A New Tiazofurin Pronucleotide: Synthesis and Biological Evaluation of CycloSaligenyl-Tiazofurin Monophosphate

Abstract

Synthesis and biological activities of cyclosaligenyl-tiazofurin monophosphate (CycloSal-TRMP), a new tiazofurin pronucleotide, are reported. CycloSal-TRMP proved to be active in vitro against human myelogenous leukemia K562 cell line and as A₁ adenosine receptor agonist.     

Increase of cyclin B by overexpression of cystatin α

Degradation of cyclin B was effectively suppressed when cells were treated with ALLN (N-acetylleucylleucylnorleucinal) which inhibits proteasome, calpain and cysteine proteinase cathepsins. In order to examine which protease degrades cyclin B, the effect of a cathepsin inhibitor, cystatin α, was investigated. The cystatin α gene was inserted into an inducible expression vector, pMSG, and transfected into NIH3T3 mouse fibroblasts. The expression of cystatin α was induced effectively in the transfected cells after treatment with dexamethasone. Overexpression of cystatin α resulted in an increase of the amount of cyclin B, suggesting that cysteine proteinase cathepsins might be involved in the degradation of cyclin B.     

Engineering Halomonas TD01 for the low-cost production of polyhydroxyalkanoates

The halophile Halomonas TD01 and its derivatives have been successfully developed as a low-cost platform for the unsterile and continuous production of chemicals. Therefore, to increase the genetic engineering stability of this platform, the DNA restriction/methylation system of Halomonas TD01 was partially inhibited. In addition, a stable and conjugative plasmid pSEVA341 with a high-copy number was constructed to contain a LacI^q-P_trc system for the inducible expression of multiple pathway genes. The Halomonas TD01 platform, was further engineered with its 2-methylcitrate synthase and three PHA depolymerases deleted within the chromosome, resulting in the production of the Halomonas TD08 strain. The overexpression of the threonine synthesis pathway and threonine dehydrogenase made the recombinant Halomonas TD08 able to produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) or PHBV consisting of 4–6 mol% 3-hydroxyvalerate or 3HV, from various carbohydrates as the sole carbon source. The overexpression of the cell division inhibitor MinCD during the cell growth stationary phase in Halomonas TD08 elongated its shape to become at least 1.4-fold longer than its original size, resulting in enhanced PHB accumulation from 69 wt% to 82 wt% in the elongated cells, further promoting gravity-induced cell precipitations that simplify the downstream processing of the biomass. The resulted Halomonas strains contributed to further reducing the PHA production cost.     

Effects of Tripeptides on the Amidolytic Activities of Urokinase, Thrombin, Plasmin and Trypsin

Eight peptides of the general formula X-d-Ser-AA-Arg-Y where X = H, Ac; AA = Ala, Gly and Y = OH, NH₂ were obtained and tested for their effect on the amidolytic activities of urokinase, thrombin, plasmin, and trypsin.     

Chronobiology of Coronary Risk Markers in Greenland Eskimos: A Comparative Study with Caucasians Residing in the Same Arctic Area

We report a comparison of fibrinolytic variables between 10 Caucasians on a predominantly European diet and 10 Greenland Eskimos on a traditional Inuit diet containing a substantial amount of fish and sea animals. We studied the diurnal variation in tissue type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) antigens and activities during a 24-h period. Blood samples were taken every 4 h. The variations of the sinusoidal curves were evaluated by the Friedman χ² test. t-PA and PAI-1 antigen in plasma fluctuated significantly during the 24 h (Eskimos p < 0.000007 and p < 0.0007; Caucasians p < 0.00003 and p < 0.02), with a peak in the early morning and a nadir in the afternoon. This also held true for PA1 activity (Eskimos p < 0.0008; Caucasians p < O.Ol), whereas t-PA activity showed an inverse but still significant pattern (Eskimos p < 0.006; Caucasians p < 0.0008). Amplitudes, areas underneath, and overall medians of the sinusoidal curves did not deviate between the two groups with respect to t-PA and PAL In contrast to the significant variation of t-PA and PAI, the plasma concentrations of fibrin degradation products (D-Dimer), a measure of effective fibrinolysis, remained constant during the 24 h, and the absolute differences between groups did not reach statistical significance. These findings suggest that circadian variation of fibrinolytic activators and inhibitors is a basic biologic phenomenon, which is not affected by life-style, dietary habits, or ethnic differences. Furthermore, the lack of diurnal variation in D-Dimer raises the question of whether there is a causal relationship between low morning activities of t-PA and the frequent onset of myocardial infarction at that time of day, as suggested by several authors.     

