scholarly journals Slow-Binding Inhibition of Tyrosinase by Ecklonia cava Phlorotannins

Marine Drugs ◽  
2019 ◽  
Vol 17 (6) ◽  
pp. 359 ◽  
Author(s):  
Jang Hoon Kim ◽  
Sunggun Lee ◽  
Saerom Park ◽  
Ji Soo Park ◽  
Young Ho Kim ◽  
...  
Keyword(s):  
Active Site ◽  
Time Course ◽  
Enzyme Reaction ◽  
Single Step ◽  
Ecklonia Cava ◽  
Binding Mechanism ◽  
Skin Whitening ◽  
Binding Inhibition ◽  
Ic50 Values ◽  
Tyrosinase Inhibitors

Tyrosinase inhibitors improve skin whitening by inhibiting the formation of melanin precursors in the skin. The inhibitory activity of seven phlorotannins (1–7), triphlorethol A (1), eckol (2), 2-phloroeckol (3), phlorofucofuroeckol A (4), 2-O-(2,4,6-trihydroxyphenyl)-6,6′-bieckol (5), 6,8′-bieckol (6), and 8,8′-bieckol (7), from Ecklonia cava was tested against tyrosinase, which converts tyrosine into dihydroxyphenylalanine. Compounds 3 and 5 had IC50 values of 7.0 ± 0.2 and 8.8 ± 0.1 μM, respectively, in competitive mode, with Ki values of 8.2 ± 1.1 and 5.8 ± 0.8 μM. Both compounds showed the characteristics of slow-binding inhibitors over the time course of the enzyme reaction. Compound 3 had a single-step binding mechanism and compound 5 a two-step-binding mechanism. With stable AutoDock scores of −6.59 and −6.68 kcal/mol, respectively, compounds 3 and 5 both interacted with His85 and Asn260 at the active site.

scholarly journals The Guanidine Pseudoalkaloids 10-Methoxy-Leonurine and Leonurine Act as Competitive Inhibitors of Tyrosinase

Biomolecules ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 174
Author(s):  
Jang Hoon Kim ◽  
Hyun Hee Leem ◽  
Ga Young Lee
Keyword(s):  
Benzene Ring ◽  
Active Site ◽  
In Silico ◽  
Guanidine Group ◽  
Lead Compounds ◽  
In Silico Modeling ◽  
Competitive Inhibitors ◽  
Ic50 Values ◽  
Tyrosinase Inhibitors ◽  
Micromolar Range

Tyrosinase plays a key role in the production of melanin. A variety of industrial fields have shown interest in the development of tyrosinase inhibitors from plants. In this study, compounds 1–5 derived from Leonurus japonicas were evaluated to determine their ability to inhibit tyrosinase. Of these, 10-methoxy-leonurine (1) and leonurine (2) exhibited IC50 values of 7.4 ± 0.4 and 12.4 ± 0.8 μM, respectively, and acted as competitive inhibitors of tyrosinase, with Ki values in the micromolar range. In silico modeling revealed a guanidine group located in the inner cavity and a benzene ring docked within the active site of these compounds. These guanidine pseudoalkaloids show potential not only as tyrosinase inhibitors but also as lead compounds in new scaffolds for the development of novel inhibitors.

The Effect of Active Site-inhibited Factor VIIa on Tissue Factor-initiated Coagulation Using Platelets before and after Aspirin Administration

1997 ◽  
Vol 78 (04) ◽  
pp. 1202-1208 ◽  
Author(s):  
Marianne Kjalke ◽  
Julie A Oliver ◽  
Dougald M Monroe ◽  
Maureane Hoffman ◽  
Mirella Ezban ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Active Site ◽  
Large Scale ◽  
Thrombin Generation ◽  
Factor Viia ◽  
Dependent Manner ◽  
Antithrombotic Agent ◽  
Before And After ◽  
Ic50 Values

