the activity of monophenolase and diphenolase. For monophenolase activity, the inhibition rate was observed to be dose-dependent with an IC 50 of 11.6 ± 3.4 μg/mL for the steady-state rate. For diphenolase activity, OPC inhibited PPO activity (IC 50 = 15.75 ± 2.1 μg/mL) with a reversible and competitive mechanism and quenched fluorescence of PPO by forming OPC-PPO complex with one binding site in a static procedure. In addition, the data obtained from storage assays revealed that OPC could enhance the quality of harvested loquat fruits by attenuating the PPO activity, augmenting the content of total phenolics and flavonoids, and simultaneously delaying the browning of loquats. In this research, we identified a potent PPO inhibitor and expanded its potential as a food preservative. [ABSTRACT FROM AUTHOR]

The rosaceous branch borer, Ospheranteria coerulescens, is an important pest of rosaceous trees. This insect feeds on the twigs and branches of living trees and causes their death. The characterization of the insect phenoloxidase (PO) is of interest when doing comparative investigations, and so that we may be able to understand its biochemical properties. When designing new methods of insect control such as the use of PO inhibitors, an understanding of the biochemical properties is fundamental. In this study, PO from hemolymph of the rosaceous branch borer was purified using ammonium sulfate precipitation, gel-filtration, and ion-exchange chromatography. The biochemical properties were characterized using 1-dihydroxyphenylalanine (L-DOPA) as the specific substrate. The apparent molecular weights of the three isoforms of PO were determined by SDS-PAGE to be 85.23, 79.45, and 66.06 kDa. Optimal pH for PO activity was pH 8, and the optimal temperature was 45°C. Phenoloxidase lost less than 50% of its relative activity after a 60 min incubation at the optimal temperature. The effects of ions and chemical materials such as K+, Ba+, Zn+ and EDTA on PO showed that PO activity was strongly inhibited by Zn+. The Michaelis constant (Km) and maximum velocity (Vmax) were 88.61 mM and 0.14 µmol/min, respectively. The inhibitory effects of kojic acid, 4-hexylresorsinol, and quercetin on PO were determined, and the IC50s (inhibitory concentration)were estimated as 23.31 for kojic acid, 35.75 for 4-hexylresorcinol, and 60.8 µM for quercetin. The inhibitory potency of kojic acid was 1.54 times higher than that of 4-hexylresorcinol and 2.58 times higher than that of quercetin. Phenoloxidase was effectively inhibited by 4-hexylresorcinol, and the inhibition type was competitive. The inhibition types of PO by kojic acid and quercetin were found to be mixed. [ABSTRACT FROM AUTHOR]

The article presents the findings of a research conducted on the identification of interaction site of propeptide toward mature carboxypeptidase Y (mCPY), based on the similarity between propeptide and CPY inhibitor (IC). Under the research, sequence alignment between IC and proCPY indicated that a sequence similar to the N-terminal region of IC was present in proCPY. It concludes that C-terminal region of the propeptide might bind to the substrate-binding site of mCPY.