Kiyoshi Fukuhara

Solubilization of fullerenes into water with polyvinylpyrrolidone applicable to biological tests

C60 and C70 can be solubilized into water with poly(vinylpyrrolidone)(PVP) and the aqueous solutions of C60 and C70 are applied to haemolysis test.

Conversion of procyanidin B-type (catechin dimer) to A-type: evidence for abstraction of C-2 hydrogen in catechin during radical oxidation

Abstract Procyanidin B-1 and B-2 were converted into A-1 and A-2 by radical oxidation using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals under neutral conditions, respectively. Transformation of procyanidin B-type into A-type certainly shows abstraction of the hydrogen atom at the C-2 position during radical oxidation.

Photoinduced nitric oxide release from a hindered nitrobenzene derivative by two-photon excitation.

Here, we demonstrated photoinduced NO generation from a 2,6-dimethylnitrobenzene-based compound (Flu-DNB) via a two-photon excitation (TPE) process. After pulse laser irradiation to a solution of Flu-DNB, oxidation products of NO were observed. This is the first account of a non-nitrosyl-chelated metal ion containing NO donor which can be controlled by the TPE technique.

Lysine-Specific Demethylase 1-Selective Inactivators: Protein-Targeted Drug Delivery Mechanism†

Reversible histone methylation, a process controlled by two counteracting enzyme families, the histone methyltransferases and the histone demethylases, plays a pivotal role in the regulation of epigenetic gene expression. Lysine-specific demethylase 1 (LSD1) removes methyl groups from monoand dimethylated Lys4 of histone H3 (H3K4me1/2) through flavin adenine dinucleotide (FAD) dependent enzymatic oxidation. LSD1 also demethylates H3K9me1/2 in prostate cell lines and in cells infected with herpesviruses. Furthermore, histone demethylation by LSD1 is suggested to be associated with certain disease states, including cancer and herpes simplex infection. 3b, 4] trans-2-Phenylcyclopropylamine (PCPA/Tranylcypromine), which was originally found as an inhibitor of monoamine oxidases (MAOs; also FAD-dependent enzymes), is the best-studied LSD1 inhibitor, and biological studies using PCPA have uncovered important roles of LSD1 in several diseases. 4a,c,d] In addition, several groups, including ours, have reported PCPA derivatives with LSD1 inhibitory activity. While many of these LSD1 inhibitors have been suggested to be potential lead compounds for anticancer agents, most of them have various disadvantages, including poor intracellular activity, insufficient inhibitory potency, or inadequate selectivity for LSD1 over MAO A and MAO B. To overcome these issues, we hypothesized that LSD1 could be potently and selectively inactivated by delivering PCPA directly to the LSD1 active site. Herein we describe the design and synthesis of a series of LSD1 inactivators based upon this concept. PCPA inhibits LSD1 by a single-electron-transfer mechanism (Figures 1 and 2 A). In the active site of LSD1, FAD first extracts one electron from the nitrogen atom of PCPA to form a cation radical. Then, opening of the cyclopropyl ring occurs and subsequent covalent bond formation with FAD. In the course of LSD1 inactivation, the nitrogen atom of PCPA is released as an ammonia molecule through hydrolysis of the imine intermediate. Taking this mechanism into account, together with our idea of delivering PCPA directly to the

NMR-based metabolomics of urine in a mouse model of Alzheimer’s disease: identification of oxidative stress biomarkers

Alzheimer’s disease (AD) is the most common cause of neurodegenerative dementia among elderly patients. A biomarker for the disease could make diagnosis easier and more accurate, and accelerate drug discovery. In this study, NMR-based metabolomics analysis in conjunction with multivariate statistics was applied to examine changes in urinary metabolites in transgenic AD mice expressing mutant tau and β-amyloid precursor protein. These mice showed significant changes in urinary metabolites throughout the progress of the disease. Levels of 3-hydroxykynurenine, homogentisate and allantoin were significantly higher compared to control mice in 4 months (prior to onset of AD symptoms) and reverted to control values by 10 months of age (early/middle stage of AD), which highlights the relevance of oxidative stress to this neurodegenerative disorder even prior the onset of dementia. The level of these changed metabolites at very early period may provide an indication of disease risk at asymptomatic stage.

Design and synthesis of estrogen receptor degradation inducer based on a protein knockdown strategy

We designed and synthesized estrogen receptor (ER) degradation inducers 5, 6, and 7, which crosslink the ER and the cellular inhibitor of apoptosis protein 1 (cIAP1). Compounds 5, 6, and 7 induced cIAP1-mediated ubiquitylation of ERα resulting in its proteasomal degradation.

