scholarly journals Thyroid Peroxidase Activity is Inhibited by Phenolic Compounds—Impact of Interaction

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2766
Author(s):  
Ewa Habza-Kowalska ◽  
Agnieszka A. Kaczor ◽  
Justyna Żuk ◽  
Dariusz Matosiuk ◽  
Urszula Gawlik-Dziki
Keyword(s):  
Chlorogenic Acid ◽  
Rosmarinic Acid ◽  
Molecular Level ◽  
Combination Index ◽  
3D Structure ◽  
Thyroid Peroxidase ◽  
Ic50 Values ◽  
Insight Into ◽  
Rutin And Quercetin

The aim of this study was to estimate the mode of thyroid peroxidase (TPO) inhibition by polyphenols: Chlorogenic acid, rosmarinic acid, quercetin, and rutin. All the tested polyphenols inhibited TPO; the IC50 values ranged from 0.004 mM to 1.44 mM (for rosmarinic acid and rutin, respectively). All these pure phytochemical substances exhibited different modes of TPO inhibition. Rutin and rosmarinic acid showed competitive, quercetin—uncompetitive and chlorogenic acid—noncompetitive inhibition effect on TPO. Homology modeling was used to gain insight into the 3D structure of TPO and molecular docking was applied to study the interactions of the inhibitors with their target at the molecular level. Moreover, the type and strength of mutual interactions between the inhibitors (expressed as the combination index, CI) were analyzed. Slight synergism, antagonism, and moderate antagonism were found in the case of the combined addition of the pure polyphenols. Rutin and quercetin as well as rutin and rosmarinic acid acted additively (CI = 0.096 and 1.06, respectively), while rutin and chlorogenic acid demonstrated slight synergism (CI = 0.88) and rosmarinic acid with quercetin and rosmarinic acid with chlorogenic acid showed moderate antagonism (CI = 1.45 and 1.25, respectively). The mixture of chlorogenic acid and quercetin demonstrated antagonism (CI = 1.79). All the polyphenols showed in vitro antiradical ability against 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid), ABTS. The highest ability (expressed as IC50) was exhibited by rosmarinic acid (0.12 mM) and the lowest value was ascribed to quercetin (0.45 mM).

scholarly journals Derivatization of Rosmarinic Acid Enhances its in vitro Antitumor, Antimicrobial and Antiprotozoal Properties

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1078 ◽  
Author(s):  
Silvia Bittner Fialová ◽  
Martin Kello ◽  
Matúš Čoma ◽  
Lívia Slobodníková ◽  
Eva Drobná ◽  
...  
Keyword(s):  
Rosmarinic Acid ◽  
Antimicrobial Agents ◽  
Biological Activities ◽  
Fold Increase ◽  
Inhibitory Effect ◽  
Phosphonium Salts ◽  
Ros Scavenging ◽  
Ic50 Values ◽  
Quaternary Phosphonium Salts

On its own, rosmarinic acid possesses multiple biological activities such as anti-inflammatory, antimicrobial, cardioprotective and antitumor properties, and these are the consequence of its ROS scavenging and inhibitory effect on inflammation. In this study, two quaternary phosphonium salts of rosmarinic acid were prepared for the purpose of increasing its penetration into biological systems with the aim of improving its antimicrobial, antifungal, antiprotozoal and antitumor activity. The synthetized molecules, the triphenylphosphonium and tricyclohexylphosphonium salts of rosmarinic acid, exhibited significantly stronger inhibitory effects on the growth of HCT116 cells with IC50 values of 7.28 or 8.13 μM in comparison to the initial substance, rosmarinic acid (>300 μM). For the synthesized derivatives, we detected a greater than three-fold increase of activity against Acanthamoeba quina, and a greater than eight-fold increase of activity against A. lugdunensis in comparison to rosmarinic acid. Furthermore, we recorded significantly higher antimicrobial activity of the synthetized derivatives when compared to rosmarinic acid itself. Both synthetized quaternary phosphonium salts of rosmarinic acid appear to be promising antitumor and antimicrobial agents, as well as impressive molecules for further research.

scholarly journals The SARS-CoV-2 Spike Variant D614G Favors an Open Conformational State