SummaryActive site-inactivated factor VIIa has potential as an antithrombotic agent. The effects of D-Phe-L-Phe-L-Arg-chloromethyl ketone-treated factor VIla (FFR-FVIIa) were evaluated in a cell-based system mimicking in vivo initiation of coagulation. FFR-FVIIa inhibited platelet activation (as measured by expression of P-selectin) and subsequent large-scale thrombin generation in a dose-dependent manner with IC50 values of 1.4 ± 0.8 nM (n = 8) and 0.9 ± 0.7 nM (n = 7), respectively. Kd for factor VIIa binding to monocytes ki for FFR-FVIIa competing with factor VIIa were similar (11.4 ± 0.8 pM and 10.6 ± 1.1 pM, respectively), showing that FFR-FVIIa binds to tissue factor in the tenase complex with the same affinity as factor VIIa. Using platelets from volunteers before and after ingestion of aspirin (1.3 g), there were no significant differences in the IC50 values of FFR-FVIIa [after aspirin ingestion, the IC50 values were 1.7 ± 0.9 nM (n = 8) for P-selectin expression, p = 0.37, and 1.4 ± 1.3 nM (n = 7) for thrombin generation, p = 0.38]. This shows that aspirin treatment of platelets does not influence the inhibition of tissue factor-initiated coagulation by FFR-FVIIa, probably because thrombin activation of platelets is not entirely dependent upon expression of thromboxane A2.

Novel Piperazine Amides of Cinnamic Acid Derivatives as Tyrosinase Inhibitors

2018 ◽  
Vol 16 (1) ◽  
pp. 36-44 ◽  
Author(s):  
Zehra Tuğçe Gür ◽  
Fatma Sezer Şenol ◽  
Suhaib Shekfeh ◽  
İlkay Erdoğan Orhan ◽  
Erden Banoğlu ◽  
...  
Keyword(s):  
Cinnamic Acid ◽  
Active Site ◽  
Agaricus Bisporus ◽  
Biological Activities ◽  
Docking Simulation ◽  
Cinnamic Acid Derivatives ◽  
In Silico Docking ◽  
Amide Derivatives ◽  
Tyrosinase Inhibitors ◽  
Further Development

Background: A series of novel cinnamic acid piperazine amide derivatives has been designed and synthesized, and their biological activities were also evaluated as potential tyrosinase inhibitors. Methods: Compounds 9, 11 and 17 showed the most potent biological activity (IC50 = 66.5, 61.1 and 66 µM, respectively). In silico docking simulation was performed to position compound 11 into the Agaricus bisporus mushroom tyrosinase’s active site to determine the putative binding interactions. Results and Conclusion: The results indicated that compound 11 could serve as a promising lead compound for further development of potent tyrosinase inhibitors.

scholarly journals Modeling and synthesis of antiplasmodial chromones, chromanones and chalcones based on natural products of Kenya

2018 ◽  
Vol 16 (1) ◽  
pp. 8-21
Author(s):  
MANYIM SCOLASTICA ◽  
ALBERT J. NDAKALA ◽  
SOLOMON DERESE
Keyword(s):  
Natural Products ◽  
Drug Design ◽  
Active Site ◽  
Docking Studies ◽  
Moderate Activity ◽  
Vigorous Activity ◽  
Structure Based Drug Design ◽  
Web Based ◽  
Ic50 Values ◽  
Accessible Form

Scolastica M, Ndakala AJ, Derese S. 2018. Modeling and synthesis of antiplasmodial chromones, chromanones and chalcones based on natural products of Kenya. Biofarmasi J Nat Prod Biochem 16: 8-21. Despite numerous research that has been done on plants of Kenya resulting in the isolation of thousands of natural products, data on these natural products are not systematically organized in a readily accessible form. This has urged the construction of a web-based database of natural products of Kenya. The database is named Mitishamba and is hosted at http://mitishamba.uonbi.ac.ke. The Mitishamba database was queried for chromones, chromanones, and chalcones that were subjected to structure-based drug design using Fred (OpenEye) docking utility program with 1TV5 PDB structure of the PfDHODH receptor to identify complex of ligands that bind with the active site. Ligand-based drug design (Shape and electrostatics comparison) was also done on the ligands against query A77 1726 (38) (the ligand that co-crystallized with PfDHODH receptor) using ROCS and EON programs, respectively, of OpenEye suite. There was a substantial similarity among the top performing ligands in the docking studies with shape and electrostatic comparison that led to the identification of compounds of interest which were targeted for synthesis and antiplasmodial assay. In this study, a chromanone (7-hydroxy-2-(4-methoxyphenyl) chroman-4-one (48)) and two intermediate chalcones (2',4'-dihydroxy-4-methoxychalcone (45) and 2’,4’-dihydroxy-4-chlorochalcone (47)), were synthesized and subjected to antiplasmodial assay. Among these substances, 45 showed vigorous activity, whereas 47 and 48 had moderate activity against the chloroquine resistant K1 strain of P. falciparum with IC50 values of 4.56±1.66, 17.62 ± 5.94 and 18.01 ±1.66 µg/ml, respectively. Since the synthesized compounds showed antiplasmodial potential, there is a need for further computational refinement of these compounds to optimize their antiplasmodial activity.

