scholarly journals New cinnamid and rosmarinic acid derived compounds biosynthesized in Escherichia coli as Leishmania amazonensis arginase inhibitors

2020 ◽  
Author(s):  
Julio Abel Alfredo dos Santos Simone Come ◽  
Yibin Zhuang ◽  
TianZhen Li ◽  
Simone Brogi ◽  
Sandra Gemma ◽  
...  
Keyword(s):  
Rosmarinic Acid ◽  
Competitive Inhibition ◽  
Binding Mode ◽  
Competitive Inhibitor ◽  
Leishmania Amazonensis ◽  
New Drugs ◽  
E Coli ◽  
Caffeic Acid Esters ◽  
Key Residues ◽  
Arginase Inhibitors

AbstractArginase is a metalloenzyme that plays a central role in Leishmania infection. Previously, rosmarinic and caffeic acids were described as antileishmanial and as a Leishmania amazonensis arginase inhibitor and now, we describe the inhibition of arginase in L. amazonensis by rosmarinic acid analogs (1-7) and new caffeic acids derived amides (8-10). Caffeic acid esters and amides were produced by means of the engineered synthesis in E. coli and tested against L. amazonensis arginase. New amides (8-10) were biosynthesized in E. coli cultured with 2 mM of different combinations of feeding substrates. The most potent arginase inhibitors showed Ki(s) between 2 - 5.7 μM. Compounds 2-4 and 7 inhibited L-ARG through a noncompetitive mechanism, and 9 showed a competitive inhibition. By applying an in silico protocol we determined the binding mode of compound 9. The competitive inhibitor of L-ARG targets key residues within the binding site of the enzyme establishing a metal coordination bond with the metal ions as well as a series of hydrophobic and polar contacts supporting its micromolar inhibition of L-ARG. These results highlight that the dihydroxycinnamic-derived compounds can be used as the basis for the development of new drugs using a powerful tool based on the biosynthesis of arginase inhibitors.

Kinetic Aspects of the Interaction of Blood Clotting Enzymes

1968 ◽  
Vol 19 (03/04) ◽  
pp. 364-367 ◽  
Author(s):  
H. C Hemker ◽  
P. W Hemker
Keyword(s):  
Enzyme Kinetics ◽  
Blood Clotting ◽  
Competitive Inhibition ◽  
Competitive Inhibitor ◽  
Kinetics Of

SummaryThe enzyme kinetics of competitive inhibition under conditions prevailing in clotting tests are developed and a method is given to measure relative amounts of a competitive inhibitor by means of the t — D plot.

scholarly journals Structure activity relationships and the binding mode of quinolinone-pyrimidine hybrids as reversal agents of multidrug resistance mediated by P-gp

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jerónimo Laiolo ◽  
Priscila Ailin Lanza ◽  
Oscar Parravicini ◽  
Cecilia Barbieri ◽  
Daniel Insuasty ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Molecular Complexes ◽  
Binding Mode ◽  
Reversal Agents ◽  
Structure Activity Relationships ◽  
Structure Activity ◽  
Doxorubicin Toxicity ◽  
Key Residues ◽  
Nanomolar Range ◽  
Experimental Structure

AbstractP-gp-associated multidrug resistance is a major impediment to the success of chemotherapy. With the aim of finding non-toxic and effective P-gp inhibitors, we investigated a panel of quinolin-2-one-pyrimidine hybrids. Among the active compounds, two of them significantly increased intracellular doxorubicin and rhodamine 123 accumulation by inhibiting the efflux mediated by P-gp and restored doxorubicin toxicity at nanomolar range. Structure–activity relationships showed that the number of methoxy groups, an optimal length of the molecule in its extended conformation, and at least one flexible methylene group bridging the quinolinone to the moiety bearing the pyrimidine favored the inhibitory potency of P-gp. The best compounds showed a similar binding pattern and interactions to those of doxorubicin and tariquidar, as revealed by MD and hybrid QM/MM simulations performed with the recent experimental structure of P-gp co-crystallized with paclitaxel. Analysis of the molecular interactions stabilizing the different molecular complexes determined by MD and QTAIM showed that binding to key residues from TMH 4–7 and 12 is required for inhibition.

