Mitsuji Yamashita

Utilization of dendritic framework as a multivalent ligand: a functionalized gadolinium(III) carrier with glycoside cluster periphery

Abstract A new type of designed and functionalized ligand for a lanthanide ion based on dendritic architecture was synthesized. The dendrimers, which contain four and twelve glucose moieties on the molecular surfaces, were readily synthesized with good yields in every step. The NMR and GPC analyses precisely demonstrated successful constructions of the dendritic structures, while the formations of gadolinium chelates were deduced on the basis of HPLC study.

Synthesis of 5,6-dideoxy-3-O-methyl-5-C-(phenylphosphinyl)-d-glucopyranose and its 1,2,4-triacetate

Methyl phenylphosphonite or dimethyl phosphite underwent acid-catalyzed addition reactions with some hexofuranos-5-ulose 5-(p-tolylsulfonylhydrazones) (7, 9, and 16), to give the corresponding adducts, 17, 18, 19, and 21. The isomer ratios of the adducts were affected by a 3-substituent in the hydrazones. Treatment of adduct 21 with sodium borohydride and sodium dihydrobis(2-methoxyethoxy)-aluminate (SDMA), followed by acid hydrolysis, gave 5,6-dideoxy-3-O-methyl-5-C-(phenylphosphinyl)-d-glucopyranose (26), which was acetylated to give the 1,2,4-tri-O-acetyl derivatives 27a and 27b. Conformational analysis of compound 27a by X-ray crystallography revealed that the compound was 1,2,4-tri-O-acetyl-5,6-dideoxy-3-O-methyl-5-C-[(S)-phenylphosphinyl]-β-d-glucopyranose in the 4C1(d) form having all substituents equatorial.

Synthesis of 1,2,4-tri-O-acetyl-3,6-di-O-benzyl-5-deoxy-5-C-[(S)-phenylphosphinyl]-β-d-glucopyranose: The first gluco type of hexopyranose derivative having phosphorus in the hemiacetal ring

Abstract Oxidation of 3,6-di- O -benzyl-1,2- O -isopropylidene-α- d -glucofuranose with pyridinium chlorochromate in the presence of molecular sieves, followed by conversion into the p -tolylsulfonylhydrazone, addition of methyl phenylphosphinate, and reduction with sodium borohydride, provided the key intermediate, namely, 5( R , S )-3,6-di- O -benzyl-5-deoxy-1,2- O -isopropylidene-5- C -[(methoxy)phenylphosphinyl]-α- d - xylo -hexofuranose, in 23% overall yield. Treatment of this compound with sodium dihydrobis(2-methoxyethoxy)aluminate, followed by the action of mineral acid and acetic anhydride, yielded the crystalline title compound, the structure of which was established on the basis of mass and 400-MHz, 1 H-n.m.r. spectra. A general dependence of 2 J PH values on the OPCH dihedral angles effectively served for assigning the configuration of C-1, C-5, and the ring-phosphorus atom of the present product and other such 5- C -phosphinylhexopyranoses.

Synthesis of a 6-c-nitro-d-glucopyranose derivative having phosphorus in the hemiacetal ring

Abstract 5,6-Dideoxy-6-C-nitro-5-(phenylphosphino)- d -glucopyranose was prepared by addition of phenylphosphine to 3-O-acetyl-5,6-dideoxy-1,2-O-isopropylidene-6-C-nitro-α- d -xylo-hex-5-enofuranose, followed by hydrolysis of the resulting 3-O-acetyl-5,6-dideoxy-1,2-O-isopropylidene-6-C-nitro-5-(phenylphosphino)- d -glucofuranose (10). Acetylation of 10 gave the crystalline 1,2,3,4-tetraacetate (16). 5,6-Dideoxy-6-C-nitro-5-(phenylphosphinyl)- d -glucopyranose (15) was obtained by oxidation of 10, and hydrolysis of the resulting 5-phenylphosphinyl compound. Acetylation of 15 gave the 1,2,3,4-tetraacetate (17). Although the n.m.r. spectrum of 17 was complex, the n.m.r. spectrum of 16 was rather simple. The n.m.r. data showed that 16 is the α anomer in the 4C1( d ) conformation.

Synthesis of 4,5-dideoxy-4-C-[(R,S)-phenylphosphinyl]-d-ribo- and l-lyxo-furanose and their 1,2,3-triacetates

Abstract 2,3- O -Isopropylidene- d -ribose diethyl dithioacetal, prepared from d -ribose, was converted in three steps into the corresponding dimethyl acetal, which was monotosylated at O-5, and the ester oxidized at C-4 with pyridinium chlorochromate; addition of methyl phenylphosphinate to the resulting pentos-4-ulose derivative then provided (4 R,S )-4,5-anhydro-2,3- O -isopropylidene-4- C -[( R,S )-(methoxy)phenylphosphinyl]- d - erythro -pentose dimethyl acetal. Hydrogenation of this compound in the presence of Raney Ni, followed by reduction with SDMA, hydrolysis, and acetylation, yielded the title compounds (seven kinds), the structures of which were established on the basis of their 400-MHz, 1 H-n.m.r. and mass spectra. A general dependence of the 2 J PH and 3 J PH values on the OPCH and PCCH dihedral angles provided an effective method for the assignment of the configurations and conformations of these 4-deoxy-4-phosphinyl-pentofuranoses.