Tablets Prepared by Single-Step Granulation/Tabletting: Interparticulate Binding Mechanism and Stability

2005 ◽  
Vol 10 (3) ◽  
pp. 397-403 ◽  
Author(s):  
A. Vermeire ◽  
E. I. Keleb ◽  
F. Kiekens ◽  
I. Van Driessche ◽  
S. Hoste ◽  
...  
Keyword(s):  
Single Step ◽  
Binding Mechanism

scholarly journals A Recombinant Multiepitope Protein for Hepatitis B Diagnosis

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Marilen Queiroz de Souza ◽  
Alexsandro Sobreira Galdino ◽  
José Carlos dos Santos ◽  
Marcus Vinicius Soares ◽  
Yanna C. de Nóbrega ◽  
...  
Keyword(s):  
Hepatitis B ◽  
Time Course ◽  
Clinical Stage ◽  
Acute Infection ◽  
Single Step ◽  
Liver Inflammation ◽  
E Coli ◽  
Terminal Time ◽  
Gene Coding ◽  
B Virus

Hepatitis B is a liver inflammation caused by hepatitis B virus (HBV) and can be diagnosed in clinical stage by hepatitis B core antibody from IgM class (anti-HBcIgM). Hepatitis B core antibody from IgG class (Anti-HBcIgG) appears quickly after IgM, reaching high titers in chronic hepatitis, and remains even after cure. Since hepatitis B core antibody (anti-HBc) is the first antibody identified and sometimes the only marker detected during the course of infection, it can be used both to indicate HBV acute infection (anti-HBc-IgM) and to identify individuals who have come into contact with the virus (anti-HBc-IgG). In this work we propose a recombinant hepatitis B core multiepitope antigen (rMEHB) to be used for diagnosis of hepatitis B. For this purpose, a synthetic gene coding for rMEHB was designed and cloned into vector pET21a with a 6xHis tag at the C-terminal. Time course induction inE. colishowed an induced protein with an apparent molecular mass of ~21 kDa. Protein purification was performed by a single step with affinity chromatography Ni-NTA. Circular dichroism spectroscopy indicated rMEHB as a thermal stable protein at pH 7.0 and 8.0. In these conditions rMEHB was successfully used to perform an enzyme linked immuno sorbent assay (ELISA) with positive and negative sera.

The Natural Product Borrelidin Induces UPR and Apoptosis in AML Cell Lines

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4260-4260
Author(s):  
Leah Jackson ◽  
Shelby Bechler ◽  
Justin Miller ◽  
Amy Brownell ◽  
Danielle Garshott ◽  
...  
Keyword(s):  
Cell Death ◽  
Er Stress ◽  
Natural Product ◽  
Cell Lines ◽  
Time Course ◽  
Conflicts Of Interest ◽  
Xenograft Model ◽  
Myelogenous Leukemia ◽  
Ic50 Values