Quinolin-2-one-pyrimidine Hybrids Acting as Potent Reversal Agents on the P-gp-mediated Multidrug Resistance: Insights into Structure-activity Relationships and the Binding Mode

2021 ◽  
Author(s):  
Jerónimo Laiolo ◽  
Priscila Ailin Lanza ◽  
Oscar Parravicini ◽  
Cecilia Barbieri ◽  
Daniel Insuasty ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Molecular Complexes ◽  
Binding Mode ◽  
Reversal Agents ◽  
Structure Activity Relationships ◽  
Structure Activity ◽  
Doxorubicin Toxicity ◽  
Key Residues ◽  
Nanomolar Range ◽  
Experimental Structure

Abstract P-gp-associated multidrug resistance (MDR) is a major impediment to the success of chemotherapy. With the aim of finding non-toxic and effective P-gp inhibitors, we investigated a panel of quinolin-2-one-pyrimidine hybrids. Among the active compounds, two of them significantly increased intracellular doxorubicin and rhodamine 123 accumulation by inhibiting the efflux mediated by P-gp and restored doxorubicin toxicity at nanomolar range. Structure-activity relationships showed that the number of methoxy groups, an optimal length of the molecule in its extended conformation, and at least one flexible methylene group bridging the quinolinone moiety favored the inhibitory potency of P-gp. The best compounds showed a similar binding pattern and interactions to those of doxorubicin and tariquidar, as revealed by MD and hybrid QM/MM simulations performed with the recent experimental structure of P-gp co-crystallized with paclitaxel. Analysis of the molecular interactions stabilizing the different molecular complexes determined by MD and QTAIM showed that binding to key residues from TMH 4–7 and 12 is required for inhibition.

scholarly journals The toxic effect of Vu-Defr, a defensin from Vigna unguiculata seeds, on Leishmania amazonensis is associated with reactive oxygen species production, mitochondrial dysfunction, and plasma membrane perturbation

2018 ◽  
Vol 64 (7) ◽  
pp. 455-464 ◽  
Author(s):  
Géssika Silva Souza ◽  
Lais Pessanha de Carvalho ◽  
Edésio José Tenório de Melo ◽  
Valdirene Moreira Gomes ◽  
André de Oliveira Carvalho
Keyword(s):  
Reactive Oxygen Species ◽  
Mitochondrial Membrane ◽  
Biological Activities ◽  
Reactive Oxygen ◽  
Leishmania Amazonensis ◽  
New Drugs ◽  
Oxygen Species ◽  
Membrane Perturbation ◽  
Plant Defensins

Plant defensins are plant antimicrobial peptides that present diverse biological activities in vitro, including the elimination of Leishmania amazonensis. Plant defensins are considered promising candidates for the development of new drugs. This protozoan genus has great epidemiological importance and the mechanism behind the protozoan death by defensins is unknown, thus, we chose L. amazonensis for this study. The aim of the work was to analyze the possible toxic mechanisms of Vu-Defr against L. amazonensis. For analyses, the antimicrobial assay was repeated as previously described, and after 24 h, an aliquot of the culture was tested for viability, membrane perturbation, mitochondrial membrane potential, reactive oxygen species (ROS) and nitric oxide (NO) inductions. The results of these analyses indicated that after interaction with L. amazonensis, the Vu-Defr causes elimination of promastigotes from culture, membrane perturbation, mitochondrial membrane collapse, and ROS induction. Our analysis demonstrated that NO is not produced after Vu-Defr and L. amazonensis interaction. In conclusion, our work strives to help to fill the gap relating to effects caused by plant defensins on protozoan and thus better understand the mechanism of action of this peptide against L. amazonensis.

scholarly journals Mitochondrial adenosine triphosphatase from human placenta--inhibition by free magnesium ions of ITP hydrolysis.

