The discovery and structural requirements of inhibitors of p-hydroxyphenylpyruvate dioxygenase

Weed Science ◽  
1997 ◽  
Vol 45 (5) ◽  
pp. 601-609 ◽  
Author(s):  
David L. Lee ◽  
Michael P. Prisbylla ◽  
Thomas H. Cromartie ◽  
Derek P. Dagarin ◽  
Stott W. Howard ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Biosynthetic Pathway ◽  
Carotenoid Biosynthesis ◽  
Phytoene Desaturase ◽  
Rat Urine ◽  
Meristematic Tissue ◽  
Chemically Induced ◽  
Mammalian Enzyme ◽  
Unique Mechanism

The benzoylcyclohexane-1,3-diones, the triketones, are potent bleaching herbicides whose structure-activity relationships and physical properties are substantially different from classical bleaching herbicides, which affect phytoene desaturase. The first clue to their unique mechanism of action was the discovery that rats treated with a triketone were found to be tyrosinemic. Additionally, examination of the rat urine revealed the accumulation of p-hydroxyphenylpyruvate (HPP) and p-hydroxyphenyllactate. These results suggested that this chemically induced tyrosinemia was the result of the inhibition of p-hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27), and this suggestion was confirmed when a triketone was shown to be a potent inhibitor of rat liver HPPD. In plants, HPPD is a component of the biosynthetic pathway to plastoquinone (PQ), which in turn is a key cofactor of phytoene desaturase. The expectation that triketone-treated plants should accumulate tyrosine while having reduced PQ levels was dramatically demonstrated in the meristematic tissue of ivyleaf morningglory. Plant HPPD, like the mammalian enzyme, was inhibited in vitro by triketones. These biochemical effects provide evidence that the triketone herbicidal mechanism of action is HPPD inhibition leading to a deficiency of PQ, a key cofactor for carotenoid biosynthesis. Other chemical classes of bleaching herbicides were also examined for their ability to elevate tyrosine and deplete PQ as a definitive means of establishing their mode of action and for delineating the structural and physical chemical requirements for an HPPD herbicide. Evidence is provided to support the claim that a 2-benzoylethen-1-ol substructure is the minimum substructure required for a potent HPPD inhibitor.

Anti-clastogenic effect of b-glucan extracted from barley towards chemically induced DNA damage in rodent cells

2006 ◽  
Vol 25 (6) ◽  
pp. 319-324 ◽  
Author(s):  
J Pf Angeli ◽  
L R Ribeiro ◽  
M F Bellini ◽  
M S Mantovani
Keyword(s):  
Dna Damage ◽  
Cell Line ◽  
Dna Polymerase ◽  
Mechanism Of Action ◽  
Methylmethane Sulfonate ◽  
Chemically Induced ◽  
Clastogenic Effect ◽  
Chromosomal Aberration Assay ◽  
Mutagenic Mechanism

b-Glucan (BG) was tested in vitro to determine its potential clastogenic and/or anti-clastogenic activity, and attempts were made to elucidate its possible mechanism of action by using combinations with an inhibitor of DNA polymerase. The study was carried out on cells deficient (CHO-k1) and cells proficient (HTC) in phases I and II enzymes, and the DNA damage was assessed by the chromosomal aberration assay. BG did not show a clastogenic effect, but was anti-clastogenic in both cell lines used, and at all concentrations tested (2.5, 5 and 10 mg/mL) in combination with damage inducing agents (methylmethane sulfonate in cell line CHO-k1, and methylmethane sulfonate or 2-aminoanthracene in cell line HTC). BG also showed a protective effect in the presence of a DNA polymerase b inhibitor (cytosine arabinoside-3-phosphate, Ara-C), demonstrating that BG does not act through an anti-mutagenic mechanism of action involving DNA polymerase b.

scholarly journals Identification of apilimod as a first-in-class PIKfyve kinase inhibitor for treatment of B-cell non-Hodgkin lymphoma

Blood ◽  
2017 ◽  
Vol 129 (13) ◽  
pp. 1768-1778 ◽  
Author(s):  
Sophia Gayle ◽  
Sean Landrette ◽  
Neil Beeharry ◽  
Chris Conrad ◽  
Marylens Hernandez ◽  
...  
Keyword(s):  
B Cell ◽  
Anticancer Activity ◽  
Mechanism Of Action ◽  
Kinase Inhibitor ◽  
Lysosomal Function ◽  
Non Hodgkin Lymphoma ◽  
Key Points ◽  
Unique Mechanism

Key Points Apilimod has broad anticancer activity in vitro and in vivo across all subtypes of B-NHL. Apilimod induces B-NHL cytotoxicity through a unique mechanism of action that involves the disruption of lysosomal function.

