Synthesis of C-2 substituted vitamin D derivatives having ringed side chains and their biological evaluation, especially biological effect on bone by modification at the C-2 position

In order to obtain vitamin D derivatives, which have strong activity for enhancing bone growth, we designed vitamin D derivatives with various substitutions at the C-2 position. Novel 2 α-substituted vitamin D derivatives were synthesized starting from d-glucose as a chiral template of the A-ring with a CD-ring bromoolefin unit using the Trost coupling method. We evaluated these compounds by two in vitro assays, affinity to VDR and transactivation assays, using human osteosarcoma (Hos) cells, and demonstrated the SAR of the C-2 position of VD(3). Furthermore, by using the OVX model, we found that compound 5c, which has a hydroxypropoxy side chain at C-2 and 2,2-dimethyl cyclopentanone in the CD-ring side chain, has a strong activity for enhancing bone growth, same as the reported compound, 2α-(3-hydroxypropoxy)-1α,25-dihydroxyvitamin D(3)1d, and this derivative shows a possibility that calcemic activity is less than 1d in vivo.     

Correlation analyses on binding affinity of sialic acid analogues and anti-influenza drugs with human neuraminidase using ab initio MO calculations on their complex structures--LERE-QSAR analysis (IV)

We carried out full ab initio fragment molecular orbital (FMO) calculations for complexes comprising human neuraminidase-2 (hNEU2) and sialic acid analogues including anti-influenza drugs zanamivir (Relenza) and oseltamivir (Tamiflu) in order to examine the variation in the observed inhibitory activity toward hNEU2 at the atomic and electronic levels. We recently proposed the LERE (linear expression by representative energy terms)-QSAR (quantitative structure-activity relationship) procedure. LERE-QSAR analysis quantitatively revealed that the complex formation is driven by hydrogen-bonding and electrostatic interaction of hNEU2 with sialic acid analogues. The most potent inhibitory activity, that of zanamivir, is attributable to the strong electrostatic interaction of a positively charged guanidino group in zanamivir with negatively charged amino acid residues in hNEU2. After we confirmed that the variation in the observed inhibitory activity among sialic acid analogues is excellently reproducible with the LERE-QSAR equation, we examined the reason for the remarkable difference between the inhibitory potencies of oseltamivir as to hNEU2 and influenza A virus neuraminidase-1 (N1-NA). Several amino acid residues in close contact with a positively charged amino group in oseltamivir are different between hNEU2 and N1-NA. FMO-IFIE (interfragment interaction energy) analysis showed that the difference in amino acid residues causes a remarkably large difference between the overall interaction energies of oseltamivir with hNEU2 and N1-NA. The current results will be useful for the development of new anti-influenza drugs with high selectivity and without the risk of adverse side effects.     

Direct assembly synthesis of metal complex-semiconductor hybrid photocatalysts anchored by phosphonate for highly efficient CO2 reduction

Hybrid photocatalysts consisting of a ruthenium complex and p-type photoactive N-doped Ta(2)O(5) anchored with an organic group were successfully synthesized by a direct assembly method. The photocatalyst anchored by phosphonate exhibited excellent photoconversion activity of CO(2) to formic acid under visible-light irradiation with respect to the reaction rate and stability.     

Concise synthesis of catechin probes enabling analysis and imaging of EGCg

A concise synthesis of APDOEGCg (3) was accomplished. Due to the reactivity of its amine group, the compound could be easily converted to the fluorescein probe 21 and immunogen probe 22 efficiently. We then demonstrated the usefulness of the probes for imaging studies and the generation of antibodies.     

PET imaging of nobiletin based on a practical total synthesis

A practical synthesis of nobiletin, a polymethoxylated citrus flavone, was accomplished by utilizing our novel flavone synthesis. Synthetic nobiletin was labelled by selective demethylation and rapid incorporation of (11)C atom. Positron emission tomography images successfully visualized the brain distribution, which may provide therapeutic benefits in the treatment of Alzheimer's disease.     

One-pot synthesis of imines from alcohols and amines with TiO2 loading Pt nanoparticles under UV irradiation

TiO(2) loading Pt nanoparticles (Pt@TiO(2)) promote one-pot synthesis of imines from alcohols and amines under UV irradiation at room temperature. This is achieved via a Pt-assisted photocatalytic oxidation of alcohols and a catalytic condensation of the formed aldehydes with amines on the TiO(2) surface.     

Efficient enumeration of stereoisomers of outerplanar chemical graphs using dynamic programming

Exhaustive and nonredundant generation of stereoisomers of a chemical compound with a specified constitution is an important tool for molecular structure elucidation and molecular design. It is known that many chemical compounds have outerplanar graph structures. In this paper we deal with chemical compounds composed of carbon, hydrogen, oxygen, and nitrogen atoms whose graphical structures are outerplanar and consider stereoisomers caused only by asymmetry around carbon atoms. Based on dynamic programming, we propose an algorithm of generating all stereoisomers without duplication. We treat a given outerplanar graph as a graph rooted at its structural center. Our algorithm first recursively computes the number of stereoisomers of the subgraph induced by the descendants of each vertex and then constructs each stereoisomer by backtracking the process of computing the numbers of stereoisomers. Our algorithm correctly counts the number of stereoisomers in O(n) time and space and correctly enumerates all of the stereoisomers in O(n3) time per stereoisomer on average and in O(n) space, where n is the number of atoms in a given structure.     

Ring-methylation of pyrrole and indole using supercritical methanol

The ring-methylation of pyrrole or indole using supercritical methanol proceeded at 623 K without the further addition of catalysts. Pyrrole produced a mixture of unreacted pyrrole and mono-, di-, tri-, and tetra-methylpyrroles at the reaction time of 8 h. On the other hand, indole was selectively methylated at the C3 position to afford 3-methylindole in 79% yield at the reaction time of 5 h. The ring-methylation of indole using supercritical methanol was claimed to proceed via (1H-indol-3-yl)methanol. The conversion of indole to (1H-indol-3-yl)methanol would be achieved by the electrophilic aromatic substitution between the indol-1-ide (indole anion) and H₂C⁺–OH. The (1H-indol-3-yl)methanol must be reduced to 3-methylindole in the presence of supercritical methanol.