1994 ◽  
Vol 41 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Z Aleksandrowicz
Keyword(s):  
Competitive Inhibition ◽  
Competitive Inhibitor ◽  
Hill Coefficient ◽  
Negative Cooperativity ◽  
Magnesium Ions ◽  
Beef Liver ◽  
Bicarbonate Ions ◽  
The Hill ◽  
Kinetics Of ◽  
Free Magnesium

The effects of Mg2+ and bicarbonate on the kinetics of ITP hydrolysis by soluble ATPase (F1) from human placental mitochondria were studied. Increasing amounts of Mg2+ at fixed ITP concentration, caused a marked activation of F1 followed by inhibition at higher Mg2+ concentration. The appropriate substrate for the mitochondrial F1 seems to be the MgITP complex as almost no ITP was hydrolysed in the absence of magnesium. Mg2+ behaved as a competitive inhibitor towards the MgITP complex. In this respect the human placental enzyme differ from that from other sources such as yeast, beef liver or rat liver. The linearity of the plot presenting competitive inhibition by free Mg2+ of MgITP hydrolysis (in the presence of activating bicarbonate anion) suggests that both Mg2+ and MgITP bind to the same catalytic site (Km(MgITP) = 0.46 mM, Ki(Mg) = 4 mM). When bicarbonate was absent in the ITPase assay, placental F1 exhibited apparent negative cooperativity in the presence of 5 mM Mg2+, just as it did with MgATP as a substrate under similar conditions. Bicarbonate ions eliminated the negative cooperativity with respect to ITP (as the Hill coefficient of 0.46 was brought to approx. 1), and thus limited inhibition by free Mg2+. The results presented suggest that the concentration of free magnesium ions may be an important regulatory factor of the human placental F1 activity.

scholarly journals Evaluation of the antimicrobial activity and cytotoxicity of different components of natural origin present in essential oils

2018 ◽  
Author(s):  
Sara García-Salinas ◽  
Hellen Elizondo ◽  
Manuel Arruebo ◽  
Gracia Mendoza ◽  
Silvia Irusta
Keyword(s):  
Essential Oils ◽  
Rosmarinic Acid ◽  
Pathogenic Bacteria ◽  
Antimicrobial Action ◽  
Eukaryotic Cells ◽  
Natural Origin ◽  
E Coli ◽  
Mammalian Cell Lines ◽  
Animal Pathogens ◽  
Potential Synergy

AbstractThe antimicrobial action of different components present in essential oils including carvacrol, cinnamaldehyde, thymol, squalene, rosmarinic acid, tyrosol, eugenol and β-Caryophyllene against Gram-positive and Gram-negative bacteria is here reported. Planktonic bacteria as well as a model of biofilm forming bacteria were challenged against those components being carvacrol, cinnamaldehyde and thymol the components with the highest antimicrobial action in both different settings. The potential synergy of some of those components against pathogenic bacteria was also analyzed. The antimicrobial mechanism of the different components was analyzed by means of flow cytometry and by electronic and confocal microscopy. Finally, subcytotoxic doses against mammalian cell lines are here reported to highlight the reduced cytotoxicity of those components against eukaryotic cells. Carvacrol, cinnamaldehyde and thymol showed the highest antimicrobial action of all the natural origin compounds tested and lower cytotoxicity against eukaryotic cells than conventional antiseptics such as chlorhexidine. The high inhibition in biofilm forming activity of those components highlight also their demonstrate benefits in reducing pathogenic microorganisms.ImportanceThe use and misuse of antibiotics has led to the emergence of antibiotic resistance to human and animal pathogens. Compounds from natural sources such as animals, plants, and microorganisms have been proposed as renewed potential antimicrobial alternatives. The comparative antimicrobial action of different components commonly present in essential oils including carvacrol, cinnamaldehyde, thymol, squalene, rosmarinic acid, tyrosol, eugenol and β-Caryophyllene against S. aureus and E. coli is here reported. Carvacrol, cinnamaldehyde and thymol are the components with the highest antimicrobial action. Bacteria membrane disruption represents the bactericidal mechanism attributable to these compounds. In addition, the presence of carvacrol, cinnamaldehyde and thymol hinders S. aureus biofilm formation and partially eliminates preformed biofilms. Those components are less toxic to human cells than chlorhexidine.