Herbicide Symptomology and the Mechanism of Action of Methiozolin

Weed Science ◽  
2020 ◽  
pp. 1-38
Author(s):  
Chad Brabham ◽  
Philipp Johnen ◽  
Janneke Hendriks ◽  
Michael Betz ◽  
Alexandra Zimmermann ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Mechanism Of Action ◽  
Acid Content ◽  
Fatty Acid Content ◽  
Alpha Tocopherol ◽  
Minor Effect ◽  
Exploratory Research ◽  
Meristematic Tissue ◽  
Mva Pathway

Abstract Methiozolin is a new herbicide for control of annual bluegrass (Poa annua L.) in several warm and cool season turfgrasses with an unknown mechanism of action (MOA). In the literature, methiozolin was proposed to be a pigment inhibitor via inhibition of tyrosine aminotransferases (TATs) or a cellulose biosynthesis inhibitor (CBI). Here, exploratory research was conducted to characterize the herbicide symptomology and MOA of methiozolin. Arabidopsis (Arabidopsis thaliana L.) and P. annua exhibited a similar level of susceptibility to methiozolin and arrestment of meristematic growth was the most characteristic symptomology. For example, methiozolin inhibited Arabidopsis root growth (GR50 8 nM), shoot emergence (GR80 ~50 nM), and at rates greater than 500 nM apical meristem growth was completely arrested. We concluded that methiozolin was neither a TAT nor a CBI inhibitor. Methiozolin had a minor effect on chlorophyll and alpha-tocopherol content in treated seedlings (< 500 nM) and supplements in the proposed TAT pathway could not lessen phytotoxicity. Examination of microscopy root images revealed methiozolin treated (100 nM) and untreated seedlings had similar root cell lengths. Thus, methiozolin inhibits cell proliferation and not elongation from meristematic tissue. Subsequently, we suspected methiozolin was an inhibitor of the mevalonic acid (MVA) pathway because its herbicidal symptomologies were nearly indistinguishable from those caused by lovastatin. However, methiozolin did not inhibit phytosterol production and MVA pathway metabolites did not rescue treated seedlings. Further experiments showed that methiozolin produced a very similar physiological profile across a number of assays as cinmethylin, a known inhibitor of fatty acid synthesis through inhibition of thioesterases (FATs). Experiments with Lemna showed that methiozolin also reduced fatty acid content in Lemna with a profile similar, but not identical, to cinmethylin. However, there was no difference in fatty acid content between treated (1 µM) and untreated Arabidopsis seedlings. Methiozolin also bound to both Arabidopsis and Lemna FATs in vitro. Modeling suggested that methiozolin and cinmethylin have comparable and overlapping binding sites to FAT. While there was a discrepancy in the effect of methiozolin on fatty acid content between Lemna and Arabidopsis, the overall evidence indicates that methiozolin is a FAT inhibitor and acts in a similar manner as cinmethylin.

scholarly journals Unravelling the Allosteric Targeting of PHGDH at the ACT-Binding Domain with a Photoactivatable Diazirine Probe and Mass Spectrometry Experiments

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 477
Author(s):  
Quentin Spillier ◽  
Séverine Ravez ◽  
Simon Dochain ◽  
Didier Vertommen ◽  
Léopold Thabault ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Anticancer Drugs ◽  
Mechanism Of Action ◽  
Rational Design ◽  
Biosynthetic Pathway ◽  
Allosteric Site ◽  
Site Of Action ◽  
Phosphoglycerate Dehydrogenase ◽  
New Anticancer Drugs

The serine biosynthetic pathway is a key element contributing to tumor proliferation. In recent years, targeting of phosphoglycerate dehydrogenase (PHGDH), the first enzyme of this pathway, intensified and revealed to be a promising strategy to develop new anticancer drugs. Among attractive PHGDH inhibitors are the α-ketothioamides. In previous work, we have demonstrated their efficacy in the inhibition of PHGDH in vitro and in cellulo. However, the precise site of action of this series, which would help the rational design of new inhibitors, remained undefined. In the present study, the detailed mechanism-of-action of a representative α-ketothioamide inhibitor is reported using several complementary experimental techniques. Strikingly, our work led to the identification of an allosteric site on PHGDH that can be targeted for drug development. Using mass spectrometry experiments and an original α-ketothioamide diazirine-based photoaffinity probe, we identified the 523Q-533F sequence on the ACT regulatory domain of PHGDH as the binding site of α-ketothioamides. Mutagenesis experiments further documented the specificity of our compound at this allosteric site. Our results thus pave the way for the development of new anticancer drugs using a completely novel mechanism-of-action.

scholarly journals Transformation of the Green Alga Haematococcus pluvialis with a Phytoene Desaturase for Accelerated Astaxanthin Biosynthesis

2006 ◽  
Vol 72 (12) ◽  
pp. 7477-7484 ◽  
Author(s):  
Jens Steinbrenner ◽  
Gerhard Sandmann
Keyword(s):  
Green Alga ◽  
Haematococcus Pluvialis ◽  
Carotenoid Biosynthesis ◽  
Phytoene Desaturase ◽  
Site Directed Mutagenesis ◽  
Carotenoid Content ◽  
Desaturase Gene ◽  
Vitro Assay ◽  
Gene And Protein Expression

