Leszek Siergiejczyk

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BACKGROUND The aim of this study was to evaluate the relationship between N-acetylaspartate (NAA) levels in selected brain regions and cognitive performance in patients with first-episode schizophrenia. MATERIAL/METHODS Thirty patients (20 male, 10 female; mean age: 22.5 years) with the diagnosis of first-episode schizophrenia and 19 comparable healthy(More)
Syntheses of "glycospirostanes" from 3beta-hydroxy-23,24-dinor-5alpha-cholano-22,16-lactone and 3alpha-hydroxy-23,24-dinor-5beta-cholano-22,16-lactone were performed. The key step of these syntheses was ring-closing metathesis of the corresponding C,O-diallyl derivative. Further elaboration of the six-membered ring F consisted of allylic hydroxylation with(More)
Natural retinoids and curcuminoids are known for their broad spectrum of biological properties, such as antioxidant, anti-inflammatory, antitumor, and so forth. In this work, a convenient synthesis of aromatic retinoids and curcuminoids from vinyl or allyl ketones, and the corresponding alcohols, using olefin metathesis as a key reaction, was elaborated.(More)
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(More)
The reaction of 23-oxotigogenin acetate with TMSOTf in THF afforded the corresponding bisnorcholanic lactone in 60% yield. The analogous reactions carried out in dichloromethane or benzene gave the rearranged products--the isomeric spirostanic ketone (10-15%) and bisfuran (40-42%). Similar products were also obtained upon treatment of 23,24-epoxysapogenins(More)
A group of biologically active 4-azasteroids was studied by 13C-NMR spectroscopy in solution and in the solid phase. A full assignment of signals in the spectra of samples in chloroform was performed for thirteen 4-azasteroids using two-dimensional techniques. Substituent and steric effects of a nitrogen atom, and their influence on chemical shifts of the(More)
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