2020 ◽  
Author(s):  
Rachael A. Mansbach ◽  
Srirupa Chakraborty ◽  
Kien Nguyen ◽  
David C. Montefiori ◽  
Bette Korber ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Molecular Level ◽  
Receptor Binding Domain ◽  
Target Region ◽  
Infected People ◽  
Viral Loads ◽  
Rapid Transition ◽  
Open States ◽  
Insight Into

SummaryThe COVID-19 pandemic underwent a rapid transition with the emergence of a SARS-CoV-2 variant that carried the amino acid substitution D614G in the Spike protein that became globally prevalent. The G-form is both more infectious in vitro and associated with increased viral loads in infected people. To gain insight into the mechanism underlying these distinctive characteristics, we employed multiple replicas of microsecond all-atom simulations to probe the molecular-level impact of this substitution on Spike’s closed and open states. The open state enables Spike interactions with its human cellular receptor, ACE2. Here we show that changes in the inter-protomer energetics due to the D614G substitution favor a higher population of infection-capable (open) states. The inter-protomer interactions between S1 and S2 subunits in the open state of the D-form are asymmetric. This asymmetry is resolved in the G-form due to the release of tensile hydrogen bonds resulting in an increased population of open conformations. Thus, the increased infectivity of the G-form is likely due to a higher rate of profitable binding encounters with the host receptor. It is also predicted to be more neutralization sensitive due to enhanced exposure of the receptor binding domain, a key target region for neutralizing antibodies.

scholarly journals Synthesis, Biological Evaluation and Docking Studies of 13-Epimeric 10-fluoro- and 10-Chloroestra-1,4-dien-3-ones as Potential Aromatase Inhibitors

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1783 ◽  
Author(s):  
Rebeka Jójárt ◽  
Péter Traj ◽  
Édua Kovács ◽  
Ágnes Horváth ◽  
Gyula Schneider ◽  
...  
Keyword(s):  
Biological Activity ◽  
Inhibitory Action ◽  
Molecular Level ◽  
Docking Studies ◽  
Biological Evaluation ◽  
Computational Simulations ◽  
Simultaneous Application ◽  
Methyl Group ◽  
Ic50 Values

Fluorination of 13-epimeric estrones and their 17-deoxy counterparts was performed with Selectfluor as the reagent. In acetonitrile or trifluoroacetic acid (TFA), 10β-fluoroestra-1,4-dien-3-ones were formed exclusively. Mechanistic investigations suggest that fluorinations occurred via SET in acetonitrile, but another mechanism was operative in TFA. Simultaneous application of N-chlorosuccinimide (NCS) and Selectfluor in TFA led to a 1.3:1 mixture of 10β-fluoroestra-1,4-dien-3-one and 10β-chloroestra-1,4-dien-3-one as the main products. The potential inhibitory action of the 10-fluoro- or 10-chloroestra-1,4-dien-3-one products on human aromatase was investigated via in vitro radiosubstrate incubation. The classical estrane conformation with trans ring anellations and a 13β-methyl group seems to be crucial for the inhibition of the enzyme, while test compounds bearing the 13β-methyl group exclusively displayed potent inhibitory action with submicromolar or micromolar IC50 values. Concerning molecular level explanation of biological activity or inactivity, computational simulations were performed. Docking studies reinforced that besides the well-known Met374 H-bond connection, the stereocenter in the 13 position has an important role in the binding affinity. The configuration inversion at C-13 results in weaker binding of 13α-estrone derivatives to the aromatase enzyme.

scholarly journals Phenolic Profiles, Antimicrobial and Cytotoxic Properties of Both Micropropagated and Naturally Growing Plantlets of Calamintha sylvatica subsp. sylvatica Bromf.

