Essential structure of co-pigment for blue sepal-color development of hydrangea

Blue sepal-color of Hydrangea macrophylla might be due to a supramolecular metal-complex pigment consisting of delphinidin 3-glucoside (1), co-pigments (5-O-caffeoylquinic acid (2), and/or 5-O-p-coumaroylquinic acid (3)) and Al³⁺ in an aqueous solution around pH 4.0. To clarify the mechanism of blue sepal-color development of hydrangea, we tried to reproduce the blue color in vitro by mixing 1 with designed synthetic co-pigments in the presence of Al³⁺ at pH 4.0. We at first succeeded in clarifying the essential functional structure in the co-pigment that could form the stable blue solution. Here, we present the structure of the blue pigment caused by an Al-complex coordinating of 1 at ortho-dihydroxyl groups of the B-ring, 1-hydroxy, 1-carboxylic acid, and the carbonyl residue in the ester at 5-position of 2 and/or 3. The hydrophobic interaction between the aromatic acyl residue at 5-position and the nucleus of 1 may also contribute to stabilize the complex.     

Two new meroterpenoids, penisimplicin A and B, isolated from Penicillium simplicissimum

In the course of our research for new antifungal agents, two new meroterpenoids, penisimplicin A (1) and B (2), were isolated from Penicillium simplicissimum. The absolute structures of 1 and 2 were established by spectroscopic and chemical investigation. Penisimplicin A (1) and B (2) are rare examples of D-ring seco-meroterpenoids. Since compounds 1 and 2 showed no antifungal activities, the isolation of the compounds with antifungal activity will be attempted.     

Structure of cinerarin,a tetra-acylated anthocyanin isolated from the blue garden cineraria, Senecio cruentus

Structure of cinerarin is determined to be 3-0-(6-0-malonyl-β-D-glucopyranosyl)-7-0-(6-0-(4-0-(6-0-caffeyl-β-D-glucopyranosyl)caffeyl)-β-D-glucopyranosyl)-3′-0-(6-0-caffeyl-β-D-glucopyranosyl)delphinidin.     

Contributions of the distance-dependent reorganization energy and proton-transfer to the hole-transfer process in DNA

A kinetic study of the single-step hole transfer in DNA was performed by measuring time-resolved transient absorption. DNA molecules with various sequences were designed and conjugated with naphthalimide (NI) and phenothiazine (PTZ) to investigate the sequence and distance dependence of the single-step hole transfer between guanines (Gs). Hole injection into DNA was accomplished by excitation of the NI site with a 355 nm laser pulse, and the kinetics of the hole-transfer process were investigated by monitoring the transient absorption of the PTZ radical cation (PTZ.+). Kinetic analysis of the time profile of PTZ.+ based on the kinetic model showed that the distance dependence of the hole-transfer process was significantly influenced by the DNA sequence. Results of temperature- and isotope-effect experiments demonstrated that the activation energy increased as the number of bridge bases separating the Gs increased. This is because of the distance-dependent reorganization energy and contribution of the proton-transfer process to the hole transfer in DNA.     

A novel photochemical reaction of 2-alkoxynicotinates to cage-type photodimers

Irradiation of a benzene solution of 2-alkoxynicotinic acid alkyl esters gave cage-type photodimers in good yields, the structure of which was established by X-ray single-crystal analysis. The maximum quantum yield was 8.0 x 10(-)(2) when a 5.0 M (almost neat) solution was used. Photolysis of phenyl 2-methoxynicotinate promoted photo-Fries rearrangement to give 1,3- and 1,5-rearranged products. Excimer emission of methyl 2-methoxynicotinate was observed at 77 K.     

Amino acid sequences of 60B8 antigens induced in HL-60 cells by 1,25-dihydroxyvitamin D3. The antigens are identical with macrophage-related protein-14 and -8

A differentiation antigen 60B8 appeared in human promyelocytic leukemia HL-60 cells which had been induced to differentiate into macrophage-like cells by treatment with 1,25-dihydroxyvitamin D3. The antigen was purified by immunoaffinity chromatography and separated into two proteins, 60B8-A and -B antigens, by reverse-phase high performance liquid chromatography (HPLC). Both proteins were digested with proteases, and the resulting peptides were subjected to amino acid sequence analysis after purification by reverse-phase HPLC. The amino acid sequences of 60B8-A and -B antigens were identical with those of the proteins MRP-14 and -8, respectively, which were recently predicted from the nucleotide sequences of their complementary deoxyribonucleic acid (cDNA) clones by Odink et al. (Nature (London), 330, 80 (1987)). Although they did not characterize the chemical properties of the two proteins, our results clearly indicate that macrophage-related protein (MRP)-14 and -8 are expressed without post-translational modification, except that the amino-terminus of MRP-14 is blocked, in differentiated HL-60 cells.     