scholarly journals Decoding Antibacterial and Antibiofilm Properties of Cinnamon and Cardamom Essential Oils: A Combined Molecular Docking and Experimental Study

2021 ◽  
Author(s):  
Elahe Pourkhosravani ◽  
fatemeh dehghan nayeri ◽  
Mitra Mohammadi Bazargani
Keyword(s):  
Cell Attachment ◽  
Antibacterial Properties ◽  
Binding Mode ◽  
Dilution Method ◽  
Antibiofilm Activity ◽  
Bacterial Strains ◽  
Biofilm Growth ◽  
Computational Docking ◽  
E Coli ◽  
Industrial Strains

Abstract This study sets out to compare the antibacterial and antibiofilm profiles of Ci/Ca EOs alone and in combination together against infectious bacterial strains. MIC assay was carried out to survey the effectiveness of prepared EOs by two-fold serial dilution method and MTT evaluation. Synergic antibacterial properties of EOs against target strains were studied by using checkerboard titration method. Biofilm growth and development were evaluated using CV and XTT reduction assays. Antibacterial activity was observed for EOs against both bacterial strains with stronger activity for CiEO against both bacteria. The synergistic antibacterial effect was observed only against B. subtilis. Based on the FIC index, combinations could not inhibit the growth of E. coli. The pure EOs and their combination inhibited cell attachment for both studied bacteria with stronger effect on E. coli. CV and XTT reduction assays results showed that Ci EO and its combination with CaEO had the highest antibiofilm activity at lowest MIC value 0.08% and 0.04/0.02% against biofilm formed by E. coli and B. subtilis respectively, indicating a high antibiofilm potential. Computational docking analyses also postulated that the active constituents of evaluated EOs have the potential to interact with different bacterial targets, suggested binding mode of action of EOs metabolites. By and large, synergistic anti-biofilm properties of EOs may provide further options for developing novel formula to inhibit a variety of infectious clinical and industrial strains without (or less) toxicity effects on human body.

scholarly journals Structural Basis for the Inhibition of RNase H Activity of HIV-1 Reverse Transcriptase by RNase H Active Site-Directed Inhibitors

2010 ◽  
Vol 84 (15) ◽  
pp. 7625-7633 ◽  
Author(s):  
Hua-Poo Su ◽  
Youwei Yan ◽  
G. Sridhar Prasad ◽  
Robert F. Smith ◽  
Christopher L. Daniels ◽  
...  
Keyword(s):  
Active Site ◽  
Thermal Denaturation ◽  
Binding Mode ◽  
Rnase H ◽  
New Drugs ◽  
Structural Basis ◽  
Independent Manner ◽  
Approved Drugs ◽  
Hiv 1 ◽  
Rapid Emergence

ABSTRACT HIV/AIDS continues to be a menace to public health. Several drugs currently on the market have successfully improved the ability to manage the viral burden in infected patients. However, new drugs are needed to combat the rapid emergence of mutated forms of the virus that are resistant to existing therapies. Currently, approved drugs target three of the four major enzyme activities encoded by the virus that are critical to the HIV life cycle. Although a number of inhibitors of HIV RNase H activity have been reported, few inhibit by directly engaging the RNase H active site. Here, we describe structures of naphthyridinone-containing inhibitors bound to the RNase H active site. This class of compounds binds to the active site via two metal ions that are coordinated by catalytic site residues, D443, E478, D498, and D549. The directionality of the naphthyridinone pharmacophore is restricted by the ordering of D549 and H539 in the RNase H domain. In addition, one of the naphthyridinone-based compounds was found to bind at a second site close to the polymerase active site and non-nucleoside/nucleotide inhibitor sites in a metal-independent manner. Further characterization, using fluorescence-based thermal denaturation and a crystal structure of the isolated RNase H domain reveals that this compound can also bind the RNase H site and retains the metal-dependent binding mode of this class of molecules. These structures provide a means for structurally guided design of novel RNase H inhibitors.