2019 ◽  
Vol 47 (4) ◽  
pp. 1145-1152
Author(s):  
Mustafa CÜCE ◽  
Tuba BEKİRCAN ◽  
Abdul Hafeez LAGHARI ◽  
Münevver SÖKMEN ◽  
Atalay SÖKMEN ◽  
...  
Keyword(s):  
Rosmarinic Acid ◽  
Biomass Yield ◽  
Shoot Formation ◽  
Nodal Segments ◽  
Digital Object Identifier ◽  
Digital Object ◽  
Ic50 Values ◽  
Phenolic Profiles ◽  
Hexane Extracts

A rapid micropropagation protocol was designed to produce Calamintha sylvatica plantlets by using nodal segments as explants for the shoot formation. 6-BA favored the highest shoot formation and biomass yield, whilst kinetin was found superior for the highest shoot length (38.97 ± 2.85 mm) and node numbers (2.89 ± 0.63). Rosmarinic acid was detected as major phenolic acid, ranging from 7.59 mg/100 g to 81.44 mg/100 g. Hexane extracts from natural and in vitro propagated plantlets showed activity only against Staphylococcus aureus ATCC 25923 with MIC values at 6.25 and 3.33 m/mL, respectively while in the latter case, extracts from natural plantlets exerted higher cytotoxic activity than those of micropropagated ones (IC50 values were 83 µg/mL and 98 µg/mL on HeLa cells, respectively). C. sylvatica showed high micropropagation performance and produced remarkable amount of rosmarinic acid in vitro as well as antimicrobial and cytotoxic effect.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

Conformational flexibility and allosteric regulation of cathepsin K

2010 ◽  
Vol 429 (2) ◽  
pp. 379-389 ◽  
Author(s):  
Marko Novinec ◽  
Lidija Kovačič ◽  
Brigita Lenarčič ◽  
Antonio Baici
Keyword(s):  
Dermatan Sulfate ◽  
Molecular Level ◽  
Cathepsin K ◽  
Conformational Flexibility ◽  
Kinetic Properties ◽  
Collagenolytic Activity ◽  
Key Enzyme ◽  
Multiple Conformations ◽  
Insight Into

The human cysteine peptidase cathepsin K is a key enzyme in bone homoeostasis and other physiological functions. In the present study we investigate the mechanism of cathepsin K action at physiological plasma pH and its regulation by modifiers that bind outside of the active site. We show that at physiological plasma pH the enzyme fluctuates between multiple conformations that are differently susceptible to macromolecular inhibitors and can be manipulated by varying the ionic strength of the medium. The behaviour of the enzyme in vitro can be described by the presence of two discrete conformations with distinctive kinetic properties and different susceptibility to inhibition by the substrate benzyloxycarbonyl-Phe-Arg-7-amino-4-methylcoumarin. We identify and characterize sulfated glycosaminoglycans as natural allosteric modifiers of cathepsin K that exploit the conformational flexibility of the enzyme to regulate its activity and stability against autoproteolysis. All sulfated glycosaminoglycans act as non-essential activators in assays using low-molecular-mass substrates. Chondroitin sulfate and dermatan sulfate bind at one site on the enzyme, whereas heparin binds at an additional site and has a strongly stabilizing effect that is unique among human glycosaminoglycans. All glycosaminoglycans stimulate the elastinolytic activity of cathepsin K at physiological plasma pH, but only heparin also increases the collagenolytic activity of the enzyme under these conditions. Altogether these results provide novel insight into the mechanism of cathepsin K function at the molecular level and its regulation in the extracellular space.

scholarly journals The SARS-CoV-2 Spike variant D614G favors an open conformational state

2021 ◽  
Vol 7 (16) ◽  
pp. eabf3671
Author(s):  
Rachael A. Mansbach ◽  
Srirupa Chakraborty ◽  
Kien Nguyen ◽  
David C. Montefiori ◽  
Bette Korber ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Molecular Level ◽  
Conformational State ◽  
Receptor Binding Domain ◽  
Upper Airways ◽  
Target Region ◽  
Viral Loads ◽  
Rapid Transition ◽  
Insight Into

The COVID-19 (coronavirus disease 2019) pandemic underwent a rapid transition with the emergence of a dominant viral variant (from the “D-form” to the “G-form”) that carried an amino acid substitution D614G in its “Spike” protein. The G-form is more infectious in vitro and is associated with increased viral loads in the upper airways. To gain insight into the molecular-level underpinnings of these characteristics, we used microsecond all-atom simulations. We show that changes in the protein energetics favor a higher population of infection-capable states in the G-form through release of asymmetry present in the D-form inter-protomer interactions. Thus, the increased infectivity of the G-form is likely due to a higher rate of profitable binding encounters with the host receptor. It is also predicted to be more neutralization sensitive owing to enhanced exposure of the receptor binding domain, a key target region for neutralizing antibodies. These results are critical for vaccine design.

