Search results for "Toxicity"

Introducing PeptoPlexes: Polylysine-block-Polysarcosine Based Polyplexes for Transfection of HEK 293T Cells

2014

A series of well-defined polypeptide-polypeptoid block copolymers based on the body's own amino acids sarcosine and lysine are prepared by ring opening polymerization of N-carboxyanhydrides. Block lengths were varied between 200-300 for the shielding polysarcosine block and 20-70 for the complexing polylysine block. Dispersity indexes ranged from 1.05 to 1.18. Polylysine is polymerized with benzyloxycarbonyl as well as trifluoroacetyl protecting groups at the ϵ-amine group and optimized deprotection protocols for both groups are reported. The obtained block ionomers are used to complex pDNA resulting in the formation of polyplexes (PeptoPlexes). The PeptoPlexes can be successfully applied i…

Analogues of cytotoxic squamocin using reliable reactions: new insights into the reactivity and role of the α,β-unsaturated lactone of the annonaceou…

2006

Abstract A small library of squamocin analogues has been prepared and screened biologically (cytotoxicity, inhibition of mitochondrial complex I and complex III). To centre diversity on a crucial part of the molecule (i.e., the α,β-unsaturated lactone), an original and reliable lactone opening reaction has been discovered and exploited among other efficient reactions.

Design, synthesis and antiproliferative activity of methyl 4-Iodo-1-β-D-ribofuranosyl-pyrazole-3-carboxylate and related compounds

1996

Abstract In a SAR study on azole-related nucleosides we have designed some pyrazole-nucleoside analogs characterised, for the first time, by a carboxylic ester moiety. 4-Iodo-1-β-D-ribofuranosyl-pyrazole-3-carboxylate showed a wide spectrum of antiproliferative activity and a particularly low cytotoxicity against resting PBL, being, unlike the other azole nucleosides, more active than the corresponding primary amide.

Stable Expression of Heterologous Sulfotransferase in V79 Cells: Activation of Primary and Secondary Benzylic Alcohols

1994

Abstract A sulfotransferase (ST) capable of activating 1-hydroxymethylpyrene (HMP) and 9-hydroxymethylanthracene (HMA) to mutagens was purified from rat liver. This enzyme appeared to be identical with hydroxysteroid STa, whose cDNA was cloned and stably expressed in Chinese hamster V79 cells. Several primary and secondary benzylic alcohols derived from polycyclic aromatic hydrocarbons induced gene mutations, sister chromatid exchanges (SCE) and/or cytotoxicity in these cells.

Phytochemical analysis of two Weigela florida cultivars, “Pink Poppet” and “Jean’s Gold”

2020

Abstract Nine different oleanane-type glycosides were extracted and isolated by various chromatographic methods from two Weigela florida cultivars, “Pink Poppet” and “Jean’s Gold”. From the roots of W. florida “Pink Poppet”, three monodesmosidic oleanolic acid saponins 1, 4, 5 were obtained, together with one hederagenin ester 6 from the leaves, and six bidesmosidic saponins 2, 3, 6-9 were isolated from the leaves of W. florida “Jean’s Gold”. Among compounds 1-9, three were previously undescribed (1-3) and six (4-9) were already published in the literature. Their structures were assigned by spectroscopic analysis mainly 2D NMR and mass spectrometry (ESI-MS). The cytotoxicity of the isolated…

EnzymesIn Vitro as indicators for pesticides: An examination

1992

Pesticides—a serious problem especially for drinking water quality—frequently are potent inhibitors of enzymes in their target organisms. As the established chemical analyses of pesticides are time-consuming, complicated, and expensive, so-called screening methods are urgently needed. For this purpose the sensitivity of 13 different enzymes was tested in vitro by inhibiting their kinetic rates and/or substrate conversions by 16 pesticides (herbicides and fungicides). Because of the stabilization and resulting low sensitivity of enzymes commercially available—especially in test kits—it was necessary to vary the test conditions and to develop special methods for detecting enzymatic inhibition…

Use of Mechanistic Information for Adequate Metabolic Design of Genotoxicity Studies and Toxicological Interactions of Drugs and Environmental Chemic…

1995

Microorganisms as well as mammalian cells used for mutagenicity investigations have little or no activities for metabolism of premutagens and precarcinogens, i.e. of compounds ultimately leading to mutations and cancer but first requiring metabolic activation. Therefore, to such cells an exogenous activating system is added, generally the postmitochondrial supernatant fraction of the liver homogenate and a NADPH-generating system (Ames et al. 1976). In this situation enzymes requiring cofactors other than NADP(H) are unlikely to be active. Thus, this metabolic system is rather artificial. Monooxygenases are active in this system. They, for example, convert polycyclic aromatic hydrocarbons t…

Effects of soil organic matter content and temperature on toxicity of dimethoate toFolsomia fimetaria(Collembola: Isotomiidae)

1999

The purpose of these experiments was to study the effects of two major environmental factors, soil organic matter content (1.4–8.6%) and temperature (10–20°C), on chemical toxicity to a soil-dwelling collembolan Folsomia fimetaria. Dimethoate was used as a reference chemical. Effects on survival, reproduction, and juvenile size were investigated. Increasing soil organic matter content reduced toxicity significantly, but the differences disappeared when results were recalculated and expressed as soil pore-water concentrations. This supported the soil pore-water hypothesis. The effects of soil temperature were not so clear, because temperature affects not only the growth and reproduction of t…

1983

To obtain a carrier polymer for pharmacologically active components, linear polyethyleneimine (LPEI) was chemically modified by reactions with acrylic acid (1a), acrylamide (1b), acrylic acid esters (1c and 1d), sodium chloroacetate, and hydrochloric acid. All product polymers 2a – 2e are soluble in water. Among these, 2a and 2e, β- and α-amino acid derivatives, respectively, show no acute toxicity in mice up to dosages of 1 g/kg i. v. Similar types of polymers 5a and 5b and a polymer containing phosphonic acid moieties (5d) derived from branched polyethyleneimine (BPEI) were prepared. 5a and 5b are also nontoxic regardless of the molecular weight of four kinds of BPEI and of the wide range…

Oral glutathione increases hepatic glutathione and prevents acetaminophen toxicity

1990

Administration of oral glutathione (GSH) increases hepatic GSH levels in fasted rats, in mice treated with GSH depletors such as diethylmaleate and in mice treated with high doses of paracetamol. An increase in hepatic GSH levels after administration of oral GSH does not occur in animals treated with buthionine suphoximine, an inhibitor of GSH synthesis. Administration of oral GSH leads to an increase in the concentration of L-cysteine, a precursor of GSH, in portal blood plasma. Oral administration of L-methio-nine to fasted rats produced a significant decrease of hepatic ATP, but not in fed rats. Administration of N-acetyl-cysteine or GSH did not affect the hepatic ATP levels. The results…