Isosorbide-based peptidomimetics as inhibitors of hepatitis C virus serine protease

Hepatitis C infection is a cause of chronic liver diseases such as cirrhosis and carcinoma. The current therapy for hepatitis C has limited efficacy and low tolerance. The HCV encodes a serine protease which is critical for viral replication, and few protease inhibitors are currently on the market. In this paper, we describe the synthesis and screening of novel isosorbide-based peptidomimetic inhibitors, in which the compounds 1d, 1e, and 1i showed significant inhibition of the protease activity in vitro at 100 µM. The compound 1e also showed dose-response (IC₅₀ = 36 ± 3 µM) and inhibited the protease mutants D168A and V170A at 100 µM, indicating it as a promising inhibitor of the HCV NS3/4A protease. Our molecular modeling studies suggest that the activity of 1e is associated with a change in the interactions of S2 and S4 subsites, since that the increased flexibility favors a decrease in activity against D168A, whereas the appearance of a hydrophobic cavity in the S4 subsite increase the inhibition against V170A strain.     

Kinetics of 13 new cholinesterase inhibitors

Kinetics of hydrolysis of acetylcholine and acetylthiocholine by two types of acetylcholinesterase and butyrylcholinesterase inhibited by 13 new inhibitors (5 carbamates and 8 carbazates--hydrazinium derivatives) was measured in vitro in a batch reactor at 25 degrees C, pH 8, ionic strength 0.11 M and enzyme activity 3.5 U by four nondependent analytical methods. Sevin, rivastigmin (Exelon) and galantamin (Reminyl) served as comparative inhibiting standards. Kinetics of hydrolyses inhibited by all studied carbamates, sevin, carbazates (with exceptions) and rivastigmin (with exceptions) can be simulated by the competitive inhibition model with irreversible reaction between enzyme and inhibitor. Galantamin does not fulfil this model. In positive simulations, the value of inhibition (carbamoylation) rate constant k3 was calculated, describing the reaction velocity between the given enzyme and inhibitor. Physiologically important hydrolyses of acetylcholine catalyzed by acetylcholinesterase from electric eel or bovine erythrocytes and butyrylcholinesterase from horse plasma can be most quickly inhibited by carbamoylation of the mentioned enzymes by the 3-N,N-diethylaminophenyl-N'-(1-alkyl) carbamates 4 and 5. Probably this is due to a long enough hydrocarbon aliphatic substituent (hexyl and octyl) on the amidic nitrogen atom. The tested carbazates failed as inhibitors of cholinesterases. The regeneration ability of the inhibited enzymes was not measured.     

Half-inhibition concentrations of new cholinesterase inhibitors

The power of chosen carbamates and hydrazinium derivatives (carbazates) to inhibit the hydrolysis of acetylthiocholine by butyrylcholinesterase or acetylcholinesterase was tested. The determined pI50 values (= negative logarithm of the molar concentration inhibiting the enzyme activity by 50%) of the tested substances were compared with pI50 values of the commercially used drugs for the Alzheimer's disease treatment--rivastigmine and galanthamine.     

Mutation leading to increased sensitivity to chromium in Salmonella typhimurium

Corwin, L. M. (Walter Reed Army Institute of Research, Washington, D.C.), G. R. Fanning, F. Feldman, and P. Margolin. Mutation leading to increased sensitivity to chromium in Salmonella typhimurium. J. Bacteriol. 91:1509-1515. 1966.-Certain deletion mutants including the tryptophan operon in Salmonella typhimurium are unable to utilize several sugars as carbon sources in solid media, although they are able to grow in liquid media with these sugars. The addition of citrate or washing the agar with ethylenediaminetetraacetic acid permits growth on solid media. Analysis of the agar revealed that Fe(3+) and Cr(3+) were present at concentrations of 22 and 75 mum, respectively. The addition of Fe(3+) to liquid media in 0.5 mm concentrations did not inhibit the wild type or the mutants. A similar concentration of Cr(3+) did not inhibit the wild type, but concentrations as low as 0.01 to 0.05 mm inhibited the deletion mutants. Other metals were inhibitory at various concentrations, but none showed any significant differential effects on the mutants and the wild type. The increased sensitivity of the mutants to chromium may be due either to an increased permeability to Cr(3+), resulting in higher effective intracellular concentrations and inhibition of one or more metabolic functions, or to a binding of Cr(3+) to an altered cell wall, resulting in decreased permeability of required substrates.     