Interaction of liposomes with cultured cells: possible involvement of lipid peroxidation in cell growth inhibition

Systematic analyses of the interaction between liposomes and cells were examined. Liposomes were found to affect the growth of mouse NIH 3T3 cells depending upon their size, net charge, and cholesterol content. Among the charged compounds, stearylamine was the most inhibitory and showed complete inhibition of cell growth at 100 microM. The cholesterol-rich and small unilamellar vesicles were more suppressive compared to the cholesterol-poor and multilamellar ones, respectively. The binding assay of liposomes to the cells showed a positive correlation between liposome binding and the extent of growth inhibition. Suppression of liposome uptake by inhibitors of the cytoskeletal system and energy metabolism were suggestive of an endocytotic mechanism for the cellular uptake of liposomes. The growth inhibitory effect seemed secondary to the intracellular uptake of liposomes, and peroxidation of incorporated lipids would lead to cellular damage. Therefore, it is highly recommended that potential growth inhibitory effects associated with the particular composition and other properties of liposomes should be carefully assessed in any human studies, especially for long-term use.     

Conductance study of the complexation of substituted and lariat 16-crown-5 derivatives with alkali metal ions in nonaqueous solvents

Formation constants (K _ML) of 1:1 complexes of 15-(2,5-dioxahexyl)-15-methyl-16-crown-5 (L16C5) and 15,15-dimethyl-16-crown-5 (DM16C5) with alkali metal ions were determined in acetonitrile (AN) and propylene carbonate (PC) by conductometry at 25°C. Except for the case of Li⁺-and K⁺-16C5 complexes in PC, the selectivity sequences of L16C5 and DM16C5 are identical with those of the parent crown ether 16-crown-5 (16C5) regardless of the solvent (AN, PC, methanol) (Na¹ > Li⁺ > K⁺ > Rb⁺ > Cs⁺), which show the size-fit correlation. The selectivities of L16C5 and DM16C5 for the alkali metal ions are governed not by the sidearms but by the cavity size. The stability of the crown ether complex is dependent not on the dielectric constant but largely on the donor number of the solvent. TheK _ML(M₁ ⁺)/K _ML(M₂ ⁺) ratio of L16C5 or 16C5 varies very much with the solvent in the cases of M₁=Na, M₂=K and M₁=Na, M₂=Li, but that of DM16C5 is almost constant regardless of the solvent.     

Viscosity of polydimethylsiloxane–pentamer systems

Viscosities of polydimethylsiloxane–pentamer systems were measured over the whole range of concentration. Twelve samples having molecular weights from about 1000 to 5 × 10⁵ were studied. The empirical reduction scheme, plots of log η versus log _cM^0.68, suggested by Ferry and co-workers is applicable to samples of M?_v ≥ 22,000 over the entire concentration. Such satisfying superposition of data may be attributed to the systems being the homologous mixtures in which glass temperatures of polymers are very low. On the basis of the treatment of Fox and Allen, the effects of the number and weight-average molecular weight on viscosity were examined, and the friction coefficient ζ per chain atom at constant M?_n was calculated over a wide range of M?_n. The value ζ is almost constant (ζ = 7.4 × 10^?9 dyne-sec./cm.) in the region of M?_n ≥ M_c, and where otherwise it decreases rapidly with decreasing M?_n. The length of the chainend segment was tentatively calculated.     

Sensitive analysis of alkyl alcohols as decomposition products of alkyl nitrites in human whole blood and urine by headspace capillary GC with cryogenic oven trapping

The abuse of alkyl nitrites is becoming a serious social problem worldwide. In this report, a simple and sensitive method is presented for the determination of n-butyl alcohol, isobutyl alcohol, and isoamyl alcohol as decomposition products of alkyl nitrites in human whole blood and urine samples using capillary gas chromatography (GC) with cryogenic oven trapping. After heating a whole blood or urine sample containing each alkyl alcohol and t-butyl alcohol [the internal standard (IS)] in a 7-mL vial at 55 degrees C for 15 min, 5 mL of the headspace vapor is drawn into a gas-tight syringe and injected into a GC inlet port. The vapor is introduced into an Rtx-BAC2 medium-bore capillary column in the splitless mode at 0 degrees C oven temperature in order to trap the entire analytes, and then the oven temperature is programmed up to 240 degrees C for the GC measurements by flame ionization detection. These conditions give sharp peaks for each compound and the IS and low background noise for whole blood or urine samples. The detection limits of the analytes are 10 ng/mL for whole blood and 5 ng/mL for urine. Linearity and precision are also tested to confirm the reliability of this method. Isobutyl alcohol and methemoglobin could be determined from the whole blood samples of three male volunteers who had sniffed isobutyl nitrite.