scholarly journals Quinazolinones as Competitive Inhibitors of Carbonic Anhydrase-II (Human and Bovine): Synthesis, in-vitro, in-silico, Selectivity, and Kinetics Studies

2020 ◽  
Vol 8 ◽  
Author(s):  
Ajmal Khan ◽  
Majid Khan ◽  
Sobia Ahsan Halim ◽  
Zulfiqar Ali Khan ◽  
Zahid Shafiq ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Active Sites ◽  
Binding Mode ◽  
Competitive Inhibitor ◽  
Significant Inhibition ◽  
Carbonic Anhydrase Ii ◽  
Complete Agreement ◽  
Active Inhibitor ◽  
Kinetics Studies

Carbonic anhydrase-II (CA-II) is associated with glaucoma, malignant brain tumors, and renal, gastric, and pancreatic carcinomas and is mainly involved in the regulation of the bicarbonate concentration in the eyes. CA-II inhibitors can be used to reduce the intraocular pressure usually associated with glaucoma. In search of potent CA-II inhibitors, a series of quinazolinones derivatives (4a-p) were synthesized and characterized by IR and NMR spectroscopy. The inhibitory potential of all the compounds was evaluated against bovine carbonic anhydrase-II (bCA-II) and human carbonic anhydrase-II (hCA-II), and compounds displayed moderate to significant inhibition with IC50 values of 8.9–67.3 and 14.0–59.6 μM, respectively. A preliminary structure-activity relationship suggested that the presence of a nitro group on the phenyl ring at R position contributes significantly to the overall activity. Kinetics studies of the most active inhibitor, 4d, against both bCA-II and hCA-II were performed to investigate the mode of inhibition and to determine the inhibition constants (Ki). According to the kinetics results, 4d is a competitive inhibitor of bCA-II and hCA-II with Ki values of 13.0 ± 0.013 and 14.25 ± 0.017 μM, respectively. However, the selectivity index reflects that the compounds 4g and 4o are more selective for hCA-II. The binding mode of these compounds within the active sites of bCA-II and hCA-II was investigated by structure-based molecular docking. The docking results are in complete agreement with the experimental findings.

scholarly journals Characterization of platinum(II) complexes exhibiting inhibitory activity against the 20S proteasome

2020 ◽  
Vol 7 (8) ◽  
pp. 200545
Author(s):  
Tatsuto Kiwada ◽  
Hiromu Katakasu ◽  
Serina Okumura ◽  
Akira Odani
Keyword(s):  
Inhibitory Activity ◽  
Chemical Structure ◽  
Competitive Inhibition ◽  
Proteasome Inhibitors ◽  
Platinum Complex ◽  
Platinum Complexes ◽  
Binding Mode ◽  
Structure Activity Relationships ◽  
Structure Activity

Proteasome inhibitors are useful for biochemical research and clinical treatment. In our previous study, we reported that the 4N-coordinated platinum complexes with anthracenyl ring and heterocycle exhibited proteasome-inhibitory activity. In the present study, the structure–activity relationships and characterization of these complexes were determined for the elucidation of the role of aromatic ligands. Lineweaver–Burk analysis revealed that the chemical structure of heterocycles affects the binding mode of platinum complexes. Platinum complexes with anthracenyl ring and pyridine showed competitive inhibition, although platinum complexes with anthracenyl ring and phenanthroline showed non-competitive inhibition. The structure–activity relationships demonstrated that anthracenyl moiety plays a crucial role in proteasome-inhibitory activity. The platinum complexes with naphthyl or phenyl rings exhibited lower inhibitory activities than the platinum complex with anthracenyl ring. The reactivity with N-acetylcysteine varied according to the chemical structure of complexes.

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