Morpho-functional changes in the liver after exposure to cholinesterase inhibitors

A single administration of chlorophos (trichlorophon) solution (600 mg/kg) (LD50) results in vacuolar distrophy appearing in the white rat liver and is especially pronounced in 2-4 days. Thirty minutes after the poisonous chemical is administered, butyrilcholinesterase (BChE) activity is inhibited by 90%, somewhat later oxidation-reduction enzymes activity decreases and alkaline phosphatase (APh) activity increases. Cytoplasm of hepatocytes is filled with glycogene and nearly deprived of RNA. Owing to the cytophotometric analysis of the enzymatic activity and the stereologic morphometry method, it has been possible to reveal a certain synchronism in the development of distrophic processes, in a decreasing activity of the oxidation-reduction enzymes and in a disturbed synthesis of glycogene and RNA. On the 6th day after chlorophos has been administered, succinate dehydrogenase and nicotinamide-adenine-dinucleotide-phosphate-diaphorase activity, as well as contents and distribution of RNA in hepatocytes reach their control values. BChE and APh activity does not restore. During the whole experiment there is not any statistically significant change in the volumetric part of the sinusoid capillaries and in the stellate reticuloendotheliocytes. Thus, the main effect of chlorophos action is a specific inhibition of ChE, that results in certain structural changes and in changes of the histoenzymatic parameters of the liver.     

Spruce forest afforestation leading to increased Fe mobilization from soils

Biogeochemistry - Increasing exports of Fe and DOC from soils, causing browning of freshwaters, have been reported in recent decades in many regions of the northern hemisphere. Afforestation, and...     

Ligand distortion modes leading to increased chirality content of Katsuki-Jacobsen catalysts

The "chirality content" of Katsuki-Jacobsen epoxidation catalysts are computed with the Avnir continuous chirality measure (CCM). An assessment of Mn(salen) molecules from the Cambridge Structural Database shows there exist some variation in CCM and the chirality content for several triplet state complexes of these catalysts purported in the literature to be the active species show even larger CCM values. Several deformation modes were analyzed to examine how chirality content changes as catalyst distortion is induced. The deformations studied include in-plane deformations, cup-shaped puckering, ligand twisting motions, and step-like deformations. Some distortions lead to increases of chirality while others lead to a decrease in chirality content. The most influential distortion modes that can be used for ligand design are twisting and step induction.     

Selectivity of phenothiazine cholinesterase inhibitors for neurotransmitter systems

Synthetic derivatives of phenothiazine have been used for over a century as well-tolerated drugs against a variety of human ailments from psychosis to cancer. This implies a considerable diversity in the mechanisms of action produced by structural changes to the phenothiazine scaffold. For example, chlorpromazine treatment of psychosis is related to its interaction with dopaminergic receptors. On the other hand, antagonistic action of such drugs on cholinergic receptor systems would be counter-productive for treatment of Alzheimer’s disease. In a search for phenothiazines that are inhibitors of cholinesterases, especially butyrylcholinesterase, with potential to treat Alzheimer’s disease, we wished to ascertain that such molecules could be devoid of neurotransmitter receptor interactions. To that end, a number of our synthetic N-10-carbonyl phenothiazine derivatives, with cholinesterase inhibitory activity, were tested for interaction with a variety of neurotransmitter receptor systems. We demonstrate that phenothiazines can be prepared without significant neurotransmitter receptor interactions while retaining high potency as cholinesterase ligands for treatment of Alzheimer’s disease.     

Norditerpenoid alkaloids of Delphinium denudatum as cholinesterase inhibitors

Three new norditerpenoids alkaloids, 1β-hydroxy,14β-acetyl condelphine (1), jadwarine-A (2), jadwarine-B (3) along with two known alkaloids isotalatizidine hydrate (4) and dihydropentagynine (5) were isolated from medicinal plant Delphinium denudatum. The structures of natural products 1–5 were established on the basis of HR-EIMS, ¹H and ¹³C NMR (1D & 2D) spectroscopic data as well as by comparison from literature data. The structures of compound 1 and 4 were also confirmed by single crystal X-ray diffraction studies. In-vitro AChE and BChE enzyme inhibitory activities of compounds 1–5 and molecular docking studies were performed to investigate the possible molecular inhibitory mechanism of the isolated natural products. Compound 2, 4 and 5 showed competitive inhibitory effects by inhibiting AChE and BChE, respectively, while 1 and 3 showed non-competitive inhibition. This work is the first report that provides a supporting evidence about the use of constituents of Delphinium denudatum in cerebral dementia and Alzheimer diseases.     

