Recent Progress in Steroid C(sp)-H Functionalization.

Selective C-H functionalization methods could provide a valuable tool for synthesizing different steroid derivatives, which is essential not only in contexts of developing novel synthetic methodology but also as a direct way for gathering the analogues needed for studying the structure-activity relationships and obtaining biologically active compounds. The review discusses recent examples of steroid C-H functionalization to various C-X derivatives (C-O, C-C, C-N, C-S, and C-halogen) using available methods emphasizing their scope and limitations.

Mechanistic details of the actinobacterial lyase-catalyzed degradation reaction of 2-hydroxyisobutyryl-CoA.

Actinobacterial 2-hydroxyacyl-CoA lyase reversibly catalyzes the thiamine diphosphate-dependent cleavage of 2-hydroxyisobutyryl-CoA to formyl-CoA and acetone. This enzyme has great potential for use in synthetic one-carbon assimilation pathways for sustainable production of chemicals, but lacks details of substrate binding and reaction mechanism for biochemical reengineering. We determined crystal structures of the tetrameric enzyme in the closed conformation with bound substrate, covalent postcleavage intermediate, and products, shedding light on active site architecture and substrate interactions.

Differences in the efficiency of 3-deazathiamine and oxythiamine pyrophosphates as inhibitors of pyruvate dehydrogenase complex and growth of HeLa cells .

Oxythiamine (OT) and 3-deazathiamine (DAT) are the antimetabolites of thiamine. The aim of study was to compare the effects of OT and DAT pyrophosphates (-PP) on the kinetics of mammalian pyruvate dehydrogenase complex (PDHC) and the culture of HeLa cells. The kinetic study showed that 3-deazathiamine pyrophosphate (DATPP) was a much stronger competitive inhibitor ( = 0.

Synthesis of New Cisplatin Derivatives from Bile Acids.

A series of bile acid derived 1,2- and 1,3-diamines as well as their platinum(II) complexes were designed and synthesized in hope to get a highly cytotoxic compound by the combination of two bioactive moieties. All complexes obtained were subjected to cytotoxicity assays in vitro and some hybrid molecules showed an expected activity.

Synthesis of steroidal 1,2- and 1,3-diamines as ligands for transition metal ion complexation.

Two series of cholestane-based diamines (1,2 and 1,3) were synthesized using simple and efficient procedures. The convenient substrates for these syntheses were cholesteryl mesylate and tosylate, which were converted to appropriate amines via easily obtained azides. The final diamines were prepared using a substitution reaction with bromoacetonitrile (in the case of 1,2-diamines) or condensation with acrylonitrile (in the case of 1,3-diamines), followed by the reduction of intermediate aminonitriles.

Thiamine and selected thiamine antivitamins - biological activity and methods of synthesis.

Thiamine plays a very important coenzymatic and non-coenzymatic role in the regulation of basic metabolism. Thiamine diphosphate is a coenzyme of many enzymes, most of which occur in prokaryotes. Pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase complexes as well as transketolase are the examples of thiamine-dependent enzymes present in eukaryotes, including human.

Electrochemical synthesis of glycoconjugates from activated sterol derivatives.

Several derivatives of cholesterol and other 3β-hydroxy-Δ(5)-steroids were prepared and tested as sterol donors in electrochemical reactions with sugar alcohols. The reactions afforded glycoconjugates with sugar linked to a steroid moiety by an ether bond. Readily available sterol diphenylphosphates yielding up to 54% of the desired glycoconjugate were found to be the best sterol donors.

A selective electrochemical method of glycosylation of 3beta-hydroxy-Delta 5-steroids.

A new electrochemical glycosylation method is presented. According to the method cholesterol and other 3beta-hydroxy-Delta(5)-steroids can be selectively transformed to glycosides using non-activated sugars. The method is also useful for the synthesis of glycoconjugates with sugar linked to a steroid moiety by an ether bond.

Bis[3α,7α,12α-tris-(4-nitro-benzo-yloxy)-5β-cholan-24-yl] disulfide-ethyl acetate-n-hexane (4/4/1).

The crystal structure of the title compound, C(90)H(100)N(6)O(24)S(2)·C(4)H(8)O(2)·0.25C(6)H(14), solved and refined against synchrotron diffraction data, contains two formula units in the asymmetric unit with the all-trans n-hexane mol-ecule having half-occupancy and one of the ethyl acetate mol-ecules disordered over two positions. The two symmetry-independent disulfide mol-ecules are assembled by approximate face-to-face and face-to-edge inter-actions between their 4-nitro-benzo-yloxy groups into an inter-twined dimer having a double-helix-type structure.

Unusual electrochemical oxidation of cholesterol.

It has been found that cholesterol undergoes direct electrochemical oxidation on platinum electrode in dichloromethane. Voltammetric measurements show that the process is controlled by the rate of electron transfer and the height of the oxidation peak is linear vs. concentration of cholesterol.

Electrochemical studies of blocking properties of solid supported tethered lipid membranes on gold.

The insulating properties of self-assembled thiolipid monolayers and tethered lipid bilayers on polycrystalline gold electrodes were studied by means of cyclic voltammetry (CV). These films were formed by two-step self-assembly processes. Electrochemical measurements of the heterogeneous electron transfer rate constant of different redox couples such as potassium ferrocyanide (K(4)[Fe(CN)(6)]) and dopamine (DP) were used to examine the molecular integrity and structural defects and pinholes within the monolayers.