scholarly journals Transcriptome Analysis of the Eggplant Fruits Overexpressing a Gene of Chlorogenic Acid Pathway

2020 ◽  
Author(s):  
Prashant Kaushik
Keyword(s):  
Chlorogenic Acid ◽  
Transcriptome Analysis ◽  
Cell Expansion ◽  
Acid Production ◽  
Molecular Level ◽  
Phenylpropanoid Pathway ◽  
Rna Seq ◽  
Acid Pathway ◽  
Insight Into ◽  
New Strategies

AbstractChlorogenic acid is the primary phenolic acids present in Eggplant fruits. For the generation of chlorogenic acid in the eggplant hydroxycinnamoyl CoA-quinate transferase (SmHQT), is a central enzyme that catalyzes the reaction to the chlorogenic acid production. Although a precise function of SmHQT is not well defined in the eggplant fruit. In this study, the overexpression of SmHQT in the eggplant fruit’s flesh was studied using the agroinfiltration technique. Furthermore, to determine the differences at the genomic level RNA-seq analysis was performed, and its results showed that 415 genes of the phenylpropanoid pathway were upregulated in the transgenic fruit. Also, it was determined that the differentially expressed genes were dominantly related to phenylpropanoid pathway along with cell expansion, and cytokinin. The agroinfiltrated fruit exhibited more than twice the chlorogenic content in the normal fruit. Overall, the result provides new insight into the eggplant chlorogenic content increment at the molecular level and unseal the opportunities to design new strategies for the improvement of chlorogenic content as nutrition in eggplant.

scholarly journals The Molecular Basis and Biologic Significance of the β-Dystroglycan-Emerin Interaction

2020 ◽  
Vol 21 (17) ◽  
pp. 5944
Author(s):  
Wendy Lilián Gómez-Monsivais ◽  
Feliciano Monterrubio-Ledezma ◽  
Jazmin Huerta-Cantillo ◽  
Ricardo Mondragon-Gonzalez ◽  
Alma Alamillo-Iniesta ◽  
...  
Keyword(s):  
Molecular Level ◽  
Nuclear Architecture ◽  
Tm Domain ◽  
And Function ◽  
Truncated Variants ◽  
Nuclear Processes ◽  
Nanomolar Range ◽  
Insight Into

β-dystroglycan (β-DG) assembles with lamins A/C and B1 and emerin at the nuclear envelope (NE) to maintain proper nuclear architecture and function. To provide insight into the nuclear function of β-DG, we characterized the interaction between β-DG and emerin at the molecular level. Emerin is a major NE protein that regulates multiple nuclear processes and whose deficiency results in Emery–Dreifuss muscular dystrophy (EDMD). Using truncated variants of β-DG and emerin, via a series of in vitro and in vivo binding experiments and a tailored computational analysis, we determined that the β-DG–emerin interaction is mediated at least in part by their respective transmembrane domains (TM). Using surface plasmon resonance assays we showed that emerin binds to β-DG with high affinity (KD in the nanomolar range). Remarkably, the analysis of cells in which DG was knocked out demonstrated that loss of β-DG resulted in a decreased emerin stability and impairment of emerin-mediated processes. β-DG and emerin are reciprocally required for their optimal targeting within the NE, as shown by immunofluorescence, western blotting and immunoprecipitation assays using emerin variants with mutations in the TM domain and B-lymphocytes of a patient with EDMD. In summary, we demonstrated that β-DG plays a role as an emerin interacting partner modulating its stability and function.

scholarly journals Structure of a tRNA-specific deaminase with compromised deamination activity