Carbonic anhydrase inhibitors: aliphatic N-phosphorylated sulfamates--a novel zinc-anchoring group leading to nanomolar inhibitors

A small library of phosphorylated sulfamates (N-(O-alkylsulfamoyl)-phosphoramidic acids) incorporating long aliphatic chains (C8-C16) has been synthesized and investigated for their interaction with two physiologically relevant carbonic anhydrase (CA) isozymes. These compounds behaved as very potent inhibitors of both isozymes, with inhibition constants in the range of 8.2-16.1nM against isozyme hCA I, and 5.3-11.9nM against isozyme hCA II. Activity was optimal for the n-octyl derivative (similarly with that of the corresponding unsubstituted sulfamates) and gradually decreased for the longer chain derivatives. Some of these compounds are much more effective CA inhibitors as compared to the clinically used derivatives acetazolamide, sulfanilamide or topiramate, which are used as standards for the enzymatic determinations. The phosphorylated sulfamate moiety represents a novel zinc-binding group for the design of effective CA inhibitors.     

Excessive R-loops trigger an inflammatory cascade leading to increased HSPC production

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Stress interacts with peripheral cholinesterase inhibitors to cause central nervous system effects

Pyridostigmine bromide (PB), a peripheral cholinesterase inhibitor, has been shown to have central cholinesterase inhibition properties under certain conditions (such as when ingested with other chemical compounds or following a high level of stress). Here we tested if stressing rats, using an intermittent 1 hr tailshock protocol, affected the degree of brain acetylcholinesterase (AChE) inhibition caused by a subsequent single injection of PB (2.0 mg/kg) or neostigmine bromide (NB, 0.32 mg/kg), another peripheral carbamate cholinesterase inhibitor. Stressed rats treated with PB had lower levels of AChE activity in the basal forebrain/striatum, but not in other brain areas. Stressed rats treated with NB did not show basal forebrain/striatum AChE activity changes but did show minor reductions of AChE activity in the cortex and cerebellum. These results confirm that prior stress can change the characteristic actions of certain peripherally acting drugs, thus possibly leading to unexpected central nervous system effects. Possible causes for these effects are discussed.     

Antiidiotype modulation of herpes simplex virus infection leading to increased pathogenicity.

Antiidiotype reagents that recognize idiotypic determinants associated with the combining site of monoclonal antibodies to herpes simplex virus type 2 ( HSV2 ) were used to manipulate the immune response to HSV2 in BALB/c mice. The injection of antiidiotype antibodies into mice before challenge with a 50% lethal dose of HSV2 resulted in a shorter survival time than that of mice receiving either preimmune rabbit immunoglobulin G or antiidiotype reagents against hepatitis B surface antigen before HSV2 challenge. These findings indicate that the immune response to HSV2 in mice can be modulated through idiotype- antiidiotype networks, thereby increasing the pathogenicity of HSV2 infections.     

Molecular modifications of 2-arylidene-1-indanones leading to increased cytotoxic potencies

A series of 2-arylidene-1-indanones, 1, had been shown previously to display cytotoxic properties towards Molt 4/C8, CEM and L1210 cells. In the present study, two series of analogues of 1 were prepared namely various 2-arylidene-1,3-indandiones, 2, and chalcones, 3. In general, the potencies of compounds 2 and 3 were greater than the analogues bearing the same aryl substituents in series 1. Molecular modeling was undertaken in order to seek explanations for the variation in bioactivities.     

Antisense inhibition of butyrylcholinesterase gene expression predicts adverse hematopoietic consequences to cholinesterase inhibitors

Summary 1. To investigate the possibility that cholinesterase inhibitors may cause adverse hematopoietic effects, we employed antisense oligodeoxynucleotides selectively inhibiting butyrylcholinesterase gene expression (AS-BCHE). Complementary sense (S) oligonucleotides served as controls.2. In primary bone marrow cell cultures grown with interleukin 3 (IL-3), AS-BCHE but not S-BCHE reduced growth of megakaryocyte colony-forming units (CFU-MK) in a dose-dependent manner at the micromolar range.3. In cultures grown with IL-3, transferrin, and erythropoietin (Epo), cell counts increased up to twofold, yet colony counts (CFU-GEMM) remained unchanged under AS-BCHE treatment.4. Electrophoretic measurements of DNA ladder as an apoptotic index revealed that the above oligonucleotide effects were not due to nonspecific induction of programmed cell death.5. Differential cell counts demonstrated increased myeloidogenesis and reduced levels of early megakaryocytes in CFU-GEMM under AS-BCHE, suggesting requirement of the BuChE protein for megakaryopoiesis.6.In vivo injection of AS-BCHE reduced BCHE mRNA levels in both young and mature megakaryocytes for as long as 20 days, as shown byin situ hybridization.7.Ex vivo growth of primary bone marrow cells revealed a twofold reduction in CFU-MK colonies grown from the AS-BCHE- but not the S-BCHE-injected mice, 15 days posttreatment.8. These findings demonstrate that deficient butyrylcholinesterase expression, and hence interference with this enzyme's activity through treatment with or exposure to cholinesterase inhibitors, may cause hematopoietic differences in treated patients.