Kazuhiko Takatori

In Vivo Studies of Phenylalanine Hydroxylase by Phenylalanine Breath Test: Diagnosis of Tetrahydrobiopterin-Responsive Phenylalanine Hydroxylase Deficiency

Tetrahydrobiopterin (BH4)-responsive phenylalanine hydroxylase (PAH) deficiency is characterized by reduction of blood phenylalanine level after a BH4-loading test. Most cases of BH4-responsive PAH deficiency include mild phenylketonuria (PKU) or mild hyperphenylalaninemia (HPA), but not all patients with mild PKU respond to BH4. We performed the phenylalanine breath test as reliable method to determine the BH4 responsiveness. Phenylalanine breath test quantitatively measures the conversion of L-[1-13C] phenylalanine to 13CO2 and is a noninvasive and rapid test. Twenty Japanese patients with HPA were examined with a dose of 10 mg/kg of 13C-phenylalanine with or without a dose of 10 mg · kg−1 · d−1 of BH4 for 3 d. The phenylalanine breath test [cumulative recovery rate (CRR)] could distinguish control subjects (15.4 ± 1.5%); heterozygotes (10.3 ± 1.0%); and mild HPA (2.74%), mild PKU (1.13 ± 0.14%), and classical PKU patients (0.29 ± 0.14%). The genotypes in mild PKU cases were compound heterozygotes with mild (L52S, R241C, R408Q) and severe mutations, whereas a mild HPA case was homozygote of R241C. CRR correlated inversely with pretreatment phenylalanine levels, indicating the gene dosage effects on PKU. BH4 loading increased CRR from 1.13 ± 0.14 to 2.95 ± 1.14% (2.6-fold) in mild PKU and from 2.74 to 7.22% (2.6-fold) in mild HPA. A CRR of 5 to 6% reflected maintenance of appropriate serum phenylalanine level. The phenylalanine breath test is useful for the diagnosis of BH4-responsive PAH deficiency and determination of the optimal dosage of BH4 without increasing blood phenylalanine level.

An asymmetric synthesis of l-[3-13C]phenylalanine and l-[3-13C]tyrosine from [13C]carbon monoxide

Abstract l -[3- 13 C]Phenylalanine and l -[3- 13 C]tyrosine were synthesized. [α- 13 C]Benzyl bromides were prepared from [ 13 C]carbon monoxide via the palladium-catalyzed carboalkoxylation of aryl halides. The asymmetric carbon corresponding to the 2-position in phenylalanine was introduced by the diastereoselective alkylation of Dellarias oxazinone with [α- 13 C]benzyl bromides. Finally, ethanolysis, deprotection, hydrogenolysis and acid hydrolysis of the resulting alkylated oxazinones gave l -[3- 13 C]phenylalanine and l -[3- 13 C]tyrosine in high optical purity.

New chiral synthetic intermediate for prostaglandins

Preparation of an optically active synthetic intermediate 3 starting from D-mannitol and its conversion to PGF2α (1) by using [3+2] cycloaddition of the nitrile oxide derivative of 3 followed by conjugate addition of the vinylzincate to exocyclic enone 2 are described.

An asymmetric synthesis of L-[2-13C]aspartic acid from sodium [2-13C]acetate

l-[2-13C]Aspartic acid was synthesized by using Dellarias oxazinone labelled with 13C at the 3-position, prepared from phenyl [2-13C]bromoacetate and (S)-2-phenylglycinol, as a chiral glycine equivalent. Phenyl [2-13C]bromoacetate was derived from sodium [2-13C]acetate. Alkylation of the [3-13C]oxazinone with ethyl bromoacetate was achieved with high diastereoselectivity. Finally, sequential deprotection and removal of the chiral auxiliary of the alkylated [3-13C]oxazinone afforded l–[2-13C]aspartic acid. Copyright

Synthesis of (-)-Nonactic Acid: Application of g-Dithio-b-hydroxy Ester Prepared by Microbial Reduction as a Chiral Building Block

A γ-dithio-β-hydroxy ester (2), prepared by microbial reduction with bakers yeast, was used as a chiral building block, for the synthesis of (-)-nonactic acid (1). It was converted to the lithium acetylide via 5, of which 1,2-addition to the aldehyde (6) followed by reduction gave the 3-silyloxy-6-tosyloxynonane (8 b). On cleavage of the silyl ether, cyclization proceeded with complete inversion of configuration at C-6 to afford a cis-2,5-disubstituted tetrahydrofuran (9), which was led to 1

Properties of zinc uroporphyrin III produced from isopropanol by Arthrobacter hyalinus

Abstract In a large amount of porphyrins produced by a bacterium isolated from soil, Arthrobacter hyalinus , cultured in a medium containing isopropanol as the sole carbon source, zinc porphyrins, identified based on the coincidence between their m/z values in LC/MS and the molecular weight of porphyrins, were also found to be produced. Since zinc is easily separated from porphyrins in acid during the esterification of porphyrins, zinc uroporphyrin III was prepared from its octamethyl ester formed by incorporating zinc into the octamethyl ester of uroporphyrin III which was isolated from the culture broth. Its UV spectra, fluorometric spectra, fast atom bombardment (FAB)-mass spectra, and 1 H-NMR and 13 C-NMR spectra were presented.

A Diels-Alder Reaction Approach to a Homoisocarbacyclin

Abstract Synthesis of a chiral homoisocarbacyclin by using intramolecular Diels-Alder reaction and its diastereoselectivity based on MM2 transition state model (flexible model) are described.

Asymmetric Synthesis of L-[3-13C]Tryptophan

Synthesis of L-[3-13C]tryptophan (2) from N,N-dimethyl[13C]formamide (4) and Dellarias oxazinone 1 as a chiral glycine equivalent was achieved. Vilsmeier reaction of indole (5) and N,N-dimethyl[13C]formamide (4) afforded a good yield of indole-3-[13C]carbaldehyde (3), which was converted to the bromide 8. Diastereoselective alkylation of the enolate of 1 with the bromide 8 proceeded with high diastereoselectivity to give 9. Ethanolysis, hydrogenolysis and hydrolysis of 9 gave L-[3-13C]tryptophan (2).

Synthesis of Methylenebicyclo[3.2.1]octanol by a Sm(II)-Induced 1,2-Rearrangement Reaction with Ring Expansion of Methylenebicyclo[4.2.0]octanone

Direct conversion of methylenebicyclo[4.2.0]octanone to methylenebicyclo[3.2.1]octanol by a Sm(II)-induced 1,2-rearrangement with ring expansion of the methylenecyclobutane is described. Three conditions were optimized to allow the adaptation of this approach to various substrates. A rearrangement mechanism is proposed involving the generation of a ketyl radical and cyclopentanation by ketyl-olefin cyclization, followed by radical fragmentation and subsequent protonation.

Minocycline inhibits the Candida albicans budded-to-hyphal-form transition and biofilm formation

Candida albicans frequently causes bloodstream infections; its budded-to-hyphalform transition (BHT) and biofilm formation are major contributors to virulence. During an analysis of antibacterial compounds that inhibit C. albicans BHT, we found that the tetracycline derivative minocycline inhibited BHT and subsequent biofilm formation. Minocycline decreased expression of hypha-specific genes HWP1 and ECE1, and adhesion factor gene ALS3 of C. albicans. In addition, minocycline decreased cell surface hydrophobicity and the extracellular β-glucan level in biofilms. Minocycline has been widely used for catheter antibiotic lock therapy to prevent bacterial infection; this compound may also be prophylactically effective against Candida infection.