ABSTRACT
With an aim to develop a new approach to synthesize 4'-substituted nucleosides, reactions of thymidine derivatives having a benzenesulfonyl leaving group at the 4'-position with organosilicon and organoaluminum reagents were investigated. Two substrates 4alpha (alpha-L-isomer) and 4 beta (beta-D-isomer) were prepared for this purpose. Although reaction of 4alpha with organosilicon reagents gave preferentially the 4'-substituted (allyl and N(3)) beta-D-nucleoside, its reaction with AlMe(3) gave the 4'-methyl-alpha-L-thymidine as the major product. On the other hand, the substrate 4beta, upon reacting with AlMe(3), furnished the desired 4'-methylthymidine exclusively in high yield.
Subject(s)
Aluminum/chemistry , Organosilicon Compounds/chemistry , Thymidine/chemistry , Indicators and ReagentsABSTRACT
The purpose of this research was to examine the influence of the physical state of lipids on iron-promoted oxidation of methyl linolenate in octadecane oil-in-water emulsions. Octadecane and methyl linolenate oil-in-water emulsions were prepared that contained droplets having the octadecane as either liquid or solid. The physical state of the octadecane was confirmed by a differential scanning calorimeter (DSC). The effect of the physical state of the lipid on oxidation rates was determined as a function of iron concentration (80 and 160 microM), pH (3.0 or 7.0), emulsifier type, and cooling rate. Oxidation of methyl linolenate was determined by lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS). Emulsions containing solid octadecane had higher rates of lipid hydroperoxide and TBARS formation than those containing liquid octadecane. The rate at which the emulsions were cooled had no influence on oxidation rates. Oxidation rates in both emulsions increased with increasing iron concentration and decreasing pH. Oxidation rates were lowest in emulsions with cationic droplet membranes (dodecyl trimethylammonium bromide-stabilized), presumably due to the repulsion of iron from the oxidizable methyl linolenate in the emulsion droplet core. These results suggest that upon crystallization of octadecane, the liquid methyl linolenate migrated to the emulsion droplet surface, where it was more prone to oxidation because it was in closer contact with the iron ions in the aqueous phase.
Subject(s)
Emulsions/chemistry , Linolenic Acids/chemistry , Lipid Peroxidation , Lipids/chemistry , Calorimetry, Differential Scanning , Chemical Phenomena , Chemistry, Physical , Lipid Peroxides/analysis , Thiobarbituric Acid Reactive Substances/analysisABSTRACT
Xanthogranulomatous Cholecystitis is a chronic inflammatory disease of the gallbladder, a variant of the chronic cholecystitis. As xanthogranulomatous cholecystitis is occasionally seen with carcinoma of the gallbladder, the association with cancer is a controversial issue. A focal type of xanthogranulomatous cholecystitis is found simultaneously with gastric cancer diagnosed preoperatively. The resected specimen was genetically studied. Polymerase chain reaction amplification, single-strand conformational polymorphism analysis for mutation of p53 showed no abnormality indicating that less association with cancer in which the mutation of p53 is often seen. Etiopathologic factors of xanthogranulomatous cholecystitis might have relation with cancer, but xanthogranulomatous cholecystitis itself may not be the direct cause for cancer.