Abstract Abstract 4260 Acute Myelogenous Leukemia (AML) is the most common form of leukemia. Current therapies are intense and even those fortunate enough to achieve remission often relapse extending extremely poor prognoses to these patient. The most commonly used therapeutics, namely cytarabine aribinoside, the anthracyclines and etoposide, are decades old and target ubiquitous cellular processes. We have previously reported that small molecules and natural products that activate and exacerbate the unfolded protein response (UPR) can effectively and selectively induce cell death in a wide variety of solid tumor cells. We hypothesized that the UPR might be a viable new therapeutic target in AML and sought to determine whether or not the novel UPR-inducing natural product borrelidin might be used as such an agent. A luminescent proliferation assay performed with panel of four AML cell lines treated with the ER stress-inducing antibiotic tunicamycin (Tm) revealed that three of the cell lines displayed IC50 values between 0.47–2.5μ M, doses of Tm which are known to induce a low to moderate level of ER stress. We then repeated the experiment with the more general UPR-inducing natural product borrelidin, which has been shown to have potent anti-inflammatory properties in several murine assays in vivo. All four cell lines were sensitive to borrelidin, displaying IC50 values between 0.032–0.29 μ M. Time course assays performed with borrelidin revealed 4–20 fold increases in active caspase 3 and 7 indicating borrelidin-induced AML decreases in cell proliferation might be the result of apoptosis. Quantitative reverse-transcription real time PCR performed with mRNA isolated from two AML cell lines revealed an increase in the UPR-related transcripts CHOP, ATF4, and GADD34 and the cell death genes Noxa, Puma, DR5 and Bim confirming that borrelidin could induce the UPR and apoptosis in AML cells. Studies currently underway in our laboratory will determine the ability of borrelidin and other UPR-inducing agents to reduce leukemic burden in an in vivo xenograft model. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Single motoneuron succinate dehydrogenase activity.

1989 ◽  
Vol 37 (7) ◽  
pp. 1107-1114 ◽  
Author(s):  
G R Chalmers ◽  
V R Edgerton
Keyword(s):  
Enzymatic Activity ◽  
Succinate Dehydrogenase ◽  
Time Course ◽  
Processing System ◽  
Enzyme Reaction ◽  
Histochemical Assay ◽  
Computer Image Processing ◽  
Wide Range ◽  
Soma Size

We have developed a quantitative histochemical assay for measurement of succinate dehydrogenase (SDH) activity in single motoneurons. A computer image processing system was used to quantify the histochemical enzyme reaction product and to follow the time course of the reaction. The optimal concentration for each of the ingredients of the incubation medium for the SDH reaction was determined and the importance of using histochemical "blanks" in the determination of enzymatic activity was demonstrated. The enzymatic activity was linear with respect to reaction time and tissue thickness. The procedure described meets the criteria generally considered essential for establishment of a quantitative histochemical assay. The assay was then used to examine the SDH activity of cat and rat motoneurons. It was found that motoneurons with a small soma size had a wide range of SDH activity, whereas those with a large soma size were restricted to low SDH activity.

Isoprenylated Phenolic Compounds from Morus macroura as Potent Tyrosinase Inhibitors

Planta Medica ◽  
2017 ◽  
Vol 84 (05) ◽  
pp. 336-343 ◽  
Author(s):  
Yifan Wang ◽  
Liangjin Xu ◽  
Wen Gao ◽  
Lixin Niu ◽  
Chunyue Huang ◽  
...  
Keyword(s):  
Kojic Acid ◽  
Positive Control ◽  
Diels Alder ◽  
Extensive Analysis ◽  
Ic50 Value ◽  
Ic50 Values ◽  
Tyrosinase Inhibitors ◽  
Inhibitory Activities ◽  
New Compounds

AbstractThree new Diels-Alder adducts, macrourins E – G (1–3), one new 2-arylbenzofuran, macrourin H (4), and eight known Diels-Alder adducts (5–12) were isolated from Morus macroura. Their structures were elucidated through extensive analysis of spectroscopic data. The 1H NMR and ECD trends in the determination of the configurations of these Diels-Alder adducts were summarized. The tyrosinase inhibitory activities of all compounds isolated were evaluated, and the new compounds (1–4) as well as the eight known compounds (5–12) were found to be potent with IC50 values ranging from 0.39 to 4.54 µM. Among them, 1 showed the best tyrosinase inhibitory activity with an IC50 value of 0.39 µM, approximately 50 times stronger than the positive control, kojic acid.

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