Cloning and Nucleotide Sequence of the Gene Encoding a Serine Proteinase Inhibitor Named Marinostatin from a Marine Bacterium,Alteromonas sp. Strain B-10-31

The gene (mstI) encoding a serine proteinase inhibitor named marinostatin from marine Alteromonas sp. strain B-10-31 was cloned and its nucleotide sequence was analyzed. A short open reading frame of 192 bp encoded 63 amino acids with a molecular weight of 6,985. Furthermore, the initial product of marinostatin (marinostatin L) was purified and its amino acid sequence was analyzed. These results indicate that marinostatin is produced as a unique precursor consisting of the mature peptide and the leader peptide for an ATP-binding cassette (ABC) transporter, and furthermore the initial product of marinostatin is dehydrated and processed by proteolysis to give homologous forms of marinostatin.     

Anion inhibition studies of a beta carbonic anhydrase from the malaria mosquito Anopheles gambiae

An anion inhibition study of the β-class carbonic anhydrase, AgaCA, from the malaria mosquito Anopheles gambiae is reported. A series of simple as well as complex inorganic anions, and small molecules known to interact with CAs were included in the study. Bromide, iodide, bisulphite, perchlorate, perrhenate, perruthenate, and peroxydisulphate were ineffective AgaCA inhibitors, with K_Is?>?200?mM. Fluoride, chloride, cyanate, thiocyanate, cyanide, bicarbonate, carbonate, nitrite, nitrate, sulphate, stannate, selenate, tellurate, diphosphate, divanadate, tetraborate, selenocyanide, and trithiocarbonate showed K_Is in the range of 1.80–9.46?mM, whereas N,N-diethyldithiocarbamate was a submillimolar AgaCA inhibitor (K_I of 0.65?mM). The most effective AgaCA inhibitors were sulphamide, sulphamic acid, phenylboronic acid and phenylarsonic acid, with inhibition constants in the range of 21–84?µM. The control of insect vectors responsible of the transmission of many protozoan diseases is rather difficult nowadays, and finding agents which can interfere with these processes, as the enzyme inhibitors investigated here, may arrest the spread of these diseases worldwide.     

Structural Insights into the Inhibition of Zika Virus NS2B-NS3 Protease by a Small-Molecule Inhibitor

1. Download high-res image (337KB)
2. Download full-size image

     

Molecular Mechanism of Resistance in a Clinically Significant Double-Mutant Variant of HCV NS3/4A Protease

1. Download high-res image (200KB)
2. Download full-size image

     

Development of a cyclosporin A derivative with excellent anti-hepatitis C virus potency

Synthetic modification of cyclosporin A at P3-P4 positions led to the discovery of NIM258, a next generation cyclophilin inhibitor with excellent anti-hepatitis C virus potency, with decreased transporter inhibition, and pharmacokinetics suitable for coadministration with other drugs. Herein is disclosed the evolution of the synthetic strategy to from the original medicinal chemistry route, designed for late diversification, to a convergent and robust development synthesis. The chiral centers in the P4 fragment were constructed by an asymmetric chelated Claisen rearrangement in the presence of quinidine as the chiral ligand. Identification of advanced crystalline intermediates enabled practical supply of key intermediates. Finally, macrocyclization was carried out at 10% weight concentration by a general and unconventional “slow release” concept.