2020 ◽  
Vol 477 (8) ◽  
pp. 1483-1497
Author(s):  
Huijuan Liu ◽  
Saibin Wu ◽  
Dewei Ran ◽  
Wei Xie
Keyword(s):  
Molecular Level ◽  
Evolutionary Strategy ◽  
Structural Basis ◽  
Mutant Form ◽  
Binding Assays ◽  
Natural Evolution ◽  
Dimer Interface ◽  
Mycoplasma Capricolum ◽  
Insight Into

Nucleotide 34 in tRNA is extensively modified to ensure translational fidelity and efficacy in cells. The deamination of adenosine at this site catalyzed by the enzyme TadA gives rise to inosine (I), which serves as a typical example of the wobble hypothesis due to its diverse basepairing capability. However, recent studies have shown that tRNAArgACG in Mycoplasma capricolum contains unmodified adenosine, in order to decode the CGG codon. The structural basis behind the poorly performing enzyme M. capricolum TadA (McTadA) is largely unclear. Here we present the structures of the WT and a mutant form of McTadA determined at high resolutions. Through structural comparison between McTadA and other active TadA enzymes as well as modeling efforts, we found that McTadA presents multiple structural conflicts with RNA substrates and thus offered support to previous studies from a structural perspective. These clashes would potentially lead to reduced substrate binding affinity of McTadA, consistent with our in vitro deamination activity and binding assays. To rescue the deamination activity of McTadA, we carried out two rounds of protein engineering through structure-guided design. The unsuccessful attempts of the activity restoration could be attributed to the altered dimer interface and stereo hindrance from the non-catalytic subunit of McTadA, which could be the inevitable outcome of the natural evolution. Our study provides structural insight into an alternative decoding and evolutionary strategy by a compromised TadA enzyme at a molecular level.

Chickpea (Cicer arietinum L.) Lectin Exhibit Inhibition of ACE-I, α-amylase and α-glucosidase Activity

2019 ◽  
Vol 26 (7) ◽  
pp. 494-501 ◽  
Author(s):  
Sameer Suresh Bhagyawant ◽  
Dakshita Tanaji Narvekar ◽  
Neha Gupta ◽  
Amita Bhadkaria ◽  
Ajay Kumar Gautam ◽  
...  
Keyword(s):  
Biological Effects ◽  
Exchange Chromatography ◽  
Health Concern ◽  
Carbohydrate Binding ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Ic50 Values ◽  
Chickpea Lectin

Background: Diabetes and hypertension are the major health concern and alleged to be of epidemic proportions. This has made it a numero uno subject at various levels of investigation. Glucosidase inhibitor provides the reasonable option in treatment of Diabetes Mellitus (DM) as it specifically targets post prandial hyperglycemia. The Angiotensin Converting Enzyme (ACE) plays an important role in hypertension. Therefore, inhibition of ACE in treatment of elevated blood pressure attracts special interest of the scientific community. Chickpea is a food legume and seeds contain carbohydrate binding protein- a lectin. Some of the biological properties of this lectin hitherto been elucidated. Methods: Purified by ion exchange chromatography, chickpea lectin was tested for its in vitro antioxidant, ACE-I inhibitory and anti-diabetic characteristic. Results: Lectin shows a characteristic improvement over the synthetic drugs like acarbose (oral anti-diabetic drug) and captopril (standard antihypertensive drug) when, their IC50 values are compared. Lectin significantly inhibited α-glucosidase and α-amylase in a concentration dependent manner with IC50 values of 85.41 ± 1.21 ҝg/ml and 65.05 ± 1.2 µg/ml compared to acarbose having IC50 70.20 ± 0.47 value of µg/ml and 50.52 ± 1.01 µg/ml respectively. β-Carotene bleaching assay showed antioxidant activity of lectin (72.3%) to be as active as Butylated Hydroxylanisole (BHA). In addition, lectin demonstrated inhibition against ACE-I with IC50 value of 57.43 ± 1.20 µg/ml compared to captopril. Conclusion: Lectin demonstrated its antioxidant character, ACE-I inhibition and significantly inhibitory for α-glucosidase and α-amylase seems to qualify as an anti-hyperglycemic therapeutic molecule. The biological effects of chickpea lectin display potential for reducing the parameters of medically debilitating conditions. These characteristics however needs to be established under in vivo systems too viz. animals through to humans.

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