ABSTRACT Astaxanthin is a high-value carotenoid which is used as a pigmentation source in fish aquaculture. Additionally, a beneficial role of astaxanthin as a food supplement for humans has been suggested. The unicellular alga Haematococcus pluvialis is a suitable biological source for astaxanthin production. In the context of the strong biotechnological relevance of H. pluvialis, we developed a genetic transformation protocol for metabolic engineering of this green alga. First, the gene coding for the carotenoid biosynthesis enzyme phytoene desaturase was isolated from H. pluvialis and modified by site-directed mutagenesis, changing the leucine codon at position 504 to an arginine codon. In an in vitro assay, the modified phytoene desaturase was still active in conversion of phytoene to ζ-carotene and exhibited 43-fold-higher resistance to the bleaching herbicide norflurazon. Upon biolistic transformation using the modified phytoene desaturase gene as a reporter and selection with norflurazon, integration into the nuclear genome of H. pluvialis and phytoene desaturase gene and protein expression were demonstrated by Southern, Northern, and Western blotting, respectively, in 11 transformants. Some of the transformants had a higher carotenoid content in the green state, which correlated with increased nonphotochemical quenching. This measurement of chlorophyll fluorescence can be used as a screening procedure for stable transformants. Stress induction of astaxanthin biosynthesis by high light showed that there was accelerated accumulation of astaxanthin in one of the transformants compared to the accumulation in the wild type. Our results strongly indicate that the modified phytoene desaturase gene is a useful tool for genetic engineering of carotenoid biosynthesis in H. pluvialis.

scholarly journals Comparative In Vitro Efficacies of Various Catheter Lock Solutions

2006 ◽  
Vol 50 (5) ◽  
pp. 1865-1868 ◽  
Author(s):  
Robert J. Sherertz ◽  
Michael S. Boger ◽  
Casey A. Collins ◽  
Lori Mason ◽  
Issam I. Raad
Keyword(s):  
Mechanism Of Action ◽  
Broad Spectrum ◽  
Catheter Lock ◽  
Spectrum Activity ◽  
Unique Mechanism ◽  
Broad Spectrum Activity

ABSTRACT MEDTA (minocycline-edetate calcium disodium), taurolidine (2%)-polyvinylpyrolidine (5%) (T/PVP), and ethanol as potential catheter lock solutions have a unique mechanism of action, broad-spectrum activity, and anticoagulant properties. Traditional lock solutions minocycline (M), rifampin (R), ciprofloxacin (C), and vancomycin, except pharmacologic concentrations of C and R and of M and R, were less effective than MEDTA and T/PVP.

scholarly journals AT-527 is a potent in vitro replication inhibitor of SARS-CoV-2, the virus responsible for the COVID-19 pandemic

2020 ◽  
Author(s):  
Steven S. Good ◽  
Jonna Westover ◽  
Kie-Hoon Jung ◽  
Paolo La Colla ◽  
Gabriella Collu ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Average Concentration ◽  
Airway Epithelial ◽  
Free Base ◽  
Guanosine Triphosphate ◽  
Nucleotide Analog ◽  
Base Form ◽  
Normal Human ◽  
Unique Mechanism

ABSTRACTAT-527, an orally administered double prodrug of a guanosine nucleotide analog, has been shown previously to be highly efficacious and well tolerated in HCV-infected subjects. Herein we report the potent in vitro activity of AT-511, the free base form of AT-527, against several coronaviruses, including SARS-CoV-2, the causative agent of COVID-19. In normal human airway epithelial (HAE) cell preparations, the average concentration of AT-511 required to inhibit replication of SARS-CoV-2 by 90% (EC90) was 0.5 µM, very similar to the EC90 for AT-511 against HCoV-229E, HCoV-OC43 and SARS-CoV in Huh-7 cells. No cytotoxicity was observed for AT-511 in any of the antiviral assays up to the highest concentration tested (100 µM). Surprisingly, AT-511 was 30-fold less active against MERS-CoV. This differential activity may provide a clue to the apparent unique mechanism of action of the guanosine triphosphate analog formed from AT-527.

The Effect of Dipyridamole and RA 233 on Human Platelet Function in Vitro

1973 ◽  
Vol 29 (03) ◽  
pp. 694-700 ◽  
Author(s):  
Paul L. Rifkin ◽  
Marjorie B. Zucker
Keyword(s):  
Mechanism Of Action ◽  
Human Blood ◽  
Glass Bead ◽  
Heart Valves ◽  
Human Platelet ◽  
Drug Effects ◽  
Simple Relation ◽  
Prosthetic Heart Valves ◽  
Induced Aggregation

SummaryDipyridamole (Persantin) is reported to prolong platelet survival and inhibit embolism in patients with prosthetic heart valves, but its mechanism of action is unknown. Fifty jxM dipyridamole failed to reduce the high percentage of platelets retained when heparinized human blood was passed through a glass bead column, but prolonged the inhibition of retention caused by disturbing blood in vitro. Possibly the prostheses act like disturbance. Although RA 233 was as effective as dipyridamole in inhibiting the return of retention, it was less effective in preventing the uptake of adenosine into erythrocytes, and more active in inhibiting ADP-induced aggregation and release. Thus there is no simple relation between these drug effects.

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