Mutagenicity of nitrophenanthrene derivatives for Salmonella typhimurium : effects of nitroreductase and acetyltransferase

To determine the mutagenicity of nitrophenanthrenes, three mononitrophenanthrenes (NPhs), 11 dinitrophenanthrenes (diNPhs) and eight trinitrophenanthrenes (tiNPhs) were synthesized, and their mutagenicity was investigated by using Salmonella typhimurium his- strains TA98, TA100, and TA98NR, nitroreductase-deficient, and TA98/1,8-DNP6, O-acetyltransferase-deficient mutants, and strains YG1021 and YG1026, nitroreductase-overproducing mutants of TA98 and TA100, respectively, and strains YG1024 and YG1029, O-acetyltransferase-overproducing mutants of TA98 and TA100, respectively. 1-, 3- and 9-NPhis induced 329, 620 and 438 revertants per nmol in strain TA100, respectively, and 4,839, 11,309 and 16728 revertants per nmol, respectively, in strain YG1029. Mutagenicity of 1,6-, 2,6-, 2,9-, 2,10-, 3,5-, 3,6- and 3,10-diNPh was elevated in strains YG1021, YG1024, YG1026 and YG1029. Among these derivatives, 1,6-, 2,6-, 3,6- and 3,10-diNPhs were more mutagenic in strains YG1024 and YG1029 than YG1021 and YG1026, and they showed a structure-activity relationship between mutagenicity and NO2-substitution. Nitro derivatives substituted at the 3 and 6 positions of their chemical structure strongly mutated both strains YG1024 and YG1029, whereas those substituted at the 9 and 10 positions showed weak mutagenicity. In addition, nitro substituents at positions 4 and 5 were perpendicular while those on positions 2,3,6 and 7 were nearly coplanar to the aromatic ring. Furthermore, 2,6,9-, 3,6,9- and 1,6,9-trinitrophenanthrenes (triNPhs) were mutagenic for strain TA100, and their mutagenicity was more enhanced in YG1024 and YG1029 than in YG1021 and YG1026. Of the eight triNPhs all except 1,5,10-triNP were mutagenic in TA98 and TA100, and their mutagenicity was more enhanced in YG1024 and YG1029 than in YG1021 and YG1026. These results suggest that these compounds are mutagens that are activated by O-acetyltransferase esterification following nitroreductase. The nitrated derivatives substituted at the 2(7) and 3(6) positions of the phenanthrene ring were highly mutagenic. The relationship between chemical structure and the mutagenicity of NPh derivatives is discussed.

Photoinduced Nitric Oxide Release from a Nitrobenzene Derivative in Mitochondria

We report a novel NO donor (RpNO), containing a 2,6-dimethylnitrobenzene moiety for photocontrollable NO release and a rhodamine moiety for targeting to mitochondria. Photorelease of NO from RpNO in aqueous solution was confirmed by means of ESR analysis. Cellular release of NO from RpNO was confirmed with the aid of DAF-FM DA, an NO-specific fluorescence probe. RpNO was colocalized with MitoTracker Green FM, a mitochondrial stain, in HCT116 colon cancer cells and exhibited photodependent cytotoxicity. Our results indicate that RpNO is an effective NO donor for time-controlled, mitochondria-specific NO treatment.

Detection of 3,6-dinitrobenzo[a]pyrene in airborne particulates

3,6-Dinitrobenzo[a]pyrene, a new mutagen, was detected in airborne particulates collected in Santiago (Chile). The quantity of the compound in the airborne particulates was very small, accounting for 0.01 micrograms/g of total particulates (0.002 ng/m3 of air) at the lowest concentration. It was found that 3,6-dinitrobenzo[a]pyrene is readily decomposed by UV irradiation at 312 nm. The decomposed product was identified as 3-nitrobenzo[a]pyrene-6-quinone by means of mass spectrometry and proton nuclear magnetic resonance analysis. The mutagenicity of 3,6-dinitrobenzo[a]pyrene was 137,000 revertants/nmole for Salmonella typhimurium strain TA98, less than that for strain TA98/1,8-DNP6, an acetyltransferase-deficient mutant, and more than that for strain YG1024, an acetyltransferase-rich mutant.

A novel mitochondria-localizing nitrobenzene derivative as a donor for photo-uncaging of nitric oxide

We report a novel green-fluorescent NO donor, NBDNO, bearing a 2,6-dimethylnitrobenzene moiety for photocontrollable NO release and a triphenylphosphonium moiety for targeting to mitochondria. Photorelease of NO from NBDNO was confirmed by means of ESR analysis in aqueous solution. Intracellular release of NO from NBDNO was confirmed by using DAR-4M AM, an NO-specific fluorescence probe. NBDNO was colocalized with MitoRed, a mitochondrial stain, in HCT116 colon cancer cells. Our results indicate that NBDNO is an effective NO donor for time-controlled, mitochondria-specific NO treatment.