Synthesis, and x-ray structural analysis, of 1,2,3,4-tetra-O-acetyl-5,6-dideoxy-5-C-[(S)-phenylphosphinyl]-α- and -β-l-idopyranose

Abstract The title compounds and two diastereoisomers were prepared from (5 RS )-3- O -benzyl-5,6-dideoxy-5- C -[( RS )-(ethoxy)phenylphosphinyl]-1,2- O -isopropylidene-α- d - xylo -hexofuranoses upon reduction with sodium dihydrobis(2-methoxyethoxy)-aluminate, followed by hydrolysis with mineral acid, and acetylation with acetic anhydride-pyridine. Among these products, the two readily crystallized compounds were determined by X-ray crystallographic analysis to be 1,2,3,4-tetra- O -acetyl-5,6-dideoxy-5- C -[( S )-phenylphosphinyl]-α- and -β- l -idopyranose- 4 C 1 .

X-ray crystal, and molecular, structure of 1,2,3,4-tetra-O-acetyl-5,6-dideoxy-6-C-nitro-5-(phenylphosphinyl)-l-ido-pyranose: a correction of our previous work thereon

Abstract X-ray crystallographic analysis was performed on the compound to which had been assigned the structure of 1,2,3,4-tetra- O -acetyl-5,6-dideoxy-6- C -nitro-5-(phenylphosphinyl)- d -glucopyranose. The results showed that the compound has the l - ido configuration, the pyranoid ring is in the 4 C 1 ( l ) conformation, the acetoxyl groups at C-1 and C-5 and the phenyl ring on P are linked axially, and the acetoxyl groups at C-2, C-3, and C-4 are linked equatorially.

Surface Amination of Biopolymer Using Surface-Wave Excited Ammonia Plasma

Surface-wave plasma has been used to modify polymer surfaces. The density and selectivity of the functionalizations are very important for biomaterial applications. Low-temperature plasma treatment has been successfully applied to many types of polymers to generate functional surfaces. In this study, we focus on the surface modification of amino groups on chitosan surfaces by ammonia plasma treatment. Chitosan is a nontoxic, biocompatible and biodegradable polymer, which promotes the scarless healing of skin through embolization. The experimental results of X-ray photoelectron spectroscopy measurements showed that the ammonia plasma exposure to the chitosan surface increased the nitrogen incorporation on the surface from 4.67 to 9.92%. The selectivity of amino group functionalizations (–NH2/N) increased from 53.7 to 78.4% after the plasma irradiation.

Synthesis and photoluminescence study of anthracene based dendrimer and dendron

A new type of polyaromatic dendrimer composed of six anthracene groups was synthesized, which showed a monomeric fluorescence feature with a diminished quantum yield due to intramolecular self-quenching processes in the dendritic framework.

Transcriptional Repression of Cdc25B by IER5 Inhibits the Proliferation of Leukemic Progenitor Cells through NF-YB and p300 in Acute Myeloid Leukemia

The immediately-early response gene 5 (IER5) has been reported to be induced by γ-ray irradiation and to play a role in the induction of cell death caused by radiation. We previously identified IER5 as one of the 2,3,4-tribromo-3-methyl-1-phenylphospholane 1-oxide (TMPP)-induced transcriptional responses in AML cells, using microarrays that encompassed the entire human genome. However, the biochemical pathway and mechanisms of IER5 function in regulation of the cell cycle remain unclear. In this study, we investigated the involvement of IER5 in the cell cycle and in cell proliferation of acute myeloid leukemia (AML) cells. We found that the over-expression of IER5 in AML cell lines and in AML-derived ALDHhi (High Aldehyde Dehydrogenase activity)/CD34+ cells inhibited their proliferation compared to control cells, through induction of G2/M cell cycle arrest and a decrease in Cdc25B expression. Moreover, the over-expression of IER5 reduced colony formation of AML-derived ALDHhi/CD34+ cells due to a decrease in Cdc25B expression. In addition, over-expression of Cdc25B restored TMPP inhibitory effects on colony formation in IER5-suppressed AML-derived ALDHhi/CD34+ cells. Furthermore, the IER5 reduced Cdc25B mRNA expression through direct binding to Cdc25B promoter and mediated its transcriptional attenuation through NF-YB and p300 transcriptinal factors. In summary, we found that transcriptional repression mediated by IER5 regulates Cdc25B expression levels via the release of NF-YB and p300 in AML-derived ALDHhi/CD34+ cells, resulting in inhibition of AML progenitor cell proliferation through modulation of cell cycle. Thus, the induction of IER5 expression represents an attractive target for AML therapy.