Physicochemical Properties of Large-Ring Cyclodextrins (CD 18 ∼CD 21

Cyclomaltooctadecaose(CD₁₈),cyclomaltononadecaose(CD₁₉),cyclomaltoeicosaose(CD₂₀) andcyclomaltoheneicosaose(CD₂₁) are cyclic oligosaccharides composed of 18, 19, 20 and 21 D-glucose units, respectively. This report describes the physicochemical properties of CD₁₈, CD₁₉, CD₂₀ and CD₂₁ in terms of aqueous solubility, surface tension, optical rotation and acid-catalyzed hydrolysis.     

Effect of water content on the solid-state stability in two isomorphic clathrates of cephalosporin: cefazolin sodium pentahydrate (alpha form) and FK041 hydrate

This study clearly demonstrates that clathrated water molecules can contribute to both chemical stabilization and destabilization of clathrates. The solid-state stabilities for two isomorphic clathrates of cephalosporin, cefazolin sodium and FK041, were investigated in terms of the effects of water content. The isomorphic ranges of water content were estimated to be 3.5-5 mol/mol for alpha-form cefazolin sodium and 2-4 mol/mol for FK041 hydrate. Upon the isomorphic dehydration, alpha-form cefazolin sodium was destabilized as the water content decreased below 4.25 mol/mol owing to the disruption of hydrogen bonding network in lattice channels. In this case, the hydration of clathrated water up to 4.25 mol/mol contributed to the physical and chemical stability of the crystals. On the contrary, the isomorphic hydration in FK041 hydrate contributed to the chemical destabilization owing to the high water activity. The difference in water activity between alpha-form cefazolin sodium and FK041 hydrate could be attributed to the size of water channels.     

Singlet oxygen takes part in 8-hydroxydeoxyguanosine formation in deoxyribonucleic acid treated with the horseradish peroxidase-H2O2 system

Treatment of calf thymus deoxyribonucleic acid (DNA) with the horseradish peroxidase-H2O2 system resulted in efficient formation of 8-hydroxydeoxyguanosine (8-OH-dG) residues. It was concluded that singlet oxygen was the reactive species involved, based on experiments using active oxygen scavengers and D2O. For 8-OH-dG formation, a higher-ordered polynucleotide structure seems to be required: double stranded DNA was a better substrate for the reactive species than single stranded DNA, and monomeric deoxyguanosine underwent C8-hydroxylation to a lesser extent.     

Syntheses of chiral oxazolo[2,3-a]tetrahydroisoquinoline and its asymmetric alkylation. Synthesis of (S)-(−)- and (R)-(+)-sa1solidines

The isoquinolinium bromide (4), on treatment with base, underwent cyclization to give the chiral oxazolotetrahydroisoquinoline (5) with a high diastereoselectivity, which was converted to optically pure salsolidine.