The total synthesis of (±)-sarkomycin starting from diethyl 2-oxopropanephosphonate is reported. The key step in this synthesis includes the Horner-Wittig reaction of 2-diethoxy-phosphoryl-3-carboxy-cyclopentanone with formaldehyde

The total synthesis of the anticancer agent (±)-sarkomycin 1 is described. Sarkomycin 1 was prepared from 2-phenylthiomethyl-cyclopent-2-en-1-one 5 in four steps in 13% yield. The key reaction was the 1,4-addition of nitromethane to the cyclopentenone 5.

A simple procedure has been developed for the synthesis of functionalized isoprene units for use in the assembly of the rubradirin antibiotics.

A Diels-Alder entry into the highly substituted naphthoquinones present in the rubradirins and naphthomycin is described.

Because of their complexity bleomycins and their relatives are difficult molecules to structurally characterise. In this paper the first successful field desorption mass spectrometric investigations of these molecules are reported. The recently corrected structure for the glycopeptide skeleton i...

The Fanconi anaemia (FA) FANCG protein is an integral component of the FA nuclear core complex that is required for monoubiquitylation of FANCD2. FANCG is also part of another protein complex termed D1-D2-G-X3 that contains FANCD2 and the homologous recombination repair proteins BRCA2 (FANCD1) a...

Nimbolide and nimbic acid are toxic to mice only when given i.p. and i.v. but they are less toxic to rats and hamsters. The LD50 values of a single i.p. administration of nimbolide to adult male, female and weanling mice were 225, 280 and 240 mg/kg body wt, respectively, and its i.v. LD50 value ...

α-Amanitin is the major causal constituent of deadly Amanita mushrooms that account for the majority of fatal mushroom poisonings worldwide. It is also an important biochemical tool for the study of its target, RNA polymerase II. The commercial supply of this bicyclic peptide comes from Amanita...

Hyperbranched rolling circle amplification (HRCA) with a padlock probe (PLP) targeting the α-amanitin (α-AMA) gene, as a screening tool for the universal identification of lethal amanitas, was established in this study. With the isothermal HRCA assay, all of the lethal Amanita species tested f...

On the basis of chemical and physicochemical evidence, the structure of holothurin A, a biologically active major obligoglycoside o lanostane-type triterpene holothurigenol (2), has been elucidated to be 8.

Purified samples of the toxin Holothurin A (H−) elaborated by the sea cucumber Actinopyga agassizi, Selenka and of its neutral desulfated derivative (DeH) were studied for actions on the cat superior cervical ganglion preparation. It was observed that each saponin produces irreversible inactivat...

The effects of a marine toxin, holothurin A, on the electrical properties of squid axon membranes were studied. External application of holothurin A to the intact axon produced an irreversible depolarization of the membrane to nearly zero potential. Internal perfusion of squid axon with holothur...

Differences in the ability of crude holothurin to stimulate or inhibit phagocytosis allowed an interpretation based on its effect within intracellular systems or on surface components. In concentrations of 4–100 μg per ml leucocyte suspension an increase in the phagocytosis of Staphylococcus a...

SummaryThe effect of holothurin on Trypanosoma musculi infection in FN mice indicated that the drug administered prior to, simultaneously with and after inoculation of trypanosomes affected the parasitemic level during the course of infection. The infection was measured by the numbers of trypano...

A series of 4-aminomethyl derivatives of heliomycin 1 was prepared using the Mannich reaction. The modification significantly improved aqueous solubility of the initially poorly soluble antibiotic. Testing the antiproliferative efficacy revealed a potent activity of heliomycin as well as its new...

Mixed monolayers of gramicidin A (GA) and three alcohols, differing in the degree of fluorination, namely C18OH, F18OH, and F8H10OH have been investigated by means of: surface manometry (π–A isotherms) and Brewster angle microscopy (BAM) aiming at finding appropriate molecules for incorporatin...

Hydrophobic mismatch which is defined as the difference between the lipid hydrophobic thickness and the peptide hydrophobic length is known to be responsible in altering the lipid/protein dynamics. Gramicidin A (gA), a 15 residue β helical peptide which is well recognized to form ion conducting...

Electrochemical and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) techniques were employed to study the ion channel properties of gramicidin A (gA) in tethered bilayer lipid membranes (tBLMs) with varying concentrations of gA added to the outer leaflet of the bil...

The N-terminally glutamate substituted analogue of the pentadecapeptide gramicidin A [Glu1]gA has been previously described as a low-toxic uncoupler of mitochondrial oxidative phosphorylation and neuroprotector. Here, we studied ion channel-forming activity of this peptide in planar bilayer lipi...

BackgroundReactive oxygen species are grossly produced in the brain after cerebral ischemia and reperfusion causing neuronal cell death. Mitochondrial production of reactive oxygen species is nonlinearly related to the value of the mitochondrial membrane potential with significant increment at v...